Decision Support for Intraoperative Low Blood Pressure

• Sponsor: Vanderbilt University Medical Center (Other)
• Overall Status: Completed
• CT.gov ID: NCT02726620
• Collaborator: UMC Utrecht (Other)
• Enrollment: 22,435
• Location: 1
• Arms: 2
• Actual Duration (Months): 23.8
• Patients Per Site Per Month: 944.5

Study Details

Study Description

Brief Summary

The purpose of this study is to determine whether a decision support system can improve the adherence to thresholds for low blood pressure by anesthesia providers, which in turn prevents their patients from having organ injury.

Condition or Disease	Intervention/Treatment	Phase
Hypotension	Procedure: Attending real-time decision support; Procedure: In-room real-time decision support; Procedure: Attending feedback emails; Procedure: In-room provider feedback emails; Device: Anesthesia Information Management System (AIMS); Device: Perioperative Data Warehouse (PDW); Procedure: General anesthesia; Device: Pager system; Procedure: Central neuraxial anesthesia; Procedure: Non-cardiac surgery; Drug: Propofol; Drug: Sevoflurane; Drug: Desflurane; Drug: Isoflurane; Drug: Ephedrine; Drug: Phenylephrine; Drug: Norepinephrine; Drug: Epinephrine; Drug: Dobutamine; Drug: Dopamine; Drug: Isoproterenol; Drug: Milrinone; Drug: Atropine; Drug: Glycopyrrolate; Drug: Vasopressin; Drug: Terlipressin; Drug: Sodium Chloride 0.9%; Drug: Ringer's lactate; Drug: Hydroxyethyl starch solutions; Drug: Fresh Frozen Plasma; Drug: Packed Red Blood Cells; Drug: Albumin solutions; Drug: Plasma-Lyte; Drug: Lidocaine; Drug: Bupivacaine; Drug: Levobupivacaine; Drug: Ropivacaine; Drug: Mepivacaine; Drug: Tetracaine; Drug: Prilocaine; Drug: Procaine; Drug: Chloroprocaine; Drug: Benzocaine; Drug: Articaine	N/A

Detailed Description

Blood pressure management is an important part of anesthesia. Many factors contribute to a change in blood pressure during a surgical procedure, such as blood loss, manipulation by surgeons, and there are several mechanisms through which anesthesia itself changes blood pressure. Although a high blood pressure also occurs during anesthesia, most of these factors lower a patient's blood pressure. When a patient's blood pressure becomes too low, the internal organs become at risk of receiving not enough blood (low perfusion or hypoperfusion). This low perfusion state can result in organ damage (ischemia) because of an insufficient supply of oxygen and glucose. Hence the important task of anesthesia providers to maintain the blood pressure of patients, using a wide range of drugs and other interventions.

A big challenge in blood pressure management is to know when a low blood pressure indeed results in low perfusion of organs. There is a large variation between patients in how susceptible they are to low blood pressure, as well as a difference between the organs in how easily they are damaged because of low perfusion. Elder patients, or patients with preexisting hypertension, heart problems or other cardiovascular diseases are more prone to a low blood pressure and are more likely to develop organ ischemia when there is a low blood pressure. The kidneys, the heart and the brain are the organs that are most at risk of organ damage. As one cannot measure the perfusion states of individual organs in individual patients, it is very difficult to know 'how low to go' with a patient's blood pressure.

Recent studies have used large datasets of patients to demonstrate that there is statistical association between low blood pressure during surgery and various types of organ injury. As patients are already treated for low blood pressure by anesthesia providers, this suggests that patients have low organ perfusion states despite the current treatment standards. A patient's blood pressure is not simply a dial that can be adjusted to a specific level. Finding the right level of interventions can be difficult in some patients. Consequently, lower blood pressures are common in anesthesia, even with the current standards of blood pressure management.

In this proposed study the investigators will implement two forms of decision support to assist anesthesia providers in blood pressure management. The decision support aims to educate anesthesia providers about the risks of low blood pressures in direct relation to the patients that they treat. One form of decision support will provide automated notifications through pagers and through the anesthesia information management system. These automated notifications pop up when the patient's blood pressure drops below a level that is associated with a risk of organ injury, and thus alerts the anesthesia provider of the blood pressure and its associated risk. The second form of decision support will send a postoperative email the day after the procedure when the patient has had a low blood pressure for particular duration. This email then provides feedback to the anesthesia provider by informing them of the increased risks of organ injury that are associated with that low blood pressure.

The study will look at both a change in patient outcome and a change in blood pressure management and will be performed at the Vanderbilt University Medical Center (VUMC). The change in patient outcome will primarily be studied through the occurrence of acute kidney injury in the first days following the procedure at the VUMC. The change in blood pressure management (provider behavior) will be studied by observing the depth and duration of low pressures during anesthesia, and the number of interventions that have been used to treat the blood pressure. Patient outcome will be studied by comparison of a baseline phase - before the decision support is implemented and uses historic data- and the intervention phase - the period during which the intervention is active. Only routinely collected clinical data will be used for these analyses: no additional data collection is required.

As it is impossible to know which form of decision support will be the most effective, the first three months of the intervention period will be a 'nested cluster-randomized trial'. The anesthesia providers (not the patients) will be randomized to either the automated notifications or the feedback emails. After three months all anesthesia providers will receive both forms of decision support for the remainder of the intervention period. The reason why anesthesia providers are randomized only during the first three months is that cross-over or contamination between the two groups is expected. This contamination could make it impossible to study the effect of the decision support on patient outcome, as there will be no longer any difference between the study groups.

