Pathophysiologic features of pulmonary thromboembolism in man

The current study was done to clarify the recent trend of clinical pulmonary thromboembolism (PTE) in Japan. The time has long passed since thromboembolic diseases of the lung were rare in our country. We have experienced, however, twenty-four clinically manifested patients with PTE during the past two years. Although a number of symptoms and findings have been reported to facilitate the diagnosis, they were for the most part nonspecific and therefore nondiagnostic. Combined perfusion and ventilation scans showing a perfusion defect with normal ventilation were reported to be useful for diagnosis of PTE, but a special attention should be paid to the fact that a massive perfusion defect was accompanied by decreased ventilation of the affected lung. From a pathophysiologic study, an exertional dyspnea associated with increased A-aDO2 and also increased a-ETDCO2 in patients without apparent pulmonary consolidation on their chest roentgenogram was strongly suggestive of PTE. A-aDO2 and a-ETDCO2 were shown to be variables independent to each other. a-ETDCO2 was valuable for clinical diagnosis with direct evidence of high VA/Q units resulting from occluded pulmonary arteries. On the other hand, A-aDO2 which was once elevated in the acute stage of PTE was decreased according to the recovery with a close linear correlation to the actual perfusion defect and was a sensitive indicator suggestive of resolved emboli. A-aDO2 was considered to provide measures of the active severity of PTE unlike a-ETDCO2.