Understanding Parenteral Nutrition A Basis for Neonatal Nursing Care

Understanding Parenteral Nutrition A Basis for Neonatal Nursing Care MARY BETH STERK, RN, MSN The challenge in meeting the caloric and metabolic demands of infants who are critically ill, debilitated, or neurophysically immature is discussed. Advances in nutrition that have greatly improved neonatal survival are presented. Intravenous nutrition is presented as an appropriate mode of therapy to provide or supplement nutritional support in neonates who cannot derive all the requirements from oral feedings.

Advances in nutrition have greatly improved neonatal survival. However, the development and definition of optimal nutritional support remains a controversy. For the neonatal nurse caring for infants who cannot digest or absorb oral nutrients, the clinical problem is complex. Many infants in the neonatal intensive care unit are at risk for nutritional deprivation due to prematurity, malabsorption diseases, or congenital defects requiring surgery. Initiation of oral feedings can prevent problems associated with delayed feedings such as hypoglycemia, azotemia, hyperbilirubinemia, and hyperkalemia. 1-4 T h e challenge remains in meeting the caloric and metabolic demands of infants who are critically ill, debilitated, or neurophysically immature. Research by Cornblath and by Auld showed an improved survival of low birth weight infants alimented with glucose, but this nutrient alone proved to be i n a d e q ~ a t e . Infants ~.~ with limited energy stores were compromised further. Meeting the high-risk neonate's nutritional needs became more ur-

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gent as researchers discovered the disastrous effects of starvation on human brain growth in animals6 Critical periods of human brain growth are between 12 to 18 weeks of gestation and again during the third t r i m e ~ t e r . " ~Malnutrition during these critical periods may cause permanent brain deficiencies or damage. An appropriate mode of therapy was needed to provide or supplement nutritional support in neonates who could not derive all their requirements from oral feedings. Dudrickg developed techniques to provide intravenous nutrition in animals and then in humans. Solutions of concentratedglucose and amino acids were slowly infused via deep venous catheters. This mode of treatment was widely accepted." Clinical experience has helped to refine administration techniques, identify complications, and develop appropriate methods to monitor therapy.

NEONATAL CALORIC REQUIREMENTS An understanding of neonatal caloric requirements is an essential

component of the nursing care of the infant receiving parenteral nutrition. A recent study suggests that a higher caloric intake may be required for weight gain. T o attain the equivalent of the third trimester intrauterine weight gain (10 to 15 gm/kg/day), a metabolizable energy intake of approximately 60 kcal/kg/day was required in addition to 5 1.3 kcal/kg/day for maintenance energy. Caloric intake, gradually increased to an amount that will ensure optimal weight gain, allows the infant to increase his insulin secretionsslowly and prevents potential hyperglycemia and osmotic diuresis.

FLUID AND ELECTROLYTE BALANCE Proper nutritional management requires consideration of the principles of fluid and electrolyte balance in the neonate. At birth, water accounts for the greatest percentage of total body weight. At 32 weeks, 80% of a fetus' body weight consists of water. At term, the amount decreases to 78%.'* The percentage of body weight, as wa45s

Table 1.

Nursing Assessment of Fluid and Electrolyte Status*

Parameter

Dehydration

Body weight every 12 to 24 hours Physical assessment

Significant weight loss (5% to 15%/24 hours) Dry skin, mucous membranes, decreased skin turgor Increased (>1.012) Increased (>400 mOsm) Decreased ( 4 ml/kg/hr) Increased (>150 mEq/L) Increased (>300mOsm) Increased (rlO%) Increased (>6gm/dl) Decreased

Urine specific gravity Urine osmolality Urine volume Serum sodium Serum osmolality Hematocrit Serum protein Blood volume

Overhydration Significant weight gain (5% to 15%/24 hours) Edema Decreased ( 4 . 0 0 8 ) Decreased ( 4 0 0 mOsm) Increased (>3 ml/kg/hr) 30 mEq/L) Decreased (4 Decreased (<270 mOsm) Decreased (11 O0/o) Decreased (<4 gm/dl) Increased

