Nutritional Management of Infants and Children with Specific Diseases and Other Conditions1
Arthur Cooper
Richard L. Mones
WillIam C. Heird
1Abbreviations: AIDS, acquired immunodeficiency syndrome; EFA, essential fatty acid; GERD, gastroesophageal reflux disease; GFD, gluten-free diet; HAART, highly active antiretroviral therapy; HIV, human immunodeficiency virus; LBW, low birth weight; ORS, oral rehydration solution; REE, resting energy expenditure; TPN, total parenteral nutrition; VLBW, very low birth weight.
Nutritional management of infants and children with specific diseases and other conditions encountered in pediatric patients requires a working knowledge both of the causes and effects of their common ailments and of why and how these ailments alter their nutritional requirements. This chapter reviews the nutritional implications of specific diseases and other conditions that alter dietary requirements and discusses the general approach to nutritional management, with detailed reference both to enteral and parenteral nutritional support.
SPECIFIC DISEASES AND OTHER CONDITIONS REQUIRING NUTRITIONAL MANAGEMENT
Cardiopulmonary Disorders
The two major cardiopulmonary disorders for which children require nutritional support are congenital heart disease and cystic fibrosis. Other conditions causing cardiac or respiratory failure, such as congenital or acquired cardiomyopathies and interstitial lung diseases, are far less common, although a similar approach is used for their nutritional management.
Congenital Heart Disease
Chronic protein-energy malnutrition, manifested chiefly by growth failure, is a common finding in infants and children with congenital heart disease, particularly those with conditions associated with congestive heart failure and pulmonary hypertension (1, 2, 3, 4, 5, 6). Although not studied extensively in recent years, the nutrient needs of pediatric patients with mild heart disease do not seem to be much greater than those of infants or children without heart disease. However, they may be significantly greater in children with severe heart disease (1, 7, 8). Even so, in the majority of patients, the primary cause of the associated malnutrition can be traced to inadequate intake (1, 2, 3, 6, 7). In some patients, this is a result simply of poor appetite; in others, it seems to be the result of excessive tiring during feeding. In addition, fluid and sodium intakes frequently are restricted as a part of treatment, and the use of diuretics is common. Either practice, of course, may limit growth even if intake of protein and energy is adequate.
The most common form of nutritional therapy for infants with congenital heart disease is use of a high- nutrient-density formula, thereby reducing the volume that must be ingested. Tube feedings through either a nasogastric or a gastrostomy tube are frequently necessary, particularly in infants whose disease is sufficiently severe to cause excessive tiring during feeding. In general, if sufficient nutrients are delivered, most such patients will grow at a reasonably normal rate (9, 10, 11, 12, 13). In addition, catch-up growth will occur in most children following corrective surgery for congenital heart disease so long as extra protein and energy are made available (14).
Cystic Fibrosis
Cystic fibrosis is characterized by progressive deterioration of pulmonary and pancreatic function. The pulmonary disease may increase nutrient requirements somewhat, but probably it affects nutrition more by adversely affecting intake, particularly during acute exacerbations and in older children with severe pulmonary disease. Pancreatic insufficiency severely limits the absorption of fat, a major energy source of most diets. Thus, the cause of malnutrition in infants and children with this disease can be both primary (i.e., inadequate nutrient intake) and secondary (i.e., fecal losses of protein, and particularly, of fat). The secondary cause usually can be controlled with appropriate pancreatic enzyme replacement because there does not seem to be a primary defect in energy metabolism associated with the disease (15).
Traditionally, a high-protein, low-fat diet has been advocated for patients with cystic fibrosis. However, with appropriate pancreatic enzyme replacement, most patients can maintain a reasonable nutritional status with a normal diet. Younger patients usually have a very good appetite, but with advanced pulmonary disease, appetite usually decreases. In many patients with advanced disease, intakes of both protein and energy, but especially energy, are far lower than recommended. For such patients, supplemental enteral formulas may be provided; semielemental diets appear to offer no advantage over nonelemental diets so long as pancreatic enzyme replacement is maintained (16). From time to time, the theoretic possibility of essential fatty acid (EFA) deficiency secondary to poor fat absorption has also been mentioned. However, unless the intake of EFAs is quite low, this is rarely a significant problem, except in infants with meconium ileus who undergo surgical resection of the distal ileum (17).
