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

Abstract

BackgroundPredicting 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. MethodsThis 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). ResultsPatients 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. ConclusionPLR measurements might be informative in the prediction of outcome of post-CA patients even under sedation and hypothermia.