Fluids, Electrolyte, and Nutrition
Management in Neonates
N. Ambalavanan MD
Neonatologist
October 1998
www.similima.com 1
FEN Management in Neonates
Essentials of life:
Food (Nutrition)
water (Fluid/electrolyte)
shelter (control of environment - temperature etc)
Essentials of neonatal care:
Fluid, electrolyte, nutrition management (All babies)
Control of environment (All babies)
Respiratory /CVS/CNS management (some babies)
Infection management (some babies)
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Why is FEN management
important?
Many babies in NICU need IV fluids
They all don’t need the same IV fluids (either in quantity or composition)
If wrong fluids are given, neonatal kidneys are not well equipped to handle them
Serious morbidity can result from fluid and electrolyte imbalance
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Fluids and Electrolytes
Main priniciples:
Total body water (TBW) = Intracellular fluid (ICF) + Extracellular fluid (ECF)
Extracellular fluid (ECF) = Intravascular fluid (in vessels : plasma, lymph) + Interstitial fluid (between cells)
Main goals:
Maintain appropriate ECF volume,
Maintain appropriate ECF and ICF osmolality and ionic concentrations
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Things to consider:
Normal changes in TBW, ECF
All babies are born with an excess of TBW, mainly ECF, which needs to be removed
Adults are 60% water (20% ECF, 40% ICF)
Term neonates are 75% water (40% ECF, 35% ICF) : lose 5-10 % of weight in first week
Preterm neonates have more water (23 wks: 90%, 60% ECF, 30% ICF): lose 5-15% of weight in first week
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Things to consider:
Normal changes in Renal Function
Adults can concentrate or dilute urine very well, depending on fluid status
Neonates are not able to concentrate or dilute urine as well as adults - at risk for dehydration or fluid overload
Renal function matures with increasing:
gestational age
postnatal age
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Things to consider:
Insensible water loss (IWL)
“Insensible” water loss is water loss that is not obvious (makes sense?): through skin (2/3) or respiratory tract (1/3)
depends on gestational age (more preterm: more IWL)
depends on postnatal age (skin thickens with age: older is better --> less IWL)
also consider losses of other fluids: Stool (diarrhea/ostomy), NG/OG drainage, CSF (ventricular drainage), etc
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Assessment of fluid and
electrolyte status
History: baby’s F&E status partially reflects mom’s F&E status (Excessive use of oxytocin,
hypotonic IVF can cause hyponatremia)
Physical Examination:
Weight: reflects TBW. Not very useful for intravascular volume (eg. Long term paralysis and
peritonitis can lead to increased body weight and increased interstitial fluid but decreased intravascular volume. Moral : a puffy baby may or may not have
adequate fluid where it counts: in his blood vessels)
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Assessment of fluid and
electrolyte status (contd.)
Physical Examination (contd.)
Skin/Mucosa: Altered skin turgor, sunken AF, dry mucosa, edema etc are not sensitive indicators in babies
Cardiovascular:
Tachycardia can result from too much (ECF excess in CHF) or too little ECF (hypovolemia)
Delayed capillary refill can result from low cardiac output
Hepatomegaly can occur with ECF excess
Blood pressure changes very late
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Assessment of fluid and
electrolyte status (contd.)
Lab evaluation:
Serum electrolytes and plasma osmolarity
Urine output
Urine electrolytes, specific gravity (not very useful if the baby is on diuretics - lasix etc), FENa
Blood urea, serum creatinine (values in the first few days reflect mom’s values, not baby’s)
ABG (low pH and bicarbonate may indicate poor perfusion)
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Management of F&E
Goal: Allow initial loss of ECT over first week (as reflected by wt loss), while maintaining normal intravascular volume and tonicity (as reflected by HR, UOP, lytes, pH). Subsequently, maintain water and electrolyte balance, including requirements for body growth.
Individualize approach (no “cook book” is good enough!)
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Management of F&E (contd.)
