Effect of acetylcholine on the pulmonary circulation in patients with chronic pulmonary disease

Twenty-seven patients with various forms of chronic pulmonary disease have been studied with constant infusion of acetylcholine directly into the pulmonary artery. Although many showed a slight decrease in pulmonary artery pressure, this was not great and those with the highest pressures showed the least response. Pulmonary resistances showed similar small changes, if any. Arterial oxygen saturations did not fall uniformly and in those with the lowest levels, an actual increase was observed. It is suggested that vasomotor activity is only one of several factors determining pulmonary artery pressure in patients with chronic pulmonary disease and that anatomic or extravascular factors may become primary. Vasomotor activity seems to be relatively unimportant in the regulation of ventilation/perfusion relationships in patients with far-advanced disease.