A Study for Hypoxemic Mechanisms in Liver Cirrhosis

Shin, Jung Woo; Song, Il Han; Ki, Myoung Ju; Rhee, Moo Yong; Park, Seok Gun

Abstract

BACKGROUND/AIMS: Hypoxemia is often associated with liver cirrhosis without cardiopulmonary diseases. Pulmonary vascular impairments including intrapulmonary shunt have been considered as a major mechanism of hypoxemia. The aim of this study was to determine the incidence and pathophysiologic basis of hypoxemia in cirrhotic patients without respiratory symptoms. METHODS: In fourty three cirrhotic patients without heart and lung diseases, we performed the arterial blood gas analysis and calculated alveolar arterial oxygen gradient (A-aO2). According to the A-aO2, the patients were divided into hypoxemic and normoxemic groups. In each group, a Tc-99m-macroaggregated albumin (Tc-99m-MAA) scan, a contrast-enhanced echocardiography and a pulmonary function test were performed. RESULTS: Twenty-eight of 43 patients (65%) showed hypoxemia. Hypoxemic patients showed significantly more increased shunt fraction of 3.1 1.4% than normoxemic one of 2.1 1.1% in the Tc-99m-MAA scan (p<0.05). However, only two of hypoxemic patients had shunt fraction above physiologic shunt range. By contrast-enhanced echocardiography, an intrapulmonary shunt was confirmed in one patient. There was no significant correlation between the shunt fraction and the hepatic reserve based on the Child-Pugh classification in hypoxemic patients. In the results of pulmonary function test, only DLco decreased more significantly in hypoxemic group than in normoxemic group (58.4 14.2 % vs 75.3 16.5% of predicted, p<0.05). CONCLUSIONS: Hypoxemia is not infrequently observed in cirrhosis, but incidence of significant intrapulmonary shunt is low. Therefore, other mechanism such as diffusion defect may be suggested to play a role in the development of hypoxemia in cirrhotic patients without respiratory symptoms.