Study Design

• Study Type: Interventional
• Actual Enrollment: 22435 participants
• Allocation: Non-Randomized
• Intervention Model: Sequential Assignment
• Intervention Model Description: It is an interrupted time-series of a decision support package intervention that aims to study the the effect of the decision support package on patient outcome. The effects of the individual decision support components of the package on healthcare provider behavior will be studied in a nested cluster-randomized trial: in the first month the attending anesthesiologists will be randomized to near-realtime notifications or feedback emails; in the second month in-room providers will be randomized to near-realtime notifications or feedback emails. Starting month four all providers will receive both near-realtime notifications and feedback emails.It is an interrupted time-series of a decision support package intervention that aims to study the the effect of the decision support package on patient outcome. The effects of the individual decision support components of the package on healthcare provider behavior will be studied in a nested cluster-randomized trial: in the first month the attending anesthesiologists will be randomized to near-realtime notifications or feedback emails; in the second month in-room providers will be randomized to near-realtime notifications or feedback emails. Starting month four all providers will receive both near-realtime notifications and feedback emails.
• Masking: None (Open Label)
• Primary Purpose: Prevention
• Official Title: Decision Support for Intraoperative Low Blood Pressure
• Actual Study Start Date: Jan 5, 2017
• Actual Primary Completion Date: Dec 31, 2017
• Actual Study Completion Date: Dec 29, 2018

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Hypotension decision support The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.	Procedure: Attending real-time decision support; Near real-time decision support elements will notify the attending anesthesiologists of a blood pressure drop below the threshold for intraoperative hypotension (mean arterial pressure below 60 mmHg). The notification is presented through the pager system. The page will also display the associated increased risk of organ injury due to organ ischemia.; Procedure: In-room real-time decision support; Near real-time decision support elements will notify the in-room anesthesia provider of a blood pressure drop below the threshold for intraoperative hypotension (mean arterial pressure below 60 mmHg). The notification is presented through the anesthesia information management system. The decision support system will display the associated increased risk of organ injury due to organ ischemia.; Procedure: Attending feedback emails; Attending anesthesiologists will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension (mean arterial pressure below 60 mmHg or lower for a particular duration) that is associated with an increased risk of organ injury due to organ ischemia.; Procedure: In-room provider feedback emails; In-room anesthesia providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension (mean arterial pressure below 60 mmHg or lower for a particular duration) that is associated with an increased risk of organ injury due to organ ischemia.; Device: Anesthesia Information Management System (AIMS); The anesthesia electronic record keeping system; Device: Perioperative Data Warehouse (PDW); The data warehouse that is used to gather perioperative data and create user reports. In this instance the PDW will be used to send the postoperative feedback emails.; Procedure: General anesthesia; Any anesthetic drugs that are used to induce general anesthesia above the level of sedation.; Device: Pager system; The mobile pager system through which alerts can be sent; Procedure: Central neuraxial anesthesia; Regional anesthesia effectuated through the placement of local anesthetics around the nerves of the central nervous system, e.g. spinal anesthesia and epidural anesthesia.; Other Names: Regional anesthesia Spinal anesthesia Intrathecal anesthesia Subarachnoid anesthesia Epidural anesthesia Central neuraxial blockade ; Procedure: Non-cardiac surgery; Any surgical intervention that is not aimed at surgical correction of the heart; Drug: Propofol; Anesthetic drug used to maintain general anesthesia; Drug: Sevoflurane; Anesthetic drug used to maintain general anesthesia; Drug: Desflurane; Anesthetic drug used to maintain general anesthesia; Drug: Isoflurane; Anesthetic drug used to maintain general anesthesia; Drug: Ephedrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Phenylephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Norepinephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Epinephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Dobutamine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Dopamine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Isoproterenol; Cardiovascular drug used to treat intraoperative hypotension; Drug: Milrinone; Cardiovascular drug used to treat intraoperative hypotension; Drug: Atropine; Cardiovascular drugs used to treat intraoperative hypotension; Drug: Glycopyrrolate; Cardiovascular drug used to treat intraoperative hypotension; Drug: Vasopressin; Cardiovascular drug used to treat intraoperative hypotension; Drug: Terlipressin; Cardiovascular drug used to treat intraoperative hypotension; Drug: Sodium Chloride 0.9%; Intravenous fluid used to treat intraoperative hypotension; Drug: Ringer's lactate; Intravenous fluid used to treat intraoperative hypotension; Drug: Hydroxyethyl starch solutions; Intravenous fluid used to treat intraoperative hypotension; Drug: Fresh Frozen Plasma; Intravenous fluid used to treat intraoperative hypotension; Drug: Packed Red Blood Cells; Intravenous fluid used to treat intraoperative hypotension; Drug: Albumin solutions; Intravenous fluid used to treat intraoperative hypotension; Drug: Plasma-Lyte; Intravenous fluid used to treat intraoperative hypotension; Drug: Lidocaine; Local anesthetic used for central neuraxial anesthesia.; Other Names: Lignocaine ; Drug: Bupivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Levobupivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Ropivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Mepivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Tetracaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Prilocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Procaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Chloroprocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Benzocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Articaine; Local anesthetic used for central neuraxial anesthesia.
Active Comparator: Usual care group The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	Procedure: General anesthesia; Any anesthetic drugs that are used to induce general anesthesia above the level of sedation.; Procedure: Central neuraxial anesthesia; Regional anesthesia effectuated through the placement of local anesthetics around the nerves of the central nervous system, e.g. spinal anesthesia and epidural anesthesia.; Other Names: Regional anesthesia Spinal anesthesia Intrathecal anesthesia Subarachnoid anesthesia Epidural anesthesia Central neuraxial blockade ; Procedure: Non-cardiac surgery; Any surgical intervention that is not aimed at surgical correction of the heart; Drug: Propofol; Anesthetic drug used to maintain general anesthesia; Drug: Sevoflurane; Anesthetic drug used to maintain general anesthesia; Drug: Desflurane; Anesthetic drug used to maintain general anesthesia; Drug: Isoflurane; Anesthetic drug used to maintain general anesthesia; Drug: Ephedrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Phenylephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Norepinephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Epinephrine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Dobutamine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Dopamine; Cardiovascular drug used to treat intraoperative hypotension; Drug: Isoproterenol; Cardiovascular drug used to treat intraoperative hypotension; Drug: Milrinone; Cardiovascular drug used to treat intraoperative hypotension; Drug: Atropine; Cardiovascular drugs used to treat intraoperative hypotension; Drug: Glycopyrrolate; Cardiovascular drug used to treat intraoperative hypotension; Drug: Vasopressin; Cardiovascular drug used to treat intraoperative hypotension; Drug: Terlipressin; Cardiovascular drug used to treat intraoperative hypotension; Drug: Sodium Chloride 0.9%; Intravenous fluid used to treat intraoperative hypotension; Drug: Ringer's lactate; Intravenous fluid used to treat intraoperative hypotension; Drug: Hydroxyethyl starch solutions; Intravenous fluid used to treat intraoperative hypotension; Drug: Fresh Frozen Plasma; Intravenous fluid used to treat intraoperative hypotension; Drug: Packed Red Blood Cells; Intravenous fluid used to treat intraoperative hypotension; Drug: Albumin solutions; Intravenous fluid used to treat intraoperative hypotension; Drug: Plasma-Lyte; Intravenous fluid used to treat intraoperative hypotension; Drug: Lidocaine; Local anesthetic used for central neuraxial anesthesia.; Other Names: Lignocaine ; Drug: Bupivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Levobupivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Ropivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Mepivacaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Tetracaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Prilocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Procaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Chloroprocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Benzocaine; Local anesthetic used for central neuraxial anesthesia.; Drug: Articaine; Local anesthetic used for central neuraxial anesthesia.

