Unexpected cardiovascular collapse and death most often result from ventricular fibrillation in pts with acute or chronic atherosclerotic coronary artery disease. Other common etiologies are listed in Table 10-1. Arrhythmic causes may be provoked by electrolyte disorders (primarily hypokalemia), hypoxemia, acidosis, or massive sympathetic discharge, as may occur in CNS injury. Immediate institution of cardiopulmonary resuscitation (CPR) followed by advanced life support measures (see below) is mandatory. Ventricular fibrillation, or asystole, without institution of CPR within 4-6 min is usually fatal.