fluids, electrolyte, and nutrition management in neonates n. ambalavanan md neonatologist october...
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Fluids, Electrolyte, and Nutrition Management in Neonates
N. Ambalavanan MDNeonatologistOctober 1998
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)
Why is FEN management important?
Many babies in NICU need IV fluidsThey 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
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
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
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
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
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)
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
outputHepatomegaly can occur with ECF excessBlood pressure changes very late
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 bicarb may indicate poor perfusion)
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!)
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)
Management of F&E (contd.)
Guidelines for fluid therapyBirth 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
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%
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
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.
Common ‘lyte problemsSodium:
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)
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)
Increasesodium intake
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.
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
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
Management of Hyperkalemia
Stop all fluids with potassiumCalcium gluconate 1-2 cc/kg (10%) IVSodium bicarbonate 1-2 mEq/kg IVGlucose-insulin combinationLasix (increases excretion over hours)Kayexelate 1 g/kg PR (not with
sorbitol! Not to give PO for premies!)Dialysis/ Exchange transfusion
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
Things we aren’t going to discuss (i.e.) homework:
Acid-base disorders: Acidosis or Alkalosis, Metabolic or Respiratory or Mixed
HypercalcemiaMagnesium disordersMetabolic disordersMethods of feeding: Continuous vs.
Intermittent; TP vs OG vs NG vs NJ; Trophic feeds; Complications of TPN
(We can discuss these, if time permits)
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
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) CarbohydrateWater MineralsProtein VitaminsFat Trace elements
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 requiredm =mass of baby c = cry loudness
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
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
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)
CarbohydrateIV:
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
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
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.
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
ProteinTerm infants need 1.8-2.2 g/kg/dayPreterm (VLBW) infants need 3-3.5 g/kg/day
(IV or enteral)Restrict stressed infants or infants with
cholestasis to 1.5 g/kg/dayStart early - VLBW neonates may need 1.5-2
g/kg/day by 72 hoursVery high protein intakes (>5-6 g/kg/day)
may be dangerousMaintain NP Calorie/Protein ratio (at least 25-
30:1)
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 )
Vitamins
Fat soluble vitamins: A, D, E, KWater soluble vitamins: Vitamins B1,B2, B6, B12,
Biotin, Niacin, Pantothenate, Folic acid, Vitamin C
All neonates should get vit K at birthTerm neonates: No vitamin supplement
required, except perhaps vit DPreterm: 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).
Trace elements
Zinc, Copper, Selenium, Chromium, manganese, Molybdenum, Iodine
Most preterm formulas contain sufficient amounts
Fluoride supplementation not required in neonatal period
Special formulaSoy 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.
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