Pupillary reflex dilation and pain index evaluation during general anesthesia using sufentanil: a double-blind randomized controlled trial

Aim: In a single-center, double-blind, randomized controlled trial, we evaluated whether pupillometry-controlled use of sufentanil is better than free-choice administration of sufentanil by anesthesiologists. Patients & methods: 61 patients undergoing daycare gynecological or abdominal surgery were enrolled. A pupillometry pain index score chart was introduced for administration guidance of sufentanil. Results: The first objective, patient well-being, did not show a significant difference with painkiller usage and health state index at day 1 postoperatively. Secondly, we experienced difficulty in interpretation of the pupillometry score. Thirdly, opioid usage was higher in the intervention group (20.1 vs 14.8 mcg; p = 0.017). Conclusion: The use of pupillometry and pain index chart for bolus sufentanil with our protocol showed an unwanted higher sufentanil usage without a significant difference in patient wellbeing. Plain language summary: Communication with patients under general anesthesia is impossible. A potential solution is to measure pain. One of seven commercially available options is to use a pupillometer. Automated painful stimuli are given and the dilation of the pupil is measured. We hoped to use this method to better control the dose of the opioid sufentanil. During daycare gynecological and abdominal procedures, we had a 25% higher sufentanil usage in the intervention group. We experienced difficulties in reaching the right pain score in both groups. The well-being of the patients, namely pain and painkiller usage at day 1 after surgery, did not show any significant difference. With our protocol, there is no benefit to controlling the dose of sufentanil by pupillometer measurement.