Alveolar-capillary oxygen disequilibrium in hepatic cirrhosis

Hypoxemia is a frequent occurrence in patients with severe hepatic disease. Multiple mechanisms have been implicated in the production of such hypoxemia. The case of a 35-year-old man with cyanosis, clubbing, and cirrhosis is presented. Physiologic data from this patient revealed normal pulmonary function, except for a low diffusing capacity and a 28 percent shunt while the patient was breathing 100 percent oxygen. A perfusion scan with radioactive 99mtechnetium-labelled macroaggregated albumin revealed 67 percent of the labelled macroaggregated albumin in the systemic circulation. Post-mortem examination demonstrated normal pulmonary parenchyma, markedly dilated intraparenchymal capillaries and arterioles, subpleural angiomata, and cirrhosis. No anatomic arteriovenous connections were demonstrated before or after death. We conclude that the arterial hypoxemia of some patients with hepatic cirrhosis results from dilated gas-exchanging blood vessels. These widened vessels prevent end pulmonary capillary oxygen tension from reaching equilibrium with alveolar gas, perhaps because of the widened distance for diffusion.