The number of transplants continues to grow with continued medical advances in the area of solid organ transplantation and immunosuppressive therapy. Prolonged waiting times for transplant candidates—even up to 1-2 years (as long as 5-7 y for kidney transplantation)—have led to rising concerns regarding the nutritional management of these patients in combination with required medical therapy. The following conditions require early assessment of the individual's nutritional status with aggressive intervention in anticipation of positive clinical outcomes:
The goals of nutrition therapy during the wait for transplantation are (1) to replenish malnourished individuals, (2) to maintain the status of those with adequate muscle and energy reserve, (3) to promote weight loss in candidates with excessive weight based on body mass index (BMI), and (4) to manage patients' symptoms to maximize quality of life. For excellent patient education resources, visit eMedicine's Heart Center, Lung and Airway Center, and Kidneys and Urinary System Center. Also, see eMedicine's patient education articles Heart and Lung Transplant and Kidney Transplant. For further information on renal transplantation, see Mayo Clinic - Kidney Transplant Information.
Subjective global assessment Standard parameters of nutritional assessment are often invalid in end-stage organ failure, which leads to difficulty in identifying and assessing nutritional status. The combination of objective and subjective parameters has been established as the best approach in the nutritional assessment of these individuals and is an excellent independent predictor of outcomes in patients undergoing liver transplantation. Subjective global assessment (SGA) is a clinical evaluation of protein-energy malnutrition (PEM) based on evidence of edema, ascites, muscle wasting, subcutaneous fat loss, decreased functional capacity, and gastrointestinal symptoms of diarrhea, nausea, vomiting. This tool has also been studied for use in assessing patients on dialysis and candidates for lung transplantation. Based on the results of this history and physical assessment, patients can be placed in nutritional risk categories of well nourished, mildly to moderately malnourished, or severely malnourished. Patients in moderately to severely malnourished states who have progressive weight loss or muscle wasting—especially with excessive fluid retention in kidney, heart, or liver disease with ascites and decreased functional capacity—are considered high risk and require aggressive nutrition intervention. Despite the widespread use of SGA, some studies have found it to be imprecise, with a sensitivity of 22% and a specificity of 96% when evaluating patients with alcoholic cirrhosis. This problem has led to the development of other parameters for measuring nutritional status in patients awaiting transplantation. Anthropometrics and laboratory values The more traditional nutritional assessment parameters of anthropometrics, including triceps skinfold (TSF) and arm muscle circumference (AMC), can be used to assess the degree of fat or muscle store loss and are useful in monitoring changes in a patient's status over time. These measurements can be affected by hydration status, edema, or fluid overload. Assessment of lean body mass by dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance analysis (BIA) are also affected by hydration status, which limits their usefulness. Laboratory values for hemoglobin, hematocrit, serum iron, transferrin, glucose, blood urea nitrogen, creatinine, lipid profile, and protein stores of albumin and transthyretin (prealbumin) should be evaluated and monitored. Albumin synthesis is reduced with decreased hepatic synthesis. Electrolyte balance requires close monitoring for transplant candidates on diuretics or dialysis and for those with malabsorption induced by lactulose to treat hepatic encephalopathy. Other methodologies used in assessing nutritional status BIA is a recently described method used for assessing PEM in patients with chronic liver disease. Many studies have reported that BIA is an inaccurate estimate of PEM in cirrhotic persons with ascites or edema. Imprecision has also been reported in evaluating cirrhotic persons without fluid retention, particularly when extrapolating from population studies. Sophisticated measurements of body cell mass show that this central, expanding mass of working tissue and most important metabolically active component in the body is decreased in cirrhotic patients, irrespective of etiology. Three different measurements, ie, total body potassium, intracellular water, and total body protein, are decreased in cirrhotic individuals. Clinicians must remember that all methods commonly used for nutritional assessment, particularly in cirrhotic patients, are influenced by the presence of liver disease per se or are influenced in combination with renal failure, alcohol ingestion, and expansion of the extracellular water compartment. Nevertheless, nutritional assessment is beneficial in all patients awaiting organ transplantation, particularly when a composite score emphasizing anthropometry is combined with overall clinical judgment.
