Optimal concentration of the transversus abdominis plane block in enhanced recovery after surgery protocols for patients of advanced age undergoing laparoscopic rectal cancer surgery

OBJECTIVE: The transversus abdominis plane (TAP) block ameliorates visual analogue scale scores and decreases morphine requirements, but its role remains unclear. Patients of advanced age are susceptible to local anesthetic intoxication. We aimed to identify an optimal concentration that can be used in enhanced recovery after surgery (ERAS) without compromising analgesic efficacy. METHODS: In total, 120 patients aged ≥65 years undergoing laparoscopic rectal cancer surgery received general anesthesia combined with a TAP block using 0.25% ropivacaine (Group A), 0.50% ropivacaine (Group B), or 0.75% ropivacaine (Group C) in a 40-mL volume. Group D only received general anesthesia. Epinephrine, plasma cortisol, interleukin-6, and tumor necrosis factor-α were measured at baseline, skin incision, celiac exploration, and tracheal extubation. The proportions of CD4(+) and CD4(+)/CD8(+) cells were measured at baseline and postoperative days 1 and 3. RESULTS: The TAP block relieved the stress response and accelerated intestinal functional recovery as shown by significant reductions in VAS scores and anesthetic requirements. However, there was no significant difference between Groups B and C. CONCLUSION: The TAP block plays an important role in ERAS in older patients undergoing laparoscopic rectal cancer surgery, and 0.5% ropivacaine is an optimal concentration that can reduce toxicity without undermining analgesia.