Duration of Sciatic Nerve Block After Injection of Local Anesthetic In or Around the Nerve

Sponsor

University of Parma (Other)

Overall Status

Completed

CT.gov ID

NCT01981291

Collaborator

(none)

120

Enrollment

Location

Arms

Duration (Months)

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

This study was designed to assess whether the injection of local anesthetic into the nerve (intraneural), as opposed to around it (perineural), leads to longer anesthesia and analgesia of the leg.

Some reports of accidental intraneural injection mention an extremely long duration. When different drugs and doses were evaluated in a clinical trial of intraneural injection, a longer-than-expected duration was reported.

The investigators will compare the two types of injection using the same drug, so as to determine if there is an actual difference in duration.

Condition or Disease	Intervention/Treatment	Phase
Orthopedic Surgical Procedures Postoperative Pain	Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block Procedure: Femoral Nerve Block Procedure: Patient-controlled postoperative analgesia Drug: Mepivacaine	Phase 4

Detailed Description

This randomized, controlled trial will investigate prospectively for differences in sensory and motor block duration after intra- or perineural injection of 1.5% (wt/vol) mepivacaine, a short-acting local anesthetic.

Study Design

Study Type:

Interventional

Actual Enrollment :

120 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Masking:

Triple (Participant, Care Provider, Outcomes Assessor)

Primary Purpose:

Treatment

Official Title:

Duration of Subgluteal Sciatic Nerve Block After Intra- or Perineural Injection of Mepivacaine: a Randomized, Controlled Trial

Study Start Date :

Oct 1, 2012

Actual Primary Completion Date :

Jul 1, 2013

Actual Study Completion Date :

Oct 1, 2013

Arms and Interventions

Arm	Intervention/Treatment
Active Comparator: Perineural Patients in this group will receive a perineural injection of mepivacaine for subgluteal sciatic nerve block, in addition to a femoral nerve block and patient-controlled postoperative analgesia.	Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block The injection will start as the needle indents the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as "intraneural" if the drug infiltrates the space between the epimysium of the surrounding muscles and the outer epineurium of the sciatic nerve. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach. Other Names: Injection outside the common investing external layer Epineural injection Extraneural injection Procedure: Femoral Nerve Block Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated. Procedure: Patient-controlled postoperative analgesia Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication. Other Names: PCA PCIVA PCCPNB Patient-controlled continuous peripheral nerve block Drug: Mepivacaine Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block. Other Names: Local Anesthetic Carbocaine
Experimental: Intraneural Patients in this group will receive an intraneural injection of mepivacaine for subgluteal sciatic nerve block, in addition to a femoral nerve block and patient-controlled postoperative analgesia.	Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block The injection will start as the needle penetrates the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as "intraneural" if nerve cross section expansion and a reduction in echogenicity are observed. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach. Other Names: Injection beneath the common investing external layer Subepineural Injection Gluteal sciatic nerve block Subparaneural injection Procedure: Femoral Nerve Block Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated. Procedure: Patient-controlled postoperative analgesia Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication. Other Names: PCA PCIVA PCCPNB Patient-controlled continuous peripheral nerve block Drug: Mepivacaine Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block. Other Names: Local Anesthetic Carbocaine

Arm

Intervention/Treatment

Active Comparator: Perineural

Patients in this group will receive a perineural injection of mepivacaine for subgluteal sciatic nerve block, in addition to a femoral nerve block and patient-controlled postoperative analgesia.

Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block

The injection will start as the needle indents the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as "intraneural" if the drug infiltrates the space between the epimysium of the surrounding muscles and the outer epineurium of the sciatic nerve. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.

Other Names:

Injection outside the common investing external layer

Epineural injection

Extraneural injection

Procedure: Femoral Nerve Block

Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.

Procedure: Patient-controlled postoperative analgesia

Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.

Other Names:

PCA

PCIVA

PCCPNB

Patient-controlled continuous peripheral nerve block

Drug: Mepivacaine

Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block.

Other Names:

Local Anesthetic

Carbocaine

Experimental: Intraneural

Patients in this group will receive an intraneural injection of mepivacaine for subgluteal sciatic nerve block, in addition to a femoral nerve block and patient-controlled postoperative analgesia.

Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block

The injection will start as the needle penetrates the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as "intraneural" if nerve cross section expansion and a reduction in echogenicity are observed. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.

Other Names:

Injection beneath the common investing external layer

Subepineural Injection

Gluteal sciatic nerve block

Subparaneural injection

Procedure: Femoral Nerve Block

Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.

Procedure: Patient-controlled postoperative analgesia

Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.

Other Names:

PCA

PCIVA

PCCPNB

Patient-controlled continuous peripheral nerve block

Drug: Mepivacaine

Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block.

Other Names:

Local Anesthetic

Carbocaine

Outcome Measures

Primary Outcome Measures

Differences in Time to Resolution of Sciatic Nerve Block [<12 h]
The time at which sensory and motor function of the sciatic nerve have recovered at least to the following criteria: Sensory: patients feel discomfort when pricked with a thin needle (25G) Motor: patients may move both toes and ankle, albeit with reduced strength This outcome measure will be examined by an investigator every 30-60 min and reported by patients as "time to return of sensation and movement". The investigator-reported value will be preferred if both are available.

Secondary Outcome Measures

Block Onset Time [≤30 min]
Time to onset of sciatic nerve anesthesia, defined as meeting at least the following criteria: Sensory: does not feel pain or discomfort when pricked with a 25G needle. Motor: able to slightly curl toes; unable to flex the ankle.
Success Rate of Anesthetic Nerve Blocks [≤30 min]
The percentage of patients who attain the criteria for block success within 30 minutes of the injeciton. Investigators will also report the percentage of patients who successfully complete surgery without significant additional analgesia (see below); this will be defined as "clinical success rate."
Incidence and Prevalence of Neurologic Disturbances [30 days]
Patients will be interviewed at ~4 h (block resolution visit), 7 days and (if necessary) at 30 days to assess for residual neurologic disturbances in the sciatic nerve territory. The incidence/prevalence of these phenomena will be noted.

Other Outcome Measures

Extra- vs. Intraneural Minimum Electrical Stimulation Thresholds [(during the procedure)]
The minimum electrical nerve stimulation threshold will be recorded as a function of needle tip position.

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Inclusion Criteria:

Undergoing non-emergent orthopedic procedure of knee, leg, foot with thigh tourniquet
ASA Physical Status Class I-III
Consenting to surgery under peripheral nerve block anesthesia (sciatic + femoral/saphenous block)

Exclusion Criteria:

Unable to understand or communicate for the purpose of the study
Exhibiting signs of neuropathy in the ipsilateral extremity
Inability to satisfactorily image the sciatic nerve in the opinion of the attending anesthesiologist