Drug therapy in resuscitation from electromechanical dissociation

Electromechanical dissociation (EMD) (organized ECG activity without myocardial contractions) is thought to be rare and associated with poor prognosis. Epinephrine, calcium chloride, and atropine are recommended during attempted resuscitation. Epinephrine's effectiveness in other forms of cardiac arrest is due to its alpha-adrenergic action. Its beta-adrenergic effect may be a disadvantage which is not characteristic of methoxamine, a pure alpha-agonist. Forty anesthetized dogs were asphyxiated until asystolic. Five min later each had slow organized ECG activity. Ventilation with air and sternal compressions were started; 10 dogs each received saline, atropine, calcium chloride, or methoxamine iv. Resuscitation was discontinued after 10 min. Two dogs were resuscitated after saline. Results were not significantly better after atropine or calcium chloride. All 10 which received methoxamine were resuscitated; methoxamine, given at the end of the protocol to all dogs not resuscitated with atropine or calcium chloride, promptly restored spontaneous circulation.