Quantitative pupillometry and transcranial Doppler measurements in patients treated with hypothermia after cardiac arrest

Abstract

Background: Predicting outcome after cardiac arrest (CA) is particularly difficult when therapeutic hypothermia (TH) is used. We investigated the performance of quantitative pupillometry and transcranial Doppler (TCD) in this context.

Methods: This prospective observational study included 82 post-CA patients. Quantitative assessment of pupillary light reflex (PLR) and TCD measurements of the two middle cerebral arteries were performed at admission (day 1) and after 24h (day 2) during TH (33-35°C) and sedation. Neurological outcome was assessed at 3 months using cerebral performance category (CPC) scores; patients were classified as having good (CPC 1-2) or poor (CPC 3-5) outcome. Prognostic performance was analyzed using area under the receiver operating characteristic curve (AUC-ROC).

Results: Patients with good outcome (n=27) had higher PLR amplitude than patients with poor outcome (n=55) both at day 1, 13% (10-18) (median, 25th-75th percentile) vs. 8% (2-11) (P<0.001), and at day 2, 17% (13-20) vs. 8% (5-13) (P<0.001), respectively. The AUC-ROC curves at days 1 and 2 were 0.76 (95% confidence interval [CI] 0.65-0.86) and 0.82 (95% CI 0.73-0.92), respectively. The best cut-off values of PLR amplitude to predict a 3-month poor outcome were <9% and <11%, respectively. A PLR amplitude of <7% at day 2 predicted a 3-month poor outcome with a specificity of 100% (95% CI 86-100) and a sensitivity of 42% (95% CI 28-58). No differences in TCD measurements were found between the two patient groups.

Conclusion: PLR measurements might be informative in the prediction of outcome of post-CA patients even under sedation and hypothermia.

Keywords: Heart arrest; Hypothermia; Induced; Patient outcome assessment; Pupillary; Reflex; Transcranial Doppler sonography.