Biphasic defibrillation of patients following cardiac arrest is becoming increasingly common. JAN HARRIS explains the technology behind the trend

Early defibrillation is accepted as essential to revert potential life threatening ventricular arrhythmia of ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) (Bardy et al 1996). Defibrillators are therefore standard equipment in wards and departments, and increasingly in community settings. The introduction of automated external defibrillators (AEDs) in public places such as gymnasia, shopping centres and on aircraft support the theory that early defibrillation can save lives.