Outcome Measures

Primary Outcome Measures

1. Postoperative Acute Kidney Injury [Within 7 days after surgery]

   Postoperative Acute Kidney Injury (AKI), Stage I or higher according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). The staging will be based on serum creatinine values, as documentation of urine output is probably not sufficiently accurate. This will be the primary outcome for the Vanderbilt University Medical Center. The creatinine measurements are part of routine clinical care. Therefore, absence of creatinine postoperative measurements are considered to be 'no suspicion of kidney injury'. KDIGO defines AKI as any of the following: Increase in serum creatinine by 0.3mg/dL or more within 48 hours or Increase in serum creatinine to 1.5 times baseline or more within the last 7 days or Urine output less than 0.5 mL/kg/h for 6 hours. Stage 1 is 1.5-9x baseline or >0.3 increase; Stage 2 is 2-2.9x baseline; Stage 3 is 3x baseline, or increase to > 4, or initiation of renal replacement therapy.

Secondary Outcome Measures

1. 30-day Mortality [30 days after surgery]

   Vanderbilt University Medical Center: combination of in-hospital mortality and 'alive-index' (which checks for visits to the hospital in the electronic healthcare record as indication of being alive at 30 days)

2. In-hospital Mortality [All postoperative days during a single hospital admission, expected median of 5 days]

   Hospital mortality rate during a single hospital admission after the surgery

3. Postoperative Acute Kidney Injury Stage 2 [Within 7 days after surgery]

   Postoperative Acute Kidney Injury (AKI), Stage II or higher according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). The staging will be based on serum creatinine values, as documentation of urine output is probably not sufficiently accurate. The creatinine measurements are part of routine clinical care. Therefore, absence of creatinine postoperative measurements are considered to be 'no suspicion of kidney injury'. KDIGO defines AKI as any of the following: Increase in serum creatinine by 0.3mg/dL or more within 48 hours or Increase in serum creatinine to 1.5 times baseline or more within the last 7 days or Urine output less than 0.5 mL/kg/h for 6 hours. Stage 1 is 1.5-9x baseline or >0.3 increase; Stage 2 is 2-2.9x baseline; Stage 3 is 3x baseline, or increase to > 4, or initiation of renal replacement therapy.

4. Postoperative Rise in Creatinine Levels [Within 7 days after surgery]

   Absolute values for serum creatinine before and after surgery will be compared. When multiple postoperative creatinine measurements are made, the maximum difference is reported.

5. Incidence of a MAP < 60 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

   Incidence of a mean arterial pressure (MAP) < 60 mmHg during anesthesia for 1 minute or more.

6. Incidence of a MAP < 55 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

   Incidence of a mean arterial pressure (MAP) < 55 mmHg during anesthesia for 1 minute or more.

7. Incidence of a MAP < 50 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

   Incidence of a mean arterial pressure (MAP) < 50 mmHg during anesthesia for 1 minute or more.

8. Incidence of a MAP < 60 mmHg for > 10 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

   Incidence of a mean arterial pressure (MAP) < 60 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.

9. Incidence of a MAP < 55 mmHg for > 10 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

   Incidence of a mean arterial pressure (MAP) < 55 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.

10. Incidence of a MAP < 50 mmHg for > 10 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Incidence of a mean arterial pressure (MAP) < 50 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.

11. Incidence of a MAP < 60 mmHg for > 20 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Incidence of a mean arterial pressure (MAP) < 60 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.

12. Incidence of a MAP < 55 mmHg for > 20 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Incidence of a mean arterial pressure (MAP) < 55 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.

13. Incidence of a MAP < 50 mmHg for > 20 Minutes [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Incidence of a mean arterial pressure (MAP) < 50 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.

