Physiologic changes in the hepatopulmonary syndrome before and after liver transplant: A longitudinal and predictor analysis

Background and Aims: Hepatopulmonary syndrome (HPS) is a common complication of liver disease defined by abnormal oxygenation and intrapulmonary vascular dilatation, treated with liver transplantation. Little is known about changes in HPS physiological parameters over time. We sought to describe baseline clinical and physiological characteristics in HPS and their relationships, temporal changes in physiological parameters before and after transplant, and predictors of changes in oxygenation. Approach and Results: This was a retrospective cohort study in the Canadian HPS Program (n = 132). Rates of change after diagnosis were: -3.7 (-6.4, -0.96) mm Hg/year for partial pressure of arterial oxygen (PaO2); -26 (-96, 44) m/year for 6-minute walk distance, and 3.3% (-6.6, -0.011) predicted/year for diffusion capacity. Noninvasive shunt of >= 20% predicted a slower PaO2 decline by 0.88 (0.36, 1.4) mm Hg/month. We identified 2 PaO2 deterioration classes-"very severe disease, slow decliners" (PaO2 45.0 mm Hg; -1.0 mm Hg/year); and "moderate disease, steady decliners" (PaO2 65.5 mm Hg; -2.5 mm Hg/year). PaO2 increased by 6.5 (5.3, 7.7) mm Hg/month in the first year after transplant. The median time to normalization was 149 (116, 184) days. Posttransplant improvement in PaO2 was 2.5 (0.1, 4.9) mm Hg/month faster for every 10 mm Hg greater pretrans-plant orthodeoxia. Conclusions: We present a large and long longitudinal data analysis in HPS. In addition to rates of physiological decline and improvement before and after liver transplantation, we present novel predictors of PaO2 decline and improvement rates. Our findings enhance our understanding of the natural history of HPS and provide pathophysiologic clues. Importantly, they may assist providers in prognostication and prioritization before and after transplant.