Nutritional goals for patients with end-stage organ failure awaiting transplantation depend on the individual's weight history and current status. The ultimate goal is to maintain muscle and fat stores in those with adequate stores, to replete those who are moderately to severely malnourished based on SGA rating, and to promote weight loss in candidates who are obese. In liver disease, a poor nutritional state and hypermetabolism adversely affect survival after liver transplantation. On the other hand, severe obesity with BMI greater than 35 kg/m2 is associated with wound infection, multisystem organ failure, and increased transplantation costs. In heart transplant recipients, a reduction of weight-to-BMI ratio to less than 27 kg/m2 is suggested. Nutritional Requirements
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Liver Malnutrition in cirrhosis is multifactorial. Inadequate diets and unnecessary dietary restrictions of protein, fluid, and salt can lead to less palatable diets and a suboptimal oral intake. Malabsorption may occur because of bile salt or exocrine pancreatic insufficiency and decreased fat absorption, which can occur in cholestatic and noncholestatic patients. Anorexia and early satiety, especially in the presence of ascites, is common because of a reduced gastric capacity for a normally sized meal from pressure exerted on the stomach, diaphragm, and intestinal tract. Altered protein and energy metabolism can also occur with accelerated protein breakdown and amino acid oxidation for energy and an increased rate of gluconeogenesis. The incidence of protein and energy malnutrition is high in patients with end-stage liver disease who have cirrhosis, and weight loss occurs in up to 60%. Up to 100% of patients with alcoholic hepatitis may be malnourished, and they exhibit greater deficits in muscle rather than fatty stores. Quantitative disturbances in energy metabolism in cirrhosis are heterogeneous. No pattern has been consistently identified when absolute energy expenditures of control and cirrhotic patients have been compared; however, when measured energy is expressed in comparison to calculated energy expenditure, energy expenditure is normal in most cirrhotic patients, although 16-34% are hypermetabolic. The type of liver disease and stage of disease may account for some of these variables in energy expenditure. Indirect calorimetry is often useful in the hospitalized patient to assess actual energy requirements. Protein requirements in liver disease are difficult to assess when prescribing nutrition recommendations. In most stable cirrhotic patients, 0.8 grams of protein per kg is the minimum daily requirement. To promote positive nitrogen balance and to prevent endogenous protein breakdown, 1.2-1.5 grams of protein per kg are recommended. Avoid unnecessary protein restrictions, which may exacerbate malnutrition in some patients. If the patient appears to be protein sensitive with an increased incidence of encephalopathy on the higher level of protein intake, branched-chain enteral formulas with restricted aromatic amino acids can be used to assure a continued level of protein intake. Diets high in vegetable protein and soy protein may be beneficial for more optimal protein intake without exacerbating encephalopathy. Even though malnutrition is a poor prognostic factor in both adults and children undergoing liver transplantation, only one study has evaluated pretransplant nutritional therapy. This study reported that a formulation enriched with branched-chain amino acids (BCAAs) was more effective than standard amino acids for improving height and body weight in pediatric patients awaiting liver transplantation (Chin, 1992). Kidney Up to 40% of patients with chronic renal failure requiring hemodialysis or long-term peritoneal dialysis reportedly have PEM and are associated with increased morbidity and mortality rates. Decreased levels of nitrogen stores and body weight and depleted visceral protein stores of albumin and transferrin are observed. Vitamin and mineral deficiencies of vitamin B-6, folic acid, vitamin C, 1,25-dihydroxycholecalciferol, and iron are common. Causes for malnutrition are multifactorial and include blood loss, protein and other nutrient loss during dialysis, catabolism due to chronic illness, and anorexia due to altered taste sensation, suboptimal oral intake, and depression. Pancreas