14. Depth and Duration of Intraoperative Hypotension - Threshold MAP 75 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

15. Depth and Duration of Intraoperative Hypotension - Threshold MAP 70 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

16. Depth and Duration of Intraoperative Hypotension - Threshold MAP 65 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

17. Depth and Duration of Intraoperative Hypotension - Threshold MAP 60 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

18. Depth and Duration of Intraoperative Hypotension - Threshold MAP 55 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

19. Depth and Duration of Intraoperative Hypotension - Threshold MAP 50 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.

20. Estimated Intraoperative Blood Loss [During the surgical procedure: an expected average of 2 hours]

    The estimated blood loss in mL during the surgical procedure

21. Time to Discharge Readiness at the Postanesthesia Care Unit (PACU) [A specific time frame on the day of surgery: from the start of admission to the PACU to discharge from the PACU, an expected average of 4 hours]

    The time from arriving at the postanesthesia care unit (PACU) until the time the patient is considered ready for discharge (in minutes).

22. Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 65 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of propofol infusion rates during MAP < 65 mmHg episodes

23. Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 60 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of propofol infusion rates during MAP < 60 mmHg episodes

24. Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 55 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of propofol infusion rates during MAP < 55 mmHg episodes

25. Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 50 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of propofol infusion rates during MAP < 50 mmHg episodes

26. Average Use of Cardiovascular Drugs: Ephedrine [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosages would be meaningless.

27. Average Use of Cardiovascular Drugs: Phenylephrine [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.

28. Average Use of Cardiovascular Drugs: Glycopyrrolate [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.

29. Average Use of Cardiovascular Drugs: Epinephrine [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.

30. Average Use of Cardiovascular Drugs: Norepinephrine [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.

31. Timing of Cardiovascular Drugs for MAP < 65 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 60 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.

32. Timing of Cardiovascular Drugs for MAP < 60 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 60 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.

33. Timing of Cardiovascular Drugs for MAP < 55 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 55 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.

34. Timing of Cardiovascular Drugs for MAP < 50 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 50 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.

35. Intraoperative Administration of Intravenous Fluids [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Total amount (mL) of intravenous fluids (as defined under interventions) administered during the surgical procedure.

36. Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 65 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of inhalational anesthesia during MAP < 65 mmHg episodes

37. Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 60 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of inhalational anesthesia during MAP < 60 mmHg episodes

38. Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 55 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of inhalational anesthesia during MAP < 55 mmHg episodes

39. Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 50 mmHg [During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours]

    Average concentrations of inhalational anesthesia during MAP < 50 mmHg episodes

Eligibility Criteria

Criteria

• Ages Eligible for Study: 60 Years to 100 Years
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: No

Inclusion Criteria:

• 60 years and older

• Inpatients

• Scheduled for a non-cardiac surgical procedure under general or central neuraxial anesthesia

Exclusion Criteria:

• Pre-existing end-stage renal disease: operationalized as a preoperative need for dialysis

• The following surgical procedures: renal surgery, cardiac surgery, organ transplantation, ophthalmic surgery, endoscopic gastrointestinal procedures, and (interventional) radiologic procedures.

• small non-invasive or minimally-invasive procedures will also be excluded, operationalized as excluding procedures with a surgical time of less than twenty minutes.

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Vanderbilt University Medical Center	Nashville	Tennessee	United States	37212

Sponsors and Collaborators

• Vanderbilt University Medical Center
• UMC Utrecht

Investigators

• Principal Investigator: Jonathan P Wanderer, MD, MPhil, Vanderbilt University Medical Center, Department of Anesthesiology

Study Documents (Full-Text)

• Study Protocol and Statistical Analysis Plan - Dec 4, 2018

More Information

Publications

None provided.

• Responsible Party: Jonathan Wanderer, Medical Director of Procedure Preparation Center, Vanderbilt University Medical Center
• ClinicalTrials.gov Identifier: NCT02726620
• Other Study ID Numbers: 160131
• First Posted: Apr 4, 2016
• Last Update Posted: May 16, 2019
• Last Verified: Apr 1, 2019

• Individual Participant Data (IPD) Sharing Statement: No
• Plan to Share IPD: No
• Keywords provided by Jonathan Wanderer, Medical Director of Procedure Preparation Center, Vanderbilt University Medical Center: Decision support; Decision Support Systems, Clinical; Decision Support Techniques; Hypotension; Intraoperative Hypotension; Acute Kidney Injury; Postoperative Mortality; Blood Pressure
• Additional relevant MeSH terms: Hypotension; Lidocaine; Atropine; Terlipressin; Phenylephrine; Dobutamine; Dopamine; Milrinone; Isoproterenol; Vasopressins; Arginine Vasopressin; Epinephrine; Norepinephrine; Ephedrine; Glycopyrrolate; Bupivacaine; Ropivacaine; Levobupivacaine; Tetracaine; Prilocaine; Mepivacaine; Benzocaine; Chloroprocaine; Procaine; Anesthetics; Propofol; Sevoflurane; Desflurane; Isoflurane; Pharmaceutical Solutions; Plasma-lyte 148

Study Results

Participant Flow

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Period Title: Historic Cohort - Three Years
STARTED	17463	0
MAP < 65 mmHg: Primary Analysis	15624	0
COMPLETED	17463	0
NOT COMPLETED	0	0
Period Title: Historic Cohort - Three Years
STARTED	0	485
MAP < 65 mmHg: Primary Analysis	0	432
Correct IOH Notifications	0	313
COMPLETED	0	485
NOT COMPLETED	0	0
Period Title: Historic Cohort - Three Years
STARTED	0	1253
MAP < 65 mmHg: Primary Analysis	0	1103
Correct IOH Notifications	0	825
COMPLETED	0	1253
NOT COMPLETED	0	0
Period Title: Historic Cohort - Three Years
STARTED	0	3234
MAP < 65 mmHg: Primary Analysis	0	2793
Correct IOH Notifications	0	2072
COMPLETED	0	3234
NOT COMPLETED	0	0

