Fluids and Electrolytes in Pediatrics

8/7/2019 Fluids and Electrolytes in Pediatrics

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Fluids and ElectrolytesFluids and Electrolytes

In Pediatric PatientsIn Pediatric Patients


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We are all made up of salt waterWe are all made up of salt water

Adults/ adolescentsAdults/ adolescentsare about 55%are about 55%

water.water.

Infants are greaterInfants are greaterthan 75% waterthan 75% water


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Body water compartmentsBody water compartments

ExtracellularExtracellular ECFECF Interstitial, intravascular,Interstitial, intravascular, transcellulartranscellular

IntracellularIntracellular ---- ICFICF


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Water LossWater Loss

Water loss can be sensible water lossWater loss can be sensible water loss urine outputurine output

Insensible water lossInsensible water loss breathing,breathing,perspiringperspiring

Two thirds of insensible water loss occursTwo thirds of insensible water loss occurs

through the skinthrough the skin


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What makes kids so special?What makes kids so special?

Higher % water inHigher % water inECFECF esp. infantsesp. infants

Children have aChildren have ahigher metabolic ratehigher metabolic ratethan adultsthan adults

Infants and childrenInfants and childrenhave a more rapidhave a more rapidrespiratory rate thanrespiratory rate thanadults, so a greateradults, so a greaterinsensible water lossinsensible water loss


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Greater body surfaceGreater body surfacearea in relation toarea in relation tobody massbody mass

Immature immuneImmature immunesystems make themsystems make themmore susceptible thanmore susceptible thanadults to infectiousadults to infectiousdiseasesdiseases

Less likely toLess likely tocommunicate thirstcommunicate thirst


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Infant kidneys are functionally immature atInfant kidneys are functionally immature atbirth. Unable to concentrate or dilute urine tobirth. Unable to concentrate or dilute urine toconserve or excrete sodium, or to acidify theconserve or excrete sodium, or to acidify the

urine. Less able to compensate for acidosis.urine. Less able to compensate for acidosis.


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Maintenance Fluid RequirementsMaintenance Fluid Requirements

Based on normal metabolic state, at restBased on normal metabolic state, at rest

Body WeightBody Weight Amount of Fluid perAmount of Fluid perDayDay

11 10 kg10 kg 100 ml/kg/day100 ml/kg/day

1111 20 kg20 kg 1000 ml plus1000 ml plus50 ml/kg/day50 ml/kg/day

2121 30 kg30 kg 1500 ml plus1500 ml plus25ml/kg/day25ml/kg/day


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Hourly maintenance fluid rateHourly maintenance fluid rate

First 10 kg = 4 ml/kg/hourFirst 10 kg = 4 ml/kg/hour 1111 20 kg = 40ml/hour plus 2ml/kg/hr20 kg = 40ml/hour plus 2ml/kg/hr 2121 30 kg = 60ml/hr for first 20kg plus30 kg = 60ml/hr for first 20kg plus

1ml/kg/hr1ml/kg/hr


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Calculating Intake and OutputCalculating Intake and Output

1. Obtain current weight1. Obtain current weight 2. Get total mls of intake in 24 hour2. Get total mls of intake in 24 hour

periodperiod 3. Divide by current weight3. Divide by current weight

Example: 164 cc total intakeExample: 164 cc total intake 2.14kg = 76.632.14kg = 76.63ml/kg/dayml/kg/day

Output: Total outputOutput: Total output wt. in kgwt. in kg24 hours =24 hours =ml/kg/hrml/kg/hr


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FeverFever

Fever increases insensibleFever increases insensiblewater loss bywater loss byapproximately 7ml/kg/24approximately 7ml/kg/24hours for every 1 degreehours for every 1 degreerise in Temp above 37.2rise in Temp above 37.2CC

Children have a tendencyChildren have a tendencyto become more highlyto become more highlyfebrile than adultsfebrile than adults


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Acid/base balanceAcid/base balance

pH 7.35pH 7.35 7.457.45 Regulated in normal range by respiratoryRegulated in normal range by respiratory

system, kidneys, chemical bufferssystem, kidneys, chemical buffers HCOHCO33 = base CO= base CO22 = acid= acid AcidosisAcidosis pH < 7.35pH < 7.35

RespiratoryRespiratory ventilationventilation probprob

MetabolicMetabolic diarrhea, kidney failure, DKAdiarrhea, kidney failure, DKA AlkalosisAlkalosis pH > 7.45pH > 7.45

RespiratoryRespiratory test takingtest taking

MetabolicMetabolic ---- vomitingvomiting


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DehydrationDehydration

Dehydration is the most common disturbance inDehydration is the most common disturbance in

fluid and electrolyte balance in children.fluid and electrolyte balance in children.