Total fluids required:
TFI = Maintenance requirements (IWL+Urine+Stool water) + growth
In the first few days, IWL is the largest component
Later, solute load increases (80-120 Cal/kg/day = 15-20 mOsm/kg/day => 60-80 ml/kg/day to excrete wastes)
Stool: 5-10 cc/kg/day
Growth: 20-25 cc/kg/day (since wt gain is 70% water)
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Management of F&E (contd.)
Guidelines for fluid therapy
Birth Wt(kg)
Dextrose(%)
Fluid rate (ml/kg/d)
<24 hr 24-48 hr >48 hr
<1.0 5-10 100-150 120-150 140-190
1.0-1.5 10 100-120 100-120 120-160
>1.5 10 60-80 80-120 120-160
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Management of F&E (contd.)
Factors modifying fluid requirement: Maturity--> Mature skin --> reduces IWL
Elevated temperature (body/environment)--> increases IWL
Humidity: Higher humidity--> decreases IWL up to 30% (over skin and over respiratory mucosa)
Skin breakdown, skin defects (e.g. omphalocele)--> increases IWL (proportional to area)
Radiant warmer --> increases IWL by 50%
Phototherapy --> increases IWL by 50%
Plastic Heat Shield --> reduces IWL by 10-30%
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Let there be lytes!
Electrolyte requirements:
For the first 1-3 days, sodium, potassium, or chloride are not generally required
Later in the first week, needs are 1-2 mEq/kg/day (1 L of NS = 150+ mEq; 150
cc/kg/day of 1/4 NS = 5.9 mEq/kg/day which is too
much)
After the first week, during growth, needs are 2-3 or even 4 mEq/kg/day
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F&E in common neonatal
conditions
RDS: Adequate but not too much fluid. Excess leads to
hyponatremia, risk of BPD. Too little leads to hypernatremia, dehydration
BPD: Need more calories but fluids are usually
restricted: hence the need for “rocket fuel”. If diuretics are used, w/f ‘lyte problems. May need extra calcium.
PDA: Avoid fluid overload. If indocin is used, monitor
urine output.
Asphyxia: May have renal injury or SIADH. Restrict
fluids initially, avoid potassium. May need fluid challenge if cause of oliguria is not clear. www.similima.com 16
Common ‘lyte problems
Sodium:
Hyponatremia (<130 mEq/L; worry if <125)
Hypernatremia (>150 mEq/L; worry if >150)
Potassium:
Hypokalemia (<3.5 mEq/L; worry if <3.0)
Hyperkalemia > 6 mEq/L (non-hemolyzed)
(worry if >6.5 or if ECG changes )
Calcium:
Hypocalcemia (total<7 mg/dL; i<4)
Hypercalcemia (total>11; i>5) www.similima.com 17
Sodium stuff :
Hyponatremia
Sodium levels often reflect fluid status rather than sodium intake
ECF Excess Excess IVF, CHF,
Sepsis, Paralysis
Restrict fluids
ECF Normal Excess IVF, SIADH,Pain, Opiates
Restrict fluids
ECF Deficit Diuretics, CAH, NEC
(third spacing)
Increase
sodium intakewww.similima.com 18
Sodium stuff :
Hypernatremia
Hypernatremia is usually due to excessive IWL in first few days in VLBW infants (micropremies). Increase fluid intake and decrease IWL.
Rarely due to excessive hypertonic fluids (sod bicarb in babies with PPHN). Decrease sodium intake.
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Potassium stuff
Potassium is mostly intracellular: blood levels
do not usually indicate total-body potassium
pH affects K+: 0.1 pH change=>0.3-0.6 K+
change (More acid, more K; less acid, less K)
ECG affected by both HypoK and HyperK:
Hypok:flat T, prolonged QT, U waves
HyperK: peaked T waves, widened QRS, bradycardia, tachycardia, SVT, V tach, V fib
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Hypo- and Hyper-K
Hypokalemia:
Leads to arrhythmias, ileus, lethargy
Due to chronic diuretic use, NG drainage
Treat by giving more potassium slowly
Hyperkalemia:
Increased K release from cells following IVH, asphyxia, trauma, IV hemolysis
Decreased K excretion with renal failure, CAH
Medication error very common
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Management of Hyperkalemia
Stop all fluids with potassium
Calcium gluconate 1-2 cc/kg (10%) IV
Sodium bicarbonate 1-2 mEq/kg IV
Glucose-insulin combination
Lasix (increases excretion over hours)
Kayexelate 1 g/kg PR (not with sorbitol! Not to give PO for premies!)
