Determinants and significance of cerebral oximetry after cardiac arrest: A prospective cohort study.

AIM OF THE STUDY: To study the determinants and the evolution of cerebral oximetry determined by near-infrared spectroscopy after out-of-hospital cardiac arrest of cardiac origin during therapeutic hypothermia and rewarming, and to compare cerebral oximetry values between patients with good and bad prognosis.

METHODS: In this prospective, non-interventional, single center study, all consecutive patients between 18 and 80 years admitted for out-of-hospital cardiac arrest (OHCA) with a no flow less than 10min, a low flow of less than 50min and a persistent coma after ROSC with Glasgow score equal or less than seven at baseline were included.

RESULTS: Between February 2012 and January 2013, 43 patients were admitted for OHCA in our ICU. Twenty-two patients (51%) were discharged with no or minimal neurologic complications (CPC 1-2). Mortality rate in the ICU was 46.5%. Cerebral oximetry (rSO2) was correlated with temperature, heart rhythm, PaO2, hemoglobin, and mean arterial pressure. Mean rSO2 during the 48 first hours was not different between patients with good and bad neurologic outcomes, respectively, 61.8 (5.9) vs. 58.1 (8.8), P=0.13, as during the period of hypothermia. The minimal value of rSO2 during the first 48h was significantly different between patients with good prognosis and those with bad prognosis, respectively, 45.0 (6.8) vs. 31.7 (15.0), P=0.0009.

CONCLUSIONS: In this prospective cohort of OHCA patients, main determinants of rSO2 were systemic variables. Monitoring of rSO2 does not allow discriminating patients with good or bad outcome, but could be useful for identifying vulnerable periods for the development of neurologic injury.