The Velocity of Increasing End-Tidal CO2 Immediately Following Resuscitation Is Associated with Postresuscitation Myocardial Function

Introduction: End-tidal CO2 (ETCO2) serves as a sensitive indicator of hemodynamic efficacy during CPR and therefore predicts the success of resuscitation. In the present study, we investigated the relationship between the velocity of increasing ETCO2 immediately after successful resuscitation and post resuscitation myocardial function. Hypothesis: The velocity of increasing ETCO2 immediately following resuscitation is associated with the severity of post resuscitation myocardial dysfunction. Methods: Twenty rats were randomly assigned to one of two groups: (1) short duration of cardiac arrest (CA) (n = 10): ventricular fibrillation (VF) was untreated for 4 mins prior to 6 mins of CPR; (2) long duration of CA (n = 10): VF was untreated for 8 mins followed by 8 mins of CPR. After successful resuscitation, the first 20 secs of ETCO2 were analyzed. The velocity of ETCO2 changes was defined as the difference of the maximum and minimum ETCO2 value divided by the duration between the two ETCO2 values. Ejection fraction (EF) was measured by echocardiography at 8 hrs after resuscitation. Results: Increasing ETCO2 immediately following successful resuscitation was observed in all rats. However, the velocity of ETCO2 increasing in the group of short duration of CA was significantly faster than the group of long duration. This was associated with significantly greater EF at 8 hrs after resuscitation (Table). A close correlation between the velocity of increasing ETCO2 and EF was demonstrated (r=0.70, p<0.01) (Figure). Conclusion: The velocity of increasing ETCO2 immediately following resuscitation is associated with post resuscitation myocardial function.