Volumetric capnography and return of spontaneous circulation in an experimental model of pediatric asphyxial cardiac arrest

A secondary analysis of a randomized study was performed to study the relationship between volumetric capnography (VCAP) and arterial CO 2 partial pressure (PCO 2 ) during cardiopulmonary resuscitation (CPR) and to analyze the ability of these parameters to predict the return of spontaneous circulation (ROSC) in a pediatric animal model of asphyxial cardiac arrest (CA). Asphyxial CA was induced by sedation, muscle relaxation and extubation. CPR was started 2 min after CA occurred. Airway management was performed with early endotracheal intubation or bag-mask ventilation, according to randomization group. CPR was continued until ROSC or 24 min of resuscitation. End-tidal carbon dioxide (EtCO 2 ), CO 2 production (VCO 2 ), and EtCO 2 /VCO 2 /kg ratio were continuously recorded. Seventy-nine piglets were included, 26 (32.9%) of whom achieved ROSC. EtCO 2 was the best predictor of ROSC (AUC 0.72, p < 0.01 and optimal cutoff point of 21.6 mmHg). No statistical differences were obtained regarding VCO 2 , VCO 2 /kg and EtCO 2 /VCO 2 /kg ratios. VCO 2 and VCO 2 /kg showed an inverse correlation with PCO 2 , with a higher correlation coefficient as resuscitation progressed. EtCO 2 also had an inverse correlation with PCO 2 from minute 18 to 24 of resuscitation. Our findings suggest that EtCO 2 is the best VCAP-derived parameter for predicting ROSC. EtCO 2 and VCO 2 showed an inverse correlation with PCO 2 . Therefore, these parameters are not adequate to measure ventilation during CPR.