A feasibility study for the continuous measurement of pupillary response using the pupillography during CPR in out-of-hospital cardiac arrest patients

Purpose: We investigated the change in pupil size and pupil light reflex (PLR) using a pupillography capable of continuous measurement both during CPR and immediately following the return-of-spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) comatose patients in an emergency department. Methods: Pupil size and PLR were continuously measured both during CPR and immediately following ROSC until intensive care unit (ICU) admission. The changes in pupil sizes during CPR were categorized into three groups (no change-N, decreased-D, and increased-I groups). Results: Pupillography was applied for 118 and 60 patients during CPR and immediately following ROSC, respectively. Only two patients had a PLR during CPR. The number of patients included each group were 58 (N-group), 21 (D-group) and 39 (I-group). In the D-group, the proportion of witnessed arrest was higher than in the N-group and I-group (81% vs. 55% and 49%, respectively; p = 0.049). There were statistically significant shorter prehospital time in the D-group than the N-group and I-group (13 vs. 23 and 24 min, respectively; p = 0.012). PLR was observed immediately following ROSC in 14 patients. PLR was maintained in seven of these patients until admission to intensive care unit. Six of the seven patients who remained with PLR until ICU admission had survival to hospital discharge, and three of them had good neurological recovery. Conclusion: Our study demonstrated that measurement of the continuous pupillary response can be feasible. Patients with the presence of PLR following ROSC had better outcomes.