Nociception-guided versus Standard Care during Remifentanil-Propofol Anesthesia A Randomized Controlled Trial

Background: The multidimensional index of nociception, the nociception level, outperforms blood pressure and heart rate in detection of nociceptive events during anesthesia. We hypothesized that nociception level-guided analgesia reduces opioid consumption and suboptimal anesthesia events such as low blood pressure and use of vasoactive medication. Methods: In this single-blinded randomized study, 80 American Society of Anesthesiologists class I-III adult patients of either sex, scheduled for major abdominal procedures under remifentanil/propofol anesthesia by target-controlled infusion, were included. During the procedure nociception level, noninvasive blood pressure, and heart rate were monitored. Patients were randomized to receive standard clinical care or nociception level-guided analgesia. In the nociception level-guided group, remifentanil concentration was reduced when index values were less than 10 or increased when values were above 25 for at least 1 min, in steps of 0.5 to 1.0 ng/ml. Propofol was titrated to bispectral index values between 45 and 55. The primary outcomes of the study were remifentanil and propofol consumption and inadequate anesthesia events. Results: Compared with standard care, remifentanil administration was reduced in nociception level-guided patients from (mean +/- SD) 0.119 +/- 0.033 to 0.086 +/- 0.032 mu g center dot kg-1 center dot min-1 (mean difference, 0.039 mu g center dot kg-1 center dot min-1; 95% CI, 0.025-0.052 mu g center dot kg-1 center dot min-1; P < 0.001). Among nociception level-guided patients, 2 of 40 (5%) experienced a hypotensive event (mean arterial pressure values less than 55 mm Hg) versus 11 of 40 (28%) patients in the control group (relative risk, 0.271; 95% CI, 0.08-0.77; P = 0.006). In the nociception level-guided group, 16 of 40 (40%) patients received vasoactive medication versus 25 of 40 (63%) patients in the standard care group (relative risk, 0.64; 95% CI, 0.40-0.99; P = 0.044). Conclusions: Nociception level-guided analgesia during major abdominal surgery resulted in 30% less remifentanil consumption.