Fluids, Electrolytes and Nutrition for the Neonate

1. Fluids, Electrolytes and Nutrition for the Neonate Mesfin Woldesenbet, MD Neonatalogist

2. Objectives • Understand principles of fluid balance in neonates and appropriate postnatal fluid management • Learn concepts of electrolyte balance in neonates • Recognize signs and symptoms of certain electrolyte abnormalities and learn how to treat them • Learn about neonatal nutritional requirements and feeding methods

3. Principles of Fluid Balance • TBW = ICF + ECF • ECF = Intravascular + Interstitial

4. TOTAL BODY WATER COMPOSITION • Adult TBW = 60% (40% ICF + 20% ECF) • Full-term TBW = 75% (35% ICF + 40% ECF) • Pre-term TBW = 90% (30% ICF + 60% ECF) * Excess TBW esp. ECF at birth, hence diuresis within 1st week of life (up to 10% in FT, up to 15% in pre-term) http://www.revivenaturally.com/dr-yoshitaka-ohno-md-phd/maintaining-intracellular-hydration-water.html

5. SENSIBLE VS. INSENSIBLE WATER LOSS • Sensible water loss (SWL): Easily measured • Urine, stool, NG/OG output, CSF • Insensible water loss (IWL): Not readily measured • Evaporation from skin (66%) or respiratory tract (33%) • IWL greater in lower GA (immature skin) • Factors that increase: Immature skin, fever, radiant warmers, phototherapy, skin defects/breakdown • Factors that decrease: Mature skin, humidity, heat shields

6. RENAL FUNCTION IN NEONATES • Decreased capacity to concentrate or dilute urine in response to intravascular fluid status • Risk dehydration or fluid overload Adults: FENa < 1% vs. Term infants: FENa < 1% (except transient increase during diuretic phase) Vs. Pre-term infants: FENa 5-6% http://www.yalemedicalgroup.org/stw/Page.asp?PageID=STW028984

7. Assessing Fluid Status • Factors that can affect fluid status: • Maternal history: • Neonate’s status reflects mother’s • Neonatal history: • (i.e.. In utero hypoxemia associated with ATN and hypervolemia) • Clinical evaluation: • weight changes, UOP, IWL factors (humidity, phototherapy, ventilation, etc.), vital signs, perfusion • Laboratory evaluation: • serum electrolytes, BUN/Cr

8. FEN Management • Goals: • Maintain ICF and ECF volumes and osmolalities • Allowing diuresis within 1st week of life • Maintain appropriate electrolyte concentrations • Provide adequate nutrition for growth

9. Total Fluid Requirements • Total fluids = Maintenance + Growth • Maintenance = SWL + IWL http://www.champ-sportsline.de/en/nutrients-active-ingredients/fluids.html

10. STARTING POINTS AND ADVANCEMENT • Starting Points (ml/kg/day): • BW < 1250g: TF = 80 - 100 • BW 1250-1750g: TF = 60 - 80 • BW > 1750g: TF = 60

11. STARTING POINTS AND ADVANCEMENT • Advancement: Example- LBW infant • Start DOL 1 with TF = 80 • Adjust daily to maintain wt loss < 10% BW • DOL 2 with TF ~80-100 • DOL 3-4 with TF ~110-120 • DOL 4-5 with TF ~130-140 • Goal TF ~140-150

12. FLUID ISSUES ASSOCIATED WITH COMMON NEONATAL CONDITIONS • Issues requiring fluid restriction: • RDS: Excessive fluid can lead to fluid overload and increased risk of BPD/chronic lung disease • BPD: Excessive fluid can worsen therefore treated with diuretics to reduce pulmonary edema • PDA: Volume overload can open ductus and worsen respiratory status • HIE: Associated with ATN and/or SIADH and can lead to subsequent volume overload

13. Common Fluid Problems • Hypervolemia/volume overload • Hypovolemia/dehydration • Oliguria: UOP < 1 mL/kg/hr • Pre-renal, Renal, Post-renal

14. Electrolyte Requirements • First 24h of life: No electrolytes (?except Ca) • Ca especially important for preterm infants • At 24h of life: • Na: 1-3 mEq/kg/day • K: 1-2 mEq/kg/day • At 1 week of life: • Na: 3-5 mEq/kg/day • K: 2-3 mEq/kg/day * Extremely pre-term infants with metabolic acidosis (loss of bicarb in urine) may benefit from sodium acetate ** Electrolyte requirements vary based on medications, etc.

