Liposomal Bupivacaine vs Continuous Nerve Catheters for Below the Knee Amputations

Study Overview
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Brief Summary
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Through this pilot prospective trial, we aim to obtain preliminary data investigating the effectiveness of perineural catheters and liposomal bupivacaine, both currently accepted as standard care at Maine Medical Center, for the management of post-limb amputation pain. We will use the data that we collect to inform the design of a larger, appropriately powered study.

Detailed Description
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Lower extremity amputation is a common surgical procedure often due to limb ischemia or complications related to diabetes mellitus. Managing postoperative pain can be quite challenging in this patient population and persistent post-surgical pain is not uncommon. Peripheral nerve catheters (PNCs) that deliver a continuous infusion of local anesthetic have been shown to provide analgesic benefit dependent upon infusion duration and in the absence of catheter malfunction. Unfortunately, PNCs can be difficult to place and rates of dislodgement are estimated at 30%. Single shot regional nerve blocks using liposomal bupivacaine are much easier to perform than PNCs and can provide up to 72 hours of pain relief, eliminating the need for catheter placement. To date, no study has investigated the effects of liposomal bupivacaine compared to PNCs for post-surgical pain control. In this pilot study, we intend to compare pain scores, opioid consumption, and length of stay in patients randomized to both treatment strategies. We also intend to conduct an exploratory analysis investigating incidence of phantom limb pain one month following surgery. Our results will inform the design of a larger powered study to investigate treatment effects.

Official Title
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A Prospective, Randomized Trial of Liposomal Bupivacaine Compared to Continuous Nerve Catheters on Pain Control and Post-Operative Opioid Use in Receiving Popliteal Nerve Blocks for Below the Knee Amputation

Conditions
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Pain, Postoperative, Amputation

Intervention / Treatment
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* Drug: Liposomal bupivacaine
* Drug: Bupivacaine Hydrochloride 0.5 % Injectable Solution


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists Physical Status Classification I-IV Scheduled for primary amputation or stump revision English speaking Exclusion Criteria: Patients unable to cooperate or consent to the study Allergy to local anesthetics Existing infection at planned needle insertion site BMI > 40kg/m2 Patients with a history of coagulopathy Emergency amputations Contralateral amputations Patients with a substance use disorder diagnosis Patients on opioids >90 morphine milligram equivalents (MME)/day

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Single Shot Perineural Popliteal Nerve Block<br>Single shot perineural popliteal nerve block injection of 10cc 13.3% liposomal bupivacaine combined with 15cc 0.50% bupivacaine hydrochloride within one hour prior to surgery | Drug: Liposomal bupivacaine<br>* Popliteal nerve block<br>* Other names: Exparel;|
| Active Comparator: Continuous perineural popliteal nerve block catheter<br>Placement of continuous perineural popliteal nerve block catheter with injection of 30cc 0.5% bupivacaine within one hour prior to surgery, followed by continuous infusion of 10cc 0.3% ropivacaine (current standard practice) for at least 72 hours following surgery. Saphenous single shot 20cc 0.2 | Drug: Bupivacaine Hydrochloride 0.5 % Injectable Solution<br>* Continuous nerve catheter<br>* Other names: conventional bupivacaine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain assessed by Numerical Rating Scale (NRS) | Average NRS pain scores (0-10, 0=no pain, 10=worst possible pain) | 72 hours post-operatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Opioid Consumption | Total amount of opioid medication given, in morphine milligram equivalents | 72 hours post-operatively | 
| Post-operative Length of Stay | Length of stay in hours | Measured from surgical stop time to discharge time, an average of 5 days. | 
| Post-operative Pain assessed by the Short Form McGill Pain Questionnaire-2 (SFMPQ-2) | Total SFMPQ-2 score (low score of 0, no pain to a high score of 220, worst possible pain) | 30 days following surgery | 
| Phantom Limb Pain assessed using questions from the Trinity Amputation and Prosthesis Experiences Scales-Revised (TAPES-R) | Measured using questions 4 and 5 from Part II of the TAPES-R (scores can range from 0, no pain, to 22, severe pain) | 30 days following surgery |