Pupillometry pain index during day care anesthesia using remifentanil: comparison of perioperative analgesic consumption in a double blind RCT

Abstract

Background: Communication is impossible in sedated patients. Nowadays there is no single best technology to measure nociception during anesthesia.

Objectives: The primary outcome parameter was the postoperative pain intensity queried as pain intensity by numeric rating scale and the amount of pain killer usage. Our hypothesis was that patients with a good titrated remifentanil administration peroperative should have less pain and less need of pain medication. Secondary outcome parameters were the characteristics of the pupillometry introducing a pupillometry pain index chart to individual titrate remifentanil dosage. Tertiary outcome parameters were nausea and vomiting, length of stay at the post anesthesia care unit and health state index.

Design and setting: In a single center double blind randomized controlled trial we evaluated if pupillometry controlled use of remifentanil is better than free choice administration of remifentanil by anesthesiologists. Fifty-five patients undergoing elective day care surgery were enrolled. A pupillometry pain index score chart was introduced for remifentanil administration guidance.

Methods: After induction, a first pupillary reflex dilation (PRD) measurement was performed using pupillometry. A second identical evaluation was performed six minutes after remifentanil administration and adapted every 10 minutes. Remifentanil dosage was adjusted following the pupillometry pain index score (intervention group) or by the discretion of the anesthesiologist (control group).

Results: No statistically significant difference was found in pain intensity and pain killer usage at postoperative day one. The pupillometry pain index chart was usable. Although both groups received 0.21 mcg kg-1 min-1 remifentanil. No Statistically significant difference in opioïd induced side effects, nor health state index was seen.

Conclusion: This study showed no additional value for PRD assessment in response to remifentanil administration during daycare procedures with our protocol to titrate remifentanil. A pupillometry pain index score chart could be implemented. Further research to lower the remifentanil administration within this protocol is needed.

(Ethics Committee EC17/28/319 of the University Hospital of Antwerp. Registration at clinicaltrials.gov NCT03248908.)