Near-infrared spectroscopy after out-of-hospital cardiac arrest

Background Cerebral hypoperfusion may aggravate neurological damage after cardiac arrest. Near-infrared spectroscopy (NIRS) provides information on cerebral oxygenation but its relevance during post-resuscitation care is undefined. We investigated whether cerebral oxygen saturation (rSO 2 ) measured with NIRS correlates with the serum concentration of neuron-specific enolase (NSE), a marker of neurological injury, and with clinical outcome in out-of-hospital cardiac arrest (OHCA) patients. Methods We performed a post hoc analysis of a randomised clinical trial (COMACARE, NCT02698917) comparing two different levels of carbon dioxide, oxygen and arterial pressure after resuscitation from OHCA with ventricular fibrillation as the initial rhythm. We measured rSO 2 in 118 OHCA patients with NIRS during the first 36 h of intensive care. We determined the NSE concentrations from serum samples at 48 h after cardiac arrest and assessed neurological outcome with the Cerebral Performance Category (CPC) scale at 6 months. We evaluated the association between rSO 2 and serum NSE concentrations and the association between rSO 2 and good (CPC 1–2) and poor (CPC 3–5) neurological outcome. Results The median (inter-quartile range (IQR)) NSE concentration at 48 h was 17.5 (13.4–25.0) μg/l in patients with good neurological outcome and 35.2 (22.6–95.8) μg/l in those with poor outcome, p < 0.001. We found no significant correlation between median rSO 2 and NSE at 48 h, r s = − 0.08, p = 0.392. The median (IQR) rSO 2 during the first 36 h of intensive care was 70.0% (63.5–77.0%) in patients with good outcome and 71.8% (63.3–74.0%) in patients with poor outcome, p = 0.943. There was no significant association between rSO 2 over time and neurological outcome. In a binary logistic regression model, rSO 2 was not a statistically significant predictor of good neurological outcome (odds ratio 0.99, 95% confidence interval 0.94–1.04, p = 0.635). Conclusions We found no association between cerebral oxygenation measured with NIRS and NSE concentrations or outcome in patients resuscitated from OHCA. Trial registration ClinicalTrials.gov, NCT02698917 . Registered on 26 January 2016.