الفهرس 
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Abstract
Introduction: Respiratory symptoms are exceedingly common in patients who have chronic liver disease with estimates ranging as high as 50% of patients complaining of shortness of breath. The differential diagnosis of dyspnea is extensive in such patients and numerous causes should be considered. Over the last 15 years, pulmonary vascular abnormalities have been increasingly recognized as important clinical entities that influence survival and liver transplant candidacy in affected patients. The most common abnormality is the hepatopulmonary syndrome (HPS), occurs when intrapulmonary vasodilatation impairs arterial oxygenation. This syndrome is recognized as many as 15–20% of patients undergoing evaluation for orthotopic liver transplantation (OLT). The presence of hepatopulmonary syndrome increases mortality in the setting of cirrhosis and may influence the frequency and severity of complications of portal hypertension. Hepatopulmonary syndrome is classically defined by a widened alveolar-arterial oxygen gradient P (A-a) O2 on room air (>15 mmHg, or >20 mmHg in patients >64 years of age) with or without hypoxemia resulting from intrapulmonary vasodilatation in the presence of hepatic dysfunction or portal hypertension. Oxygen desaturation occurred during sleep in 70% of hepatopulmonary syndrome, the degree of which correlated with the severity of hepatopulmonary syndrome. Sleep alters respiratory mechanics and gas exchange, which can adversely affect arterial oxygenation. Whether sleep affects oxygenation in hepatopulmonary syndrome is unknown. Up to 35% of cirrhotic individuals had difficulties in the area of sleep and rest. The mechanisms responsible for these findings are poorly understood. One possibility is that abnormalities in circadian function may underlie its pathogenesis
Aim of the work: Review of nocturnal oxygen desaturation and sleep disordered-Breathing in hepatopulmonary syndrome.
Conclusions: Nocturnal oxygen desaturation is approved in hepatopulmonary syndrome patients. Sleep disordered-breathing is common between liver cirrhosis patients, however, there is still long way for understanding fully sleep architecture and sleep disordered-breathing in hepatopulmonary syndrome because of the rarity of studies done in this area.