Defibrillation refers to passing an electrical current across myocardium to depolarize the muscle in order to convert a dysrhythmia back into normal sinus rhythm. Defibrillation was first demonstrated in 1899. Application of defibrillation to convert VF into a perfusing rhythm occurred concurrently in multiple locations. The first successful use of an alternating-current internal defibrillator in a human was reported in 1947. The first successful use of an alternating-current external defibrillator on a human was reported in 1956. These defibrillators used energy from a landline (i.e., electricity from a wall socket). The first use of a portable direct-current external defibrillator (estimated weight: 3.2 kg) was reported in 1967. The first portable defibrillator in the United States was commercially available in 1968. Innovations have continued since the 1960s to produce smaller and lighter AEDS.4

The benefits of early defibrillation on survival and functional outcome though public-access defibrillation programs and greater accessibility and availability of AEDs in the community are unquestionable.1 In a paper by Pollack et al. patients shocked by a bystander were significantly more likely to survive to discharge (66.5% vs. 43.0%) and be discharged with favourable functional outcome (57.1% vs. 32.7%) than patients initially shocked by emergency medical services.5

Defibrillation within 3–5 min of collapse can produce survival rates as high as 50–70%. Each minute of delay to defibrillation reduces the probability of survival to discharge by 10–12%. When bystander CPR is provided, the decline in survival is more gradual and averages 3–5% per minute delay to defibrillation.1