The hepatopulmonary syndrome

The hepatopulmonary syndrome is a triad of liver disease, increased alveola r-arterial oxygen gradient and intrapulmonary vascular dilatations. Manifes tations include orthodeoxia, platypnoea and hyperdynamic circulation. Intra pulmonary vascular abnormalities, perhaps mediated by nitric oxide, cause h ypoxaemia by shunting, a perfusion-diffusion defect, and ventilation-perfus ion mismatching. Contrast-enhanced echocardiography is the method of choice for demonstrating pulmonary vascular abnormalities, although perfusion lun g scanning is a more specific and sensitive test. Angiography is best reser ved for patients with poor response to 100% oxygen and defines whether vasc ular dilatations are of the diffuse 'spongy type or, less commonly, discret e arteriovenous communications amenable to embolization. About 80% of patie nts with the hepatopulmonary syndrome eventually have improved oxygenation after liver transplantation, thereby making worsening hypoxaemia the primar y indication for transplantation in many instances. Nevertheless, severe hy poxaemia carries a peri-operative mortality of 30% and reliable predictors of successful outcome after transplantation remain to be determined.