Clinical and experimental studies on electromechanical dissociation.

Abstract

Electromechanical dissociation (EMD) is the most frequent cause of unsuccessful cardiac resuscitation in critically ill patients. In a clinical study of cardiac arrest, including 54 episodes in 50 fully monitored patients, 14 episodes of ventricular fibrillation were observed and 7 were reversed. In the remaining 40 instances, 36 cases of EMD were initially observed; 4 patients had asystole. None of the patients with EMD or asystole were successfully resuscitated. For objective study of EMD and its treatment, an experimental model was developed in which ventricular fibrillation was induced in mechanically ventilated dogs. EMD was predictably observed when, after an interval of 120 s, ventricular fibrillation was reversed with an external countershock. Neither metabolic acidosis nor metabolic alkalosis modified the incidence of EMD. A few dogs were pretreated with glucose-insulin K or pharmacologic doses of methylprednisolone, but this did not clearly reduce the incidence of EMD. The onset of EMD was delayed when the body temperature of the animal was spontaneously reduced.