Influence of an upright body position on the size of intrapulmonary blood shunts in patients with advanced liver cirrhosis.

Hepatopulmonary syndrome (HPS) is a complication of liver cirrhosis and is responsible for chronic hypoxemia and its negative health consequences. The most relevant diagnostic criterion of HPS is evidence of pathological intrapulmonary blood shunting (IPBS). There is still insufficient knowledge about the subclinical forms of HPS. The aim of this study was to determine whether an erect posture in patients with liver cirrhosis had a significant effect on IPBS, the diagnosis of HPS and oxygen saturation. Thirty cirrhotic patients considered for liver transplantation were enrolled in this study. Pulse oximetry and lung perfusion scintigraphy were conducted in patients while they were in supine and upright body positions. Pathological IPBS was observed in 16% and 20% of patients examined in the supine and upright body positions, respectively (mean difference 0.59%; P = 0.046). Postural-related IPBS changes were markedly greater in patients with HPS (1.76%; P = 0.011). Oxygen saturation was significantly lower in the erect posture compared to the supine posture (mean difference 1.2%; P = 0.02); however, there was no relationship between oxygen saturation and IPBS. In conclusion, an erect posture in patients with advanced liver cirrhosis leads to a subtle increase in IPBS, which is more pronounced in patients with HPS, and oxygen saturation measurements are not sensitive enough to detect these changes.