A Study of the Pulmonary Circulation in Man

1)A method of studying the pulmonary circulation in man is described.2)All persons with moderate to severe bronchial asthma have an increase in pressure in the pulmonary artery. A)Adrenalin relieves the bronchiolar spasm, but causes constriction of the pulmonary arterioles, thus maintaining pulmonary arterial pressure at the asthmatic level. However, this effect is rapidly dissipated, and the pressure returns to normal.B)Aminophyllin relieves the bronchiolar spasm, but causes dilatation of the pulmonary arterioles, thus lowering pulmonary arterial pressure below normal.C)Our observations indicate that these are vaso-motor or humoral reflexes which influence the pulmonary circulation in man.3)Patients with cor pulmonale have a high pulmonary arterial pressure because the peripheral resistance in the lung is increased. The diastolic pressure is increased two to six fold. A)The vascular bed is not fixed in cases of cor pulmonale, as is shown by the response to aminophyllin.B)Patients with cor pulmonale and congestive heart failure respond favorably to digitalization.C)Some patients with cor pulmonale had a low cardiac output; others had a high cardiac output with congestive heart failure.D)The pulmonary capillary pressure is normal in cases of cor pulmonale. This indicates that the arteriolar bed is constricted.4)In man, papaverine does not significantly alter pulmonary arterial pressure, but, aminophyllin consistently lowers it.5)Patients undergoing pneumonectomy show an average increase of 40 per cent in the systolic pressure at the time of ligation of the pulmonary artery. The remaining pulmonary vascular bed, however, compensates for this added load in a period of ½ to 1½ hours. A)Both the systolic and diastolic pressure in the pulmonary artery rise with the induction of anesthesia.B)Catheterization of the pulmonary artery in man may prove useful in evaluating the risk of pneumonectomy.6)Patients with insufficiency of the pulmonic valve have a high systolic and high diastolic pulmonary arterial pressure. Probably the most important cause of dilatation of the pulmonic ring is the high diastolic pressure.