Some concern exists that malnutrition may hasten deterioration of pulmonary function, and an increasing body of evidence supports this concern (18, 19, 20). Further, it is clear that acute improvement of nutritional status improves muscle strength and lung function (21, 22). Thus, attempts either to improve nutritional status or to prevent even minimal deterioration of nutritional status are warranted, particularly because it seems that early intervention may prevent malnutrition and improve long-term growth (23). Unfortunately, eating behaviors in infants, toddlers, and school-age children with cystic fibrosis may not be sufficient to meet the additional dietary requirements imposed by the disease (24, 25). In such cases, use of pharmacologic adjuncts (e.g., appetite stimulants such as megestrol acetate, and human growth hormone) may be effective in enhancing weight gain, but they may not improve lung function (26, 27, 28). Moreover, weight gain and improvement of other anthropometric indices may significantly underestimate the extent of malnutrition in affected children (29, 30, 31).
High-fat formulas have been advocated for patients with chronic pulmonary disease. The rationale, supported adequately by fact, is that oxidation of fat produces less carbon dioxide than oxidation of carbohydrate, and hence a high-fat intake imposes less stress on the already compromised pulmonary system. This obviously is an important consideration in patients who require mechanical ventilation or have severely compromised pulmonary function. One product based on this principle (Pulmocare; Ross Laboratories, Columbus, OH) is available for patients with pulmonary disease. Although designed for adults, the product is used in pediatric patients; however, its sodium content is quite high. Finally, attention must be given to adequate supplementation of fat-soluble vitamins, particularly vitamin K, which may be deficient in patients with cystic fibrosis (32).
Although clearly much progress has been made in the medical and nutritional management of cystic fibrosis, much more remains to be done (33). A Consensus Report on Nutrition for Pediatric Patients with Cystic Fibrosis from the Cystic Fibrosis Foundation and the North American Society for Pediatric Gastroenterology and Nutrition details current recommendations in greater depth than is possible here (34).
Gastrointestinal Disorders
Malnutrition is endemic among infants and children with gastrointestinal disorders. The cause usually is loss of nutrients secondary to the specific derangement in gastrointestinal function, either diarrhea or vomiting. However, both diarrhea and vomiting are frequently treated by withholding all nutrients except water and electrolytes. This practice, of course, contributes to the development of malnutrition.
Acute Diarrhea
Acute diarrhea caused by most common organisms rarely persists for more than 4 to 5 days. During this time, the major goal of therapy is to ensure a normal state of hydration. This can be accomplished with use of oral rehydration solution (ORS), modified ORS for malnourished children, and/or special formulas (Table 71.1), each with its own advantages and disadvantages (35). Hospitalization and intravenous fluid therapy may be necessary, particularly if fever and/or vomiting accompany the diarrhea.
What to feed and whether to feed the child with acute diarrhea have been subjects of considerable controversy for many years, and both remain unresolved. In general, stool output is greater in the patient who is fed, but this does not mean necessarily that feeding should be proscribed. In most patients, at least some nutrient intake is possible; however, the nature of this intake must be selected, carefully taking into account the age of the patient as well as the severity and probable cause of the diarrhea. One approach is outlined later; other approaches, of course, may be equally successful, particularly in developing countries, where hospital resources may be limited, thus necessitating use of a
liquid milk-based diet, and/or a dry, solid, ready to use therapeutic food that can be eaten without adding water (e.g., Plumpy’nut; Nutriset, Malaunay, France), to minimize the risk of bacterial contamination (36). A Working Group Report from the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition summarizes the latest advances in this field (37).
liquid milk-based diet, and/or a dry, solid, ready to use therapeutic food that can be eaten without adding water (e.g., Plumpy’nut; Nutriset, Malaunay, France), to minimize the risk of bacterial contamination (36). A Working Group Report from the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition summarizes the latest advances in this field (37).
