Regional cerebral oxygen saturation after cardiac arrest in 60 patients--a prospective outcome study

Non-invasive near-infrared spectroscopy (NIRS) offers the possibility to determine regional cerebral oxygen saturation (rSO2) in patients with cardiac arrest. Limited data from recent studies indicate a potential for early prediction of neurological outcome.

Sixty cardiac arrest patients were prospectively enrolled, 22 in-hospital cardiac arrest (IHCA) and 38 out-of-hospital cardiac arrest (OHCA) patients respectively. NIRS of frontal brain was started after return of spontaneous circulation (ROSC) during admission to ICU and was continued until normothermia. Outcome was determined at ICU discharge by the Pittsburgh Cerebral Performance Category (CPC) and 6 months after cardiac arrest.

A good outcome (CPC 1-2) was achieved in 23 (38%) patients, while 37 (62%) had a poor outcome (CPC 3-5). Patients with good outcome had significantly higher rSO2 levels (CPC 1-2: rSO2 68%; CPC 3-5: rSO2 58%; p<0.01). For good and poor outcome median rSO2 within the first 24h period was 66% and 59% respectively and for the following 16h period 68% and 59% (p<0.01). Outcome prediction by area of rSO2 below a critical threshold of rsO2=50% within the first 40h yielded 70% specificity and 86% sensitivity for poor outcome.

On average, rSO2 within the first 40h after ROSC is significantly lower in patients with poor outcome, but rSO2 ranges largely overlap between outcome groups. Our data indicate limited potential for prediction of poor outcome by frontal brain rSO2 measurements.