Auto-PEEP during CPR. An "occult" cause of electromechanical dissociation? A 64-year-old man with severe COPD developed refractory nonperfusing sinus rhythm after intubation and positive-pressure ventilation. Fifteen minutes after resuscitative efforts were halted, the patient was noted to have spontaneous respirations and blood pressure, suggesting that dynamic hyperinflation was responsible for the observed electromechanical dissociation (EMD). We recommend a brief trial of apnea for patients with COPD and EMD when conventional measures are unsuccessful. 