TABLE 71.1 COMPOSITION (AMOUNTS OF MAJOR INGREDIENTS/100 kcal) OF SPECIAL FORMULAS FOR INFANTS WITH DERANGED OR IMMATURE INTESTINAL FUNCTION | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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In general, the most common cause of acute diarrhea in developed countries is viral infection, chiefly resulting from contact with infected individuals; less common is bacterial infection, related either to socioeconomic dislocation or foreign travel (38, 39). Therefore, a stool culture to detect a specific pathogen usually is not helpful. The pathophysiology of most toxicogenic (i.e., enteropathogenic) bacterial diarrheas (e.g., Salmonella, Shigella, and Campylobacter spp., enteropathogenic Escherichia coli serotype O157:H7) is secretory diarrhea resulting from stimulation of the adenylate cyclase system, as occurs in cholera) (40); by contrast, the pathophysiology of most viral diarrheas (e.g., rotavirus) is both osmotic (inhibition of glucose transport as described for rotavirus) (41) and secretory. As such, testing the stool for pH and the presence of reducing substances may be very helpful, because a low pH (<6.0) and the presence of reducing substances suggest carbohydrate intolerance, hence a viral origin. The stool is best tested after a period of adequate intake of a reducing sugar (e.g., a 5% glucose solution or ORS); in addition, the water content of the stool, rather than any solid matter, should be tested.
Carbohydrate malabsorption in acute diarrhea is common but fortunately transient in most cases. Malabsorption of all carbohydrates, including glucose, may occur. However, this should not preclude administration of ORS in acute diarrhea. Occasionally, the carbohydrate malabsorption persists, and the patient develops postinfectious gastroenteritis. Young infants in lower growth percentiles who present with metabolic acidosis are particularly vulnerable to postinfectious gastroenteritis. Before the inception of total parenteral nutrition (TPN), this entity carried a high case fatality rate. However, this condition can now be managed successfully in most cases with nutritional support through the parenteral route with careful introduction of elemental or semielemental formulas.
If the origin of the diarrhea seems to be osmotic, and reintroduction of a carbohydrate-containing formula results in resumption of the diarrhea, a carbohydrate-free formula (see Table 71.1) usually is well tolerated. However, such formulas can result in ketosis and occasionally hypoglycemia; thus, some carbohydrate intake is necessary. In the hospitalized child, this can be provided intravenously. Most children who do not require hospitalization usually tolerate at least some sugar intake by the enteral route. In general, 0.5 g of glucose or sucrose per ounce of formula, provided intake is adequate but not excessive, is well tolerated and prevents ketosis and hypoglycemia. If this preparation is tolerated, the amount of carbohydrate can be increased daily or every other day as tolerance for carbohydrate increases. Once full carbohydrate content (i.e., approximately 2 g/oz) is tolerated, the patient usually can be switched to a carbohydrate-containing formula.
If the origin of the diarrhea is secretory, feeding usually does not affect the volume of stool output. In many cases, in fact, a glucose-electrolyte solution (e.g., ORS) seems to decrease the volume of stool output. In any event, fluid and electrolyte replacement must keep pace with intestinal losses until the diarrhea abates. Therefore, decisions concerning feeding must be based on clinical experience in such patients.
Regardless of the cause of the diarrhea, the tendency to avoid feedings containing lactose, especially breast milk, in most infants with diarrhea is unnecessary. In fact, continued breast-feeding should be encouraged. If stool pH is normal when the child is first seen and reducing substances are not present, lactase deficiency is an unlikely contributor to the diarrhea.
