Fluids and electrolytes in neonates

Fluids & Electrolyte in Neonates : 

Fluids & Electrolyte in Neonates Dr. Vijaysinh Bhatlawande Dept. of Pediatrics JNMC, Sawangi (M), Wardha.

F&E Management in Neonates : 

F&E 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 F & E management : 

Why is F & E management 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

Fluids and Electrolytes : 

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 : 

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 : 

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 adults. at risk for dehydration or fluid overload Renal function matures with increasing: gestational age postnatal age

Things to consider: Insensible water loss (IWL) : 

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 : 

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.)

Assessment of fluid and electrolyte status (contd.) : 

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

Assessment of fluid and electrolyte status (contd.) : 

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 : 

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.) : 

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.) : 

Management of F&E (contd.) Guidelines for fluid therapy

Management of F&E (contd.) : 

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! : 

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 : 

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 problems : 

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)

Sodium stuff : Hyponatremia : 

Sodium stuff : Hyponatremia Sodium levels often reflect fluid status rather than sodium intake

Sodium stuff : Hypernatremia : 

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 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 : 

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 : 

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

Calcium stuff : 

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 : 

Things we aren’t going to discuss Acid-base disorders: Acidosis or Alkalosis, Metabolic or Respiratory or Mixed Hypercalcemia Magnesium disorders Metabolic disorders

Common fluid problems : 

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

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