FLUID AND ELECTROLYTE MANAGEMENT

IN NEWBORN

By Dr B VIKRAM SIMHA

Guide: Dr SANJAY CHATTREE

AIM :to allow successful transition from the aquatic

environment of the uterus into the arid extra-uterine milieu in the first days of life and

to replace losses of water and electrolytes so as to maintain normal balance of these essential substances.

PHYSIOLOGICAL ASPECTS:

Urine osmolarity range : 50mmol/L to 600mmol/L (Preterm) and 800mmol/L(Term)

Acceptable Range : 300-400 mmol/L 2-3ml/Kg/Hr of UOP

Neonatal Kidney has limited capacity both to excrete and conserve Sodium-so Na+ Supplementation required.

Newborn kidney has a limited capacity to excrete excess water and sodium.

So overload of fluid or sodium in the 1st week of life morbidities like PDA, NEC and BPD

TERM 800

PRETERM 600

BODY COMPOSITIONCHANGES IN BODY WATERSOLUTE DISTRIBUTIONWATER LOSSNEUROENDOCRINE CONTROL

BODY COMPOSITIONCHANGES IN BODY WATERSOLUTE DISTRIBUTIONWATER LOSSNEUROENDOCRINE CONTROL

94% of Body WTat 3RD MONTH OF GESTATION

78% at TERM

↑RENAL FUNCTION

ATRIAL NATRIURETIC PEPTIDETBW & ECW :Preterm > TermSGA > AGAPOST NATAL ECW CONTRACTION

ECW ↓ ICW ↑

ICW > ECW by 3 months of life

CHANGES IN BODY WATER AND ELECTROLYTE COMPOSITIONDURING INTRAUTERINE AND EARLY POSTNATAL LIFE

Gestational Age (Weeks)Component 24 28 32 36 40 1 to 4Weeks

After Term Birth

Total body water (%) 86 84 82 80 78 74

Extracellular water (%) 59 56 52 48 44 41

Intracellular water (%) 27 28 30 32 34 33

Sodium (mEq/kg) 99 91 85 80 77 73

Potassium (mEq/kg) 40 41 40 41 41 42

Chloride (mEq/kg) 70 67 62 56 51 48

Changes in body water during gestation and infancy

3rd month

Distribution of body water in a term newborn infant

BODY COMPOSITIONCHANGES IN BODY WATERSOLUTE DISTRIBUTIONWATER LOSSNEUROENDOCRINE CONTROL

Ion distribution in the blood plasma, which represents extracellular fluid, and in the intracellular fluid compartment.

ECF:Plasma – Non plasma

(interstitial) = PROTEINS

BODY COMPOSITIONCHANGES IN BODY WATERSOLUTE DISTRIBUTIONWATER LOSSNEUROENDOCRINE CONTROL

WATER LOSS

SENSIBLE INSENSIBLE

Kidney GIT Skin70%

Respiratory Tract30%

PHYSIOLOGICAL WEIGHT LOSS:

Salt and Water Diuresis (48-72 hrs)

Fluid Shift ICF ECF

Weight Loss

ECF: Preterm > Term Weight Loss : Preterm (15%) > Term (10%)

INSENSIBLE WATER LOSS:

Insensible Water Loss according to Birth Weight on Day 5

BIRTH WEIGHT IWL (ml/Kg/day)

<1000 gm 60-80

1000-1500 gm 40-60

>1500 gm 20

FACTORS AFFECTING INSENSIBLE WATER LOSS IN NEWBORN INFANTS

Factor Effect On Insensible Water Loss (Iwl)

Level of maturity Inversely proportional to birth weight and gestational age Respiratory distress (hyperpnea) Respiratory IWL increases with rising minute ventilation when dry air is being

breathedEnvironmental temperature above neutral thermal zone Increased in proportion to increment in temperatureElevated body temperature Increased by up to 300%Skin breakdown or injury Increased by uncertain magnitudeCongenital skin defect (e.g.,gastroschisis, omphalocele, neural tube defect) Increased by uncertain magnitude until surgically correctedRadiant warmer Increased by about 50%Phototherapy Increased by about 50%Motor activity and crying Increased by up to 70%

FACTORS AFFECTING INSENSIBLE WATER LOSS IN NEWBORN INFANTS

Factor Effect On Insensible Water Loss (Iwl)

High ambient or inspired humidity Reduced by 30% when ambient vapor pressure Is increased by 200%Plastic heat shield Reduced by 30% to 70%Plastic blanket or chamber Reduced by 30% to 70%Semipermeable membrane Reduced by 50%Topical agents Reduced by 50%

INSENSIBLE WATER LOSS:

PREVENTION > CURE (REPLACEMENT)

IWL PRETERM>TERM

Reasons : Immaturity of Skin BarrierRespiratory Distress greater skin blood flowlarger body water*ESSENTIAL FATTY ACID DEFICIENCY

MEASURES : INCUBATOR HUMIDIFICATION SYSTEMSPLEXIGLASS HEAT SHIELDSTHIN BARRIERS OF SARANTHIN PLASTIC BLANKETSSEMIPERMEABLE MEMBRANESWATER PROOF TOPICAL AGENTS

BODY COMPOSITIONCHANGES IN BODY WATERSOLUTE DISTRIBUTIONWATER LOSSNEUROENDOCRINE CONTROL

NEUROENDOCRINE CONTROL:

Pituitary : ADH & ACTH Adrenal : Aldosterone

activators : RAS, ACTH, Na + ,K+

but poor response of TUBULESParathyroid : PTH (↑)

vs Ca2+

Thyroid : Calcitonin (↓)ANF : Na+ and H2O excretion Postnatal Diuresis

PRINCIPLES OF THERAPY:

Estimate

Calculate

Administer

Monitor

Replacement of Deficits

Maintenance

Replacement of ongoing losses

Estimate

FLUID ELECTROLYTE

½ CATIONS(¼ SODIUM + ¼ POTASSIUM)

½ ANIONS

Dehydration

Isotonic Na+= 130-150Hypertonic Na+= >150Hypotonic Na+= <130

***From clinical symptoms and

signs

E.g.1.Severe acute diarrhea – isotonic

2.High IWL – hypernatremic3.Inadequate salt loss replacement

– hypotonic.

Calculate

Replacement Maintenance

ÞRapid correctionÞException : Hypertonic DehydrationÞNa+ correction over 24 hrsÞK+ correction over 48-72 hrs.

Ongoing losses

ÞVomiting / Diarrhea/ RTA

DEFICIT – REPLACEMENT: Dehydration:

Moderate (10%) to Severe(15%)correction over 24hrsN/2 ½ in 8hrs + ½ in 16 hrs

+ Maintenance in 24 hrs

(N/5 + 10% D @ 100ml/Kg/day)

Shock:Stat NS @ 10-20 ml/Kg in 1-2 hrs

↓Correction ½ in 8hrs + ½ in 16 hrs

+ Maintenance

Type of Dehydration

SerumSodium

Concentration(mEq/L)

Calculation ofTotal Solute Deficit

(mOsm/kg)a

Solute Deficit

(mOsm/kg)

Sodium Deficit

(mEq/kg)b

Isotonic(10%)

140 (0.7 ×280)–(0.6× 280) 28 14

Hypertonic(10%)

153 (0.7 ×280)–(0.6× 306) 12 6

Hypotonic(10%)

127 (0.7 ×280)–(0.6× 254) 44 22

a Total solute deficit = (TBWe × solutee - (TBWo × soluteo), where subscripts e and o indicate expected and observed, respectively. TBW e =0.7 L/kg; TBW o = 0.7 - 0.1 = 0.6 L/kg; solutee 140 × 2 = 280 mOsm/L, assuming total solute concentration in body water is twice the sodium concentration in serum;Solute o = observed serum sodium × 2.b Total solute deficit is assumed to be half sodium. Although the serum (and ECW) has lost this amount of sodium, only half this amount has been lost to the environment; the other half has been lost into the cells in exchange for potassium, which in turn has been lost from the body. In practice, therefore, only half the amount listed as “sodium deficit” should be replacedas sodium, and the other half should be given as potassium. TBW, total body water. ECW, extracellular water.

TABLE 21-5 CALCULATION OF SODIUM DEFICIT

GUIDELINES FOR FLUID THERAPY: TERM

Birth Weight Day 1 Day 2 to Day 7 Day 7

>1500 gm 60 (+15-20) 150

1000-1500 gm 80 (+10-15) 150

Day 1 : Solutes Excreted 15 mmol/Kg/dayAcceptable Urine Osmolarity 300mmol/L Minimum UOP required 50ml/Kg/day

+ IWL 20ml/Kg/day-------------------------------- Total 60-70ml/Kg/day

10% D @ 4-6mg/Kg/min

Day 2 : Solute load increased + Fecal Losses + Growth Requirement

+15-20ml/Kg/day

+ Na+, K+ after 48 hrs

Day 7 : 150-160 ml/Kg/day

DAILY FLUID REQUIREMENTS DURING 1ST WEEK OF LIFE (ml/Kg/day)