15. COMMON ELECTROLYTE ABNORMALITIES • Hypo/hypernatremia • Hypo/hyperkalemia • Hypocalcemia • Hypermagnesemia

16. Sodium Abnormalities • Hyponatremia: Na < 130 mEq/L • Causes: Usually due to excess free water but can be increased Na losses/inadequate Na intake • Signs/sx: lethargy, seizures, coma • Tx: Restrict fluids and/or Na supplements • Hypernatremia: Na > 150 mEq/L • Causes: Usually due to high water losses, rarely excess intake • Signs/sx: lethargy, seizures, coma • Tx: Increase fluids and/or restrict Na

17. Potassium Abnormalities • Hypokalemia: K < 3.5 mEq/L • Causes: Diuretics, NG losses • Signs/sx: EKG changes (flat T waves, prolonged QT, U waves), arrhythmias, ileus, lethargy • Tx: Slowly correct IV or orally * Most K is intracellular, thus serum levels might not accurately depict total body stores ** pH affects K levels: Acidosis drives K out of cell vs. Alkalosis pushes K into cell

18. Potassium Abnormalities • Hyperkalemia: K > 6 mEq/L • Causes: Iatrogenic, severe acidosis, ARF, RBC breakdown s/p transfusion, CAH • Signs/sx: EKG changes (peaked T waves, wide QRS, brady/tachycardia, SVT, V Tach, V fib), arrhythmias, death • Tx: D/C all K, Ca gluconate, sodium bicarbonate, albuterol, insulin + glucose, lasix, kayexalate, dialysis/exchange * Most K is intracellular, thus serum levels might not accurately depict total body stores ** pH affects K levels: Acidosis drives K out of cell vs. Alkalosis pushes K into cell

19. Calcium Abnormalities • Hypocalcemia: Ca < 7 mg/dL (iCa < 1) • Causes: Prematurity, IUGR, IDM, HIE, hypoparathyroidism, Vitamin D deficiency • Signs/sx: Asymptomatic, jitteriness, irritability, seizures • Tx: Observation, repletion (Ca gluconate), or supplementation • Hypercalcemia: Ca > 11mg/dL (iCa > 5) • Rare in neonates • Usually associated with Human Milk fortifiers (HMF) * Important to follow Ca levels as well as Phos and Alk Phos levels ~every 2 weeks once on full feeds to screen for osteopenia of prematurity.

20. Magnesium Abnormalities • Hypermagnesemia: Mg > 2.3 mEq/L • Causes: Maternal treatment with magnesium for PIH or tocolysis • Signs/sx: Respiratory depression, apnea, hypotonia, decreased GI motility • Tx: Self-limited, resolves within a few days

21. Principles of Nutrition • Nutrient requirements: • Carbohydrates • Protein • Fat • Water • Minerals and trace elements • Vitamins

22. Energy Requirements • Depend on: • GA • Postnatal age • Weight • Route of intake • Ideally energy source: 65% carbohydrate + 35% lipid • Protein building block for growth • Growth rate • Activity level • Thermal environment • Medical problems

23. Energy Requirements • Typical needs: 100-120 cal/kg/day for growth • Term = 100 vs. Preterm = 120 cal/kg/day • Many need more! (ie. BPD or CHD might need 160-180) • “Healthy” enterally fed premie: 125 cal/kg/day • Resting energy expenditure: 50 cal/kg/day • Activity level (minimal): 5 cal/kg/day • Occasional cold stress: 10 cal/kg/day • Stool loss (10-15% of intake): 15 cal/kg/day • Growth (4.5 cal/g of growth): 45 cal/kg/day

24. Methods of Providing Nutrition • Total Parenteral Nutrition (TPN): • Peripheral vs. Central • Combination Parenteral/Enteral Nutrition: • Advancing feeds but still giving TPN • Total Enteral Nutrition: • Per oral route (PO) (i.e.. Bottle/breast) • Per gavage route (PG) (i.e.. NG/OG on pump) • Chronic feeding tube feeds (i.e.. G-tube)

