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Quick Test posted on 8.30.10:
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Considerations in the Selection of Parenteral Nutrition
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Indications for Parenteral Nutrition Support
The association between malnutrition and development of complications and mortality is well documented in adult and pediatric patients. Although improvement in nutrition status as defined by various clinical nutrition markers has been reported in patients who received PN, the impact on clinical outcome is difficult to demonstrate in many adult populations. Several investigations have reported a positive effect of PN on complications and mortality, whereas others have failed to demonstrate any difference. Early studies have been criticized for defects in study design, such as small sample sizes, inappropriate randomization, and inconsistent baseline nutrition status among the study group, which hindered demonstration of the effectiveness of PN therapy. The impact of PN on clinical outcome has been more successfully demonstrated in critically ill infants and children, particularly those with acquired or congenital GI tract anomalies. Consensus guidelines for PN use in adults (Table 145–1) and pediatric (Table 145–2) patients are based on clinical experience and investigations in specific patient populations. Unfortunately, conflicting data have resulted in a lack of consistency in published guidelines from different sources, which complicates identification of the patient who is most likely to benefit from PN. However, these published reports may serve as resources for development of institution-specific standards.
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Table 145-1 Indications for Adult Parenteral Nutrition
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| 1. Inability to absorb nutrients via the GI tract because of one or more of the following: |
| a. Massive small bowel resection: usually patients with less than 100 cm of small bowel distal to the ligament of Treitz without a colon, or less than 50 cm of small bowel with an intact colon |
| b. Intractable vomiting when adequate EN is not expected for 7–14 days. |
| c. Severe diarrhea |
| d. Bowel obstruction |
| e. GI fistulae: PN is indicated in patients with prolonged inadequate nutritional intake longer than 5–7 days who are not candidates for EN |
| 2. Cancer: antineoplastic therapy, radiation therapy, or HSCT |
| a. PN may be used in moderately to severely malnourished patients receiving active anticancer treatment who are not candidates for EN |
| b. PN is not routinely indicated for well-nourished or mildly malnourished patients undergoing surgery, chemotherapy, or radiation therapy |
| c. PN is unlikely to benefit patients with advanced cancer whose malignancy is unresponsive to treatment. However, use may be appropriate for carefully selected patients who have failed trials of less-invasive medical therapies and have good performance status, an estimated life expectancy of longer than 40–60 days, and strong social and financial support |
| 3. Pancreatitis: PN may be used in patients with severe pancreatitis with prolonged inadequate nutritional intake longer than 5–7 days who are not candidates for EN. PN should be used when EN exacerbates abdominal pain, ascites, or fistula output |
| 4. Critical Care |
| a. PN should be used in those patients in whom EN is contraindicated or is unlikely to provide adequate nutritional requirements within 5–10 days |
| b. Organ failure (liver, renal, or respiratory): PN should be used in patients with moderate to severe catabolism when EN is contraindicated |
| c. Burns: PN should be used in those patients in whom EN is contraindicated or is unlikely to provide adequate nutritional requirements within 4–5 days |
| 5. Perioperative PN |
| a. Preoperative: for 7–14 days for patients with moderate to severe malnutrition who are undergoing major GI surgery, if the operation can be safely postponed |
| b. Postoperative: PN should be used in patients in whom EN is contraindicated or is unlikely to provide adequate nutritional requirements within 7–10 days |
| 6. Hyperemesis gravidarum: when EN is not tolerated |
| 7. Eating disorders: PN should be considered for patients with anorexia nervosa and severe malnutrition who are unable or unwilling to ingest adequate nutrition |
| | EN, enteral nutrition; GI, gastrointestinal; HSCT, hematopoietic stem cell transplantation; PN, parenteral nutrition; SBS, short-bowel syndrome. |
From references 12 and 17.
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Table 145-2 Indications for Pediatric Parenteral Nutrition
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| 1. When enteral nutrition is unlikely to provide adequate nutritional requirements |
| a. Premature infant within 24–48 hours |
| b. Other pediatric patients within 5–7 days |
| 2. When the GI tract is not functional or cannot be assessed |
| a. Massive small bowel resection resulting in short-bowel syndrome |
| b. Neonatal necrotizing enterocolitis |
| c. Severe inflammatory bowel disease |
| d. Intractable diarrhea and/or vomiting |
| e. Graft-versus-host disease |
| f. Postchemotherapy |
| 3. Infants and children requiring extracorporeal membrane oxygenation |
| 4. Organ failure (liver, renal, pulmonary, pancreas) when enteral nutrition is contraindicated and child is catabolic |
| | From references 16 and 18. |
The decision to initiate PN is based on the assessment that the patient cannot meet his or her nutritional requirements through the GI tract. This assessment must include an evaluation of the patient's nutrition status, clinical status, age, and potential risks of initiating therapy, such as infection and other metabolic abnormalities. The appropriate length of time to wait prior to starting PN therapy is not well defined.
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Sidebar: Clinical Controversy
The most appropriate time to initiate PN in adults differs between various consensus reports because few data specifically address this issue. Some recommend initiating PN in patients who are not candidates for enteral nutrition as early as after 7 days of inadequate oral intake, whereas others recommend waiting up to 14 days in previously well-nourished or moderately malnourished patients.
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Adult PN therapy is not an emergent intervention and should not be initiated until the patient is hemodynamically stable. In general, adults who are not candidates for enteral nutrition should be considered candidates for PN after 7 to 14 days of suboptimal nutritional intake. Guidelines for use in infants and children are primarily influenced by age. The most appropriate time to initiate therapy in infants and children varies with age and nutritional status. Early PN within the first 24 hours of life has been recommended for infants with a birth weight less than 1,500 grams. Protein loss in extremely low-birth-weight infants can be twofold higher than in term infants, and frequently results in a negative nitrogen balance that cannot be corrected by glucose as a sole nutrient. Early aggressive PN in neonates can enhance protein accretion and somatic growth. However, many clinicians hesitate to initiate early PN because of concern of adverse effects associated with protein intolerance. Withholding PN for 2 to 3 days after birth, coupled with a slow advancement of substrate, only appears to contribute to the acute semistarvation and growth failure seen in many neonates. PN should be initiated within 5 to 7 days in other pediatric patients who are unable to meet their nutrient requirements with enteral nutrition. Earlier intervention should be considered in term infants (within 2 to 3 days), critically ill children (within 3 to 5 days), and children with preexisting malnutrition. Guidelines for older children are similar to those in adults.
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Quick Test Questions QUESTION 1: Enteral nutrition has been associated with economic savings compared with PN in trauma patients as a result of:
QUESTION 2: Complications commonly associated with parenteral nutrition therapy include:
QUESTION 3: Which of the following patients is the most likely candidate for central parenteral nutrition?
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