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Fluids, Electrolyte, and Nutrition

Management in Neonates

N. Ambalavanan MD

NeonatologistOctober 1998


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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 dont need the same IV fluids

(either in quantity or composition)If wrong fluids are given, neonatal

kidneys are not well equipped to handle

themSerious 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 (invessels : 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% ofweight in first week


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Things to consider:Normal changes in Renal Function

Adults can concentrate or dilute urinevery well, depending on fluid status

Neonates are not able to concentrate ordilute urine as well as adults - at risk fordehydration 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 thatis not obvious (makes sense?): throughskin (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:babys F&E status partially reflectsmoms F&E status (Excessive use of oxytocin,

hypotonic IVF can cause hyponatremia)Physical Examination:

Weight: reflects TBW. Not very useful forintravascular volume (eg. Long term paralysis andperitonitis can lead to increased body weight andincreased interstitial fluid but decreased intravascularvolume. 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 sensitiveindicators 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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Management of F&E

Goal: Allow initial loss of ECT over firstweek (as reflected by wt loss), while

maintaining normal intravascular volumeand tonicity (as reflected by HR, UOP,lytes, pH). Subsequently, maintain water

and electrolyte balance, includingrequirements for body growth.

Individualize approach (no cook book isgood 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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Guidelines for fluid therapyBirth Wt(kg)

Dextrose(%)

Fluid rate (ml/kg/d)

48 hr

1.5 10 60-80 80-120 120-160


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Factors modifying fluid requirement:Maturity--> Mature skin --> reduces IWL

Elevated temperature (body/environment)--> increasesIWL

Humidity: Higher humidity--> decreases IWL up to30% (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 requiredLater in the first week, needs are 1-2

mEq/kg/day (1 L of NS = 150+ mEq; 150cc/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 tohyponatremia, risk of BPD. Too little leads tohypernatremia, dehydration

BPD: Need more calories but fluids are usuallyrestricted: hence the need for rocket fuel. If diureticsare used, w/f lyte problems. May need extra calcium.

PDA: Avoid fluid overload. If indocin is used, monitorurine output.

Asphyxia: May have renal injury or SIADH. Restrictfluids initially, avoid potassium. May need fluid challenge

if cause of oliguria is not clear.


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Common lyte problems

Sodium:

Hyponatremia (150)

Potassium:

Hypokalemia (6.5 or if ECG changes )

Calcium:

Hypocalcemia (total5)


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Sodium stuff :

Hyponatremia

Sodium levels often reflect fluid statusrather 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)

Increasesodium intake


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Sodium stuff :

Hypernatremia

Hypernatremia is usually due to excessiveIWL in first few days in VLBW infants

(micropremies). Increase fluid intake anddecrease 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 levelsdo 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 IVGlucose-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 normallyover 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


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Things we arent going to

discuss (i.e.) homework:

Acid-base disorders: Acidosis or Alkalosis,Metabolic or Respiratory or Mixed

HypercalcemiaMagnesium 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)


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Common fluid problems

Oliguria : UOP< 1cc/kg/hr. Prerenal, Renal, orPostrenal causes. Most normal term babies peeby 24-48 hrs. Dont wait that long in sick lil

babies! Check Baby, urine, FBP. Try fluidchallenge, then lasix. Get USG if no response

Dehydration: Wt loss, oliguria+, urine sp.

gravity >1.012. Correct deficits, thenmaintenance + ongoing losses

Fluid overload: Wt gain, often hyponatremia.Fluid+ sodium restriction


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Nutrition

Goals: Normal growth and development(as compared to intrauterine growth for pretermneonates, or as compared to growth charts for

term neonates)

Nutrient requirements:

Energy (Cals) Carbohydrate

Water Minerals

Protein Vitamins

Fat Trace elements


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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 forabsorption): 70-90 Cal/kg/day+ 2.4-2.8g/kg/day Protein adequate for growth

Count non-protein calories only! Protein to bepreferred used for growth, not energy

65% from carbohydrates, 35% from lipids ideal

>165-180 Cal/kg/day not useful


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C l l ti ti l hi t


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Calculations: practical hints

for TPN

Do not starve babies! The ones who dont complain arethe 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 (0.5kg/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, startat 8 mg/kg/min.

If blood levels >150-180 mg/dL, glucosuria=>

osmotic diuresis, dehydrationInsulin can control hyperglycemia

Hyper- or hypo-glycemia => early sign of sepsis

Avoid Dextrose>12.5% through peripheral IV


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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 havesucrose, 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 humanmilk 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, severelung 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 moreMCT for this reason.

At least 3% of the total energy should besupplied 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 orenteral)

Restrict stressed infants or infants with cholestasisto 1.5 g/kg/day

Start early - VLBW neonates may need 1.5-2

g/kg/day by 72 hoursVery high protein intakes (>5-6 g/kg/day) may be

dangerous

Maintain NP Calorie/Protein ratio (at least 25-30:1)


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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. Ratioshould be 1:7:1 by wt.

Magnesium: sufficient in human milk & formulaIron: Feed Fe-fortified formula. Start Fe in breast

fed term infants at 4 months of age, and in premiesonce 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 fullfeeds established if on human milk without HMF.No need if on human milk with HMF, or preterminfant 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 sufficientamounts

Fluoride supplementation not required in

neonatal period


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Special formula

Soy formula:

Not recommended for premies: impaired mineral andprotein absorption; low vitamin content

Used if galactosemia, CMPI, secondary lactose intolerancefollowing 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.


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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

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