BsR: Reduction of Intraoperative EEG Burst Suppression

Sponsor

Technische Universität München (Other)

Overall Status

Completed

CT.gov ID

NCT03775356

Collaborator

(none)

106

Enrollment

Location

Arms

23.4

Actual Duration (Months)

4.5

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Burst suppression (BS) is a not physiological pattern in the electroencephalogram (EEG). BS during general anesthesia is mainly seen as a sign for too deep hypnosis and may increase the risk of postoperative delirium (POD), a disturbance of consciousness arising within 24 hours after surgery. This monocentric, simple masked randomized study aims primarily to investigate, whether particular anesthesiological interventions reduce the occurrence of intraoperative burst suppression. The investigator initiated trial includes 66 patients (male and female) aged ≥ 60 years in two groups (intervention and control group). Secondary aims will be the correlation of burst suppression and mean arterial pressure, concentration of anesthetics and postoperative delirium.

Condition or Disease	Intervention/Treatment	Phase
Burst Suppression EEG With Abnormally Slow Frequencies Postoperative Delirium	Other: Treatment of hypotension and/or reduction of anesthetics	N/A

Detailed Description

Intraoperative burst suppression represents a non physiological EEG pattern. According to the literature and scientific knowledge, intraoperative burst suppression patterns might be caused either by hypotension resulting in a reduced cerebral circulation or by an oversedation of anesthetics correlating with a very deep level of hypnosis.

Some publications exist that discuss the occurrence of intraoperative burst suppression especially in elderly people (aged ≥ 60 years) as a predictor of postoperative delirium and postoperative cognitive dysfunction.

None of the studies however was able to prove a causal relationship between burst suppression and postoperative delirium. Contrary it might simply be an epiphenomenon.

Conducting this interventional trail primarily aims to prove whether specific anesthesiological interventions, such as the treatment of intraoperative hypotension in first line and/or the reduction of the concentration of anesthetics in second line, reduce intraoperative burst suppression. Hence it might be possible to investigate a possible casualty between burst suppression and postoperative delirium in a second trial.

Study Design

Study Type:

Interventional

Actual Enrollment :

106 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Masking:

Double (Care Provider, Investigator)

Masking Description:

Single masked. The entropy and EEG module will be masked for the responsible anesthetist as well as the study team during the entire investigation.

Primary Purpose:

Prevention

Official Title:

Reduction of Intraoperative EEG Burst Suppression - Test of Efficacy

Actual Study Start Date :

Jan 8, 2019

Actual Primary Completion Date :

Dec 19, 2020

Actual Study Completion Date :

Dec 19, 2020

Arms and Interventions

Arm	Intervention/Treatment
No Intervention: 1 - Blinded EEG and Entropy will be blinded. The anesthesiological management will be performed by the anesthetist according to clinical standard operations.
Active Comparator: 2 - Unblinded EEG and Entropy will be unblinded. The intervention starts with the start of a positive burst suppression rate. In the case of a concurrent hypotension the anesthetist treats the hypotension according to clinical standard operations in the first step. Hypotension means blood pressure values blow the baseline value which is defined by the lowest, preoperatively measured value. If after this treatment and a reevaluation of the BSR, BSR remains positive, the anesthetist is going to reduce the concentration of anesthetics in a second step. In case of positive BSR and a blood pressure value ≥ the baseline value, the concentration of anesthetics will be reduced as a first measure. The aim is to figure out whether one or both of these interventions can reduce to total, cumulative BSR.	Other: Treatment of hypotension and/or reduction of anesthetics The treatment of hypotension can be done by the responsible anesthetist according to the clinical standard operations including any accepted drug typically used in this hospital. The reduction of anesthetics can be done either by reducing the volatile end tidal anesthetics concentration (ETAC) or the infusion rate of propofol.

Arm

Intervention/Treatment

No Intervention: 1 - Blinded

EEG and Entropy will be blinded. The anesthesiological management will be performed by the anesthetist according to clinical standard operations.

Active Comparator: 2 - Unblinded

EEG and Entropy will be unblinded. The intervention starts with the start of a positive burst suppression rate. In the case of a concurrent hypotension the anesthetist treats the hypotension according to clinical standard operations in the first step. Hypotension means blood pressure values blow the baseline value which is defined by the lowest, preoperatively measured value. If after this treatment and a reevaluation of the BSR, BSR remains positive, the anesthetist is going to reduce the concentration of anesthetics in a second step. In case of positive BSR and a blood pressure value ≥ the baseline value, the concentration of anesthetics will be reduced as a first measure. The aim is to figure out whether one or both of these interventions can reduce to total, cumulative BSR.

Other: Treatment of hypotension and/or reduction of anesthetics

The treatment of hypotension can be done by the responsible anesthetist according to the clinical standard operations including any accepted drug typically used in this hospital. The reduction of anesthetics can be done either by reducing the volatile end tidal anesthetics concentration (ETAC) or the infusion rate of propofol.

Outcome Measures

Primary Outcome Measures

Chance of the total, cumulative burst suppression rate. [During general anesthesia and within the intervention]
The total, cumulative burst suppression rate (BSR) corresponds to area under the curve and is defined by the BSR (%) and the absolute duration of BSR (t).

Secondary Outcome Measures

Burst suppression rate during induction. [During induction within the intervention]
Rate of change of the burst suppression rate during induction.
Burst suppression rate during maintenance. [During maintenance within the intervention]
Rate of change of the burst suppression ratio during maintenance.
Mean arterial blood pressure. [During burst suppression within general anesthesia]
Evaluation of the mean arterial blood pressure with positive burst suppression rate.
Endtidal anesthetic concentration (ETAC) and infusion rate of propofol. [During burst suppression within the intervention]
Evaluation of the mean ETAC and infusion rate of propofol.
Specific characteristics of the EEG frequency spectrum during burst suppression [During burst suppression within general anesthesia]
Evaluation of specific EEG frequencies differentiating BSR caused by hypotension or oversedation of anesthetics.
Postoperative delirium. [Within the first three postoperative days]
Screening of the patients regarding a postoperative delirium by a brief confession assessment method (bCAM).

Eligibility Criteria

Criteria

Ages Eligible for Study:

60 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Inclusion Criteria:

Age ≥ 60 years
Surgical interventions in general anesthesia (volatile or total intravenous anesthesia)
expected surgery duration ≥ 1h
American Society of Anesthesiologists (ASA) 1-4
written informed consent prior to study participation