Effects of propranolol on pulmonary gas exchange in patients with cirrhosis

Propranolol, a beta-blocking agent, has been proposed in the prevention of gastro-intestinal bleeding in cirrhotic patients, and is known for its bronchoconstrictive effects. Since hypoxemia is a frequent finding in patients with cirrhosis, this work was undertaken to study the effects of intravenous propranolol on pulmonary function and on gas exchange in these patients. The 10 patients studied had cirrhosis associated with an increase in the alveolar arterial O2 difference, (A-a)DO2, an index of arterial oxygenation impairment. Their 1-s forced expiratory volume/forced vital capacity (FEV1/FVC) was normal, but in most a reduction of the forced expiratory flow of 25-75% of vital capacity was observed (FEF 25-75), suggestive of some degree of small airway obstruction. Although propranolol induced a significant decrease of FEF 25-75 from 67.7 +/- 19.3% to 55.4 +/- 21.5% (P less than 0.01), suggesting a bronchoconstriction of the small airways, there was no significant decrease in mean arterial oxygen partial pressure (PaO2) (74.1 +/- 6.4 mmHg before and 77.0 +/- 6.5 mmHg after propranolol). Indeed, a slight but significant improvement of the (A-a)DO2 was observed, from 39.1 +/- 5.9 mmHg to 34.4 +/- 4.9 mmHg (P less than 0.02). Although the mechanism of this beneficial effect remains to be elucidated, we conclude that in spite of its bronchoconstrictive action, propranolol is not contra-indicated in cirrhotic patients with hypoxemia who have normal expiratory flow.