SLR - July 2015 - Priya Anand

Addition of Dexamethasone and Buprenorphine to Bupivacaine Sciatic Nerve Block: A Randomized Controlled Trial

Reference: Yadeau JT, Paroli L, Fields KG, Kahn RL, LaSala VR, Jules-Elysee KM, Kim DH, Haskins SC, Hedden J, Goon A, Roberts MM, Levine DS. Addition of Dexamethasone and Buprenorphine to Bupivacaine Sciatic Nerve Block: A Randomized Controlled Trial. Reg Anesth Pain Med. 2015 Jul-Aug; 40(4):321-9.

Scientific Literature Review

Reviewed By:
Priya Anand, DPM
Residency Program: Cambridge Health Alliance

Podiatric Relevance: Popliteal (low sciatic) nerve blocks are frequently used in foot and ankle surgery to help with post-operative pain control and limit opioid usage after the procedure.  The use of additives such as buprenorphine or dexamethasone has shown to prolong the effects of the local anesthetic block.  This article attempts to look at the effects of adding buprenorphine and dexamethasone perineurally to a local anesthesthetic sciatic block.  They also look at adding IV dexamethasone and IV buprenorphine when administering a peripheral nerve block.  The study hypothesized that by adding the perineural buprenorphine and dexamethasone they would see a reduction of patient reported pain scores at 24 hours.

Methods: Ninety patients who were undergoing foot and ankle surgery with sciatic nerve block were included in the study.  Exclusion criteria included the following: 1) Patients who had other more proximal surgical sites; 2) Bilateral foot surgery; 3) Dependence on opioids for over 3 months; 4) Altered pain perception and sensation; 5) Inability to describe pain; 6) Inability to speak or read English.  Patients were randomly assigned to 1 of 3 groups.  Group 1 was the control received a nerve block using bupivicaine and IV dexamethasone (4mg).  The second group received the control nerve block and IV buprenorphine (150ug) + IV dexamethasone (4mg).  The third group received the control nerve block and buprenorphine + dexamethasone injected perineurally.  All patients also received a multi-modal pain relief treatment plan post-operatively consisting of opioids, gabapentin, meloxicam and zofran.  All patients also received a spinal or epidural block in addition to the peripheral nerve block.  A questionnaire was given to patients to assess their pain at rest and with movement in the pre-op, PACU, 24 hour and 48 hour post-operative periods.  Pain was assessed with a numerical rating scale.  The duration of the analgesia, opioid usage, quality of sleep and any block related complications were also assessed using a questionnaire.
   
Results: The primary end point was analyzed in 83 of the 90 patients that were included in the study.  Reported pain scores at 24 hours were low for all three groups.  No statistical difference was noted between the groups.  The third group with perineurally injected buprenorphine and dexamethasone had longer block duration and lower scores for the reported “worse pain”.   Both groups 2 and 3 had less reported opioid use post-operatively the next day.  The second group consisting of IV buprenorphine reported more post-operative nausea and vomiting after the procedure compared with any of the other groups.  

Conclusions: These findings suggest that the use of perineurally injected buprenorphine and dexamethasone with a sciatic nerve block can help to prolong the duration of the nerve block and decrease opioid usage the next day.  Administering IV buprenorphine + dexamethasone in addition to a popliteal nerve block has also shown to decrease post-operative opioid usage.  Although, care must be taken when administering this since this study showed more patients complained of post-operative nausea and vomiting when receiving the IV buprenorphine.  Limitations to this study include that all patients also received a spinal or epidural in addition to the popliteal block.  They also all received a multi-modal approach to post-operative pain which may have also contributed to the low reported post-operative pain scores.  Further studies to assess the effects of perineurally injected buprenorphine or dexamethasone in a popliteal block alone may help assess the validity of these findings.  

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