Overview
Introduction
The first decision is not the energy setting. It is whether the patient has a pulse, whether the rhythm is organized, and whether perfusion is failing.
The first decision is not the energy setting. It is whether the patient has a pulse, whether the rhythm is organized, and whether perfusion is failing. Defibrillation is an unsynchronized shock used to terminate ventricular fibrillation, pulseless ventricular tachycardia, or hemodynamically intolerable polymorphic ventricular tachycardia. Synchronized cardioversion is timed to the R wave and treats an organized tachyarrhythmia in a patient who still has a pulse. That distinction determines urgency. Pulseless ventricular fibrillation requires immediate defibrillation and CPR; there is no time for sedation, consent, or a pulse-check delay. A patient with a pulse but hypotension, altered mental status, ischemic chest discomfort, acute pulmonary edema, or shock usually needs synchronized cardioversion—unless the rhythm is polymorphic, which cannot be reliably synchronized.