In a few patients, the acute episode of diarrhea does not resolve in the usual 4 to 5 days. In these patients, nutritional management becomes a much more important consideration. Although most infants can tolerate a 4- to 5-day period with little or no nutritional intake, few can tolerate a period of more than 2 weeks without becoming malnourished and developing secondary intestinal changes caused by both persistent diarrhea and malnutrition. Such infants are much more likely to develop secondary deficiencies of mucosal disaccharidases (e.g., lactase deficiency, and less commonly, sucrase deficiency). Monosaccharide intolerance may also develop. In these infants, management without hospitalization is difficult. Choice of formula again must be made on the basis of the suspected or culture-proven cause of the diarrhea; in addition, the much greater likelihood of secondary mucosal hydrolase deficiencies must be taken into account. If small volumes of a particular formula are reasonably well tolerated, it frequently is possible to deliver sufficient amounts to meet nutritional needs by use of a continuous infusion technique (41). Again, in small infants, this usually requires hospitalization.
Chronic Diarrhea
Noninfectious causes of chronic diarrhea result from a spectrum of congenital or acquired abnormalities that include changes in villous structure (e.g., celiac disease), ultrastructural abnormalities (e.g., microvillous inclusion disease), and abnormalities at the molecular level (e.g., congenital chloride diarrhea). If not managed appropriately, these disorders frequently result in the same secondary changes in mucosal function observed in acute diarrheas. The nutritional management of the two most common illnesses associated with chronic diarrhea, celiac disease and inflammatory bowel disease, are described here. Nutritional management of other chronic diarrheas, in general, is similar to that described earlier and must be
tailored to the specific cause and pathophysiology of these conditions.
tailored to the specific cause and pathophysiology of these conditions.
Celiac Disease. Celiac disease (gluten-sensitive enteropathy) has been recognized to be far more common than was previously thought (42, 43). Strict adherence to a gluten-free diet (GFD) is the cornerstone of therapy; a safe gluten threshold has been established for adults with celiac disease (44). Foodstuffs must contain less than 20 ppm to be considered gluten free. Patients with celiac disease are restricted from eating products that contain wheat, barley, or rye. Compliance is problematic among children, especially among adolescents diagnosed through mass screening, who may lack the typical symptoms (45). Fortunately, some oat cereals have been found to be a safe substitute for gluten-rich cereals and may facilitate management of children with this condition (46). Adherence to a strict GFD is important for reasons other than symptom management. Achievement of adequate growth, maintenance of normal bone mineral density, and correction of iron deficiency anemia are but a few examples of the importance of adherence to a strict GFD (47, 48, 49). Again, a Working Group Report from the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition describes the current approach to treatment of these patients (50).
Inflammatory Bowel Disease. Inflammatory bowel disease, including both ulcerative colitis and Crohn disease (regional enteritis, granulomatous colitis), is another condition associated with chronic diarrhea and growth failure that often becomes permanent despite appropriate nutritional intervention (51, 52, 53). Because ulcerative colitis afflicts only the large intestine, thus leaving the absorptive functions of the small intestine fully intact, its effects on growth are limited. However, the pathophysiology of Crohn disease, which chiefly affects the distal ileum (although it can involve any area of the alimentary canal), is transmural inflammation; the precise cause remains uncertain, but it likely involves complex interactions among environmental, immunologic, and bacterial factors in genetically susceptible hosts. Inadequate nutrition and growth failure in Crohn disease, which may affect as many as 30% of children with the disease, are the result of inadequate intake and the cumulative effects of inflammation on growth; in fact, the disease is typically heralded by an unexplained slowing of linear growth before diagnosis (54, 55, 56).
Anti-inflammatory (i.e., immunosuppressive) agents (e.g., 5-aminosalicylate derivatives) and immunomodulating agents (e.g., azathioprine) are the mainstays of therapy for induction as well as maintenance of remission; corticosteroids (e.g., prednisone) may also be prescribed, but long-term use is associated with an unacceptably high incidence of side effects in children.
The observation that patients prepared for surgical management of complications related to Crohn disease (e.g., intestinal obstruction, perforation, abscesses, fistulas) experienced improvement in symptoms led to the use of elemental and semielemental diets as a primary treatment. Although the precise mechanism of this improvement is unknown, it is clear that elemental enteral nutrition indexed to 133% of ideal body weight or 60 to 75 kcal/kg actual body weight may achieve treatment results in children, although not in adults, that are comparable to those obtained with anti-inflammatory agents (57, 58, 59, 60, 61, 62, 63).
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