Changes in Quantitative Pupillometry After General Anesthesia and Neuromuscular Blockade.

Purpose: Quantitative pupillometry (QP) standardizes pupillary assessment and may assist in the assessment of patients undergoing general anesthesia with neuromuscular blockade. This study aimed to explore the effect of general anesthesia with neuromuscular blockade on QP values.

Design: A prospective observational study.

Methods: This study obtained QP readings using a handheld pupillometer from adult patients undergoing surgery. The first reading was obtained prior to any anesthetic medication. Subsequent readings were obtained immediately after induction of general anesthesia and once every 5 minutes, up to 20 minutes or procedure start time.

Findings: Of 109 enrolled, 59 (53.6%) received rocuronium and 50 (46.4%) received succinylcholine. Following the induction of general anesthesia, several QP values were significantly reduced, including the Neurological Pupil index (4.23 to 3.47; P < .0001 for the left eye and 4.24 to 3.31; P < .0001 for the right eye), constriction velocity (1.64 to 0.94 mm/s; P < .0001 for the left eye and 1.72 to 0.99 mm/s; P < .0001 for the right eye), dilation velocity (0.80 to 0.40 mm/s; P < .0001 for the left eye and 0.85 to 0.40 mm/s; P < .0001 for the right eye), and percent change in pupil size (22.35% to 13.68%; P < .0001 for the left eye and 24.09% to 13.86%; P < .0001 for the right eye). Conversely, latency of constriction and pupil size after light exposure significantly increased (P < .0001 bilaterally for both values). There was no significant change in Neurological Pupil index after either rocuronium or succinylcholine administration.

Conclusions: QP results indicate that pupillary velocity and reactivity slow down following the induction of general anesthesia with the administration of either rocuronium or succinylcholine. Further research is warranted to study the changes of QP metrics in this context.