Dialysis/ Exchange transfusion
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Calcium stuff
At birth, levels are 10-11 mg/dL. Drop normally over 1-2 days to 7.5-8.5 in term babies.
Hypocalcemia:
Early onset (first 3 days):Premies, IDM, Asphyxia If asymptomatic, >6.5: Wait it out. Supplement calcium if <6.5
Late onset (usually end of first week)”High Phosphate” type: Hypoparathyroidism, maternal anticonvulsants, vit. D deficiency etc. Reduce renal phosphate load
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Things we aren’t going to
discuss (i.e.) homework:
Acid-base disorders: Acidosis or Alkalosis, Metabolic or Respiratory or Mixed
Hypercalcemia
Magnesium disorders
Metabolic disorders
Methods of feeding: Continuous vs. Intermittent; TP vs OG vs NG vs NJ; Trophic feeds; Complications of TPN
(We can discuss these, if time permits) www.similima.com 24
Common fluid problems
Oliguria : UOP< 1cc/kg/hr. Prerenal, Renal, or
Postrenal causes. Most normal term babies pee by 24-48 hrs. Don’t wait that long in sick l’il babies! Check Baby, urine, FBP. Try fluid challenge, then lasix. Get USG if no response
Dehydration: Wt loss, oliguria+, urine sp.
gravity >1.012. Correct deficits, then maintenance + ongoing losses
Fluid overload: Wt gain, often hyponatremia.
Fluid+ sodium restriction www.similima.com 25
Nutrition
Goals: Normal growth and development (as compared to intrauterine growth for preterm
neonates, or as compared to growth charts for
term neonates)
Nutrient requirements:
Energy (Cals) Carbohydrate
Water Minerals
Protein Vitamins
Fat Trace elements www.similima.com 26
Energy { E = mc2
}
Energy needs: depend upon age, weight,
maturation, caloric intake, growth rate, activity, thermal environment, and nature of feeds.
Growing premies: (Cal/kg/day)
Resting expenditure: 50
Minimal activity: 4-5
Occasional cold stress: 10
Fecal loss (10-15%): 15
Growth (4.5 Cal/g +): 45
125
E=energy required
m =mass of baby
c = cry loudness
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Energy
Stressed and sick infants need more energy (e.g. sepsis, surgery)
Babies on parenteral nutrition need less energy (less fecal loss of nutrients, no loss for absorption): 70-90 Cal/kg/day+ 2.4-2.8 g/kg/day Protein adequate for growth
Count non-protein calories only! Protein to be preferred used for growth, not energy
65% from carbohydrates, 35% from lipids ideal
>165-180 Cal/kg/day not useful www.similima.com 28
Calculations
To calculate a neonate’s F,E,& N:
First calculate the amount of fluid (Water)
Then calculate how you plan to give it: Parenteral (IV) or Enteral (OG/PO)
Then calculate the amount of energy required
Decide how to provide the energy: amount and nature of carbohydrates and lipids
Provide proteins, vitamins, trace elements www.similima.com 29
Calculations: practical hints
for TPN
Do not starve babies! The ones who don’t complain are the ones who need it the most.
Use birthweight to calculate intake till birthweight regained, then use daily wt
Start TPN on 2nd or 3rd day if the baby will not be on full feeds by a week
Start with proteins (1 g/kg/d) and increase slowly.
After a few days (3rd or 4th day), add lipids (0.5 kg/kg/d)
Aim for 90-100 Cal/kg/day with 2.5-3 g/kg/d Protein (NPC/N of 150-200)
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Carbohydrate
IV:
Dextrose 3.4 Cal/g = 34 Cal/100 cc of D10W.
