Laparoscopically Guided Rectus Sheath Block in Pediatric Appendicitis

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.