Use of Exparel for Postoperative Analgesia Following Bariatric Surgery

The aim of this study is to evaluate the efficacy of liposomal bupivicaine in post operative analgesia for patients undergoing bariatric surgery when compared to conventional local analgesia. Patients will be randomly selected to receive either liposomal bupivicaine or conventional bupivicaine via a transversus abdominal plane block during surgery. Patients will be followed post-operatively to assess use of narcotics, post-operative pain and nausea scores, and length of stay.

Optimizing pain management following bariatric surgery is an important aspect of patient care and post-surgical recovery. Despite advances in post-operative pain management, this remains a challenge and opioids continue to dominate as the most widely used analgesia for post-surgical pain management. Opioid use especially in the opioid-naive patient carries significant short term and long term risks including over dependence and chronic opioid use. Movements towards minimizing post-operative opioid use has shown regional anesthetic techniques to be highly effective in the management of pain in surgical patients. More specifically, liposomal bupivicaine (Exparel) is a novel non-opioid local analgesia that takes advantage of a multi-vesicular liposomal system to provide extended analgesia release over 72-96 hours. The purpose of this study to evaluate the use of liposomal bupivicaine in the management of post-operative pain following bariatric surgery via a transversus abdominis plane (TAP) block. Patients will be randomized to receiving either liposomal bupivicaine or traditional 0.25% bupivicaine locally infiltrated at the time of bariatric surgery. Both liposomal bupivicaine and traditional bupivicaine will be administered via TAP block after identification of planes via laparoscopy by the bariatric surgeon. Patients will be followed post-operatively to assess use of opioid analgesia between the two arms. In addition, they will be assessed with respect to pain and nausea using analog scores, as well as hospital length of stay.

20 ml vial of liposomal bupivacaine containing 266 mg (maximum dose), will be diluted with 20 ml of 0.25% bupivacaine (containing 50 mg of bupivacaine) and 20 ml saline (60 ml total). That total volume will be divided into two 30 ml syringes, and each will be used (per side) for the TAP blocks.

Two 30 ml of 0.25% bupivacaine is drawn up and given on each side after identification of planes and levels via laparoscopy. Medication will be given just below the last rib and extend to below the lowest incision.

266mg of liposomal bupivacaine 266 mg, 20 mL volume, will be diluted with 20 ml of 0.25% bupivacaine (50 mg of bupivacaine) and 20 ml saline, thereby totalling 60mL volume. Total volume will be divided into two 30 ml syringes, and each will be used (per side) for the TAP blocks.

0.25% bupivacaine, 60mL total, divided into two 30mL syringes and delivered via TAP block on either side.

Proportion of patients requiring narcotics post-procedure until discharge as recorded via their electronic medical record.

Pain will be assessed in the post-anaesthesia care unit (PACU) at 2 occasions - upon arrival and before transfer to ward. Subsequently, pain scores will then be reassessed at 8 am, 2 pm, and 8pm until discharge. Pain will be measured on an 11-point scale from 0 (no pain) to 10 (most pain imaginable) and the average of the PACU and ward scores will be used as the final outcomes.

Postoperative nausea scores will be assessed daily at 8 am, 2 pm, and 8pm until discharge using an 11-point scale from 0 (no nausea) to 10 (most nausea imaginable)

Postoperative narcotic use will be recorded in morphine equivalent units and recorded via their electronic medical record.

Total length of stay will be calculated from registration until discharge to home; usually spans 2-5 days.

Inclusion Criteria: The patient previously met NIH criteria for bariatric surgery and has not received a previous bariatric surgical procedure The patient is aged 18-65 years and has completed the screening and preparation process prescribed by the Ontario Bariatric Network Exclusion Criteria: Inability to give informed consent ASA > 4 Planned procedure other than Roux-en-Y gastric bypass (RYGB) or contraindications to RYGB BMI > 55 kg/m2 Revisional procedure Allergies or suspected allergies to local anesthetic medications (bupivicaine) Renal insufficiency (GFR < 30ml/min) History of chronic pain needing daily medications for the last >3 months

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