Tiny babies are less able to tolerate dextrose. If < 1 kg, start at 6 mg/kg/min. If 1-1.5 kg, start at 8 mg/kg/min.
If blood levels >150-180 mg/dL, glucosuria=> osmotic diuresis, dehydration
Insulin can control hyperglycemia
Hyper- or hypo-glycemia => early sign of sepsis
Avoid Dextrose>12.5% through peripheral IV www.similima.com 31
Carbohydrate
Enteral:
Human milk/ 20 Cal/oz formula = 67 Cal/100 cc
Lactose is carbohydrate in human milk and term formula. Soy and lactose free formula have sucrose, maltodextrins and glucose polymers
Preterm formula has 50% lactose and 50% glucose polymers (lactase level lower in premies, but glycosidases active)
Lactose provides 40-45% of calories in human milk and term formula
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Fat
Parenteral:
20% Intralipid (made from Soybean) better than 10%
High caloric density (2 Cal/cc vs 0.34 for D10W)
Start low, go slow (0.5-3 g/kg/day)
Avoid higher amounts in sepsis, jaundice, severe lung disease
Maintain triglyceride levels of < 150 mg/dL. Decrease infusion if >200-300 mg/dL.
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Fat
Enteral:
Approximately 50% of the calories are derived from fat. >60% may lead to ketosis.
Medium-chain triglycerides (MCT) are absorbed directly. Preterm formula have more MCT for this reason.
At least 3% of the total energy should be supplied as EFA
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Protein
Term infants need 1.8-2.2 g/kg/day
Preterm (VLBW) infants need 3-3.5 g/kg/day (IV or enteral)
Restrict stressed infants or infants with cholestasis to 1.5 g/kg/day
Start early - VLBW neonates may need 1.5-2 g/kg/day by 72 hours
Very high protein intakes (>5-6 g/kg/day) may be dangerous
Maintain NP Calorie/Protein ratio (at least 25-30:1) www.similima.com 35
Minerals (other than Na,K, Cl)
Calcium & Phosphorus:
Third trimester Ca accretion (120-150mg/kg/day) and PO4 (75-85 mg/kg/day) is more than available in human milk. Hence, HMF is essential. Premie formula has sufficient Ca/PO4. Ratio should be 1:7:1 by wt.
Magnesium: sufficient in human milk & formula
Iron: Feed Fe-fortified formula. Start Fe in breast fed term infants at 4 months of age, and in premies once full feeds are reached. (Does not prevent Anemia of Prematurity )
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Vitamins
Fat soluble vitamins: A, D, E, K
Water soluble vitamins: Vitamins B1,B2, B6, B12, Biotin, Niacin, Pantothenate, Folic acid, Vitamin C
All neonates should get vit K at birth
Term neonates: No vitamin supplement required, except perhaps vit D
Preterm: Start vitamin supplements once full feeds established if on human milk without HMF. No need if on human milk with HMF, or preterm infant formula (except: add vit D if on SSC24).
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Trace elements
Zinc, Copper, Selenium, Chromium, manganese, Molybdenum, Iodine
Most preterm formulas contain sufficient amounts
Fluoride supplementation not required in neonatal period
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Special formula
Soy formula:
Not recommended for premies: impaired mineral and protein absorption; low vitamin content
Used if galactosemia, CMPI, secondary lactose intolerance following gastroenteritis
Pregestimil: (Alimentum is similar, but with sucrose)
Hydrolyzed casein; 50% MCT; glucose polymers
Used if malabsorption or short bowel syndrome
Portagen:
Casein; 75% glucose polymers+25% sucrose; 85% MCT
Useful for persistent chylothorax. Can cause EFA def. www.similima.com 39
Special formula (contd.)
Similac PM 60/40:
Low sodium and phosphate; high Ca/PO4 ratio
Used in renal failure, hypoparathyroidism
Similac 27:
High energy with more Protein, Ca/Po4, Lytes
Used for fluid restricted infants: CHF, BPD
Nutramigen:
Hypoallergenic, lactose and sucrose free
Used for protein allergies, lactose intolerance www.similima.com 40