Pupillary Dilation Reflex (PDR) Evaluation During General Anesthesia

In this study, the pupillary dilation reflex is measured as a nociceptive indicator during elective abdominal surgery under general anesthesia.

An infrared camera of the video pupillometer measures the pupillary dilation reflex (PDR) in response of a nociceptive stimulus. This autonomic reflex, parasympathetic mediated in sedated patients, can be generated by various pain stimuli (built in standardized protocol, surgical incision, …) The PDR is a robust reflex, even in patients under general anesthesia, and provides a potential evaluation of the autonomous circuit within the nociceptive evaluation based on pupil dilation upon A-delta and C fibers in both electrical or mechanic stimulation. This mono-centric project involving American Society of Anesthesiologists (ASA) classification I-II patients undergoing elective abdominal surgery under general anesthesia are recruited. Enrolled patients perioperative undergo PDR measurements at four different standardized times.

Pupillometry (PDR) at four standardized times perioperatively after induction, before opioid administration after opioid administration, steady state surgical incision end of procedure

Pupillary Reflex Dilation is measured four times intraoperatively as a possible indicator of success of analgesia

Increased vital signs (heart rate, blood pressure) during surgery as a common used indicator for pain

Inclusion Criteria: Scheduled abdominal surgery ASA I-II Exclusion Criteria: History of eye deformity, invasive ophthalmologic surgery, impaired pupil reflex in advance Kown cranial nerve(s) deficit Infection of the eye Predicted difficult airway management (DAF Guidelines) Chronic opioid use (>3 months) Ongoing treatment with beta-blockers, dopamine antagonists, topical atropine