Abstract 298: End-Tidal Carbon Dioxide Values as an Indicator of Arrest Etiology and Prognosis

Abstract

Background: During cardiopulmonary resuscitation (CPR), end tidal carbon dioxide (PetCO2) is used to assess the quality of compressions, return of spontaneous circulation (ROSC), and the futility of continued resuscitative efforts. In out-of-hospital cardiac arrest, the first measured PetCO2 correlates with the etiology of arrest, distinguishing between asphyxial and ventricular fibrillation/ventricular tachycardia (VF). This has not been analyzed in the inpatient setting. Objective: To compare the initial PetCO2 during CPR for inpatients with cardiopulmonary arrest (CPA) from VF versus asphyxia. Methods: This study was performed in two urban, academic inpatient facilities. Patients were enrolled from July 2006-May 2013. A comprehensive database of all inpatient resuscitative events is maintained at these institutions, including demographic, clinical, and outcomes data. Arrests are stratified by primary etiology of arrest using a priori criteria. Patients with CPA from asphyxia versus VF and in whom PetCO2 data were available were included in the analysis. Patients in whom capnography was placed after ROSC or more than ten minutes following initiation of CPR were excluded. Patients with VF versus asphyxia were compared with regard to initial PetCO2 values. In addition, initial PetCO2 values for asphyxial arrest victims with and without ROSC were compared. Results: A total of 63 patients with pre-ROSC capnography data were identified; 16 of these had asphyxial arrest and 3 had VF. Initial PetCO2 values were higher in asphyxial arrest victims (25.4 mmHg versus 9 mmHg, p=0.005). In addition, patients with ROSC had higher initial PetCO2 values among all patients (p=0.011) and in the subgroup with asphyxial arrest (30 mmHg versus 15 mmHg). Conclusions: Initial PetCO2 values are higher in inpatients with asphyxial versus VF etiology of arrest. This is consistent with published data on initial etCO2 during OHCA. In addition, initial PetCO2 values are higher in patients with eventual ROSC. This analysis is limited by relatively small sample sizes.