AdaDted from Korones.12

ter, decreases with advancing gestational age. Birth, regardless of gestational age, has a tremendous impact on an infant’s water balance. Maternal “intravenous” sources of water and nutrition cease at birth. Additional water losses to the environment occur via evaporation from the infant’s skin and respiratory passages. Thus, at birth, the neonate loses a considerable amount of water weight. T h e extent of the weight loss is inversely related to the gestational age of the infant. T h e less mature infant may have more weight loss and this reduction of extracellular fluid may be physiologically essential in the transition to extrauterine life. l 3 Environmental factors, such as radiant heat, low humidity, and phototherapy, cause insensible water losses. T h e younger an infant is, the greater the water losses due to the larger surface area of the skin. T h e immature infant’s skin is thin and densely vascularized, enhancing heat transport and loss to the environment. Renal losses account for about half of the infant’s total water loss. T h e amount of solute excreted and the volume of water available will determine the extent of renal water losses. Because nephrogenesis is not complete until the 35th week of gestation, the premature

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infant has limited capacities to concentrate or dilute urine.I4 Renal concentration can compensate for the unavailability of water by using less water for solute excretion. Due to physical immaturity, the premature infant cannot adequately compensate for water losses. Clinical assessment of fluid and electrolyte status is imperative in planning and providing nursing care (Table 1). Systematic monitoring will fulfill two purposes: First, monitoring will provide information about the clinical and chemical signs pertaining to hydration status. Second, proper judgments can be made regarding the provision of water requirements. In planning fluid therapy, the fo1)owingobjectives should be met: maintain normal body fluid composition and volume; prevent dehydration or overhydration; and replace ongoing water losses. A wide range of possible water requirements exist for neonates. Requirements must be established and evaluated for individual patients in consideration of influencing factors that will vary depending upon the gestational age and illness of an infant. Fluid requirements will vary with the warming device used, the use of humidity, and the use of phototherapy. Infants cared for in an incubator may

require only 65 ml/kg/day of fluid whereas fluid needs for infants cared for in radiant warmers may be as much as 185 ml/kg/day.13 Recommendations for fluid therapy must be reviewed carefully as many have evolved from studies of infants subjected to various environmental stressors while receiving large fluid volumes. T h e volume of fluid administered should be increased slowly to the desired amount during the first few days. Fluids also should be administered to meet the daily requirements for electrolyte balance. Infants generally require 2 mEq/ kg of sodium and potassium per day and 2 to 4 mEq/kg of chloride. Smaller infants weighing less than 1500 gm may need increased sodium intakes of 3 to 4 mEq/kg due to greater sodium losses.“ Intravenous therapy is initiated when an infant cannot orally receive daily fluid and electrolyte requirements. Absorption of nutrients from the gastrointestinal tract may be inhibited by prematurity o r disease. Depending on the acuity of an infant, intravenous therapy may supplement o r totally replace oral provision of fluids and electrolytes. When an infant cannot orally ingest and absorb nutrients for a prolonged time period, nutritional needs can be met by hyperalimentation solutions. T h e hyperalimentation solution is a concentrated liquid mixture of dextrose, protein, electrolytes, and trace elements. Neonatal nutritional requirements are prepared to meet individual infants’ metabolic and caloric needs.

HYPERALIMENTATION COMPOSITION Carbohydrates Dextrose is the most common carbohydrate source in hyperalimentation solutions. Each gram of dextrose provides four calories. T h e appropriate method of infu-

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sion will be determined by the concentration of dextrose in the solution. Generally, solutions of 10% to 12% dextrose can be safely infused peripherally. More concentrated solutions are administered centrally to promote dilution.

Protein Exact protein requirements for the neonate are unknown. When assessing an infant's nutritional status, the nurse must look for signs of protein deficiency such as poor growth, delayed wound healing, or generalized weakness. Mixtures of crystalline amino acids are used as the source of protein. Freaminem and Aminosyn@have replaced, casein and fibrin hydrolysates. Protein intakes of 2 to 4 gm/kg/day seems to promote growth and maintain positive nitrogen balance.

Minerals Guidelines exist for the calculation of electrolyte requirenients. The neonatal nurse should be able to recognize factors that will alter. the infant's needs. This demands a daily review of serum electrolytes, renal function, fluid losses, and current fluid therapy. Serum electrolytes may need to be assessed more often in unstable infants. T h e recommended mineral requirements are listed in Table 2.

Vitamins The importance of vitamins has been well documented by investig a t o r ~ . ' ~One . ' ~ milliliter of Multivitamin Infusion ( M V P ) added daily to the solution contains all the necessary vitamins except folic acid, vitamin K , and vitamin B12.These vitamins are administered at intervals determined by the clinician.

