INTERRUPTION OF PULMONARY ARTERIAL FLOW WITH INADEQUATE VENTILATION LEADS TO PULMONARY INFARCTION

We examined the effect of interruption of pulmonary arterial flow and inadequate ventilation on the development of pulmonary infarction in r ats. Pulmonary arterial flow was blocked by the injection of agar into the inferior vena cava and inadequate ventilation was produced by obs tructing the left main bronchus with a polypropylene tip. Histological and angiographic examination of the lung demonstrated that: pulmonary artery embolism alone does not induce pulmonary infarction; obstructi on of a bronchus does not induce significant changes, but that pulmona ry infarction develops when pulmonary artery embolism and obstruction of a bronchus occur simultaneously. It has been thought that pulmonary infarction is caused by acute obstruction of a pulmonary artery, howe ver, the alveolar walls are supplied with oxygen by both the pulmonary circulation and by ventilation. Interruption of pulmonary arterial fl ow alone is probably not sufficient to induce pulmonary infarction, wh ich is probably caused by deficiency of oxygen supply to the alveolar walls by a synergy between interruption of pulmonary arterial flow and inadequate ventilation.