Pancreas transplants are usually performed in combination with kidney transplants to treat diabetic nephropathy and to improve metabolic processes and quality of life. Nutritional management of pancreas transplant candidates is often quite variable, requiring management of renal function to prevent further nutritional decline. Even though obesity with BMI greater than 27 kg/m2 is not a contraindication to pancreas transplantation, it is thought to be a factor in delayed wound healing in the early posttransplant period. Greater weight gains following transplantation have been reported. Such weight gain in women may lead to poorer graft function and survival rates. Heart Malnutrition has been reported in 45% of patients awaiting heart transplant; these patients are at risk for developing cardiac cachexia. The specific form of PEM is thought to be caused by anorexia and hypermetabolism attributable to increased cardiac and respiratory workload. These patients display depleted visceral protein stores in addition to loss of fatty tissue and lean body mass. Adequate nutrition to achieve and maintain optimal nutritional status before transplantation is essential to reduce the postoperative length of stay and morbidity and mortality rates. When nutritional repletion is required, 35-40 calories per kg and 1.5-2 grams of protein per kg may be needed. Therefore, it is important to individualize diet recommendations to the specific patient, to provide energy-dense nutritional supplements as needed to meet energy requirements, and to restrict fluid or sodium only when necessary. If weight loss is required to attain a BMI of less than 27 kg/m2, calories should be restricted by 500 per day to promote 1 pound of weight loss per week. Encourage exercise as tolerated to promote loss of fatty tissue while maintaining lean muscle mass. The encouragement of exercise applies to all adults awaiting transplantation, particularly those requiring weight loss because of an excessive BMI. Lung The incidence of malnutrition among patients with lung disease varies depending upon the etiology of their disease. Those with increased breathing work (eg, those with emphysema, cystic fibrosis, and other types of bronchiectasis) appear to be the most hypermetabolic and have the greatest incidence of malnutrition. In patients with cystic fibrosis, malnutrition may also be due to chronic lung infections and malabsorption. Poor oral intake due to early satiety, edema, and ascites from intra-abdominal pressure, in addition to hypoxia contributing to anorexia, lead to an increased incidence of malnutrition. When nutrition repletion is required, 35-40 calories per kg and 1.5-2.0 grams of protein per kg may be required. Frequent ingestion of small portions of energy-dense foods and supplements can help patients achieve optimal oral nutrition. If patients cannot consistently meet increased nutritional demands, they may benefit from enteral nutrition supplementation. Small bowel The main goal of small bowel transplantation is to offer patients previously dependent on total parenteral nutrition (TPN) an equal or better chance of survival than that offered by dependency on TPN. Other goals of SBT include reducing TPN-related complications such as metabolic bone disease, cholestasis, and liver failure. Metabolic bone disease, which occurs in up to 15% of patients within a few months after beginning TPN, can lead to osteomalacia, thus causing debilitating bone disease, joint pain, vertebral compression, and pathologic fractures. Chronic cholestasis occurs in 15-85% of patients on home TPN. This problem may be due to the length of time on TPN, the TPN prescription, and the possibility of intestinal or systemic conditions associated with intestinal failure. Chronic and end-stage liver disease continues to occur in patients on long-term TPN even though development of new TPN formulations has been pursued to reduce the incidence of hepatobiliary dysfunction, especially steatosis. In patients receiving long-term TPN, liver failure and death can ensue. Intestinal transplantation is now a possible option for long-term TPN-dependent patients in order to achieve nutritional autonomy and to remain well nourished and free from TPN within 3 months posttransplant, barring any unforeseen complications that necessitate TPN therapy (eg, chylous ascites, increased intestinal transit time).
