What is the cause of severe hypoxic respiratory failure in a patient with Hepatopulmonary Syndrome (HPS), confirmed by Transthoracic Echocardiogram (TTE), Transesophageal Echocardiogram (TEE), and Nuclear Medicine (NM) lung perfusion scan, with no other chronic lung pathology, and currently inactive on the transplant list with a non-standard Model for End-Stage Liver Disease (MELD) exception for Malignant Melanoma (MMaT)?

From the Guidelines

The patient should be reactivated on the liver transplant list with a MELD exception due to her diagnosis of Hepatopulmonary Syndrome (HPS), as liver transplantation is the only curative treatment for this condition and can reverse the intrapulmonary vascular dilatations causing hypoxemia. The patient's severe hypoxic respiratory failure, confirmed by multiple tests including transthoracic echocardiogram, transesophageal echocardiogram, and nuclear medicine lung perfusion scan, is consistent with HPS, and Pulmonary/Critical Care specialists have ruled out other chronic lung pathologies as contributing factors 1. According to the EASL clinical practice guidelines, HPS can be an isolated indication for liver transplantation, and the severity of HPS is not related to the severity of liver disease 1.

Key considerations in the management of this patient include:

• Providing supplemental oxygen to maintain oxygen saturation
• Avoiding positions that worsen hypoxemia, such as standing
• Considering pentoxifylline (400 mg three times daily) to potentially improve oxygenation
• Regular monitoring of arterial blood gases and pulse oximetry
• Avoiding TIPS procedure, as it may worsen hypoxemia in HPS patients 1.

It is essential to note that patients with HPS and PaO2 <50 mmHg may have a risk of irreversible respiratory failure in the post-transplant period and a high risk of perioperative mortality 1. Therefore, careful perioperative management and close monitoring are crucial to minimize these risks. Liver transplantation should be considered as soon as possible, given the significant mortality associated with untreated HPS and the potential for improvement and reversibility of HPS after transplantation.

From the Research

Hepatopulmonary Syndrome (HPS) Diagnosis and Treatment

• HPS is a pulmonary complication of cirrhosis and/or portal hypertension, characterized by hypoxemia due to alterations in pulmonary microvascular tone and architecture 2, 3.
• The syndrome occurs in 4-32% of patients with cirrhosis and is defined by a widened alveolar-arterial oxygen gradient (AaPO2) on room air (>15 mmHg, or >20 mmHg in patients >64 years of age) with or without hypoxemia resulting from intrapulmonary vasodilatation 2.
• Clinical manifestations of HPS include progressive hypoxemia through diffuse vasodilatation of the pulmonary microcirculation, and patients with HPS have a higher mortality than those with cirrhosis without the disorder 4, 3.

Treatment Options for HPS

• Liver transplantation is the only effective therapeutic option for HPS, resulting in complete resolution or significant improvement in gas exchange in over 85% of patients 2, 4, 3, 5, 6.
• There are no established medical therapies for HPS, although selected patients may benefit from other surgical or radiological interventions 5.

Diagnostic Tests for HPS

• Pulse oximetry is a useful screening test for HPS, which can guide subsequent use of arterial blood gases 6.
• Contrast-enhanced transthoracic echocardiography is the most effective test to demonstrate intrapulmonary vascular dilatation (IPVD) 6.
• Radionuclide lung perfusion scanning, using technetium-labeled macroaggregated albumin particles, is another method for detecting IPVD 6.