Cardiorespiratory Studies in Hamman-Rich Syndrome

Two cases of Hamman-Rich Syndrome, representing extremes of the clinical spectrum, are presented. Special emphasis has been directed to the results of the simultaneous studies of alveolo-respiratory and hemodynamic function which were carried out. The first patient, his diagnosis having been established by lung biopsy, was studied initially shortly after clinical onset of the disease. He was found to have a normal pulmonary artery pressure at rest, but pulmonary hypertension during exercise. Coincident with the development of pulmonary hypertension, a diffusion insufficiency for oxygen appeared. This latter state was defined by development of an abnormally wide alveolararterial oxygen tension gradient, in the absence of any fixed intrapulmonary right to left shunt. The same patient was restudied after six months of steroid therapy, at which time he had attained improvement both in subjective clinical symptoms and the radiologic extent of the pulmonary infiltrate. Despite such apparent amelioration of the process, the repeat cardiopulmonary evaluation revealed no alteration of the initial physiologic deficits. The second patient, whose diagnosis was established at autopsy, was studied in the terminal phase of her illness, one month prior to death. In this instance, pulmonary hypertension and a severe diffusion insufficiency for oxygen were present in the resting state. Both defects were improved when pulmonary blood flow was decreased by the carefully-monitored infusion of a ganglionic blocking agent, hexamethonium. In both cases, the pulmonary vascular resistance was found to be fixed and elevated. These findings have led to the conclusion that pulmonary hypertension and diffusion insufficiency for oxygen are a consequence of the same primary disorder; namely, extensive destruction of the pulmonary capillaries, which is reflected by the elevated and fixed pulmonary vascular resistance. In the face of this abnormality, the degree of pulmonary hypertension and diffusion insufficiency for oxygen are directly related to the pulmonary blood flow which the diminished vascular bed is called upon to accept. Both of these functional defects are heightened by increased blood flow and ameliorated when flow is lowered.