Physiologic Studies of Pulmonary Edema at High Altitude

Abstract

Cardiac catheterization studies have been performed in four patients during acute pulmonary edema at an elevation of 12,300 feet in the central Peruvian Andes. Pulmonary hypertension, low cardiac output, arterial unsaturation, and low normal pulmonary artery wedge pressures were observed. Oxygen breathing was accompanied by a prompt, marked fall in pulmonary artery pressure and a slight rise in wedge pressure, indicating the presence of anoxic pulmonary arteriolar constriction. In one patient, pulmonary artery wedge pressures were not elevated during added hypoxia nor during exercise. The blood pressure response to the Valsalva maneuver was normal. Similar studies were carried out in four subjects after recovery from pulmonary edema. One 9-year-old boy had persisting pulmonary hypertension. None had evidence of underlying cardiac disease. An abnormal rise in pulmonary artery pressure during induced hypoxia was observed in three of four patients. It is concluded that pulmonary edema at high altitude is a unique form of pulmonary edema produced by hypoxia under certain conditions of exposure at high altitude. Severe pulmonary hypertension due to anoxic pulmonary arteriolar constriction is present. There is no evidence that pulmonary venous constriction and cardiac failure are causative mechanisms.