Longitudinal Quantitative Pupillometry and Its Association with the Best Documented Level of Consciousness During ICU Hospitalization: A Single-Center Retrospective Cohort Study

Background/Objectives: Quantitative pupillometry objectively assesses neurological status and has demonstrated prognostic value after cardiac arrest. Nonetheless, it remains unclear whether longitudinal changes in quantitative pupillary parameters are associated with concurrent trajectories of consciousness recovery during the acute phase of intensive care unit (ICU) hospitalization in comatose patients with heterogeneous underlying etiologies. We investigated associations between longitudinal quantitative pupillary trajectories and recovery of consciousness. Methods: This single-center retrospective cohort study included 126 adult ICU patients with Glasgow Coma Scale scores ≤8 who underwent serial constriction velocity (CV) and percentage change in pupil diameter (%CH) measurements during the first 5 ICU days. Neurological outcomes were classified into Good (minimally conscious state or better) and Bad (unresponsive wakefulness syndrome or coma) groups. Longitudinal changes were analyzed using generalized linear mixed models. Results: The Good outcome group consistently had higher CV and %CH than the Bad outcome group. Generalized linear mixed models showed significant group and time effects on bilateral CV and %CH, with significant group-by-time interactions only for bilateral %CH. %CH continued increasing in the Good outcome group but plateaued after Day 3 in the Bad outcome group. Conclusions: Serial quantitative pupillometry revealed a concurrent longitudinal association between changes in quantitative pupillary parameters and neurological status in a heterogeneous cohort of comatose ICU patients. These findings suggest that longitudinal assessment of quantitative pupillary parameters may complement multimodal neurological evaluations by providing objective information reflecting the ongoing process of consciousness recovery and dynamic changes in neurological status during the acute phase.