GUIDELINES FOR FLUID THERAPY: PRETERM

Day 1 : UOP PRETERM = TERM but ACCORDING TO BODY WEIGHT THE LOSS IS PRETERM > TERMso fluid req. PT > TERM 80ml/Kg/day10% D @ 4-6mg/Kg/min

Day 2 : +10-15ml/Kg/day

+ Na+, K+ after 48 hrs

Day 7 : 150-160 ml/Kg/day +Na+ supplementation @ 3-5 mEq/Kg upto 32-34 corrected weeks

1.Birth weight : Term 1-3% per Day / 5-10% first weekPreterm2-3% per Day / 15-20% first weekIncreased loss fluid correctionDecreased loss fluid restriction

2.Clinical Examination : signs unreliable10% dehydration-signs of dehydration15% dehydration-shock

3.Serum Biochemistry : Na+ & plasma osmolarityNormal 135-145mmol/L

Na+

Hypernatremia Hyponatremia

Weight: + - + -

Disturbance : H2O excess Sodium Depletion

Salt and H2O overload

Dehydration

Treatment: Fluid Restriction Sodium Replacement

Salt andFluid Restriction

Fluid correction(48 hrs)

Monitor:

4.Urine Parameters : Acceptable Range:

Output 1-3ml/Kg/hrSpecific Gravity 1.005-1.012 (by Dipstick or Refractometer)Osmolarity 100-400 mOsm/L (Freezing point osmometer)

5.Blood Gas : Poor perfusion and Shock Metabolic Acidosis

6.Fractional Excretion of Na+: assess Renal Tubular Function limited value in Preterm (immaturity)

7.Serum Creatinine, BUN : assess Renal Functionexponential fall in Serum Creat ( excretion of Maternal )serial samples – better indicator Renal failure

Monitor:

LABORATORY GUIDELINES:

IV FLUIDS:

ELECTROLYTES:

↑ ↓

> 3% per day or > 20% cumulative

Weight loss < 1% per day or < 5% cumulative

> 145 mEq/L Serum Na+ < 130 mEq/L

> 1.020/> 400 mOsm/L

Urine Specific Gravity/

Osmolarity

< 1.005/< 100 mOsm/L

< 1 ml/Kg/hr UOP > 3ml/Kg/hr

ELECTROLYTE RECOMMENDATION

Na+ After 48 hrs@ 2-3 mEq/Kg/day

K+

Ca2+ For first 3 days in high risk conditions

@ 4 ml (40 mg)/Kg/day

Dextrose 10%5%

@ 4-6 mg/Kg/minIf ≥1250 gmIf <1250 gm

EONH:-> Premature(<32wks)

-> Preeclampsia->IDM

->Perinatal Asphyxia (Apgar<4 @ 1 min)-> Maternal Hyper PTH

->IUGR->Iatrogenic alkalosis

SPECIFIC CLINICAL CONDITIONS:1.Extreme Prematurity : < 28 wks

<1000 Kg- large IWL upto 1-2 wks till Stratum Corneum matures- ↓ requirement by ↓ing loss- 5% D ; electrolyte free on day 1- Na+ K+ supplementation after 48 hrs

2. RDS : RDS hypoxia ACIDOSIS ↓ RENAL FUNCTION+VE PRESSURE VENTILATION ↑ ALDOSTERONE & ADH H2O Retention Symptomatic PDA.

3. Perinatal Asphyxia & Brain injury: SIADH ↓HYPONATREMIA

=> FLUID RESTRICTION (2/3RD Maintenance till Na+ normal)

Renal Parenchymal Injury ATNOliguric or Anuric RFÞ↓ FLUID(only replace IWL & Metabolic Requirement) @ 40ml/Kg or 400ml/m2

ÞAt RECOVERY --Na+ K+ losses –to be calculated n replaced4. Diarrhea :

of FLUID DEFICIT over 24 hrs Ongoing losses @ 6-8 hrs

FLUID RESTRICTION:

ÞCochrane meta-analysis:

Restricted fluid therapy

Greater Wt loss + dehydration ↓ incidence of PDA, NEC & DEATH

Water(mL)

Sodium(mEq)

Potassium(mEq)

Deficit 300 21 21

Maintenance 300 6 6

Ongoing losses 0 0 0

Total 600 27 27

Total/kg 200 9 9

a Water deficit: 0.10 × 3 kg.b Electrolyte deficits calculated as in Table 21-5 (14 mEq/kg × 3 kg divided between sodium and potassium).c Potassium deficit should be replaced slowly over 48 to 72 hours.d Maintenance water requirement assumed to be 100 mL/kg/day.

TABLE 21-7 CALCULATION OF FLUID AND ELECTROLYTE INTAKE FOR A 3-KG INFANT WITH 10% ISOTONIC DEHYDRATION

THANQ