Nutrition in the Pediatric Surgical Patient

Healthy children need regular nourishment, including energy (ie, carbohydrates and fat), protein, vitamins, and minerals, for maintenance and growth. Surgical patients need nourishment for optimal wound healing. The daily nutritional needs of healthy children are best met by a balanced oral diet. However, it is not always possible to meet the needs of pediatric surgical patients in this fashion.

Although previously healthy children have reserves of energy and protein that allow survival and wound healing without exogenous nutritional support, these reserves are limited. Surgeons must be aware of these limits, must constantly monitor their patients' nutritional status, and must ensure that nutritional support is provided when necessary. This is particularly true for patients who are already undernourished and for those undergoing major gastrointestinal (GI) surgery who may not be able to tolerate a regular diet during the critical first 1-2 postoperative weeks.

Surgical patient populations at risk include the following:

• Neonates (especially those born prematurely)
• Patients with cancer receiving chemotherapy
• Patients with major trauma, burn injuries, or both
• Patients with inflammatory bowel disease
• Patients with chronic renal failure
• Patients with chronic neurologic disorders
• Patients with fever, sepsis, or both

Surgical diagnoses and procedures associated with an increased need for nutritional support include the following:

• Necrotizing enterocolitis
• Gastroschisis
• Perforating appendicitis
• Bowel resection

The basic energy and protein needs of healthy children are summarized in Table 1 below. Although it would seem logical to measure each patient’s energy needs by means of indirect calorimetry and to deliver calories accordingly, this is impractical and of unproven value. In practice, estimating protein and energy needs from standard references and monitoring the patient’s progress over time is acceptable.

Table 1. Normal Daily Recommendations for Energy and Protein (Open Table in a new window)

Children also need daily vitamins (A, B6, B12, C, D, E, K, thiamin, niacin, riboflavin, folate, pantothenic acid, biotin, choline), essential fatty acids, minerals (calcium, fluoride, iron, magnesium, phosphorus, zinc), and trace elements (chromium, copper, iodine, molybdenum, manganese, selenium).

Although previously healthy children can do without these nutrients for days, children who have been chronically malnourished, have abnormal GI losses, or require prolonged nutritional support may already have or may develop critical deficits of vitamins, essential fatty acids, minerals, and trace elements.

With the exception of those with major burns and trauma, pediatric surgical patients do not require more than the normal recommended amounts of energy and protein. Linoleic and linolenic acid are the essential fatty acids in infants, and standard lipid emulsions contain both. Insulin infusion has been shown to decrease protein breakdown in critically ill infants on extracorporeal membrane oxygenation (ECMO) when adequate dietary protein is provided. ^[1]

Nutritional assessment

The nutritional status of surgical patients can be assessed in several ways, as follows:

• Clinical evaluation (history and physical examination)
• Anthropometry
• Biochemical tests
• Body composition

Clinical assessment of nutritional status should be included in the history and physical examination of every surgical patient. The presence or absence of anorexia, nausea, and vomiting and chronic or recent weight loss should be documented in every case. The use of clinical judgment as the basis for global nutritional assessment has been validated for children. ^[2]

In addition to the complete history and physical examination, the patient should be weighed, and body length or height should be carefully measured and compared with standard growth charts. Evidence of malnutrition, including hair loss, skin breakdown, peripheral edema, and muscle wasting, should be sought during the physical examination.

Recent weight loss suggests acute protein-calorie malnutrition (PCM). Children whose weight is below the fifth percentile or who have recently lost more than 5% of body weight require further assessment and may need nutritional support. Abnormally low length or height for age suggests chronic PCM. Data also suggest that body mass index (BMI) determinations are useful in assessing overall nutritional status, and normative age-related values are available.

Other anthropometric measurements may provide information regarding current nutritional status and the response to rehabilitation. These include measurements of frontal-occipital head circumference (FOC), triceps skin-fold (TSF) thickness, and midarm circumference (MAC). FOC below the fifth percentile suggests chronic PCM. TSF thickness reflects fat (energy) stores, whereas MAC reflects lean body mass.

Serum levels of albumin, prealbumin, and retinol-binding protein are used as indices of protein synthesis. Reduced levels of these proteins in the blood represent another indication for nutritional support. Both retinol-binding protein and prealbumin are more sensitive markers for recent-onset nutritional deficits, in that the half-lives of these proteins are much shorter than the half-life of albumin.

Body composition can be directly or indirectly measured by means of several different methods, including total body water, body density, total body potassium, total body nitrogen, and bioelectric impedance. However, none of these has proved useful in clinical practice.