Since the incidence of malnutrition among patients with end-stage organ failure is high, intensive nutritional assessment and development of an individualized nutrition care plan is required. Patients requiring intensive intervention include those determined to be in moderately to severely malnourished states (based on SGA) or potential transplant candidates with excessive body weight (based on BMI). The first line of nutrition intervention is optimizing the oral intake of patients with depleted muscle and fat stores. Small, frequent meals and snacks of energy dense foods are suggested. Commercially available liquid nutritional supplements help achieve optimal energy and protein intake based on assessed requirements. Self-recorded food logs can assist in serial monitoring of nutritional progress on routine clinic visits. More aggressive intervention should be considered only if the patient cannot maintain an adequate level of oral intake to sustain his or her weight or to promote nutritional repletion. Enteral nutrition supplementation can be implemented and managed well in the home setting with the support of today's home health care agencies. These agencies educate the patient and family and provide monitoring and troubleshooting assistance. Nutrition studies assessing outcomes of improvement in nutritional status, immune function, infection rates, length of stay, and posttransplant morbidity and mortality rates have shown positive benefits with aggressive pretransplant nutrition intervention. The skill and direction of the primary care physician in identifying and treating reversible causes of organ failure, in optimizing the patient's health and nutrition, and in anticipating ongoing potential problems the patient may incur lead to improved quality of life and lengthen the bridge to transplantation despite prolonged waiting periods for organs to become available.
Herbal therapy In today's health care environment, it has become evident that more patients are including dietary supplements in their own health care practices with the intention of optimizing their energy, health, and sense of well-being. Many products are readily available, including botanicals, vitamins, and minerals. Health care professionals must routinely inquire about the use of dietary supplements and other products, some of which may lead to adverse health effects. The literature identifies some herbal therapies as potentially helpful in protecting the liver from oxidative injury, promoting virus elimination, and blocking fibrogenesis (Schuppan, 1999). Herbal therapies include glycyrrhizin, phyllanthin, silibinin, picroside, and baicalein, which are derivatives of licorice root, milk thistle, and sho-saiko-to. Other herbal preparations that have proven hepatotoxicity include comfrey, greater celandine, chaparral, germander, and Chinese herbal mixtures. Issues of herbal therapy in perioperative care have recently raised concern as having a negative impact in this presurgical population. Worrisome herbs include Echinacea, ephedra, garlic, ginkgo, ginseng, kava, St John's wort, and valerian. Issues of bleeding from the use of garlic, ginkgo, and ginseng; cardiovascular instability from ephedra; and hypoglycemia from ginseng have been reported. Increased sedative effects of anesthetics by kava and valerian and increased metabolism of drugs used in the perioperative period are reportedly associated with St John's wort. Without full knowledge of potential adverse effects, many patients with end-stage organ failure are attempting to find over-the-counter medications to help in caring for themselves. As many studies have yet to be performed to assess the potential benefits of herbal therapies, health care professionals must stay familiar with the commonly used herbal medications and must recognize when such use should be discontinued. Bone disease Patients living with a chronic disease may not only show signs of malnutrition with muscle wasting and weight loss upon SGA but may also present with osteopenia, partly because of the lack of physical activity. The exact cause of low bone mineral density in cholestatic patients is not fully understood. Bone mineral density is best measured by DEXA. Optimizing the patient's nutritional status, assuring a calcium intake of 1-1.5 grams per day, and monitoring vitamin D levels can aid in supportive therapy to reduce this loss of bone density. Heart and kidney transplant candidates may also exhibit bone loss due to long-term use of loop diuretics or abnormalities in vitamin D, phosphorus, and calcium metabolism. The assurance of optimal medical management and reduction of further bone loss is essential because of the effects of posttransplant immunosuppressive therapy on bone mass.
Appropriate nutritional assessment and identification of specific nutrition requirements—whether maintenance, repletion, or the need for weight reduction prior to transplantation—require individualized assessment and, in some cases, aggressive nutrition intervention. The goals are to maintain the patient with end-stage organ failure prior to transplantation and to reduce postoperative complications after transplantation.
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