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 CO2 [P(a-et)CO2] 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 CO2 (EtCO2), P(a-et)CO2, and VdA/Vt 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)CO2, and lower VdA/Vt value than non-survivors. Receiver operator characteristic (ROC) curves of serum lactate, P(a-et)CO2, and VdA/Vt showed significant sensitivity and specificity for hospital mortality. Specifically, lactate >= 10.0mmol/L, P(a-et)CO2 >= 12.5 mmHg, and V-dA/V-t >= 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)CO2 and high VdA/Vt during early ROSC in cardiac arrest patients suggest high hospital mortality. If future studies validate this model, the P(a-et)CO2 and VdA/Vt may provide useful guidelines for the early post-resuscitation care of cardiac arrest patients in emergency departments. (c) 2006 Elsevier Ireland Ltd. All rights reserved.