[Significance of the alveolo-arterial PO2 gradient in the diagnosis of pulmonary thromboembolism].

The diagnostic value of alveolar-arterial PO2 gradient P(A-a)O2 in pulmonary thromboembolism is tested. The significance of alveolar-arterial PO2 gradient in acute pulmonary thromboembolism was determined in prospective study. The study group consisted of 7 patients with pulmonary thromboembolism documented by digital-subtraction angiography (DSA) and lung scans and ten healthy subjects with normal alveolar-arterial PO2 gradient. Hypoxemia was present in 3 patients, hypocapnia in 4 patients and an increased P(A-a)O2 gradient in all 7 patients. The results suggest that a normal P(A-a)O2 gradient in patients during room air breathing can be used as evidence against the presence of pulmonary emboli. P(A-a)O2 gradient is a very sensitive diagnostic parameter in acute pulmonary embolism but procedure is fast.