FLUID AND ELECTROLYTE THERAPY IN CHILDREN BY Dr. S. E. NWIZU Consultant Paediatrician Premier Specialists’ Med. Centre.

FLUID AND ELECTROLYTE THERAPY IN CHILDRENBY

Dr. S. E. NWIZUConsultant Paediatrician

Premier Specialists’ Med. Centre.

OUTLINE

• INTRODUCTION• BASIC FLUID AND ELECTROLYTE THERAPY• DEHYDRATION• ELECTROLYTE PROBLEMS

INTRODUCTION

• Distribution of fluids and electrolytes:.Water is by far the most abundant component of the human body..BODY WATER AND AGE:

Age TBW ECF ICF(%bwt) (%bwt) (%bwt)

Prem 85 55 30Term 80 45 351-3yrs 65 25 40Adults 65 25 40

.The fall in the % body weight with increasing age is due to accumulation of fat. Fat is low in water content..Increasing cellular tissue growth and increasing rate of growth of collagen relative to muscle during the early months of life may explain the increase in ICF and decrease in ECF.

• FLUID COMPARTMENTS1. Intracellular (30%-40% of body weight)2. Extracellular (20%-25% of body weight)

Plasma 5% of body weightInterstitial 15% of body weightTranscellular 1-3% of body wt eg GI

secretions,CSF,Intraocular,pleural,peritoneal3. Slowly exchangeable compartments (8-10% of body wt).

BoneDense CTCartilage.

This compartment is not accessible to the body fluid regulating mechanisms

• Electrolyte distribution in compartments:ECF ICF

Cations:Na 140mmols/l K 140mmols/lAnions: Cl proteins

HCO3 sulphates• Regulation of Body Water

Plasma osmolality=285-295mosm/kg. This is maintained by a finely regulated feedback system involving osmoreceptors.These receptors can be found in the hypothalamus,posterior pituitary,atria,collecting ducts of nephrons

• Sources of water – Intake which is stimulated by thirst. - Oxidation of CHO, fat and protein

• Major stimuli for thirst – plasma osmolality increases of 1-2%.

- depletion of ECF vol by ≥ 10%

Basic Fluid and Electrolyte therapy• Maintenance: GOAL; Intake=output, zero bal

• Maintenance fluid req is defined as the volume of daily fluid intake which replaces the insensible losses(from breathing and skin ), and at the same time, allows excretion of the daily production of excess solute load(Ur, Cr, electrolytes etc) in a volume of urine that is of an osmolality similar to plasma.

• Major objectives of maintenance fluids are: prevent dehydration

prevent electrolyte disordersprevent ketoacidosisprevent protein degradation

eg 5% D in maintenance fluids(supplying 17 calories/100ml) will provide ≈20% of the normal caloric needs of the patient. This is enough to prevent starvation ketoacidosis starting and diminishes protein degradation that could occur if the pt received no calories.

• The commonly used method for ≈ the water requirement is the Holliday-Segar normogram.It relates water loss to the caloric expenditure. The approach assumes that for every 100 kilocalories metabolized,100ml of water is required. 1st 10kg → → 100mls/kg/24hrs2nd 10kg → → 50mls/kg/24hrsSubs. Kg → → 20mls/kg/24hrs

• Main electrolytes: aimed at replacing normal urinary loses and provide additional, needed for growth.Na 2-3mEq/kg/dayCl 2-3mEq/kg/dayK 2 mEq/kg/day

• Conditions that increase Fluid requirement:.phototherapy.radiant warmers.in persistent pyrexia illnesses.abnormal fluid losses.hypermetabolic states.increased urinary vol associated with

glycosurea• Circumstances that req a reduction maintenance fluid

include: .In edematous and antidiuretic states.In sedated or paralyzed pts..In the presence of compromised renal fxn and

oligoanuria

DEHYDRATION• This occurs when loss of water and salts exceeds the

intake.• Etiology : vomiting

diarrhea burns excess sweating 3rd space losses eg bowel obstructn DKA

• Classification : Tonicity Signs and symptoms

Tonicity• Isotonic Dehydration Hypotonic Dehydration

Hypertonic Dehydration• Isotonic Dehydration:

.Commonest

.Losses of water and electrolytes are proportional..no shift of fluids from ICF to ECF or vice- versa..serum Na 130-150mEq/l

• Hypotonic:.loss of salt over a period exceeds loss of water.tonicity of the body fluids reduces..Serum Na < 130mEq/l

• Hypertonic:.loss of water exceeds loss of salt.commonly in infants < 6 months of age..Serum Na >150mEq/l.Fluid losses are predominantly intracellular..CNS signs and symptoms are common possibly due to intracellular dehydration.

• TYPES OF DEHYDRATION/PHYSICAL SIGNSIso Hypo Hyper

.ECF volMarked ↓ Severely ↓ ↓

.ICF vol Maint Increased ↓

.Phy signsSkinTemp. Cold Cold ColdTurgor Poor Very poor FairFeel Dry Clammy Doughy

.Mucous memb Dry Slightly moist ParchedEyeball Sunken Sunken Sunken

& soft

Iso Hypo Hyper.Psyche Lethargic Coma

Hyperirritable

.Pulse Rapid Rapid Mod. Rapid

.BP low Very low Mod low

Clinical Correlates of Dehydration• Severity Signs Fluid therapy(mls/kg)

Infants Adol.Mild Slightly 50(5%) 30(3%)

dry mucmemb,↑thirst, slightyly↓ U.O.

Mod Dry mucous memb,lethargylittle or no U.O.sunken eyes & 100(10) 50-60(5-6%) fontanelle,lossof skin turgor

Severe Above+rapidthready pulseno tears,cyanosis, 150(15) 70-90(7-9%)rapid breathing,delayed cap refillhypotension,mottled skin, coma

Rehydration Therapy• Fluid Replacement : Maintenance +

Deficit + Ongoing losses

Phase 1 → over 8 hoursPhase 2 → over 16 hoursSHOCK• Types of fluids that can be used: .ORS .Ringers lactate → Na, K ,Ca, Cl, lactate .½ Strength Darrows → Na, K, Cl, lactate .4.3% D/S →Glucose, Na,Cl .Normal Saline →Na,Cl.

• Indications for IV Therapy:Severe dehydration ± shockUncontrollable vomitingProlonged oliguria or anuriaStructural or functional GI obstructnSevere diarrhea > 10ml/kg/hr of stools

• Signs of fluid overload:Puffiness of eyesCoughTachypnoeaBasal crepitationsHepatomegaly

• Monitoring:.Input/output.Body weight.Oedema.Palpation of peripheral pulses.Auscultation of heart and lungs.PCV.Blood sugar.Serum urea

ELECTROLYTE DEFICIT CORRECTION• Sodium Deficit

(Desired – Observed) x wt x0.6Desired is taken as 140mEq/l

Potassium Deficit (Desired – Observed) x wt x0.6 Desired is taken as 4mEq/l

Bicarbonate Deficit (Desired – Observed) x wt x0.3Desired is taken as 20mEq/l

• Correction of Na must not exceed an increase of 0.5mmol/hr or 10mmol/24hrs.

• Correction of K , ensure child is making urine , never give K as a bolus and never exceed 40mE/l without ECG monitoring.

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