Neonatal Medication and Fluid CalculationsSneha Sood, MD

Fluid CompartmentsExtracellular (ECF) = intravascular and

interstitialIntracellular (ICF) = within cellsTotal body water (TBW) = ECF + ICF

Body CompositionTotal body water preterm>term>adult

(preterm 80% BW, term 70-75% BW, adult 50-60% BW)

Greater ECF in neonate (40% vs 20%)ICF increases with proliferation of

cells and maturation of organs

From Pedaitrics in Review, 1992, McLeod and Evans.

Fluids in the NeonateWeight loss over first 7-10 days normal

phenomenon in all babies. Causes include:Reduction of ECF most important cause of

weight lossInadequate calorie intake may play smaller

roleMechanism of postnatal contraction of ECF

unclearDiuresis seen in LBW infants over first five

days associated with contraction of ECF

Maintenance FluidsTotal fluids based on insensible loss (skin and

respiratory tract) + urine + stool water.Recommendation:

Always calculate total fluids at 80 ml/kg/day and use D10W without added NaCl or KCl. Need to add heparin, 1 unit/ml if running through a central line such as a UVC.

Fluids can be increased or decreased after discussion with the Pediatrician or Neonatologist.

Factors Affecting Insensible Water LossFactor Effect on Insensible Water

Loss

Maturity Losses inversely proportional to BW and GA

Elevated environmental temperature

Increased losses

Elevated body temperature Increased losses

High ambient or inspired humidity

Reduces insensible losses

Skin breakdown Increased losses

Congenital skin defects (oomphalocele or gastroschisis)

Increased losses

Radiant warmer Increased losses

Phototherapy Increased losses

Double wall incubator or plastic heat shield

Decreased lossesModified from Dell and Davis, Chapter 34, Neonatal-Perinatal Medicine, 8 th ed.,

Possible Indications for Decreasing or Increasing Total Fluids

Decreased Fluid Requirements:Term infant > 2500 gramsHypoxic-ischemic encephalopathy (HIE)Renal insufficiency or renal failure

Increased Fluid Requirements:Preterm infant ≤ 1000 grams (ELBW or extremely low

birth weight)Abdominal wall defect (e.g. gastroschisis)PhototherapyHypoglycemia to increase glucose infusion rate (gir)Increased GI losses (vomiting, diarrhea, NG output)Infant > 24-48 hours of life

Preterm vs. Term NewbornLarge insensible losses primarily due to

immature skin in premature babies especially if ≤ 1000 grams.

In tertiary care center losses can be minimized by placement in humidified isolette; in community hospitals saran wrap shield can be used to decrease insensible losses but will not be as effective as a humidified isolette.

Dextrose ConcentrationD10W is the standard dextrose concentration in

newbornsGlucose Infusion Rate (GIR) expressed as mg/kg/min Ideal GIR 4-8 mg/kg/minIn hypoglycemic infants higher GIR may be necessary;

this can be achieved by increasing the dextrose concentration or by increasing total fluids.

Maximum dextrose concentration in peripheral IV fluids = D12.5

ELBW babies may require lower dextrose concentration due to hyperglycemia because of increased fluid requirements due to high insensible losses.

ElectrolytesNo maintenance Na, K, or Cl necessary

during the first 1-2 days of life.Generally electrolytes do not need to be

checked until 24 hours of life.More frequent monitoring of electrolytes may

be required in premature babies or sick babies with excessive fluid shifts.

Urine OutputUrine output is a measure of fluid and

electrolyte balanceAdequate urine output in the first few days of

life: 1-3 ml/kg/hour

CalciumCa, Mg, and P accumulate between 24 weeks to term with peak

at 34-36 weeks.Serum Ca concentrations high at birth but fall to nadir between

24-48 hours.This fall is accentuated in preemies, infants of diabetic mothers,

and after birth asphyxia.Although calcium should be monitored, especially in sick babies,

it should not be added to peripheral IV fluids. If needed calcium gluconate can be given slowly over one hour. Usually unnecessary to check calcium in first 24 hours unless symptoms suspicious for hypocalcemia or baby very sick.

Usually unnecessary to add calcium to initial IV fluids in newborn < 24 hours of life even if through a central line. Calcium will be added through the parenteral nutrition or to the fluids at the tertiary care center.

Umbilical Artery CatheterSizes*:

2.5 F (if available) if < 750 grams 3.5 F if 750-1500 grams5 F for all others

Placement:High line: T6-T9Low line: L3-L4

Calculation for placement of high line:3 x wt (kg) + 9 cm* From Kapi’olani Medical Center Transport Guidelines

Umbilical Artery Catheter

Fluids: ½ NS with 1 u heparin/ml at 0.5-1 ml/hr

Lab draws: Withdraw 1.5-2 ml blood; give back blood and flush with heparinized solution (1/2 NS with 1 u heparin/ml) in 3 ml syringe.

From: Kapi’olani Medical Center Guidelines

Umbilical Vein CatheterSizes*:

5 F if > 2500 grams3.5 F if < 2500 grams5F for all stabilization UVC catheters

Calculation of distance for placement½ distance of UAC + 1 cm for indwelling UVCStabilization UVC: advance until blood return noted;

usually 2-4 cm and possibly less in a premature baby.Single lumen:

Long term lineStabilization line

Double lumenSick babies, multiple drips, micropreemies

* From Kapi’olani Medical Center Transport Team Guidelines

Umbilical Vein CatheterIf single lumen run maintenance IVF; add 1 unit

heparin/ml.Double lumen:

Maintenance fluids through smaller lumen; run maintenance D10W with 1 u heparin/ml

Blood draws, blood products, medications through second but larger lumen; heparin lock with 0.3 ml of 10u heparin/ml every 8 hours and prn*.

For blood draws withdraw 1.5-2 ml of blood; give blood back after specimen obtained; flush with heparinized solution (1/2NS with 1 u heparin/ml) in 3 ml syringe

From Kapi’olani Medical Center Guidelines

Umbilical Catheters

While umbilical lines can be pulled back, never advance an umbilical catheter that has slipped out—use a clean line instead unless still under sterile prep and drape!