Baseline Characteristics

Arm/Group Title	Usual Care Group	Hypotension Decision Support	Total
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.	Total of all reporting groups
Overall Participants	17463	4972	22435
Age (years) [Median (Inter-Quartile Range) ]
Median (Inter-Quartile Range) [years]	68	68	68
Sex: Female, Male (Count of Participants)
Female	7731 44.3%	2141 43.1%	9872 44%
Male	9707 55.6%	2822 56.8%	12529 55.8%
Race (NIH/OMB) (Count of Participants)
American Indian or Alaska Native	18 0.1%	4 0.1%	22 0.1%
Asian	113 0.6%	36 0.7%	149 0.7%
Native Hawaiian or Other Pacific Islander	0 0%	0 0%	0 0%
Black or African American	1111 6.4%	380 7.6%	1491 6.6%
White	15571 89.2%	4348 87.4%	19919 88.8%
More than one race	0 0%	0 0%	0 0%
Unknown or Not Reported	650 3.7%	204 4.1%	854 3.8%
Region of Enrollment (participants) [Number]
United States	17463 100%	4972 100%	22435 100%
Body Mass Index (kg/m^2) [Median (Inter-Quartile Range) ]
Median (Inter-Quartile Range) [kg/m^2]	28	28	28
ASA Class (Count of Participants)
ASA Class 1	74 0.4%	16 0.3%	90 0.4%
ASA Class 2	3109 17.8%	765 15.4%	3874 17.3%
ASA Class 3	12344 70.7%	3578 72%	15922 71%
ASA Class 4	1885 10.8%	585 11.8%	2470 11%
ASA Class 5	51 0.3%	28 0.6%	79 0.4%
Hypertension (Count of Participants)
Count of Participants [Participants]	11403 65.3%	3348 67.3%	14751 65.7%
Cardiac disease (Count of Participants)
Count of Participants [Participants]	4843 27.7%	1489 29.9%	6332 28.2%
Renal Disease (Count of Participants)
Count of Participants [Participants]	1432 8.2%	511 10.3%	1943 8.7%
Peripheral vascular disease (Count of Participants)
Count of Participants [Participants]	1947 11.1%	596 12%	2543 11.3%
Diabetes Mellitus (Count of Participants)
Count of Participants [Participants]	4456 25.5%	1296 26.1%	5752 25.6%
Type of anesthesia (Count of Participants)
General anesthesia	17051 97.6%	4750 95.5%	21801 97.2%
Central neuraxial anesthesia	412 2.4%	222 4.5%	634 2.8%
Procedure urgency (Count of Participants)
Elective surgery	16452 94.2%	4631 93.1%	21083 94%
Emergency surgery	1011 5.8%	341 6.9%	1352 6%
Procedure duration (minutes) [Median (Inter-Quartile Range) ]
Median (Inter-Quartile Range) [minutes]	201	196	200
Surgical service (Count of Participants)
ENT	1891 10.8%	528 10.6%	2419 10.8%
Gynecology	113 0.6%	30 0.6%	143 0.6%
General surgery	3638 20.8%	1001 20.1%	4639 20.7%
Neurosurgery	2138 12.2%	622 12.5%	2760 12.3%
Orthopedic surgery	4283 24.5%	1222 24.6%	5505 24.5%
Plastic surgery	776 4.4%	195 3.9%	971 4.3%
Thoracic surgery	1056 6%	310 6.2%	1366 6.1%
Urology	2648 15.2%	778 15.6%	3426 15.3%
Vascular surgery	920 5.3%	286 5.8%	1206 5.4%
AKI risk based on IOH depth and duration (Count of Participants)
AKI risk: none	3684 21.1%	1174 23.6%	4858 21.7%
AKI risk: mild	6622 37.9%	1985 39.9%	8607 38.4%
AKI risk: moderate	4290 24.6%	1136 22.8%	5426 24.2%
AKI risk: high	2867 16.4%	677 13.6%	3544 15.8%

Outcome Measures

1. Primary Outcome

Title	Postoperative Acute Kidney Injury
Description	Postoperative Acute Kidney Injury (AKI), Stage I or higher according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). The staging will be based on serum creatinine values, as documentation of urine output is probably not sufficiently accurate. This will be the primary outcome for the Vanderbilt University Medical Center. The creatinine measurements are part of routine clinical care. Therefore, absence of creatinine postoperative measurements are considered to be 'no suspicion of kidney injury'. KDIGO defines AKI as any of the following: Increase in serum creatinine by 0.3mg/dL or more within 48 hours or Increase in serum creatinine to 1.5 times baseline or more within the last 7 days or Urine output less than 0.5 mL/kg/h for 6 hours. Stage 1 is 1.5-9x baseline or >0.3 increase; Stage 2 is 2-2.9x baseline; Stage 3 is 3x baseline, or increase to > 4, or initiation of renal replacement therapy.
Time Frame	Within 7 days after surgery

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
AKI stage I or greater	1333 7.6%	372 7.5%
No AKI - Confirmed by measurement	9670 55.4%	2785 56%
No postoperative creatinine measurement	4621 26.5%	1171 23.6%

2. Secondary Outcome

Title	30-day Mortality
Description	Vanderbilt University Medical Center: combination of in-hospital mortality and 'alive-index' (which checks for visits to the hospital in the electronic healthcare record as indication of being alive at 30 days)
Time Frame	30 days after surgery

