Should we screen for hepatopulmonary syndrome in liver transplant candidates?

Patient selection for liver transplantation

Improved outcomes in liver transplant recipients reflect advances in surgical technique, post-operative care, immunosuppression as well as better selection of potential candidates. The pre-transplant evaluation is a multidisciplinary process intended to recognize and treat important comorbid conditions that may impair outcomes during the peri- and post-transplant periods. Important psychosocial issues should also be ascertained and tackled early during the pre-transplant evaluation with an overarching intention to improve the success of liver transplantation.

Hepatopulmonary syndrome and portopulmonary hypertension

The pulmonary complications of end-stage liver disease include hepatopulmonary syndrome and portopulmonary hypertension. The etio-pathogenesis of these conditions is as yet unclear. Hepatopulmonary syndrome is a gas exchange abnormality and usually manifests as hypoxemia secondary to intra-pulmonary vascular shunts. These shunts can be demonstrated by echocardiography using agitated saline injections, and quantitated by lung perfusion scans. Liver transplantation is the treatment of choice for hepatopulmonary syndrome, and there are no effective pharmacological therapies. Portopulmonary hypertension is a hemodynamic problem which manifests as fatigue and right sided cardiac failure. Several vasoactive agents have been used to lower mean pulmonary arterial pressures. Portopulmonary hypertension is a relative contraindication to liver transplantation.

Therapy Insight: hepatopulmonary syndrome and orthotopic liver transplantation

Hepatopulmonary syndrome (HPS)--a pulmonary complication observed in patients who have chronic liver disease and/or portal hypertension--is attributed to intrapulmonary vascular dilatation and induces severe hypoxemia. HPS is mainly detected when patients are included on the waiting list for orthotopic liver transplantation (OLT) and can be diagnosed by blood gas analysis, transthoracic contrast-enhanced echocardiography or body scan with (99m)Tc-labeled macroaggregated albumin perfusion. When the partial pressure of arterial oxygen (PaO(2)) is >or=80 mmHg, it is unlikely that the patient has HPS. When the PaO(2) is <80 mmHg, imaging techniques should be used to confirm or exclude pulmonary vascular dilatation. When a diagnosis of HPS is confirmed, knowing the degree of hypoxemia is crucial for optimum patient management. Patients who have a PaO(2) >or=50 mmHg but <60 mmHg should be prioritized for OLT. This procedure is not indicated for patients with a PaO(2) between 60 mmHg and 80 mmHg, although follow-up every 3 months is recommended to detect any deterioration of the PaO(2). A PaO(2) of <50 mmHg might preclude OLT, because mortality and morbidity after OLT are greatly increased in these patients.