The prohibition on shocking apparent asystole: a history and critique of the argument.

A recommendation against shocking asystole has been part of the American Heart Association's Emergency Cardiovascular Care (ECC) Guidelines since 1992. The principal rationale offered then for the prohibition on shocking apparent asystole (PSAA) has since been refuted and has gradually been dropped, but the recommendation itself remains in the 2005 Guidelines. The PSAA now rests mainly on the lack of solid evidence of a survival benefit--a curious criterion given the lack of such evidence for most ECC treatment recommendations. "Occult" ventricular fibrillation and problems with distinguishing between fine ventricular fibrillation and asystole may lead to delays and omissions of potentially lifesaving shocks. No studies on the subject have been conducted since the PSAA first appeared. Removal of the PSAA from the ECC Guidelines is warranted to reopen research on this topic and support the goal of early defibrillation.