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). For a large group of patients no mortality information was available.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	4667	1285
Count of Participants [Participants]	511 2.9%	143 2.9%

3. Secondary Outcome

Title	In-hospital Mortality
Description	Hospital mortality rate during a single hospital admission after the surgery
Time Frame	All postoperative days during a single hospital admission, expected median of 5 days

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	487 2.8%	137 2.8%

4. Secondary Outcome

Title	Postoperative Acute Kidney Injury Stage 2
Description	Postoperative Acute Kidney Injury (AKI), Stage II or higher according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). The staging will be based on serum creatinine values, as documentation of urine output is probably not sufficiently accurate. The creatinine measurements are part of routine clinical care. Therefore, absence of creatinine postoperative measurements are considered to be 'no suspicion of kidney injury'. KDIGO defines AKI as any of the following: Increase in serum creatinine by 0.3mg/dL or more within 48 hours or Increase in serum creatinine to 1.5 times baseline or more within the last 7 days or Urine output less than 0.5 mL/kg/h for 6 hours. Stage 1 is 1.5-9x baseline or >0.3 increase; Stage 2 is 2-2.9x baseline; Stage 3 is 3x baseline, or increase to > 4, or initiation of renal replacement therapy.
Time Frame	Within 7 days after surgery

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
AKI stage II or greater	1 0%	0 0%
No stage II or greater - Confirmed by measurement	11002 63%	3157 63.5%
No postoperative creatinine measurement	4621 26.5%	1171 23.6%

5. Secondary Outcome

Title	Postoperative Rise in Creatinine Levels
Description	Absolute values for serum creatinine before and after surgery will be compared. When multiple postoperative creatinine measurements are made, the maximum difference is reported.
Time Frame	Within 7 days after surgery

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). Patients with no routine postoperative creatinine measurements are excluded from the analysis.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	11003	3157
Median (Inter-Quartile Range) [mg/dL]	0.00	0.00

6. Secondary Outcome

Title	Incidence of a MAP < 60 mmHg
Description	Incidence of a mean arterial pressure (MAP) < 60 mmHg during anesthesia for 1 minute or more.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	13779 78.9%	3798 76.4%

7. Secondary Outcome

Title	Incidence of a MAP < 55 mmHg
Description	Incidence of a mean arterial pressure (MAP) < 55 mmHg during anesthesia for 1 minute or more.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	10991 62.9%	3045 61.2%

8. Secondary Outcome

Title	Incidence of a MAP < 50 mmHg
Description	Incidence of a mean arterial pressure (MAP) < 50 mmHg during anesthesia for 1 minute or more.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	7781 44.6%	2196 44.2%

9. Secondary Outcome

Title	Incidence of a MAP < 60 mmHg for > 10 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 60 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	6989 40%	1723 34.7%

10. Secondary Outcome

Title	Incidence of a MAP < 55 mmHg for > 10 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 55 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	3181 18.2%	759 15.3%

11. Secondary Outcome

Title	Incidence of a MAP < 50 mmHg for > 10 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 50 mmHg for a cumulative duration of all hypotensive episodes of more than 10 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	1159 6.6%	326 6.6%

12. Secondary Outcome

Title	Incidence of a MAP < 60 mmHg for > 20 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 60 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	3632 20.8%	792 15.9%

13. Secondary Outcome

Title	Incidence of a MAP < 55 mmHg for > 20 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 55 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	1223 7%	284 5.7%

14. Secondary Outcome

Title	Incidence of a MAP < 50 mmHg for > 20 Minutes
Description	Incidence of a mean arterial pressure (MAP) < 50 mmHg for a cumulative duration of all hypotensive episodes of more than 20 minutes during the anesthetic phase of the procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	304 1.7%	85 1.7%

15. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 75 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	485	417

16. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 70 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	273	235

17. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 65 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	96	86

18. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 60 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	57	52

19. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 55 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	23	23

20. Secondary Outcome

Title	Depth and Duration of Intraoperative Hypotension - Threshold MAP 50 mmHg
Description	Depth and duration of intraoperative hypotension will be modeled by calculating areas under the threshold for mean arterial pressures (MAPs). Thresholds will vary from 75 mmHg to 50 mmHg in 5 mmHg decrements. Together these variables represent the depth and duration of intraoperative hypotension. To optimize goodness of fit of these variables, the decremental steps may be increased to 10 mmHg and more restrictive lowest and highest thresholds may be chosen for the statistical analysis.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mmHg*minute]	19	19

21. Secondary Outcome

Title	Estimated Intraoperative Blood Loss
Description	The estimated blood loss in mL during the surgical procedure
Time Frame	During the surgical procedure: an expected average of 2 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mL]	100	75

22. Secondary Outcome

Title	Time to Discharge Readiness at the Postanesthesia Care Unit (PACU)
Description	The time from arriving at the postanesthesia care unit (PACU) until the time the patient is considered ready for discharge (in minutes).
Time Frame	A specific time frame on the day of surgery: from the start of admission to the PACU to discharge from the PACU, an expected average of 4 hours

Outcome Measure Data

Analysis Population Description

Only patients with a postoperative stay at the postanesthesia care unit (PACU). Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	13082	3580
Median (Inter-Quartile Range) [minutes]	67	60

23. Secondary Outcome

Title	Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 65 mmHg
Description	Average concentrations of propofol infusion rates during MAP < 65 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 65 mmHg and a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	14333	3926
Median (Inter-Quartile Range) [mcg/kg/min (propofol)]	60.10	48.59

24. Secondary Outcome

Title	Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 60 mmHg
Description	Average concentrations of propofol infusion rates during MAP < 60 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 60 mmHg and either a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	11621	3145
Median (Inter-Quartile Range) [mcg/kg/min (propofol)]	61.07	50.00

