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

Abstract

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) mmHg/year for PaO2; -26 (-96, 44) m/year for six-minute walk distance, and 3.3% (-6.6, -0.011) predicted/year for diffusion capacity. Non-invasive shunt of ≥ 20% predicted a slower PaO2 decline by 0.88 (0.36, 1.4) mmHg/month. We identified two PaO2 deterioration classes – “very severe disease, slow decliners” (PaO2 45.0 mmHg; -1.0 mmHg/year); and “moderate disease, steady decliners” (PaO2 65.5 mmHg; -2.5 mmHg/year). PaO2 increased by 6.5 (5.3, 7.7) mmHg/month in the first year after transplant. Median time to normalization was 149 (116–184) days. Post-transplant improvement in PaO2 was 2.5 (0.1, 4.9) mmHg/month faster for every 10 mmHg greater pre-transplant orthodeoxia. Conclusions: We present the largest and longest 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 understanding of the natural history of HPS and provide pathophysiologic clues. Importantly, they may assist providers in prognostication and prioritization before and after transplant.