ARTERIAL HYPOXEMIA IN CIRRHOSIS - FACT OR FICTION

Background-Although low arterial oxygen tension (PO2) has been claimed to occur in one to two thirds of patients with cirrhosis, hypoxaemia appears to be rare in clinical practice. Aims-To assess the frequency of arterial hypoxaemia in cirrhosis in relation to clinical and haemod ynamic characteristics. Patients-One hundred and forty two patients wi th cirrhosis without significant hepatic encephalopathy (grades 0-I) ( 41 patients in Child class A, 57 in class B, and 44 in class C) and 21 patients with hepatic encephalopathy. Results-Mean PO2 in kPa was 11. 3 in Child class A, 10.8 in class B, 10.6 in class C, and 10.6 in pati ents with encephalopathy (p<0.05). The fraction of patients with PO2 b elow the lower normal limit of 9.6 kPa was 10%, 28%, 25%, and 43%, res pectively in class A, B, C, and in patients with encephalopathy (p<0.0 5). Oxygen saturation (So,) in these groups was respectively: 96%, 96% , 96%, and 93% (NS), SO2 was below the lower limit of 92% in 0%, 9%, 7 %, and 24% (p<0.05). In patients without hepatic encephalopathy, a mul tivariate regression analysis revealed that independent determinants o f a low PO2 were a high arterial carbon dioxide tension, a low systemi c vascular resistance, and a low indocyanine green clearance (p<0.0001 ). Conclusion-The prevalence of arterial hypoxaemia in cirrhosis is ab out 22% in patients without encephalopathy, but it varies from 10-40% depending on the degree of hepatic dysfunction. Arterial hypoxaemia in patients with cirrhosis of differing severity seems lower than previo usly reported, and patients with severe arterial hypoxaemia are rare.