Pupillary Pain Index-Guided Postoperative Pain Therapy in ENT Surgery: A Randomized Trial

Background: Postoperative pain levels and opioid requirements vary considerably, even among patients undergoing similar surgical interventions. The pupillary pain index-a pupillometry-derived measure of nociception-antinociception balance-may help individualize postoperative analgesia. We therefore tested the hypothesis that a pupillary pain index-guided opioid titration at the end of surgery reduces postoperative pain and opioid consumption compared with standard care. Methods: At the end of surgery, a portable infrared pupilometer was used to measure pupillary dilation reflex during stepwise tetanic stimulation (10-60 mA), generating a pupillary pain index score. Adult patients undergoing elective ear-nose-throat surgery under general anesthesia were randomized to pupillary pain index-guided opioid therapy or standard care. Opioid administration in the pupillary pain index group followed predefined pupillary pain index cutoffs; in the control group, analgesia was managed per routine practice. Postoperative opioid consumption and pain-assessed using a numerical rating scale (NRS, 0-10)-were recorded every 30 min for 2 h in the post-anesthesia care unit. Linear models with covariates including remifentanil, weight, nose surgery, and sex were calculated to compare outcomes between groups. Results: Mean (±SD) opioid consumption during the first 2 postoperative hours was 4.9 ± 4.3 mg in the pupillary pain index-guided group and 6.5 ± 4.3 mg in the control group (adjusted p = 0.12). Mean pain scores were 2.0 ± 1.1 and 2.6 ± 1.4, respectively (adjusted p = 0.10). Conclusions: Pupillary pain index-guided analgesia resulted in a nearly 25% reduction in opioid consumption and lower pain scores, although not statistically significant. This suggests that PPI-guided analgesia is not inferior to standard care in terms of pain management.