Laparoscopically Guided Rectus Sheath Block in Pediatric Appendicitis

Overview

The study will investigate the pain control effects of a rectus sheath block after laparoscopic surgery to remove the appendix. A rectus sheath block is the injection of local anesthetic (numbing agent) into the space between the muscles of the belly wall. Children having surgery for appendicitis age 8-17 at the Stollery Children's Hospital will be eligible to participate. Patients with complicated appendicitis (perforation or abscess), chronic pain, bleeding disorders, or inability to document pain scores will be excluded from this study. Participants will be randomly assigned to either rectus sheath block or standard local anesthetic. The standard local anesthetic group will have local anesthetic (numbing agent) injected around their surgery cut sites. The rectus sheath block group will have this standard plus the rectus sheath block with local anesthetic. Participants, parents, anesthesiologists and nursing staff will not know which group the participant has been assigned to. The surgeon will know the group. The same pain and nausea medications will be ordered for all participants after the surgery. Pain scores will be measured using the Faces Pain Scale - Revised tool. Participants will be asked to rate their pain in the recovery room, in their hospital room at 3 and 6 hours after the surgery and again before going home. This tool has been shown to be useful for rating children's pain levels. The study will also measure the amount of pain and nausea medications that participants are given during their surgery and recovery. Participants will see their surgeon at 6 weeks after their surgery where they will be asked about any problems after being discharged home. Data will be analyzed with a linear mixed model.

Purpose: To determine if a bilateral laparoscopically guided rectus sheath block improves pain control over conventional local anesthetic infiltration around port site incisions following laparoscopic appendectomy. Hypothesis: Bilateral rectus sheath block will improve post-operative pain scores following laparoscopic appendectomy for acute uncomplicated appendicitis. Justification: Children have significant pain after laparoscopic appendectomy and many receive post-operative opioids for analgesia. The Faces pain scale - revised (FPS-R) is a simple validated method of measuring post-operative pain in children. Ultrasound-guided bilateral rectus sheath block (RSB) has been shown to decrease pain scores in the early post-operative period following pediatric laparoscopic appendectomy and elective umbilical hernia repair.2,4 The use of image-guidance for needle placement has improved both achievement of appropriate anatomic location of the block as well as analgesia associated with the block. Under ultrasound guidance, this extra step requires additional equipment, time, and sometimes dedicated personnel to complete. The investigators propose a bilateral RSB performed intra-operatively under laparoscopic guidance may alleviate the need for these extra resources while achieving the desired analgesic effects. The analgesic effect of the standard of care injection of local anesthesia is limited to the superficial layers of the abdominal wall. The rectus sheath block targets the nerves running within the fascia and provides a more complete block to the deep and superficial layers of the abdominal wall. Objectives: Primary Objective: Determine if intra-operative laparoscopic guided bilateral RSB improves self-reported post-operative pain scores at 3 hours post-operatively. Secondary Objectives: Determine if intra-operative laparoscopic guided bilateral RSB improves self-reported post-operative pain scores in the PACU, at 6 hours post-operatively, and prior to discharge home. Determine if intra-operative bilateral laparoscopic guided bilateral RSB decreases intra-operative narcotic use, post-operative opioid use, and post-operative antiemetic use. Research Methods/Procedures: Randomization: Simple Blinding: Single-blind. Surgeon cannot be blinded to the intervention. Anesthesiologist, participants, parents, and nursing staff in the OR, recovery room, and ward will be blinded. Control: Standard of care infiltration of local anesthetic at incisions. Treatment and standard care arms will run in parallel. Standard Care: Intra-operative infiltration of 2ml of 0.25% Bupivacaine with 1:200 000 epinephrine at each port site incision. Experimental Treatment: Bilateral RSB with up to 7ml of 0.25% Bupivacaine with 1:200 000 epinephrine plus 2ml infiltrated around each port site incision as in the standard care group. The total volume used will not exceed 20ml or 2mg/kg, whichever is lower. Each participant will be followed in the recovery room and surgical ward and asked to report their pain level immediately after surgery, at 3 and 6 hours after surgery, and prior to discharge home. Each participant will have a scheduled follow up visit at 6 weeks with their operating surgeon where they will be asked about any complications experienced since discharge. Participation will be voluntary. Participants will receive standard of care if they choose not to participate in the study. Informed consent will be obtained from the participant's parent or legal guardian by the operating surgeon or delegate pre-operatively. Participants will be asked to provide assent. Plan for Data Analysis: 100 participants will be required with a target of 50 in each group. Sample size calculations were completed based on an estimated 20% effect size with consideration for a potential 10-15% dropout rate to achieve a power of 80% and alpha 5%. Effect size is estimated conservatively from data in previous studies showing an average 30% decrease in early post-operative pain scores. Data will be analyzed in an intent to treat manner using a linear mixed model. We have undertaken an initial consultation with a WCHRI biostatistician.