Effect of Pupilometer Guided Analgesia on Postoperative Pain

"At least 10 min after anesthesia induction by target-controlled infusion of propofol and remifentanil, baseline values for pupillary diameter is recorded before any surgical procedure.~During the operation, propofol effect-site target concentration (Ce) is adjusted to maintain the bispectral index (BIS) value between 40 and 60. Remifentanil Ce is adapted every 5 min based on the changes of pupillary diameter. If the pupillary diameter is increased by more than 30% compared to baseline value, remifentanil concentration is increased by 0.5 ng/ml. If the pupillary diameter is maintained between 5 and 30 % change compared with baseline, remifentanil is not modified. In a case of pupillary diameter is decreased less than 5 % change of baseline, remifentanil concentration is decreased by 0.5 ng/ml."

During the operation, SPI value should be maintained between 20 and 50 by changing the infusion rate of remifentanil. Even if the SPI is maintained within the target range, the remifentanil infusion rate is increased by 0.5 ng/ml in a case of the SPI value suddenly arises by more than 10.