Liposomal Bupivacaine vs Continuous Nerve Catheters for Below the Knee Amputations

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

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.

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.

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