Etiology and frequency of gas exchange abnormalities in cirrhosis.

OBJECTIVE: gas exchange abnormalities are frequent in cirrhosis. These abnormalities can be considered an indication or contraindication for liver transplantation. The aim of this study was to investigate the etiology and frequency of these alterations. METHOD: seventy-eight patients with cirrhosis and 20 healthy subjects were selected randomly. Arterial basal blood gases, diffusing capacity of carbon monoxide (DLco), pulmonary function test (PFT) and contrast transthoracic echocardiography (CTTE) with 0. 9% saline were done. RESULTS: patients showed lower DLco (79 +/- 23. 2 vs 96 +/- 20; p < 0.01), lower PaCO2 levels (32.2 +/- 4.5 vs 37.5 +/- 4; p < 0.001) and higher alveolar-arterial oxygen difference (AaPaO2) (22.5 +/- 11.4 vs 12 +/- 7.4; p < 0.001) than controls, but the difference between groups in mean PaO2 levels was not significant. Twenty-three patients (29.5%) had pulmonary vasodilatation (PV) and 28 (36%) altered PFT. Hypocapnia was the most frequently observed alteration in gas exchange (73.4%). Hypoxemia and decreased DLco were more frequent in the presence of altered PFT than in the presence of PV. Both PFT abnormalities and PV were associated with increased AaPaO2. Child stage was higher in patients with PV (7.9 +/- 2.3 vs 9.2 +/- 2; p = 0.01) than in those without PV. CONCLUSIONS: gas exchange abnormalities are frequent in cirrhosis. The most frequent alteration is hypocapnia, which is associated with PV. The main cause of severe hypoxemia in these patients is PFT abnormality. Pulmonary vasodilatation is more frequent and more severe in patients with advanced hepatocellular dysfunction.