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1. Hepatopulmonary syndrome
Given the patient's history of cirrhosis with an apparent non-cardiac right to left shunt, hepatopulmonary syndrome is the most likely cause of her hypoxemia. A ventilation-perfusion scan and a pulmonary angiogram were performed and showed only early detection of tracer or dye in the arterial circulation. An attempt to balloon occlude the pulmonary lobar branches showed no improvement in oxygenation.
Although first described by Fluckiger in 1884, the term hepatopulmonary syndrome (HPS) was coined by Kennedy and Knudson (2) while at the University of Arizona in Tucson. They observed a syndrome characterized by hypoxemia aggravated by exercise, orthodeoxia (fall in arterial blood oxygen on assuming the upright posture), hypocapnia, and evidence of hyperdynamic circulation, but otherwise normal indices of pulmonary air flow, volume, and distribution of ventilation as an infrequent complication of hepatic cirrhosis. An illustrative case was described, supporting the presence of a shunt or shunt-like mechanism consisting of low-resistance vascular communications within the lung. Although the cause of HPS is no entirely clear it may be a pulmonary manifestation of spider angiomata. There is also evidence of excessive NO production which may result in excessive pulmonary artery vasodilatation (3).
Which of the following have been proposed as treatments for hepatopulmonary syndrome? (Click on the correct answer to proceed to the sixth and final panel)