Trace Elements In the past, little was known about trace element requirements

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for the neonate. Periodic plasma Table 2. Daily Mineral transfusions had been suggested as Requirementsa source of trace elements. Currently, clinicians are more knowlMineral Requirement edgeable. Copper and zinc defiSodium 3-4.0 mmol/kg ciencies have been d e ~ c r i b e d . " ~ ' ~ Potassium 2-3.0 mmol/kg Infants have limited trace element Calcium 2-2.5 mmol/kg stores arid the following elements Magnesium 1 mmd/kg should be added to the nutrient phosphorus 2.5 mmol/kg solution daily: 100-300 mg/kg Adapted from Avery.'' zinc; 20 mg/kg copper; 10 mg manganese; and 0.2 mg chromium.I9 cult to present specific recommendations concerning dosage of parFat Emulsion Therapy enteral lipid emulsions. Until simple and reliable methods for Before the successful introducmonitoring serum lipids become tion of fat or lipid infusates, soluavailable, the American Academy tions required much higher dexof Pediatrics recommends that lipid t.rose concentrations t o provide infusates in neonates should not adequate carbohydrates. This exceed 3 gm/kg/day (33 calories/ resulted in a hyperosmolar solukg/day)." T h e solution should be tion that had to be delivered via a infused at a slow rate, preferably central venous catheter. T h e delivover 24 hours, rather than a bolus. ery of lipid infusates has been used I t is essential to maintain sterility to provide neonatal patients with when delivering lipids as they will essential fatty acids. Lipid infusates avidly support the growth of mican be peripherally infused with croorganisms. Lipids are not fillower glucose solutions, providing tered and can be piggybacked into adequate carbohydrates. the hyperalimentation delivery sysT h e ability of the neonate to tem with a Y-connector near the dispose metabolically of fat emulinfusion site. sions has been questioned. T h e ability of the premature infant to Methods of Administration use and dispose of lipids compeHyperalimentation solutions can t.ently will require further investigation. Inadequate metabolism of be infused into central or peripheral veins. T h e choice of a method fats can have an adverse effect on pulmonary diffusion capacity. Elof delivery is based on how long an infant will require therapy. Beevated serum lipid levels-hyperlipemia-partially blocks reticulocause peripheral administration endothelial function. Infants with precludes the use of hyperosmolar respiratory difficulties or infecsolution, optimal weight gain cannot be assured. However, the petious disease should receive lipid infusates only when serum triglycripheral administration method eride levels can be monitored may be chosen when additional calclosely. Administration of lipid inories are provided with internal feedings or lipid infusions. In profusates is dangerous in icteric infants because free fatty acids comviding peripheral parenteral nutripete with bilirubin for binding sites tion, a butterfly needle or angiocath is placed at a predetermined t o albumin. €lyperlipemia may alsite. T h e nurse must aseptically ter erythrocyte membrane comprepare the site and insert the inposition and enhance red blood travenous device. cell and platelet clumping.20 Nursing assessments include baT h e uncertainties make it diffi-

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Table 3.

Complications of Parenteral Nutrition Metabolic

Catheter

Azotemia Hyperglycemia or glycosuria Hypocalcemia Hypophosphatemia Hyperammonia Cholestasis Hepatocellular damage Hypokalemia Radiographic bone changes (rickets, osteoporosis) Trace element deficiency

Sepsis-bacteremia, septicemia, or fungemia

sic principles related to intravenous therapy: monitoring the prescribed infusion rate and volume; assessing the insertion site for infiltration or infection; and monitoring and documenting fluid balance. Hourly site assessments are essential to prevent infiltration of the hyperalimentation solution into the peripheral tissue. T h e hyperosmolarity of the solution is very caustic and can cause severe tissue necrosis and sloughing if the infiltration is severe. In such cases, subcutaneous injections of the enzyme hyaluronidase (Wydase@)a t the infiltrate site may actually enhance absorption of the solution and minimize potential tissue damage. Cautious administration of Wydase is necessary as this use is not a recommended indication of the drug at the present tinie. Infants who require total parenteral nutrition for an extended period of time a r e candidates for central venous administration. In t h e central technique, a radiopaque silastic catheter is surgically inserted into the internal or external jugular vein. T h e catheter tip then is threaded into the superior vena cava near the right atrium. Placement a t this site of rapid blood flow promotes dilution of hyperosmolar solutions and allows the use of concentrated dextrose solutions. Placement of the central venous catheter is a surgi48s

Thrombosis of major vessels or air emboli Hemorrhage Extravasation of fluid Peripheral: sloughs and local cellulitis

cal procedure done under aseptic conditions. Before hyperalimentatiori solutions can be administered, correct placement of the catheter must be determined by radiography.

