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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13054-019-2428-3) contains supplementary material, which is available to authorized users.