Effect of IoC2-guided analgesic titration on intraoperative opioid consumption in older patients undergoing laparoscopic colorectal surgery: a randomized controlled trial.

purposeHemodynamic variables may be unreliable indicators of intraoperative nociception in older patients. We evaluated whether a prespecified IoC2-based sufentanil dosing protocol reduces intraoperative sufentanil use compared with conventional hemodynamic guidance in older patients undergoing laparoscopic colorectal surgery.

methodsIn this prospective, single-center, parallel-group, single-blind randomized trial, patients aged 65-90 years with ASA physical status II-III undergoing elective laparoscopic colorectal resection were randomized 1:1 to IoC2-guided or hemodynamic-guided analgesia. Anesthesia, antiemetic prophylaxis, neuromuscular blockade, and postoperative analgesia were standardized. The prespecified primary outcome was weight- and time-normalized intraoperative sufentanil consumption (μg/kg/h); total intraoperative sufentanil dose was also reported. The secondary outcomes included postoperative pain and sufentanil consumption, interleukin-6 concentrations, intraoperative hemodynamic safety events, vasoactive drug use, recovery outcomes, postoperative nausea and vomiting (PONV), and delirium.

resultsFifty-eight patients were analyzed (IoC2, n = 28; control, n = 30). The prespecified primary endpoint, weight- and time-normalized intraoperative sufentanil consumption, was lower with the prespecified IoC2-based protocol than with hemodynamic guidance (median [IQR], 0.10 [0.09-0.13] vs 0.17 [0.14-0.22] μg/kg/h; p < 0.001). Total intraoperative sufentanil dose was also lower in the IoC2 group (20.0 [16.9-26.3] vs 36.0 [27.8-44.4] μg; p < 0.001). Postoperative pain scores and sufentanil requirements were similar between groups, with no significant differences in hypotension, bradycardia, vasoactive drug use, baseline-adjusted interleukin-6 concentrations, or delirium. PACU PONV was less frequent in the IoC2 group (3.6% vs 30.0%; p = 0.012).

conclusionA prespecified IoC2-based sufentanil dosing protocol reduced weight- and time-normalized intraoperative sufentanil consumption without worsening early postoperative pain outcomes in older patients undergoing laparoscopic colorectal surgery. This finding should be interpreted as the effect of the tested dosing protocol rather than validation of the IoC2 target range or treatment threshold. The lower PACU PONV incidence was a secondary finding and requires confirmation in larger trials.