Plastic Surgery Research Council
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PSRC 60th Annual Meeting

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The Analgesic Efficacy of the Transversus Abdominis Plane (TAP) Block on the Abdominal Donor Site Following Autologous Tissue Breast Reconstruction: A Double-Blind, Placebo-Controlled Randomized Trial
Toni Zhong, MD, MHS, Marie Ojha, RN-EC, MN, Shaghayegh Bagher, Msc, Kate Butler, MHSc, Coimbatore Srinivas, MD, Stuart A McCluskey, MD, Hance Clarke, MD, Anne O'Neil, MD, PHD, Christine Novak, PHD, Stefan OP Hofer, MD, PHD.
University Health Network, Toronto, ON, Canada.

Purpose
The Transversus Abdominis Plane (TAP) block is a peripheral nerve block of the T6-L1 intercostal nerves of the abdominal wall. The analgesic efficacy of the TAP nerve block for postoperative pain control following abdominally-based breast reconstruction has never been studied in a randomized controlled trial (RCT).
Methods
We conducted a double-blind, placebo-controlled RCT that followed a single-centre, 1:1 allocation, two-arm parallel group superiority design in patients undergoing microsurgical abdominally-based breast reconstruction. Intraoperatively, bilateral multi-orifice epidural catheter were inserted under direct vision into the transversus abdominis plane (TAP) through a 3cm incision in the Triangle of Petit. Postoperatively, patients were randomly assigned to receive intermittent boluses of a 0.2 mL/kg of 0.25% Bupivacaine (study group) or saline (placebo group) through the bilateral TAP catheters every 8 hours for the first 2 postoperative days (POD). In both groups, patients received intravenous hydromorphone through a patient-controlled analgesic (PCA) pump programmed for the demand-only mode set at 0.1mg/bolus every 5 minutes with no basal rate. Both the TAP catheters and PCA were discontinued on POD 3. The primary objective was compare the mean daily opioid consumption in the first 3 days following surgery between the control and study groups in intravenous morphine equivalent units. The secondary outcome measures included total in-hospital cumulative opioid and anti-nausea consumption, daily patient-reported pain scores, nausea and sedation scores, Quality of Recovery score, time to ambulation, and duration of hospital stay. All results were analyzed using intention-to-treat.
Results
Between September 2011 and April 2013, of the 155 patients assessed for eligibility, 18 were ineligible, 44 declined participation, and 93 patients enrolled into the trial and underwent randomization and surgery. Forty-nine patients received Bupivacaine (study arm) and 44 receive isotonic saline (control arm) in their TAP catheters postoperatively. A total of 85 patients completed the primary outcome assessments, 47/49 patients in the study group and 38/44 in the control group. Seventy-one patients had DIEP flaps and 14 patients had free muscle-sparing TRAM flaps. There were 11 postoperative complications (13%), 7 in the treatment group, 4 in the control group, and none was related to TAP catheter, and there were no flap failures. Randomization resulted in a balanced distribution of patients, and there were no differences in age, BMI, clinical or demographic characteristics between the two groups. For the primary outcome, the reduction in parenteral morphine consumption was only significantly different between the two groups on POD 1. (Figure 1) In the Bupivacaine group, the mean parenteral morphine consumption was 20.7 (SD=20.1) mg compared to 30.0(SD=19.1) mg in the placebo group (p=0.02) on POD 1. There were no differences between the two groups in any of the secondary outcomes measures.
Conclusions
This double-blind, placebo-controlled RCT showed that the TAP block is a safe peripheral nerve block and it provides a significant reduction in parenteral morphine consumption in the early postoperative period following abdominally-based microsurgical breast reconstruction.


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