Abstract 53: Automated External Defibrillators Do Not Reduce Time to First Shock in Patients who present with Pulseless Ventricular Tachycardia or Ventricular Fibrillation during In-hospital Cardiac Arrest
BACKGROUND: Automated External Defibrillators (AEDs) improve survival in out-of hospital cardiac arrest due to pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF). This is attributed to reduction in time to first shock and resultant increased effectiveness of first shock. We hypothesized that for in-hospital VT or VF arrests, AEDs would allow floor nurses to delivery therapy before arrival of the CPR team, thereby reducing time to first shock and increasing effectiveness of first shock.
METHODS: The study population consisted of inpatients at an 1100 bed tertiary care facility. Two time periods were tested: before introduction of AEDs (Monophasic, n=193) and after complete deployment of AEDs (AED, n=224). Clinical and cardiac arrest variables were recorded prospectively.
RESULTS: Of 417 cardiac arrest patients, 58 had the initial rhythm recorded as VT or VF and 154 had VT or VF at any point during resuscitation. There were no differences between groups in the probability of receiving a shock, survival to end of resuscitation, 24 hour survival, or survival to discharge.
CONCLUSIONS: Compared to monophasic defibrillators, AEDs failed to improve time to first shock, effectiveness of first shock, or mortality for initial VT/VF in-hospital cardiac arrest. AEDs significantly decreased time to first shock by 3.3 minutes in cardiac arrest patients who had any VT or VF. Unfortunately, this did not improve effectiveness of first shock or survival. This suggests a time window of less than 7 minutes for successful defibrillation, beyond which AEDs show no advantage over monophasic defibrillators.