Review Question - QID 213877

This patient is presenting with altered mental status and asterixis in the setting of having a transjugular intrahepatic portosystemic shunt (TIPS) placed (this implies that his serum ammonia level is elevated). The most appropriate treatment is to start lactulose.

Hepatic encephalopathy results from elevated ammonia levels reaching the brain and subsequently altering cerebral function. This elevated ammonia level results from either impaired liver function or portosystemic shunting, such as the patient with TIPS. The first step in treating these patients is to lower the serum ammonia level. This is best accomplished with lactulose, lactol, or rifamixin. Lactulose is the first step in therapy to lower serum ammonia levels. It enters the colon and is metabolized by bacterial flora into short chain fatty acids such as lactic and acetic acid. This acid production lowers the colonic pH and converts NH3 (ammonia) into NH4+ (ammonium), which becomes trapped in the colon and subsequently lowers the ammonia serum level.

Incorrect Answers:
Answer 2: Observation is inappropriate as it will worsen the patient's mental status resulting in the need for intubation and possible cerebral herniation from cerebral edema. Cerebral edema results from ammonia being converted into glutamine within astrocytes. Glutamine is osmotically active and pulls water into astrocytes, causing them to swell.

Answer 3: Protein restricted diet is not recommended in hepatic encephalopathy. Protein restriction is associated with higher mortality in patients with cirrhosis. Protein restriction would be warranted in patients who have undergone portosystemic shunting but with severe hepatic encephalopathy. Protein restriction is accomplished with vegetable protein or branch chain amino acids.

Answer 4: Rifamixin inhibits bacterial RNA synthesis, which decreases the number of bacteria that are producing ammonia. This is reserved for patients who do not improve with lactulose or lactitol.

Answer 5: Transjugular intrahepatic portosystemic shunt revision is reserved for patients who do not respond to medical management. The revision is performed to decrease the amount of shunting into the systemic circulation; however, if the shunting is suboptimal, the patient stops receiving the benefit of shunting, which is supposed to address the consequences of portal hypertension (e.g., ascites and varices.)

Bullet Summary:
First-line treatment for hepatic encephalopathy is with lactulose, which decreases the colonic pH and converts ammonia into ammonium trapping it in the colon and decreasing serum ammonia levels.