Pulmonary function studies and oxygen transfer in patients with liver cirrhosis and different degree of portasystemic encephalopathy.

Pulmonary function and oxygen transfer was studied in five patients with cirrhosis of the liver and different degrees of portasystemic encephalopathy. Four patients were restudied after a change in CNS function. The contribution of various parameters of pulmonary gas exchange to the unsaturation found was evaluated employing the graphic analysis described by King and Briscoe. The following results were obtained: (1) there was no inequality of ventilation as judged by a nitrogen washout study; (2) a large true venous admixture was found in all patients; (3) in four patients studied twice venous admixture was larger when mean EEG frequency was lower; (4) besides the true venous admixture a low overall D/Q ratio was an important factor contributing to unsaturation in most cases; (5) in some cases a decreased overall V/Q ratio contributed to the unsaturation. This decreased V/Q ratio appeared to be due to an increase in pulmonary perfusion without a concomitant rise in ventilation. Changes in pulmonary perfusion pathways are suggested as the most likely cause of the defect in oxygen transfer found in patients with cirrhosis.