The Relation between Time-weighted Mean Oxygen Tension and Outcome in Out-of-hospital Cardiac Arrest Survivors Treated with Therapeutic Hypothermia

ABSTRACT

PURPOSE: Studies to determine the relation between oxygen tension and outcome in cardiac arrest survivors treated with therapeutic hypothermia (TH) are lacking. We investigated the relation of time-weighted mean oxygen tension (TWMO2) and outcome in cardiac arrest survivors treated with TH. METHODS: This was a retrospective observational study including 177 out-of-hospital cardiac arrest (OHCA) survivors. The patients were divided into four categories according to quartile values of TWMO2. The primary outcome was neurologic outcome at discharge and the secondary outcome was all cause in-hospital mortality. We assessed neurologic outcome using the Cerebral Performance Categories (CPC) at hospital discharge. Neurologic outcome was dichotomised as either good neurologic outcome (CPC1 and CPC2) or poor neurologic outcome (CPC 3 to 5). The odds ratio with 95% confidence interval (CI) was estimated. RESULTS: The median value of PaO2 was 139(104.5-170.0) mmHg. Among a total of 1,239 PaO2 values, 22(1.8%) values were hypoxia (300 mmHg). Results of univariate logistic regression analysis showed a significantly low odds ratio for poor neurologic outcome [0.353(95% CI, 0.133-0.938) and 0.321(95% CI, 0.121-0.850), respectively] and for in-hospital mortality [0.338(95% CI, 0.132-0.870) and 0.387(95% CI, 0.154-0.975), respectively] for the third quartile and the fourth quartile. However, results of multivariate logistic regression analysis showed no significant relation between TWMO2 and outcomes. CONCLUSION: In OHCA survivors treated with TH, time-weighted oxygen tension did not show an association with neurologic outcome and in-hospital mortality.