[Technical requirements for early defibrillation: what are the capabilities of automated external defibrillators]

Modern automated external defibrillators (AEDs) offer a variety of technical improvements which increase the efficacy of early defibrillation, facilitate the application by not or minimally trained persons and improve safety. The development of biphasic shocks allows better myocardial protection, the use of lithium batteries, and a marked decrease of AEDs, in size. Microprocessors realize complex acoustic and visual prompts which lead the user through all steps of cardiopulmonary resuscitation (CPR) according to current guidelines. The design of AEDs has been simplified; many devices provide only a single button which can be used for all active processes. Memory functions record the whole CPR with all details which can be transferred to other computers and analyzed off-line. The introduction of AEDs has reduced the delay between collapse and defibrillation to less than 4 min in several studies thus increasing the success of CPR and the proportion of patients dismissed from hospital alive and without neurological deficit. Up to 93% of untrained volunteers were able to successfully complete defibrillation with the use of an AED, sixth-form pupils without experience in CPR were only few sec slower with an AED than staff of emergency medical services. The ability to perform CPR after defibrillation guided by the AED depends primarily on the clarity of acoustic prompts which have to consider the terms and abbreviations of the respective language. Currently available AEDs surpass performance goals of the AHA. However, all devices exhibit advantages and disadvantages which will be discussed in this review.