A Basis for the Nursing Management of Feeding the Premature Infant
Section snippets
Development of the Gastrointestinal System
Immaturity of enzyme and transport systems, absorption mechanisms, muscular development, and coordination affect the premature infant’s ability to maintain adequate nutrition for growth. Many of the limitations of the premature infant’s gastrointestinal system are related to the stage of development reached before birth (Table 1). The limitations can be overcome with careful attention to nutritional management. Accurate nutritional management is especially important since premature infants are
Fats
Although a minute amount of fat is digested in the stomach, the majority of fat reaches the small intestine for catabolism by pancreatic and intestinal lipases. Bile salts must emulsify the fat into di-gestable globules before the lipases can act efficiently. The digestive tract of the premature infant lacks both lipases and bile salts.3,4Therefore, commonly used cow’s milk formulas containing long chain triglycerides are not well metabolized by the premature infant. Some special premature
Carbohydrates
Immaturity of the infant also affects carbohydrate metabolism. Before carbohydrates can be absorbed, they must be broken down to monosaccharides by enzymes in the intestinal tract. Sucrase, which breaks down sucrose, and lactase, which acts on lactose, are both important to the metabolic process. Sucrase is present in early fetal life, increases at term, and remains stable in postnatal life. Lactase, however, is found in very low amounts before 24 weeks gestation, at which time it begins to
Protein
Proteins provide the structural components of cells and act as enzymes which control chemical reactions within the cells. Amino acids which link to form proteins are either derived from the diet or synthesized from other amino acids by certain liver enzymes. The premature infant lacks some of the enzymes involved and cannot convert phenylalanine to tyrosine or methionine to cystine. Because of these deficiencies, the quality rather than the quantity of the protein in the diet needs to be
Additional Requirements
A definition of the optimal rate of growth for premature infants is very controversial. Intrauterine growth curves are used as a guideline, but the goals of extrauterine nutrition are to prevent catabolism and to promote adequate cell growth as evidenced by normal blood chemistries and physical assessment. Caloric, fluid, and vitamin requirements are based on studies of the effects of various diets on weight and head circumference as well as an increasing knowledge of the special needs of the
Vitamins
Formulas and human milk contain adequate amounts of most vitamins, but supplementation is necessary for premature infants because of poor absorption and low intake. Vitamin D and E and folate deficiencies have been noted in premature infants. Multivitamin preparations including the aforementioned vitamins should be given daily as soon as feedings are well tolerated.9
Vitamin E requires special consideration because of its significance to the premature infant. Vitamin E storage increases with
Iron
Iron supplementation also needs to be considered. Iron is necessary for hemoglobin formation and is especially important at about eight weeks of age when red blood cell production increases. Until this time, iron is stored in the body for future use.8 The American Academy of Pediatrics recommends two mg/kg/day for preterm infants.12 Iron supplementation should start by eight weeks of age but may start as early as tolerated as long as vitamin E intake is adequate.8, 11 Iron can be given via
Fluid Requirements
Each premature infant must be assessed individually for adequate fluid intake. An increase in water loss is a problem common to all premature infants because their skin is more permeable, and they have a larger skin surface to body mass ratio.13 Studies have shown that radiant warmers and phototherapy, as well as high incubator temperatures, increase insensible water losses.14
An infant’s hydration status can be assessed in several ways. Daily weight measurement or, in the case of very small
Initiation of Feeding
Decisions have to be made regarding the method of feeding, the amount and type of feeding, and when to begin feeding the premature infant. The infant must be assessed for cardio-respiratory status, fluid needs, weight, gestational age, and blood glucose level. Because of the rapid fluid loss that occurs after birth and the premature infant’s risk of hypoglycemia, feedings should be started as soon as the infant has stable vital signs: This may be after two hours, but glucose and fluid intake
Feeding Methods
The appropriate feeding method for a premature infant is an essential part of nutritional management. Hospital procedures and techniques may vary, but the nurse must choose from three basic methods of feeding: nipple feeding, intermittent gavage, or continuous feeding (via nasogastric tube, jejunal tube, or gastrostomy). The nurse must assess the infant regularly and decide which method of feeding is appropriate for an individual infant. Once the decision is made, the care given in
Common Feeding Problems
Infants will vary in their ability to tolerate feeding in the first few days of life. Feedings may have to be changed or adjusted several times before the correct combination is found. The nurses’ ability to diagnose and solve problems can directly influence the premature infant’s success or failure in feeding.
Several commonly occurring problems may be solved by the expertise of the nurse. The following may be indicative of serious complications; thus, a complete physical assessment should be
Summary
Adequate nutrition for the premature infant is often very difficult to achieve. The subject of nutritional management also is complicated by policies and techniques, such as feeding methods and feeding of ventilated infants, that vary between institutions. Basic facts about premature infant development, requirements, and metabolism of nutrients have been presented, however, to give the nurse the basis upon which to make decisions. With this knowledge, the nurse can continue to emerge as a
Footnote
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Cited by (6)
Oral stimulation accelerates the transition from tube to oral feeding in preterm infants
2002, Journal of PediatricsRelationship Between Integrated Sucking Pressures and First Bottle‐Feeding Scores in Premature Infants
1988, Journal of Obstetric, Gynecologic, & Neonatal NursingStandardised feeding regimens: Hope for reducing the risk of necrotising enterocolitis
2005, Archives of Disease in Childhood: Fetal and Neonatal EditionEnteral feeding for high-risk neonates: A digest for nurses into putative risk and benefits to ensure safe and comfortable care
2005, Journal of Perinatal and Neonatal NursingOral-motor management of the high-risk neonate
1986, Physical and Occupational Therapy in Pediatrics