Arterial minus end-tidal CO2 as a prognostic factor of hospital survival in patients resuscitated from cardiac arrest

AIMS: The purpose of this study was to determine the clinical value of arterial minus end-tidal CO(2) [P(a-et)CO(2)] and alveolar dead space ventilation ratio (V(dA)/V(t)) as indicators of hospital mortality in patients that have been resuscitated from cardiac arrest at emergency department. MATERIALS AND METHODS: Forty-four patients with a return of spontaneous circulation (ROSC) after cardiac arrest were studied in the emergency department of a university teaching hospital from March 2004 to February 2006. Mean arterial pressure (MAP), serum lactate, arterial blood gas studies, end-tidal CO(2) (EtCO(2)), P(a-et)CO(2), and V(dA)/V(t) were evaluated at 1 h after ROSC. We compared these variables between hospital survivors and non-survivors. RESULTS: The rates of ventricular fibrillation and pulseless ventricular tachycardia in hospital survivors were higher than those of non-survivors (53.0 and 9.7%, respectively, p=0.002). Hospital survivors had significantly higher MAP, lower serum lactate, lower P(a-et)CO(2), and lower V(dA)/V(t) value than non-survivors. Receiver operator characteristic (ROC) curves of serum lactate, P(a-et)CO(2), and V(dA)/V(t) showed significant sensitivity and specificity for hospital mortality. Specifically, lactate > or = 10.0 mmol/L, P(a-et)CO(2) > or = 12.5 mmHg, and V(dA)/V(t) > or = 0.348 were all associated with high hospital mortality (p=0.000, 0.001 and 0.000, respectively). CONCLUSIONS: This study showed that high serum lactate, high P(a-et)CO(2) and high V(dA)/V(t) during early ROSC in cardiac arrest patients suggest high hospital mortality. If future studies validate this model, the P(a-et)CO(2) and V(dA)/V(t) may provide useful guidelines for the early post-resuscitation care of cardiac arrest patients in emergency departments.