25. Secondary Outcome

Title	Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 55 mmHg
Description	Average concentrations of propofol infusion rates during MAP < 55 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 55 mmHg and either a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	8254	2196
Median (Inter-Quartile Range) [mcg/kg/min (propofol)]	63.95	50.00

26. Secondary Outcome

Title	Intravenous Anesthetic Drug Use During Intraoperative Hypotension: MAP < 50 mmHg
Description	Average concentrations of propofol infusion rates during MAP < 50 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 50 mmHg and a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	5135	1413
Median (Inter-Quartile Range) [mcg/kg/min (propofol)]	65.00	50.00

27. Secondary Outcome

Title	Average Use of Cardiovascular Drugs: Ephedrine
Description	Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosages would be meaningless.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). In addition, only patients that actually received any ephedrine are analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	9310	2718
Median (Inter-Quartile Range) [mg]	20	15

28. Secondary Outcome

Title	Average Use of Cardiovascular Drugs: Phenylephrine
Description	Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). In addition, only patients that actually received any phenylephrine are analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	12211	3685
Median (Inter-Quartile Range) [mg]	0.90	1.30

29. Secondary Outcome

Title	Average Use of Cardiovascular Drugs: Glycopyrrolate
Description	Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). In addition, only patients that actually received any glycopyrrolate are analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	11093	1257
Median (Inter-Quartile Range) [mg]	0.40	0.40

30. Secondary Outcome

Title	Average Use of Cardiovascular Drugs: Epinephrine
Description	Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). In addition, only patients that actually received any epinephrine are analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	1215	409
Median (Inter-Quartile Range) [mg]	1.00	0.70

31. Secondary Outcome

Title	Average Use of Cardiovascular Drugs: Norepinephrine
Description	Cardiovascular drugs as defined under interventions. Average use for each drug will be calculated. Cardiovascular drugs that were given in <1% of cases are not reported, as the average dosage would be meaningless.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section). In addition, only patients that actually received any norepinephrine are analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	762	233
Median (Inter-Quartile Range) [mg]	0.62	0.70

32. Secondary Outcome

Title	Timing of Cardiovascular Drugs for MAP < 65 mmHg
Description	Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 60 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 65 mmHg and an administration event of a cardiovascular drugs within 5 minutes before the start of the hypotensive episode (the first value below 65 mmHg) and 15 minutes after the start of the episode.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	13932	3975
Median (Inter-Quartile Range) [minutes]	2	1.14

33. Secondary Outcome

Title	Timing of Cardiovascular Drugs for MAP < 60 mmHg
Description	Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 60 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 60 mmHg and an administration event of a cardiovascular drugs within 5 minutes before the start of the hypotensive episode (the first value below 60 mmHg) and 15 minutes after the start of the episode.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	12292	3458
Median (Inter-Quartile Range) [minutes]	0.8	1.5

34. Secondary Outcome

Title	Timing of Cardiovascular Drugs for MAP < 55 mmHg
Description	Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 55 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 55 mmHg and an administration event of a cardiovascular drugs within 5 minutes before the start of the hypotensive episode (the first value below 55 mmHg) and 15 minutes after the start of the episode.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	9706	2752
Median (Inter-Quartile Range) [minutes]	1	0.5

35. Secondary Outcome

Title	Timing of Cardiovascular Drugs for MAP < 50 mmHg
Description	Cardiovascular drugs as defined under interventions. Time of first administration of cardiovascular drug relative to the time at which the mean arterial pressure (MAP) drops below 50 mmHg. Per patient the average time to first administration of all hypotensive episodes was calculated. That average time is used as the outcome variable. A negative value indicates that administration occurred before the drop in MAP.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 50 mmHg and an administration event of a cardiovascular drugs within 5 minutes before the start of the hypotensive episode (the first value below 50 mmHg) and 15 minutes after the start of the episode.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	6789	1989
Median (Inter-Quartile Range) [minutes]	1	0

36. Secondary Outcome

Title	Intraoperative Administration of Intravenous Fluids
Description	Total amount (mL) of intravenous fluids (as defined under interventions) administered during the surgical procedure.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Median (Inter-Quartile Range) [mL]	1500.00	1400.00

37. Post-Hoc Outcome

Title	Postoperative Acute Kidney Injury
Description	Postoperative Acute Kidney Injury (AKI), Stage I or higher according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). The staging will be based on serum creatinine values, as documentation of urine output is probably not sufficiently accurate. This will be the primary outcome for the Vanderbilt University Medical Center. The creatinine measurements are part of routine clinical care. Therefore, absence of creatinine postoperative measurements are considered to be 'no suspicion of kidney injury'. KDIGO defines AKI as any of the following: Increase in serum creatinine by 0.3mg/dL or more within 48 hours or Increase in serum creatinine to 1.5 times baseline or more within the last 7 days or Urine output less than 0.5 mL/kg/h for 6 hours. Stage 1 is 1.5-9x baseline or >0.3 increase; Stage 2 is 2-2.9x baseline; Stage 3 is 3x baseline, or increase to > 4, or initiation of renal replacement therapy.
Time Frame	Within 7 days after surgery

Outcome Measure Data

Analysis Population Description

Post-Hoc analysis: all patients, not only those with any MAP < 65 mmHg.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	17463	4972
AKI stage I or greater	1477 8.5%	435 8.7%
No AKI - Confirmed by measurement	10690 61.2%	3166 63.7%
No postoperative creatinine measurement	5296 30.3%	1371 27.6%

38. Post-Hoc Outcome

Title	Usage Frequency of Cardiovascular Drugs: Ephedrine
Description	Cardiovascular drugs as defined under interventions. Frequency of patients receiving the drug. Cardiovascular drugs that were given in <1% of cases are not reported.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	9310 53.3%	2718 54.7%

