Changes in Pulmonary Hemodynamics Produced by Isoproterenol Infusion in Emphysematous Patients

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Abstract
Eighteen patients with pulmonary emphysema were studied at rest and during isoproterenol infusion with measurement of the cardiac output and pulmonary artery pressure in all subjects and determination liters/minute, while the mean pulmonary artery pressure decreased 3 mm Hg, and the wedge pressure was unchanged. Mean pulmonary vascular resistance decreased 114 dynes sec. cm-5 during the infusion, while minute ventilation increased 1.5 liters/minute, and arterial saturation rose 2.3%. Thirteen subjects were also studied during "steady state" exercise and during exercise with isoproterenol infusion with determination of the same parameters. Wedge pressures were obtained in 10 of the 13 subjects. The mean cardiac output during infusion while exercising increased 1.2 liters /minute above the value during exercise alone, while the mean pulmonary artery pressure decreased 4 mm Hg, and wedge pressure was unchanged. Mean pulmonary vascular resistance decreased 78 dynes sec. cm-5 during this period of infusion and exercise, and minute ventilation increased 2.3 liters/minute. Mean arterial saturation during drug infusion and exercise increased 2.9%. Isoproterenol is capable of altering the pulmonary vascular bed of resting and exercising emphy-sematous subjects in such a manner that increases in pulmonary blood flow are associated with a fall in pulmonary artery pressure and a marked decrease in calculated pulmonary vascular resistance.