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Types of dehydrationTypes of dehydration

Related to the plasma sodiumRelated to the plasma sodiumconcentrationconcentration

IsonatremicIsonatremic HyponatremicHyponatremic HypernatremicHypernatremic


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Isotonic dehydrationIsotonic dehydration

In isotonic dehydration the plasma sodiumIn isotonic dehydration the plasma sodiumis going to be normalis going to be normal 130130 150 mEq/l150 mEq/l

Vomiting and diarreahVomiting and diarreah most commonmost commoncausecause

Very real danger of shockVery real danger of shock


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Hypotonic (Hyponatremic)Hypotonic (Hyponatremic)

DehydrationDehydration Plasma sodium is less than 130 mEq/lPlasma sodium is less than 130 mEq/l The loss of sodium is greater than the lossThe loss of sodium is greater than the loss

of water.of water.

Fluid loss is mostly from the extracellularFluid loss is mostly from the extracellularor intravascular space, so theor intravascular space, so the

cardiovascular effects will be greater withcardiovascular effects will be greater withsmaller amounts of deficit.smaller amounts of deficit.


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CausesCauses

GastroenteritisGastroenteritis Inappropriate IV therapyInappropriate IV therapy Syndrome of Inappropriate AntidiureticSyndrome of Inappropriate Antidiuretic

Hormone (SIADH)Hormone (SIADH)

UnreplacedUnreplaced gastric suctiongastric suction


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Hypertonic (hypernatremic)Hypertonic (hypernatremic)

DehydrationDehydration This type of dehydration is the mostThis type of dehydration is the most

dangerous. Fluid shifts from the ICF todangerous. Fluid shifts from the ICF to

the ECF. This causes a shift of fluid fromthe ECF. This causes a shift of fluid fromthe intracellular to the intravascularthe intracellular to the intravascularcompartment, so intravascular volume iscompartment, so intravascular volume is

maintained at the expense of intracellularmaintained at the expense of intracellulardehydration.dehydration.

Plasma sodium is greater than 150 mEq/lPlasma sodium is greater than 150 mEq/l


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CausesCauses

Vomiting/diarreahVomiting/diarreah Diabetes insipidusDiabetes insipidus


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TreatmentTreatment

Replace deficit gradually over 48 hoursReplace deficit gradually over 48 hoursand avoid rapid fall in serum sodiumand avoid rapid fall in serum sodium

If serum sodium is lowered too quickly,If serum sodium is lowered too quickly,cerebral edema or cerebrovascularcerebral edema or cerebrovascularhemorrhage may develop.hemorrhage may develop.


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Minimal < 3% loss of bodyMinimal < 3% loss of body wtwt

Severe >10% loss of body wt.Severe >10% loss of body wt.


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Physical Signs of DehydrationPhysical Signs of Dehydration

TachycardiaTachycardia this is one of the earliest signs butthis is one of the earliest signs butis also indicative of fever or infectionis also indicative of fever or infection

Dry skin and mucous membranesDry skin and mucous membranes Sunken fontanelsSunken fontanels Cool, mottled extremitiesCool, mottled extremities

Loss of skin elasticityLoss of skin elasticity abnormal skin turgorabnormal skin turgor Prolonged capillary refill time > 2 secProlonged capillary refill time > 2 sec Irritable and lethargicIrritable and lethargic TachypneaTachypnea


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Late signs of dehydrationLate signs of dehydration

Falling blood pressureFalling blood pressure Metabolic acidosisMetabolic acidosis


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Fluids and Electrolytes in Pediatrics

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