Snapshot A 60-year-old man presents with increasing shortness of breath. He reports that this symptom worsens when he is in the upright position and improves when he is laying in bed. Medical history is significant for end-stage liver disease due to hepatitis C infection. On physical exam, there is decreased breath sounds on pulmonary auscultation and spider nevi. Arterial blood gas analysis is significant for an alveolar-arterial gradient of 20 mmHg. Introduction Clinical definition liver disease leading to severe pulmonary vascular complications Epidemiology Incidence dependent on the patient population and diagnostic criteria in patients with cirrhosis it is approximately 15-30% Demographic the middle-aged no sex difference Location intrapulmonary vasculature Risk factors liver disease portal hypertension can be with or without cirrhosis ETIOLOGY Pathophysiology pathoanatomy unclear believed to be due to increased vasodilator (e.g., nitric oxide and carbon monoxide) production secondary to liver disease resulting in ventilation-perfusion (V/Q) mismatch alveolar-capillary oxygen disequilibrium Associated conditions liver disease increased alveolar-arterial (A-a) gradient Presentation Symptoms dyspnea on exertion or at rest platypnea increased dyspnea when upright and improves when supine weakness and fatigue Physical exam orthodeoxia decreased arterial oxygen tesion when upright and improves when supine signs of liver disease spider angiomata palmar erythema gynecomastia jaundice spider nevi (spider angiomas) Imaging Transthoracic contrast echocardiography indications in patients who have evidence of impaired arterial oxygention (e.g., increased A-a gradient) considered gold standard for detecting intrapulmonary vascular dilatation and diagnosing hepatopulmonary syndrome (HPS) finding intrapulmonary vascular dilatation Studies Labs arterial blood gas (ABG) analysis indications when there is clinical suspicion for hepatopulmonary syndrome ≥ 15 mmHg is suggestive of HPS ≥ 20 mmHg is suggestive of HPS in patients > 64-years-old Differential Arteriovenous malformations Atrial septal defect Hepatic hydrothorax Portopulmonary hypertension Anemia Treatment Conservative observation indication in patients with mild-to-moderate HPS long-term oxygen therapy indication in patients with severe HPS Operative liver transplantation indications in patients with severe HPS Complications Pneumonitis Panacinar emphysema Prognosis Liver transplantation may result in resolution of hepatopulmonary syndrome