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

Abstract

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 (rSO2) 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 rSO2 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 rSO2 and serum NSE concentrations and the association between rSO2 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 rSO2 and NSE at 48 h, rs = - 0.08, p = 0.392. The median (IQR) rSO2 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 rSO2 over time and neurological outcome. In a binary logistic regression model, rSO2 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.

Keywords: Cardiac arrest; Cerebral oxygenation; Hypoxic ischemic encephalopathy; Intensive care; Neuron-specific enolase (NSE).

Conflict of interest statement

Ethics approval and consent to participate

The study protocol was approved by the research ethics committees of the Northern Savo Hospital District, Finland (decision No. 295/2015), and the Midtjylland region, Denmark (decision No. 1-10-72-163-16). In addition, the trial protocol was approved by the institutional review board at each site.

A deferred consent to participate was obtained from the patients’ next of kin. In addition, an informed consent was obtained from all patients who regained sufficient neurological function for independent decision-making (CPC 1–2) after the intervention period.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

Screened, excluded and included patients in the study

Fig. 2

Scatter plots of serum neuron-specific enolase (NSE) concentration at 48 h after cardiac arrest vs. median regional cerebral oxygen saturation (rSO2) during the first 36 h in intensive care unit in patients with good (Cerebral Performance Category [CPC] 1–2) and poor (CPC 3–5) neurological outcome

Fig. 3

Median (inter-quartile range) regional cerebral oxygen saturation (rSO2) during the first 36 h of intensive care in patients with good (Cerebral Performance Category [CPC] 1–2) and poor (CPC 3–5) neurological outcome