Acute Pulmonary Edema

clinical practice T h e ne w e ngl a nd jou r na l o f m e dic i ne A 62-year-old man presents with a three-day history of progressive dyspnea, nonproductive cough, and low-grade fever. He had been hospitalized two years earlier for congestive heart failure. His blood pressure is 95/55 mm Hg, his heart rate 110 beats per minute, his temperature 37.9°C, and his oxygen saturation while breathing ambient air 86 percent. Chest auscultation reveals rales and rhonchi bilaterally. A chest radiograph shows bilateral pulmonary infiltrates consistent with pulmonary edema and borderline enlargement of the cardiac silhouette. How should this patient be evaluated to establish the cause of the acute pulmonary edema and to determine appropriate therapy? the clinical problem The following two fundamentally different types of pulmonary edema occur in humans: cardiogenic pulmonary edema (also termed hydrostatic or hemodynamic edema) and noncardiogenic pulmonary edema (also known as increased-permeability pulmonary edema, acute lung injury, or acute respiratory distress syndrome). Although they have distinct causes, cardiogenic and noncardiogenic pulmonary edema may be difficult to distinguish because of their similar clinical manifestations. Knowledge of the cause of acute pulmonary edema has important implications for treatment. Patients with cardiogenic pulmonary edema typically are treated with diuretics and afterload reduction, although the underlying cause may require other treatment, including coronary revascularization. 1 Patients with noncardiogenic pulmonary edema who require mechanical ventilation should be ventilated with a low tidal volume (6 ml per kilogram of predicted body weight) and a plateau airway pressure less than 30 cm of water. This lung-protective strategy of ventilation reduces mortality in patients with acute lung injury. 2,3 In addition, for patients with severe sepsis, recombinant activated protein C 4 and low-dose hydrocortisone 5 should be considered. Prompt diagnosis of the cause of acute pulmonary edema with the use of noninvasive methods, supplemented by catheterization of the pulmonary artery when there is diagnostic uncertainty, facilitates timely and appropriate treatment. Accurate diagnosis of acute pulmonary edema requires an understanding of microvascular fluid exchange in the lun