Hepatic failure
Introduction
Hepatic failure, also known as liver failure, is a severe condition characterized by the inability of the liver to perform its normal synthetic and metabolic functions. This condition can be acute or chronic, with each form having distinct etiologies, pathophysiology, and clinical presentations. The liver is a vital organ responsible for numerous functions, including detoxification, protein synthesis, and the production of biochemicals necessary for digestion. When the liver fails, these functions are compromised, leading to a cascade of systemic effects.
Types of Hepatic Failure
Acute Hepatic Failure
Acute hepatic failure, also known as acute liver failure, is a rapid deterioration of liver function, typically occurring within days or weeks. It is often caused by acetaminophen overdose, viral hepatitis, or exposure to hepatotoxins. The hallmark of acute hepatic failure is the development of hepatic encephalopathy and coagulopathy, often accompanied by jaundice.
Chronic Hepatic Failure
Chronic hepatic failure, or chronic liver failure, develops over months or years and is often the result of chronic liver diseases such as cirrhosis, chronic hepatitis B or C infection, and non-alcoholic fatty liver disease (NAFLD). In chronic hepatic failure, the liver gradually loses its ability to function, leading to complications such as portal hypertension, ascites, and variceal bleeding.
Pathophysiology
The pathophysiology of hepatic failure involves complex interactions between hepatocyte injury, inflammation, and fibrosis. In acute hepatic failure, massive hepatocyte necrosis occurs, leading to a sudden loss of liver function. In contrast, chronic hepatic failure involves progressive hepatocyte damage and fibrosis, eventually resulting in cirrhosis. The liver's regenerative capacity is overwhelmed, and the remaining functional liver mass is insufficient to maintain normal metabolic and synthetic activities.
Clinical Manifestations
The clinical manifestations of hepatic failure vary depending on the type and severity of the condition.
Symptoms of Acute Hepatic Failure
- **Jaundice**: Yellowing of the skin and eyes due to elevated bilirubin levels. - **Coagulopathy**: Impaired blood clotting leading to easy bruising and bleeding. - **Hepatic Encephalopathy**: Confusion, altered mental status, and coma due to the accumulation of toxins like ammonia. - **Renal Dysfunction**: Often seen in the form of hepatorenal syndrome.
Symptoms of Chronic Hepatic Failure
- **Ascites**: Accumulation of fluid in the abdominal cavity. - **Portal Hypertension**: Increased pressure in the portal venous system leading to varices. - **Muscle Wasting**: Due to malnutrition and metabolic disturbances. - **Spider Angiomas**: Small, spider-like blood vessels visible on the skin.
Diagnosis
Diagnosis of hepatic failure involves a combination of clinical assessment, laboratory tests, and imaging studies.
Laboratory Tests
- **Liver Function Tests**: Elevated liver enzymes (AST, ALT), bilirubin, and alkaline phosphatase. - **Coagulation Profile**: Prolonged prothrombin time (PT) and international normalized ratio (INR). - **Serum Ammonia Levels**: Often elevated in hepatic encephalopathy.
Imaging Studies
- **Ultrasound**: To assess liver size, texture, and presence of ascites. - **CT/MRI**: Detailed imaging to evaluate liver structure and detect complications like tumors or thrombosis.
Management
Management of hepatic failure focuses on treating the underlying cause, supporting liver function, and managing complications.
Acute Hepatic Failure
- **N-Acetylcysteine**: Antidote for acetaminophen toxicity. - **Antiviral Therapy**: For viral hepatitis. - **Liver Transplantation**: Considered in cases of irreversible liver damage.
Chronic Hepatic Failure
- **Lifestyle Modifications**: Alcohol cessation, dietary changes, and weight management. - **Medications**: Diuretics for ascites, beta-blockers for portal hypertension, and lactulose for hepatic encephalopathy. - **Liver Transplantation**: Definitive treatment for end-stage liver disease.
Prognosis
The prognosis of hepatic failure depends on the etiology, severity, and timely intervention. Acute hepatic failure has a high mortality rate without liver transplantation, while chronic hepatic failure progresses slowly but can lead to life-threatening complications.
Prevention
Preventive measures include vaccination against hepatitis viruses, avoiding hepatotoxic substances, and managing risk factors for chronic liver disease.