Complicating Cirrhosis

NEJM 2008;358:2378-87.

A few weeks ago we had an autopsy on a patient with just about every complication of cirrhosis one can have: severe portal hypertension requiring TIPS (transjugular intrahepatic portosystemic shunt) placement in the portal vein, esophageal varices necessitating banding and cautery, hepatic encephalopathy, and coagulopathy related to impairment of hepatic synthetic function. She would be a great case study for medical students learning about cirrhosis. Based on the autopsy findings, we think she developed cirrhosis from chronic hepatitis C infection and chronic alcoholism, two of the most usual suspects in the etiology of cirrhosis. One complication that was not suspected clinically was hepatopulmonary syndrome (HPS). This and hepatorenal syndrome are two entities that have been explored more recently in the medical literature.

The New England Journal has a decent review article on HPS that I stumbled across today in researching complications of cirrhosis. I thought it had a good image of the pathogenesis of hypoxemia in HPS. In any acute or chronic liver disease (usually with portal hypertension), pulmonary capillaries may be dilated with nonuniform flow and potential right-to-left capillary shunts. What results is a ventilation-perfusion mismatch and restricted diffusion of oxygen into the dilated capillaries. The efferent blood flow from the normal alveoli mixes with poorly oxygenated blood from those alveoli with dilated capillaries (potentially mixing with an intrapulmonary shunt) to give blood that lacks the usual oxygen concentration (hypoxemia). This can then result in inadequate supply to tissues and organs, rendering them hypoxic (hypoxia) [an aside: I often get hypoxemia and hypoxia confused...typing out the differences helps unmuddle this issue].