Acute cardiogenic pulmonary edema is a frequent medical emergency. Several studies have shown that continuous positive airway pressure is effective in acute cardiogenic pulmonary edema, through improvement in gas exchange, reduction in intubation rate and a trend towards reduced mortality. CPAP is usually obtained with a hermetic nasal or facemask witch has an expiratory valve to maintain a positive pressure at the end of the expiration. With this support, the patient does not receive any assistance with respiration.