Transcript
Chapter 22: Alterations in Liver Function
Chapter Summary
ALF is diagnosed based on clinical criteria: coagulopathies, including INR greater than 1.5; encephalopathy in the absence of any previous history of cirrhosis; and duration of fewer than 26 weeks. It is subclassified by speed of onset of jaundice in relation to encephalopathy as hyperacute, acute, or subacute.
Causes of ALF include drug-induced, infectious, vascular, metabolic, and miscellaneous. In the United States, acetaminophen toxicity is the leading cause and results from a toxic metabolite of acetaminophen, NAPQI, which can accumulate in the liver, damaging hepatocytes. Infectious causes of ALF are hepatitis viruses, especially HBV in the United States. HEV is a common cause in other parts of the world. Vascular causes include shock liver, heart failure, and vascular obstruction. Metabolic causes include HELLP syndrome, Reye’s syndrome, and Wilson’s disease. There are a variety of other, uncommon (miscellaneous) causes, such as autoimmune hepatitis, malignancy, and mushroom poisoning.
The pathophysiologic basis of ALF is widespread destruction of hepatocytes with loss of liver function, which results in coagulopathies, reduced protein synthesis, and loss of ability to clear toxins.
Diagnosis of ALF requires a thorough history, physical examination, and blood work to determine the underlying cause and disease severity. A CT scan or ultrasound of the liver may also be conducted. Treatment of ALF depends partially on the cause. Acetaminophen toxicity requires clearing of the GI tract of any remaining drug. N-acetylcysteine (NAC) is a mainstay of therapy for reversing the toxic effects.
Complications of ALF include hepatic encephalopathy (HE) (graded in levels of severity from grade I to grade IV), cerebral edema, coagulopathy, hypoglycemia and electrolyte abnormalities, infection, cardiopulmonary abnormalities, and acute kidney injury. Each complication has its own set of clinical manifestations and treatments.
Treatment of HE focuses on reduction of ammonia levels. Lactulose is a major treatment, as it acidifies the colon, which inhibits absorption of ammonia through the GI tract and has a cathartic effect that results in rapid elimination of GI contents, which also decreases ammonia. Antibiotics, such as neomycin or rifaximin, may be administered to inhibit bacterial growth in the intestinal tract and reduce the formation of ammonia.
Patients with chronic liver disease may require high-acuity care for complications of their disease or for unrelated reasons (for example, trauma injury). Their chronic disease must be taken into consideration when planning care.
Esophageal variceal bleeding is a major, life-threatening complication of chronic liver disease. Varices (dilated, tortuous vessels) occur from backup pressure in the portal vascular system, and are prone to rupture. When rupture occurs, volume resuscitation is required and bleeding must be stopped. Interventions may include insertion of a Sengstaken–Blakemore tube for tamponading bleeding vessels as well as endoscopic interventions. A transjugular intrahepatic portosystemic shunt (TIPS) procedure may be considered to shunt blood from the portal vein into the inferior vena cava.
Ascites, an abnormal collection of protein-rich fluid in the peritoneal cavity, results from the shifting of intravascular fluids into the peritoneal cavity. It is caused by portal hypertension and hypoalbuminemia. Large volumes of fluid can accumulate in the abdomen, resulting in compromised ventilation and patient discomfort. Paracentesis, a needle aspiration procedure, may be performed to remove 4 or more liters of ascites to improve ventilation and make the patient more comfortable. Large-volume paracentesis requires protein replacement through administration of intravenous albumin.
Nursing management of the patient with ALF requires frequent monitoring of multiple system parameters and is a collaborative endeavor. The nurse supports efforts to determine and correct the underlying cause and support organ function while the liver recovers, the patient receives a liver transplant, or the patient dies. Interventions focus on maintaining hemodynamic and ventilatory stability and preventing or minimizing secondary complications.
