Chicote B, et al. - Given the possibility of achieving improved prediction of shock success with ventricular fibrillation (VF) waveform analysis via surrogate markers of perfusion like end-tidal end-tidal CO₂ (EtCO₂), researchers investigated EtCO₂ as predictor of shock success, both individually and in combination with VF-waveform analysis. They analyzed 514 shocks from 214 out-of-hospital cardiac arrest (OHCA) patients (75 first shocks). Defibrillation success was predicted with MEtCO₂ only for first shocks. Addition of MEtCO₂ to VF-waveform analysis improved prediction of shock success in first shocks. From the device files, VF-waveform features and MEtCO₂ were automatically calculated; hence, the investigators suggested introducing these methods in current defibrillators adding only new software.