39. Post-Hoc Outcome

Title	Usage Frequency of Cardiovascular Drugs: Phenylephrine
Description	Cardiovascular drugs as defined under interventions. Frequency of patients receiving the drug. Cardiovascular drugs that were given in <1% of cases are not reported.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	12211 69.9%	3685 74.1%

40. Post-Hoc Outcome

Title	Usage Frequency of Cardiovascular Drugs: Glycopyrrolate
Description	Cardiovascular drugs as defined under interventions. Frequency of patients receiving the drug. Cardiovascular drugs that were given in <1% of cases are not reported.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	11093 63.5%	1257 25.3%

41. Post-Hoc Outcome

Title	Usage Frequency of Cardiovascular Drugs: Ephinephrine
Description	Cardiovascular drugs as defined under interventions. Frequency of patients receiving the drug. Cardiovascular drugs that were given in <1% of cases are not reported.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	1215 7%	409 8.2%

42. Post-Hoc Outcome

Title	Usage Frequency of Cardiovascular Drugs: Norepinephrine
Description	Cardiovascular drugs as defined under interventions. Frequency of patients receiving the drug. Cardiovascular drugs that were given in <1% of cases are not reported.
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

Per study protocol only patients with any MAP < 65 mmHg will be included in the primary analysis (See also 'Participant Flow' section).

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	15624	4328
Count of Participants [Participants]	762 4.4%	233 4.7%

43. Secondary Outcome

Title	Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 65 mmHg
Description	Average concentrations of inhalational anesthesia during MAP < 65 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 65 mmHg and a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	14333	3926
Sevoflurane (EndTidal %)	1.35	1.27
Isoflurane (EndTidal %)	0.68	0.68
Desflurane (EndTidal %)	4.10	2.31

44. Secondary Outcome

Title	Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 60 mmHg
Description	Average concentrations of inhalational anesthesia during MAP < 60 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 60 mmHg and either a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	11621	3145
Sevoflurane (EndTidal %)	1.35	1.25
Isoflurane (EndTidal %)	0.68	0.67
Desflurane (EndTidal %)	4.36	2.33

45. Secondary Outcome

Title	Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 55 mmHg
Description	Average concentrations of inhalational anesthesia during MAP < 55 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 55 mmHg and either a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	8254	2196
Sevoflurane (EndTidal %)	1.34	1.25
Isoflurane (EndTidal %)	0.68	0.67
Desflurane (EndTidal %)	4.60	4.65

46. Secondary Outcome

Title	Inhaled Anesthetic Drug Use During Intraoperative Hypotension: MAP < 50 mmHg
Description	Average concentrations of inhalational anesthesia during MAP < 50 mmHg episodes
Time Frame	During the anesthetic phase of the surgical procedure: an expected average of 2.5 hours

Outcome Measure Data

Analysis Population Description

All patients with any MAP < 50 mmHg and a continuous administration of one of the following anesthetics: propofol, sevoflurane, isoflurane, desflurane. On occasion, the anesthesiologist may switch between anesthetic drugs. The numbers analyzed in one or more rows thus does not match the overall number analyzed.

Arm/Group Title	Usual Care Group	Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).	The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
Measure Participants	5135	1413
Sevoflurane (EndTidal %)	1.32	1.23
Isoflurane (EndTidal %)	0.65	0.65
Desflurane (EndTidal %)	4.28	4.70

Adverse Events

Time Frame	We analyzed adverse events in this patient population during their intraoperative course (adverse events sourced from our adverse event reporting system; from entry into OR to exit from OR), and during their hospitalization (source for mortality data; from hospital admission to hospital discharge).
Adverse Event Reporting Description	We utilized our perioperative information management system to determine the number of adverse events that occurred associated with the patients' intraoperative course. We used our hospital registration system to determine all cause mortality for this patient population.
Arm/Group Title	Usual Care Group		Hypotension Decision Support
Arm/Group Description	The 'before' period - or historic control group - during which no decision support for intraoperative hypotension was being used, also known as 'usual care'. This is the three year period prior to the intervention period (the 'Intraoperative hypotension decision support' arm).		The intervention period. Several decision support elements are implemented to notify anesthesia providers: attending anesthesiologists and in-room anesthesia providers of intraoperative hypotension (threshold of a mean arterial pressure below 60 mmHg). Two types of decision support will be implemented: near real-time decision support and feedback emails. Near real-time decision support elements will notify the anesthesia providers of a blood pressure drop below the threshold and display the associated increased risk of acute kidney injury. The notification is presented through the pager system for attending anesthesiologists and through the anesthesia information management system for the in-room anesthesia provider. All providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension that is associated with an increased risk of organ injury due to organ ischemia.
All Cause Mortality
	Usual Care Group		Hypotension Decision Support
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	534/17463 (3.1%)		158/4972 (3.2%)
Serious Adverse Events
	Usual Care Group		Hypotension Decision Support
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	1811/17463 (10.4%)		541/4972 (10.9%)
Investigations
Mortality	534/17463 (3.1%)		158/4972 (3.2%)
Renal and urinary disorders
Acute Kidney Injury Stage I or greater	1477/17463 (8.5%)		435/4972 (8.7%)
Other (Not Including Serious) Adverse Events
	Usual Care Group		Hypotension Decision Support
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/17463 (0%)		0/4972 (0%)

Limitations/Caveats

Due to development issues the UMC Utrecht could not participate: myocardial injury was dropped as primary outcome, as well as some secondary outcomes. Technical issues at the VUMC resulted in absent IOH notifications (see 'Participant Flow').

More Information

Certain Agreements

All Principal Investigators ARE employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.