LOW-ENERGY IMPEDANCE-COMPENSATING BIPHASIC WAVE-FORMS TERMINATE VENTRICULAR-FIBRILLATION AT HIGH-RATES IN VICTIMS OF OUT-OF-HOSPITAL CARDIAC-ARREST

Introduction: New automatic external defibrillators (AEDs), which are smaller, lighter, easier to use, and less costly make the goal of wide spread AED deployment and early defibrillation for out-of-hospital car diac arrest feasible. The objective of this study was to observe the p erformance of a low-energy impedance-compensating biphasic waveform in the out-of-hospital setting on 100 consecutive victims of sudden card iac arrest. Methods and Results: AEDs incorporating a 150-J impedance- compensating biphasic waveform were used by 12 EMS systems. Data were obtained from the AED PC card reporting system. Defibrillation was def ined as conversion to an organized rhythm or to asystole. Endpoints in cluded: defibrillation efficacy for ventricular fibrillation (VF); res toration of an organized rhythm at the time of patient transfer to an advanced life support (ALS) team or to the emergency department (ED); and time from AED power-on to first defibrillation. The AED correctly identified 44 of 100 patients presenting in VF as requiring a shock (1 00% sensitivity) and 56 of 100 patients not in VF as not requiring a s hock (100% specificity). The time from 911 call to first shock deliver y averaged 8.1 +/- 3.0 minutes. A single 150-J biphasic shock defibril lated the initial VF episode in 39 of 44 (89%) patients, The average t ime from power-on to first defibrillation was 25 +/- 17 seconds. At pa tient transfer to ALS or ED care, an organized rhythm was present in 3 4 of 44 (77%) patients presenting with VF. Asystole was present in 7 ( 16%) and VF in 3 (7%). Conclusions: Low-energy impedance-compensating biphasic waveforms terminate long-duration VF at high rates in out-of- hospital cardiac arrest. Use of this waveform allows AED device charac teristics consistent with widespread AED deployment and early defibril lation.