Nutritional support in hepatic failure: current thought in practice

Enteral and parenteral feedings. Guidelines and recommendations

The clinician is confronted with many options in choosing appropriate nutritional support for a patient. Several major issues emerge. 1. Supplemental nutritional support is appropriate in patients who will not be able to take oral calories for more than 7 days. Individuals with preexisting deficits due to lifestyle or disease should have support started more promptly. 2. The use of TPN as a preoperative adjunct in surgical patients appears to be beneficial only to those with severe malnutrition. 3. In the vast majority of patients, the enteral route is preferred. Total parenteral nutrition appears to be beneficial in those with inadequate absorptive capacity, fistula, acute hepatic/renal failure, inflammatory bowel disease, and as an adjunct to cancer therapy. 4. Complications associated with enteral and parenteral nutrition delivery can be minimized by careful attention to detail and adequate monitoring of responses. 5. An exciting area beyond the scope of this monograph is the emergence of the field of "Nutritional Pharmacology" where one manipulates the patient's diet to achieve a desired physiologic result, just as one will change antibiotics or pressors. This will provide an additional tool to the clinician in the treatment of critically ill patients.

Nutritional support for the patient with pancreatobiliary disease

Critically ill patients with severe pancreatobiliary disease exhibit multiple nutritional alterations compounded by the stress response. Acute pancreatitis may present as a life-threatening illness; patients are likely to be hypermetabolic and may have hyperglycemia and hypocalcemia. Nutritional support from parenteral or enteral feeding will probably be required in patients presenting with three or more positive risk factors as determined by Ranson criteria. Nutritional therapies for liver disease vary according to the specific disorder manifested. Patients with fulminant hepatic failure need to be monitored for profound hypoglycemia. Encephalopathy may develop in patients with acute-on-chronic liver disease, necessitating a protein restriction. Patients undergoing liver transplant are a perioperative challenge due to the combination of preoperative malnutrition, an extensive surgical procedure, and postoperative stress. Such patients require individualized assessment and management.

Nutritional support in liver failure

The most important manifestations of advanced liver disease are malnutrition, encephalopathy, and hepatorenal syndrome. Appropriate and optimal nutritional and metabolic support with specially formulated solutions enriched in branched-chain amino acids, together with other advanced treatments such as plasmapheresis, hemofiltration, and continuous arteriovenous hemodialysis, can correct the most important metabolic and clinical aberrations and temporarily improve the quality of life. However, the ultimately poor prognosis of patients with severe liver failure has not been altered significantly to date by the provision of nonspecific or specifically tailored nutrient regimens. The prognosis appears to depend on the arrest, correction, or reversal of the primary pathophysiologic process.

Nutrition and alcoholic liver disease

While the rate of malnutrition is relatively modest in alcoholic patients without alcoholic liver disease, the rate of malnutrition is virtually 100% in patients with alcoholic hepatitis and/or alcoholic cirrhosis. The reasons for malnutrition in the alcoholic hepatitis patient include various factors such as anorexia, poor diet, malabsorption, and altered metabolic state. When the patient is hospitalized, the malnutrition frequently worsens because of fasting for tests, continued anorexia, and complications such as gastrointestinal bleeding. Patients with severe acute hepatitis appear to be both hypermetabolic and hypercatabolic, whereas data are much more conflicting concerning patients with more stable liver disease. Most studies suggest that patients with alcoholic liver disease require at least 60 g of protein per day to maintain positive nitrogen balance. Consistent alterations in plasma amino acid profiles occur in alcoholic liver disease, and specialized nutritional formulations have been devised to correct this amino acid profile with the intent of improving overall nutritional status, hepatic encephalopathy, and mortality. The effects of nutritional support (including use of specialized products) on outcome, on acute hepatic encephalopathy, and on chronic or latent portal systemic encephalopathy are reviewed.

Pathophysiology and clinical basis of prevention and treatment of complications of chronic liver disease

Chronic liver failure is characterized by the appearance of jaundice, ascites, encephalopathy and/or gastrointestinal bleeding. Acute episodes of hepatic decompensation are frequently precipitated by additional events, e.g. septicaemia, diuretic therapy or excessive protein intake. Identification, correction and treatment of these precipitating factors are first steps in the management of chronic liver failure. Nutritional support is important in the treatment of cirrhotic patients, because malnutrition is one of the major determinants of patient outcome. Management of encephalopathy reduces the appearance of gut-derived nitrogenous toxins and corrects imbalances in amino acid metabolism. Treatment of ascites is salt restriction supported by gentle and incremental administration of diuretics. Ursodesoxycholic acid has become a new and promising modality in the management of cholestatic liver diseases. If conservative therapy fails to recompensate liver function, liver transplantation may be indicated.