NURSING MANAGEMENT

Successful nursing management of infants receiving hyperalimentation depends on diligent monitoring a n d clinical assessment. Careful evaluation can minimize possible complications of this therapy (Table 3). Complications a r e generally catheter related or metabolic; therefore, nursing assessments must encompass both areas. Infection is the greatest hazard from an indwelling catheter. Hyperalimentation solutions a r e prepared aseptically under laminar flow in the pharmacy. Since the solution is an ideal medium for bacterial growth, it must be refrigerated. Intravenous tubing should be attached to a 0.22 u micropore filter and changed every 24 hours. Hyperalimentation solutions should be discarded 2 4 hours after opening. TOminimize infection, both the solution a n d intravenous set need t o be changed together daily. A practice that promotes infection control is t o attach the intravenous tubing t o the solution under laminar flow in the

pharmacy. Intravenous ports remain closed in the tubing, and the entire solution set is delivered to t h e nursery in a heat-sealed plastic bag. Care of the Catheter Site

A new dressing material, OpSite@,eliminates the need for freq u e n t dressing changes of the catheter site. Op-Site is a thin, transparent, elastic, membranous dressing cover that is waterproof and occlusive. T h e hypoallergenic backing adheres and conforms to the body contours. Since the catheter site is clearly visible, inspection does not require removal and reapplication of a sterile dressing. Dressing changes a r e less frequent and can be done at the nurse’s discretion (Table 4). Investigators have not found an increased incidence of infection when Op-Site dressings a r e changed based on nursing assessments.21 Monitoring Growth and Metabolic Parameters

T h o r o u g h nursing assessment and care can minimize complications and avert deficiencies. An important aspect of nursing care is routinely monitoring growth and metabolic parameters. Body weights should be measured every 24 hours and every 12 hours in unstable patients. Serum determinations such as hemoglobin, hematocrit, electrolytes, and plasma osmolarity provide information about the infant’s hydration status. With each void, urine volume, p H , a n d osmolarity should be measured; this information will alert the nurse to changes in the status of an infant’s fluid balance. Dextrostix determinations should be done frequently when parenteral nutrition is initiated. Dextrose concentrations then can be adjusted until serum homeostasis is achieved. Later, Dextrostix determinations should be routinely, May/June 1983 JOGN Nursing (Supplement)

Table 4.

Dressing Change Indications and Procedure

Indications for Dressing Change -Loosening of the edges of the OpSite@dressing compromising sterility -Blood, moisture, or exudate under the dressing -Manipulation of the catheter site dislodging it from dressing Dressing Change Procedure 1. Remoie old dressings and cleanse site around catheter with acetone/alcohol

swabsticks. (Do not touch the catheter itself.) 2. Vigorously cleanse the same 2 cm X 2 cm area surrounding the catheter with Betadine@swabsticks. The area should dry at least 30 seconds to ensure the effectiveness of the iodine. 3. Coil a Small length of the catheter proximal to the insertion site and secure with [email protected] will reduce potential tension at the catheter insertion site. 4. Place a small dab of Betadine ointment at the catheter insertion site. 5. Apply a premeasured Op-Site dressing, pinching it together under the catheter hub. The connection between the catheter hub and the extension tubing should be left outside the dressina.

though less frequently, performed. Routine monitoring of certain clinical and metabolic parameters will aid the nurse in developing a plan of care (Table 5 ) . ’ * ~ * ~ General 1y , in fan t s requiring parenteral nutrition will receive it

Table 5.

for three to four weeks. T h e initiation of enteral feedings is done slowly when bowel function is mature and function will not be compromised. Intravenous feedings of hyperalimentation solution or dextrose solutions should complement

Clinical Monitoring of Infants Receiving Hyperalimentation Solution* Variable

Growth Weight Head circumference Length Laboratory Dextrostix Sodium, potassium, and chloride Calcium, phosphorus, and magnesium Albumin, bilirubin Liver: function studies Serum ammonia pH, blood gases Hemoglobin Leukocyte Cultures Trace elements Urine Volume Glucose Specific gravity Clinitest/Acetest Labstix (protein, pH)

