Influence of Sevoflurane on the Neurological Pupil Index in Surgical and Critically Ill Patients: A Pilot Study

Background: The aim of this study was to compare the effects of sevoflurane on the neurologic pupil index (NPi), obtained by means of automated pupillometry, between intensive care unit (ICU) and surgical patients. Methods: This was a prospective single-center study conducted between December 2021 and February 2023. The eligible population comprised all patients undergoing general anesthesia (GA) for visceral surgery (VS) or neurosurgery (NS) and ICU patients receiving inhaled sevoflurane, according to the decision of the treating physician. The NPi measurements were conducted before GA (T0), after induction (T1), after the initiation of sevoflurane (T2), and at the point of discontinuation of sevoflurane (T3). Results: A total of 41 VS, 16 NS, and 22 ICU patients (out of which, 12 had a brain injury) were included. In the VS and NS groups, there was a significant decrease in the NPi over time, which remained within normal ranges. The NPi values decreased over time in the ICU group after sevoflurane administration. At T2, the NPi values were lower in the ICU group compared to the other groups. Lower NPi values were observed in the ICU patients with a brain injury compared to other patients. Conclusions: The administration of inhaled sevoflurane was associated with a significant reduction in the NPi values of the ICU patients with a concomitant brain injury.