The FDA is investigating energy levels in external biphasic defibrillators with shocks of at least 200 J, after receiving reports of 14 events since 2006, in which a 200 J biphasic defibrillator was ineffective in providing defibrillation/cardioversion therapy to a patient, whereas a subsequent shock from a different 360 J biphasic defibrillator resulted in immediate defibrillation/cardioversion.
According to the agency, the majority of events occurred during attempts at cardioversion of atrial fibrillation, but there was at least one instance with defibrillation of a ventricular arrhythmia as well.
An analysis of the 14 cases does not suggest the need for any change to current clinical practice, and as the FDA continues its evaluation of this situation, providers are encouraged to follow the American Heart Association’s (AHA) guidelines/algorithms for treatment of cardiac arrhythmias and to follow manufacturers’ instructions for using defibrillators.
The FDA said it is seeking additional information in order to interpret the significance of these events, and to determine whether the agency's activities are advised. If a problem with a defibrillator is suspected, such as a situation where a patient received shocks from multiple devices, the problem should be reported to the FDA's MedWatch Safety Information and Adverse Event Reporting Program.