Frequency

Every 12-24 hours Weekly Weekly Every 4 hours initially, then daily Daily, every other day when stable Initially, then weekly Initially, then weekly Initially, then weekly As indicated As indicated Twice weekly As indicated As indicated If available weekly after 1 month of therapy Every void Every 8-1 2 hours Every 8-1 2 hours Every 8-1 2 hours Every 8-1 2 hours

Adapted from Averyi9 and Kerner and S~nshine.‘~

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trial feedings of sterile water and, later, glucose water. Diluted formula preparations or breast milk should be given slowly while bowel function is continually assessed. In time, the concentration and volume of feedings can be increased to meet the infant’s requirements. Hyperalimentation has been a tremendous asset to critically ill infants. However, further investigation of this nutritional source and current methods of administration is required. Neonatal nurses can participate in this research as they develop and create a plan of nursing care for infants receiving hyperalimentation. References 1. Smallpiece V, Davies PA. Immediate feeding of premature infants with undiluted breastmilk. Lancet 1964;2:1399. 2. Hansen JD, Smith RA. Effects of withholding fluids in the immediate neonatal period. Pediatrics 1953;12:99. 3. Hubbell JP, Drobaugh JE, Rudolph AJ, Auld PAM, Cherry RB, Smith CA. “Early” us. “late” feedings of infants of diabetic mothek. N Engl J Med 1961; 265~835. 4. Auld PAM, Bhangananda P, Mehta S. T h e influence of an early caloric intake with intravenous glucose in catabolism of premature infants. Pediatrics 1966; 37:592. 5. Cornblath M , Forbes AE, Pildes RS, et al. A controlled study of early fluid administration on survival o f low birth weight infants. Pediatrics 1966;28:547. 6. Winnick M. Cellular growth in intrauterine malnutrition. Pediatr Clin North Am 1970;17:69. 7. Dobbing J, Sands J. Quantitative growth and development of human brain. Arch Dis Child 1973;48:757. 8. Dobbing J, Sands J. Vulnerability of developing brain. Biol Neonate 197 1; 19:362. 9. Dudrick SJ, Wilmore DW, Vars HM. Long-term total parenteral nutrition with growth in puppies and positive nitrogen balance in patients. Surg Forum 1967; 18:356.

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10. Tejani A, Mahadedan R, Dobias B, et al. Total parenteral nutrition of the neonate-A long term follow-up. J Pediatr 1979;94:803. 1 1 . Reichman B, et al. Portioning of energy metabolism and energy cost of the very low-birth weight infant. Pediatrics 1982;69:446. 12. Korones S. High-risk newborn infants. 3rd ed. St. Louis: CV Mosby, 1981. 13. Arant B. Fluid therapy in the neonate-concepts in transition. J Pediatr 1982;10 1 :387. 14. Nash M, Edelmann C. T h e developing kidney: immature function or inappropriate standard? Nephron 1973;1 1 :71 . 15. Bell E, Filer L. T h e role of vitamin E in the nutrition of premature infants. Am J Clin Nutr 1981;34:414.

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16. Hoff N, Hoddard J, Feitelbaum S, et al. Serum concentrations of 25-hydroxyvitamin D in rickets of extremely premature infants. J Pediatr 1979;94:460. 17. Al-Rashid R, Spangler J. Neonatal copper deficiency. N Engl J Med 1971;285:841. 18. Srouji M, Balisteri F, Coleb M, et al. Zinc deficiency during parenteral nutrition: skin manifestations and immune incompetence in a premature infant. J Pediatr Surg 1978;13:570. 19. Avery G. Neonatology. Philadelphia: JB Lippincott, 198 1 . 20. American Academy of Pediatrics Committee on Nutrition. American Academy of Pediatrics: use of intravenous fat emulsions in pediatric patients. Pediatrics 1981 ; 68:738.

21. Curtas S, Grant JP. Evaluation of op-site as a total parenteral nutrition dressing. NITA 198 1 ; 4~414-5. 22. Avery GB. Neonatology. 2nd ed. Philadelphia: JB Lippincott, 1981:1038. 23. Kerner J, Sunshine P. Parenteral alimentation. Semin Perinatol 1979;3:417-32.

Address for correspondence: Mary Beth Sterk, RN, 430 Home Ave, Apt. 304S, Oak Park, IL 60302

Mary Beth Sterk is the nursing staff development instructor for maternal-child health at Loyola University Medical Center in Maywood, Illinois.

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