25. Total Parenteral Nutrition • Goal: Provide energy and nutrients to promote growth when unable to adequately feed by enteral means • Calculations typically based on birth weight for first week of life, then use actual weight thereafter • Must account for: • Total fluid volume (mL/kg/day) • Total daily caloric requirements (cal/kg/day) • Dextrose concentration and glucose infusion rate (mg/kg/min) • Protein (g/kg/day) • Lipid (g/kg/day) • Electrolytes, trace elements, minerals, vitamins

26. STARTING POINTS AND ADVANCEMENT

27. STARTER TPN FOR PREMIES • Goal: Provide protein and calcium within first 24h of life (when unable order regular TPN yet) • Rationale: ELBW infants lose >1% of protein stores daily, must provide protein to balance loss • Components: • Dextrose 10% • Protein (60 g/L): 3g/kg/day • Calcium (4 mEq/L) • Minimal/no electrolytes • Heparin

28. Types of Enteral Nutrition • Breast milk is the best milk! • Lactation counselors can help moms • Donor breast milk an option for some premies • Variety of formulas available: • Term (20 cal): Good Start, Enfamil, Similac • Late Pre-term/Transitional (22cal): Enfacare, Neosure • Pre-term (24 cal): Similac Special Care • Supplements to increase calories, etc.: • HMF (protein, Ca), Neosure powder, MCT oil

29. Types of Enteral Nutrition • Specialty formulas available: • Lactose Intolerance/Galactosemia: Soy varieties • Feeding Intolerance: GentleEase, Similac sensitive • Semi-Elemental: Alimentum, Nutramigen, Pregestimil • Elemental: Neocate, Elecare • Renal disease: Similac PM 60/40 • Chylothorax: Enfaport

30. INITIATION OF ENTERAL FEEDING • Preterm < 1250 gms: • Goal to start preterm feedings within first 12 hours of life • Start with non-nutritive feeds q3-6h: • Low volume (usually 10-15 mL/kg/day) • Acclimate the GI tract to feeds • Stimulate gut hormone secretion • Promote GI tract maturation • Preterm 1250-1750 gms: • Start within first 12 hours of life with ~20 mL/kg/day (q3h) • Preterm > 1750 gms or Full term: • If stable, start feeds within first 6 hours of life q3h • May consider ad lib feeds

31. ADVANCEMENT OF ENTERAL FEEDING • Goal: Advance slowly to reach full enteral feeds within ~1-2 weeks of life • Advance daily as tolerated per feeding protocol (~10-20 mL/kg/day for premies) • Monitor for symptoms of intolerance: • Abdominal distension • Vomiting • Bilious aspirates/residuals

32. ADVANCEMENT OF ENTERAL FEEDING

33. ADVANCEMENT OF ENTERAL FEEDING • As enteral feedings increase, amount of parenteral feedings decrease • Write TPN for NPO rate in case feeds stopped • Decrease lipid rate accordingly (ie. Decrease to 50% once at ½ full feeds, etc.) • Fortify feeds with HMF once infant receiving 100 mL/kg/day of human milk • First fortify to 22 cal then to 24 cal • Consider further increase in calories overtime from to 27 or 30 cal formula +/- MCT depending on growth curves

34. TRANSITION from GAVAGE to PO FEEDING • Infant must: • Weight > 1000 grams and corrected GA > 32 wks • Clinically stable with full strength feeds • Developmental cues of readiness (suck/swallow) • Advancement: • Start with trial of po once daily • Then twice daily • Then every few/every other feed (PG/PG/PO, PO/PG, PO/PO/PG) • Then all po (PO Ad Lib with minimum, PO Ad Lib) • Cue based * Some infants 32-34 weeks might not be ready for all po, consider alternating po/pg feeds

35. ADDITIONAL NUTRITIONAL CONSIDERATIONS • Iron fortification: Prevent Fe-deficient anemia • Fe supplement given to breast-fed term/all pre-term infants • Some formula-fed might need if insufficient volume • Vitamin supplementation: • Poly-vi-sol for term/pre-term breast-fed infants once full feeds • Vitamin D supplementation: • Term/pre-term breast-fed infants need 400 IU daily • Supplement amount depends on feeding method/amount

