In this article, Dr. Saira Khaderi is a guest blogger for this this important topic that our patients with chronic liver disease face.
Hepatic Encephalopathy (HE) is reversible impaired brain function in someone with advanced liver failure. Although the exact cause of HE is unknown, we know that decreased metabolism of ammonia in liver disease plays a large role.
Most of the ammonia in our body is absorbed through the intestinal tract and enters circulation from the portal vein. A well functioning liver clears almost all of the ammonia from the portal vein and prevents it from entering the systemic circulation. In patients with liver failure, increased ammonia levels are a consequence of decreased clearance and shunting of blood around the liver. Ammonia causes impaired brain function when it crosses the blood-brain barrier and leads to swelling of special cells in the brain called astrocytes.
Some studies show that in over 80% of cases of HE a precipitating factor can be found. Some of the most common precipitating factors include:
· GI bleed
· Infection
· Dehydration
· Electrolyte abnormalities
· Constipation
· Use of sedatives and tranquilizers (thought to be secondary to increased sensitivity for these medications in patient with liver failure)
· After a transjugular intrahepatic portosystemic shunt (TIPS) placement
Unless they have acute liver failure, most patients who deal with HE have chronic advanced liver disease. Physical signs of liver failure include muscle wasting, jaundice, ascites, and edema. Many patients may also have asterixis (flapping motion of the hands when the patient is asked to hold up their arms and flex their hands).
How do you diagnose HE?
The diagnosis of HE is usually made based on clinical symptoms and the exclusion of other causes of mental status change (stroke, head trauma, etc). Common symptoms that occur in HE include change in sleep patterns, mild confusion, forgetfulness, and mood changes. More severe symptoms include disorientation, moderate confusion or drowsiness, slurred speech and even unresponsiveness. In the most severe cases, a patient may have to be intubated to protect their airway.
Checking ammonia levels to diagnose HE is controversial and not commonly used in practice. This is for two reasons: 1. The accuracy of ammonia levels is influenced by many factors (most of which have to do with how the blood sample was handled). 2. Ammonia levels can be elevated in many physiologic conditions besides liver failure. . A CT scan of the brain should be considered if there is any question of the cause of symptoms (rule out cerebral hemorrhage).
What is the treatment for HE?
The treatment for HE aims at either reducing the absorption of ammonia in the intestinal tract or increasing the removal of ammonia.
Lactulose works by decreasing the absorption of ammonia in the intestinal gut. When lactulose is catabolized by bacteria in the gut, it lowers the colonic pH. This lower pH then favors ammonia’s conversion to ammonium which is nonabsorbable in the colon thereby reducing the overall ammonia concentration in the body. Most patients are instructed to take enough lactulose so that they have 3-4 soft stools daily. The most common side effects of lactulose are abdominal cramping, diarrhea and flatus.
Rifaxamin is an antibiotic that treats HE by decreasing the production and absorption of ammonia. Although this medication may be better tolerated, it tends to be more costly than lactulose and is best suited for patients who cannot tolerate lactulose. In combination with lactulose, rifaximin may be more effective than either drug alone.
What should I do if I think a loved one has acute HE?
The best thing to do is call your doctor’s office. By asking a few questions over the phone, a qualified health care professional can determine if symptoms are mild and an office visit is appropriate, or if the patient needs to be admitted to a hospital for further evaluation and treatment. If symptoms are more severe (patient is unarousable), call 911 immediately.
What is the best way to prevent HE?
The best thing you can do to prevent HE is take your medicines as prescribed by your hepatologist and follow-up with your doctor regularly. If you have advanced liver disease, it is always important to let your doctor know of any signs of infection (fever), constipation, dehydration (decreased urine output, dizziness) and mental status changes.
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