Pulmonary Edema of High Altitude

An hypothesis is presented to explain the development of pulmonary edema of high altitude. According to the hypothesis, there is a constitutional susceptibility by which certain persons react abnormally to hypoxic stress. The susceptibility is manifested in the form of greater pulmonary vascular resistance at the precapillary level, presumably as a result of an increased amount of circular muscle fibers in the arterioles in certain areas of the lung. Under hypoxic stress severe contraction of muscular arterioles results in wider opening of perpendicular nonmuscular arterioles; this floods the capillaries supplied by them. A sudden increase in hydrostatic pressure of the capillaries in certain areas, coupled with increased permeability of the alveolocapillary membrane caused by hypoxic stress, leads to pulmonary edema. Because of the same abnormal reactivity of muscular arterioles, the peripheral arterioles may constrict to the point of occlusion and produce stasis of blood in the capillaries, which, coupl...