36. PREP BOARD REVIEW QUESTION #1 A mother in your pediatric practice recently delivered a 28 weeks’ gestation infant who is in the NICU. She exclusively breastfed her previous child who was born at 36 weeks’ gestation. She is concerned that something is wrong with her milk for this infant because it is being combined with HMF. You reassure her that fortification helps to meet the additional needs of her preterm infant. Of the following, the MOST important role of such fortification is to: A. augment the immunologic properties of human milk B. boost the carbohydrate content of human milk C. decrease the osmolality of human milk D. enhance the absorption of iron from human milk E. increase the protein content of human milk

37. PREP BOARD REVIEW QUESTION #1 • Answer: E. increase the protein content of human milk • Preterm infants need more protein. • Preterm 3-4 g/kg/day • Term 1.5-2 g/kg/day • HMF provides extra protein to be added to breast milk.

38. PREP BOARD REVIEW QUESTION #2 A 30 weeks’ gestation very low-birth weight (VLBW) 1,400-g infant has respiratory distress syndrome (RDS). He is receiving assisted ventilation following administration of 3 doses of surfactant. On his second postnatal day, his mother asks if she can breastfeed her infant. You explain that he will not be able to breastfeed until he is extubated and able to suckle. She asks whether she should pump her breast milk. Of the following, the BEST response is that expressed human milk feedings: A. are contraindicated in VLBW infants who have RDS B. are too difficult for VLBW infants to digest C. can be fed by NG tube D. have no net benefit for VLBW infants once frozen E. have too much protein for VLBW infants

39. PREP BOARD REVIEW QUESTION #2 • Answer: C. can be fed by NG tube • Breast milk is the best milk! • NG feeds can be given when babies cannot yet tolerate po feeds.

40. PREP BOARD REVIEW QUESTION #3 A 27 weeks’ gestation preterm male infant who weighs 900 grams is delivered at a community hospital by emergent cesarean section. After intubation in the delivery room, he is taken to the nursery for stabilization, including umbilical venous line placement, prior to transfer to a tertiary care center. Of the following, the MOST appropriate initial solution for parenteral administration would include: A. 5% dextrose B. 5% dextrose and 0.2% sodium chloride C. 10% dextrose D. 10% dextrose and 0.2% sodium chloride E. 0.9% sodium chloride

41. PREP BOARD REVIEW QUESTION #3 • Answer: C. 10% dextrose • Preterm babies are at risk of hypoglycemia and need to have careful blood glucose monitoring. • Initial parenteral fluids typically include 10% dextrose solutions. • Infants do not need sodium administration within the first few days of life.

42. PREP BOARD REVIEW QUESTION #4 A 4-month-old male infant presents with abdominal distension, vomiting, and poor weight gain. His temperature is 37.3°C, heart rate is 110 beats/min, respiratory rate is 32 breaths/min, and blood pressure is 96/56 mm Hg. On physical examination, you note abdominal distension, with a palpable mass above the pubic symphysis. Results of laboratory tests include: Na 136, K 7.2, Cl 110, Bicarb 16, BUN 25, Cr 1.3, Ca 9.5, Mg 1.8, P 5.5 Of the following, the next BEST step in the management of this patient’s electrolyte abnormality is administration of: A. intravenous calcium gluconate B. intravenous dextrose and insulin C. nebulized albuterol D. oral furosemide E. oral sodium polystyrene sulfonate

43. PREP BOARD REVIEW QUESTION #4 • Answer: A. intravenous calcium gluconate • All treatment options are correct but first-line approach is Ca gluconate. • The infant has abdominal distension, FTT, palpable suprapubic mass, hyperkalemia, azotemia, and normal anion gap metabolic acidosis. • Diagnosis is likely obstructive uropathy (posterior urethral valves) with Type IV RTA and hyperkalemia.

44. References • Fanaroff and Martin’s Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant • Ambalavanan, N et al. Fluid, Electrolyte, and Nutrition Management of the Newborn. emedicine.com, Last updated June 29, 2010. • Yale-New Haven Hospital Newborn Guidelines • PREP Self-Assessment Pediatrics Review and Education Program, AAP, 2009-2011

45. Questions or Comments www.handsforbabies.org