Acute cardiogenic pulmonary edema

Acute cardiogenic pulmonary edema is a common cause of acute respiratory failure; however, with appropriate management few patients require intubation and mechanical ventilation. The explosive onset of dyspnea with typical clinical and radiographic findings differentiates patients with cardiogenic pulmonary edema from those with chronic congestive heart failure who present with slowly increasing dyspnea, fatigue, and peripheral edema. The predominant pathophysiologic problem is diastolic heart failure, and although many patients have coexistent systolic heart failure, this problem rarely dominates the clinical presentation. Management must concurrently aim to decrease left ventricular diastolic pressure (primarily by decreasing central blood volume), promote coronary blood flow, and correct the acute respiratory failure. The action of nitroglycerin (initially sublingually and then by intravenous infusion) combines venodilatation, reduction of left ventricular afterload, and correction of myocardial ischemia. Although parenteral furosemide is almost universally administered, both as a venodilator and a potent diuretic, it may acutely raise the pulmonary artery occlusion pressure and lower cardiac output in patients with chronic congestive heart failure. Mask continuous positive airway pressure has been shown to dramatically reduce the need for intubation and mechanical ventilation in patients with severe acute respiratory failure; this technique is well tolerated and is usually required for less than 10 hours. Beneficial effects as compared with oxygen therapy include quicker correction of hypoxemia and reduction in respiratory work, left ventricular preload, and left ventricular afterload. In patients for whom systolic dysfunction is the dominant feature, mechanical ventilation, positive inotropic agents, and left ventricular assist devices may be needed.