Evaluation of transversus abdominis plane block for renal transplant recipients - A meta-analysis and trial sequential analysis of published studies

Background: Patients undergoing renal transplant (RT) have altered drug/opioid pharmacokinetics. Transversus abdominis plane (TAP) block in renal transplant recipients has been recently evaluated for analgesic and opioid-sparing potential by many trials. Methodology: The studies comparing TAP-block to conventional analgesic regimens for RT were searched. Comparisons were made for total opioids consumed (as morphine-equivalents) during the first postoperative 24-h (primary objective), intraoperative, and immediate-postoperative period. Pain scores and postoperative nausea-vomiting (PONV) were also evaluated. Trial sequential analysis (TSA) was used to quantify the strength of analysis. Results: Ten-trials with 258 and 237 patients in control and TAP-block group, respectively, were included. TAP-block decreased the 24-h (reported in 9-trials) opioid consumption by 14.61 ± 4.34 mg (reduction by 42.7%, random-effects, P < 0.001, I² = 97.82%). Sample size of the present analysis (472) was well past the required 'information-size' variable (396) as per the TSA for a power of 85%. Intraoperative opioid consumption also decreased by 2.06 ± 0.63 mg (reduction of 27.8%) (random effects, P < 0.001, I² = 98.84%). Pain scores with TAP-block were significantly lower in both early and delayed postoperative phase. Odds ratio for PONV without TAP block was 1.99 ± 1.05 (Fixed-effects, P = 0.04, I² = 0%). Publication bias was likely (Egger's test, X-intercept=7.89, P < 0.05). Conclusions: TAP-block significantly lowers the intraoperative and cumulative postoperative 24-h opioid consumption in RT recipients. Persistent and better pain control is achieved when TAP-Block is used. Benefits of TAP block extend beyond the analgesic actions alone as it also decreases the 24-h incidence of postoperative nausea vomiting as well. The technique of the block needs standardization for RT recipients.