Paradoxical Role of Inhaled Nitric Oxide in Advanced Liver Disease

Abstract

Because an increased level of exhaled nitric oxide has been noted in patients with severe liver cirrhosis, it seems unlikely that inhaled nitric oxide would ameliorate portopulmonary hypertension or hepatopulmonary syndrome. However, a few reports have suggested a beneficial effect. Therefore, we designed a prospective study of the effects of inhaled nitric oxide in patients with end-stage liver disease. Patients presenting for orthotopic liver transplantation who were identified as having moderate to severe portopulmonary hypertension or hepatopulmonary syndrome were treated with inhaled nitric oxide, and its effects on pulmonary hemodynamics and oxygenation were studied. In portopulmonary hypertension, a positive effect was defined as a ≥20% decline in mean pulmonary artery pressure or pulmonary vascular resistance. In hepatopulmonary syndrome patients, a positive effect was defined as an increase in arterial oxygen tension of ≥20%. Of 434 consecutive patients evaluated, 20 patients met the study criteria. Sixteen patients had portopulmonary hypertension, and 4 patients had hepatopulmonary syndrome. Two patients with portopulmonary hypertension responded to inhaled nitric oxide, as did 1 patient with type 2 hepatopulmonary syndrome. In conclusion, the role of nitric oxide in end-stage liver disease may not be consistent and may vary with different pathophysiological states.