Preoperative nutritional support

Undernutrition is a predictor of poor surgical outcomes. ^{[3, 4, 5]} Preoperative refeeding can reduce the risk of postoperative complications in malnourished patients but provides no benefit to healthy, well-nourished surgical patients. Significant reductions in morbidity with the use of preoperative nutritional support are seen only in patients with severe undernutrition. ^[6] Enteral nutrition has been shown to reduce septic complications and to enhance wound healing, ^[6] and it is preferred to parenteral nutrition when practical.

Preoperative nutritional support, either enteral or parenteral, depending on the status of the GI tract ^[7] , should be considered for patients who are below the fifth percentile in weight for age or who have a recent 10% weight loss. To be effective, this support should be continued for at least 1 week. ^[6]

Although evidence suggests that the provision of nutrients to improve the nutritional status of surgical patients is beneficial, no compelling evidence suggests that specific amino acid supplementation (eg, glutamine) or the administration of anabolic adjuncts (eg, growth hormone or insulin) is beneficial.

Postoperative nutritional support

Endogenous carbohydrate stores are limited, and whereas muscle amino acids are available for gluconeogenesis in the stressed state, protein should not be considered a viable energy source under any clinical condition. Thus, fat is the only macronutrient stored in sufficient quantity to represent a useful endogenous energy source in the perioperative period.

The metabolic response to major surgery is not unlike that to major trauma. In the fasting postoperative patient, skeletal muscle protein is mobilized to provide protein for acute-phase reactants and wound healing. Energy is supplied mainly by mobilizing fat stores. In this situation, total parenteral nutrition (TPN) supplies needed energy to limit breakdown of body fat and protein, and this nutritional therapy prevents depletion of skeletal muscle by providing sufficient protein to maintain the circulating amino acid pool and to aid in tissue repair.

Although withholding oral feeding after GI surgery is a common practice, no proven benefit is noted. ^[8] The dictum is, “If the gut works, use it.” Early refeeding is beneficial, ^[9] in part because it stimulates enteric digestive enzyme synthesis. Enteral nutrients are also required to maintain intestinal mucosal integrity and local immunity, given that the gut derives roughly 50% of its overall nutritional requirements from luminal sources.

Postoperative parenteral nutritional support should be considered if the patient has been or is expected to be restricted to a nothing-by-mouth diet for more than 2 days in term neonates and infants or more than 5 days in older children. As stated, the enteral route should be used whenever possible (eg, after esophageal atresia repair via a transanastomotic feeding tube or gastrostomy).

Indications

The enteral route is safer and cheaper and is therefore preferred whenever nutritional support is required, provided that the GI tract is functional. This does not mean that the gut has to be completely healthy. For example, elemental formulas may work well in cases with distal enterocutaneous or colocutaneous fistulas.

Delivery

Although many patients tolerate oral dietary supplements in addition to regular food, children often have a difficult time consuming a sufficient volume of a chemically defined liquid formula by mouth to meet their full nutritional needs.

Accordingly, some type of feeding tube is usually required. For short-term support (as long as several weeks), a nasogastric tube may suffice. A nasoduodenal or nasojejunal tube may be helpful in the presence of gastroesophageal reflux (GER). However, all esophageal tubes tend to cause GER and esophagitis; thus, for long-term use, a feeding gastrostomy or jejunostomy is indicated.

Formula composition

Many liquid diets are available, with varying sources and composition of protein, fat, and carbohydrates. This variety usually allows the choice of an appropriate formula for the individual patient based on the composition of the formula, the underlying diagnosis, and the physiology of the GI tract.

Formulas commonly recommended for pediatric surgical patients (see Table 2 below) range in energy content from 0.67 cal/mL (equal to human milk) to around 1 cal/mL. All provide adequate protein for healing and growth. In addition, many formulas are designed for neonates and infants, including special formulas for premature infants and for those with cow’s milk protein allergy.

Table 2. Formulas Often Recommended for Pediatric Surgical Patients (Open Table in a new window)

Complications

Transesophageal tubes may cause GER, which can, in turn, lead to esophagitis, esophageal stricture, and aspiration pneumonia. Unless positioned and monitored carefully, they may inadvertently be placed into the trachea, leading to aspiration of feeds.

Abdominal cramps and diarrhea may occur if tube feeds are introduced too rapidly. This may be avoided by starting with dilute formula at a reduced rate and gradually working up to full feeds.

Gastrojejunal feeding tubes require frequent replacement and repositioning. ^[10] A simple jejunostomy may be preferable, especially for long-term use.

Indications

Total parenteral nutrition (TPN) is indicated in the following circumstances:

• When the GI tract is not accessible or not functioning (eg, with mechanical obstruction, paralytic ileus, or malabsorption)
• When gut rest is needed (eg, with proximal enterocutaneous fistula)
• When oral or enteral feeding does not meet the patient’s nutritional needs

In general, even healthy neonates should be given parenteral feeding if they are unable to begin or resume enteral feeding for more than 1-2 days. For previously healthy infants and young children, TPN is indicated after 3-5 days; for adolescents, TPN is indicated after 7 days. TPN should be started at any time, if enteral feeding will clearly not be possible for at least these durations.

In a study by Fivez et al that included 1440 critically ill children admitted to a pediatric intensive care unit (ICU), withholding parenteral nutrition for 1 week while administering micronutrients intravenously was found to be clinically superior to early parenteral nutrition. ^[11]  The primary end points were (1) new infection acquired during the ICU stay and (2) duration of ICU dependency. The new infection rate was 7.8 percentage points lower in children receiving late parenteral nutrition than in those receiving early parenteral nutrition, and the duration of ICU stay was 2.7 days shorter the former than in the latter.

Venous access

The choice of venous access for parenteral feeding primarily depends on the duration of TPN. For short-term needs, peripheral intravenous (IV) lines can be used as long as 7-10 days, especially in infants, for whom lower concentrations of dextrose (< 12.5%) combined with lipid emulsions can deliver adequate calories. However, with peripheral-vein TPN, IV lines must be changed frequently, and tissue damage is always a risk with extravasation.

Percutaneous nontunneled central venous lines may also be used for short courses of TPN (as long as a few weeks). Peripherally inserted central catheters (PICCs) have become increasingly popular. ^[12] These lines are inserted into a peripheral vein by means of the Seldinger technique under ultrasonographic guidance and are advanced, usually with the help of fluoroscopy, into a central vein. PICCs can be used in all age groups and can be maintained for weeks to months, thereby greatly reducing the need for needle sticks. They can also be used for blood tests.

When long-term TPN is required, a tunneled, cuffed, silicone rubber catheter is preferred. Ideally, this is tunneled from a skin exit site on the chest wall and inserted into the internal jugular vein via the Seldinger technique with ultrasonography used to locate the vein, then advanced into the superior vena cava (SVC) under fluoroscopic guidance. Other veins (eg, subclavian) can also be used. For premature infants weighing less than 1 kg and for patients with bleeding diatheses, cutdown to the external jugular or other superficial vein is a safe alternative.

All venous access devices can cause thrombosis and may become infected. Pneumothorax and arterial injury are also risks during the insertion of internal jugular and subclavian catheters. These complications can be avoided by using a PICC.

Formula composition

TPN solutions are designed to include all the basic nutrients that pediatric patients require for maintenance of normal body composition, growth, and tissue repair. These include protein, energy, carbohydrate, lipid emulsion, water, electrolytes, minerals, and trace elements.

Complications

Complications of TPN are uncommon but can be serious. Infants may be at greater risk for complications than older children are. ^[13] Routine monitoring of all patients on TPN should include fluid input and output assessment, regular weight measurements, and once- or twice-weekly measurement of blood urea nitrogen, creatinine, electrolytes, triglyceride, magnesium, and phosphate levels. Liver function and hemoglobin, albumin, calcium, iron, and zinc levels should be periodically checked.

The complications of TPN may be categorized as follows:

• Catheter-related - Infection
• Thrombotic - Cardiac arrhythmia, pulmonary embolism
• Metabolic - Hyperglycemia, hypoglycemia, metabolic acidosis, hypertriglyceridemia, electrolyte disturbance, cholestasis, fatty liver

Catheter infections usually necessitate removal and replacement of the line, especially if the organism is Staphylococcus aureus, a gram-negative bacteria, or a yeast. Guidelines for the prevention of intravascular catheter-related infections have been published by the Healthcare Infection Control Practices Advisory Committee (HICPAC). ^[14]

Some coagulase-negative staphylococcal infections can be cured with IV antibiotics without removal of the central venous line. Even in these cases, however, the catheter should be removed if blood culture findings remain positive. ^[15] Reports also suggest that ethanol locks can prevent or cure infections in silicone rubber central lines. ^[16]

Central venous thrombosis is a serious potential complication among children with intestinal failure who receive long-term parenteral nutrition via central venous access. ^{[17, 18]}  

Catheter-related complications, including infection, ^[19] may be limited by requiring that only personnel trained and credentialed in catheter management be permitted access to central venous lines.