Amy M Zidron Stork, DO/PhDAssistant Professor of Pediatrics OU-HCOM 3/24/14

Credit- Eric Bowman, DO

12885- Normal fluid and electrolyte balances in pediatrics12886- Presentation, diagnosis, and treatment of dehydration in pediatrics

Fluid BasicsHomeostasis and RegulationPractical UseMaintenance Fluids and CalculationFluid Deficits/DehydrationBolus and CalculationORTTypes of DehydrationSimpleSodium InvolvementShock

Total Body Water (TBW) as a percentage of body weightHighest in fetus, decreases to 75% birth weight by termDecreases to about 60% by puberty50% for girlsOverweight children also have lower TBWECF and ICF components stable by 5 y/o

Behrman: Nelson Textbook of Pediatrics, 17th ed., Copyright 2004 ElsevierNeonatal DiuresisCell Growth

Driving force behind water movementPrimary process for shifting is change in ECF osmolality Normal plasma osmolality 285-295 mOsm/kg Serum osmolality = 2 x Na + [Glucose]/18 + BUN/2.8Calculated slightly lower than measuredBUN: Ineffective osmole / Glucose: Effective osmole

Equal osmolality between IC and ECPO intake + oxidative water production = measured and insensible water lossHypothalamus senses increased effective osmoles & secretes ADHCan sense only 1% changeADH amount based on degree of osmolality changeStimulates thirst 1-2% dehydrated at this point

Na is primarily responsible for IV volume

Volume status is primary determinant of renal sodium excretion Na intake exceeds output: Volume overloadRenal failure, hyperaldosteronism or renal artery stenosisNa loss exceeds intake: Volume depletion Gastroenteritis, burns, CF, vigorous exercise, oral hydration without adequate solute

Water losses also impacts Na balance Isolated water loss (diabetes insipidus) has greatest impact on intracellular space Why?

Meet daily requirement when intake inadequateOlder kids, adults - NPO up to 18 hoursCalculations not idealOn maintenance fluid alone - up to 1% daily wt. lossMF Goal:Maintain intravascular / intracellular volumesPrevent electrolyte disorders, ketoacidosis, protein degradation

Whats typically in it?DextroseNaKCl

Deficient in Ca, phosphorus, Mg, HCO3

What are we replacing?Urine loss (60%)Gives kidney room to dilute and concentrateAllows for relatively imprecise calculationsStool (5%)Sweat, breath, etc(35%)

Calculations100/50/204/2/1

The 100/50/20 Ruledaily maintenanceWt in kilogramsFirst 10 kg = 100 ml/kgFrom 11-20 kg = add 50 ml/kgFrom 20 and up = add 20 ml/kg

The 4/2/1 Rulehourly maintenanceFirst 10 kg x 4 ml/kgThe next 10 kg x 2 ml/kg and add to aboveEverything above 20 kg x 1 ml/kg and add to above

How much fluid should a 28 kg child get per day and per hour?

First 10 kg = 100x10 = 1000 ml11-20 kg = 50x10 = 500 mlEach kg beyond 20 kg (8) = 20x8 = 160 ml

1000+500+160 = 1660 ml/day1660/24 hrs = 69 ml/hr

How much fluid should a 28 kg child get per hour?

First 10-kg = 4x10 = 40 ml11-20 kg = 2x10 = 20 mlEvery kg beyond 20 kg (8 kg) = 8x1 = 8 ml

40 + 20 + 8 = 68 ml/hr68x24 = 1632 ml/day

Balance lossesSodium2-3 mEq/100ml/dayPotassium1-2 mEq/100ml/dayChloride replaced 1:1 with NaGlucose5% Dextrose = 17 cal per 100 ml (20% daily cal)Effective and destructive diet

Normal Saline0.9% NaCl solution154 mEq Na/L 154 mEq Cl/Lisotonic Normal saline 0.45% NaCl77 mEq Na/L77 mEq Cl/LHypotonic Normal saline 0.225% NaCl38.5 mEq Na/L38.5 mEq Cl/L hypotonicRingers Lactate130 mEq Na/L109 mEq Cl/L28 mEq lactate/L4 mEq K/L3 mEq Ca/LSlightly hypotonic in reality but can be used as isotonic for bolus

Normal plasma osmolality is 285295mOsm/kg

Extremely hypotonic sol: Possible hemolysis

Want osmolality close to or greater than 285

NS (osmolality = 77): NOT good

D5 NS (osmolality = 355) or D5 NS + 20mEq/L KCl (osmolality = 472)

Most simple dehydration: D5 or D5 normal saline (with 10-20 mEq/L KCl)Assume normal renal function, no pathologyDont add the K to the fluids until patient has urinated

Some simple rules 25 kg - NS due to higher free water needs per kg> 25 kg to adult normal saline

Source Causes of Increased Causes of Decreased Water Needs Water Needs Skin Radiant Warmer Mist Tent Fever Sweat Burns Lungs Tachypnea Humidified Ventilator Tracheostomy Mist tent GI Diarrhea Emesis NG suction Renal Polyuria Oliguria/anuria Misc. Surgical drainage Hypothyroidism Third spacing

Recognize it!Most important tool is your eyes!Add in historyIntake (What type of fluid?), urine and stool output, activity level, fevers, respiratory status, other morbidities and PM history, medsThen physical, including vital signsLabs to confirm, assess degree of deficit

3-5% 7-10% 10-15%Mental StatusalertrestlesslethargicPulsenormalrapid rapid/weakFontanelnormalnormal/sunkensunkenBlood pressurenormalnormal lowSkin Turgornormalreduced poorEyesnormaldecreased tears sunkenMucous membranenormaldry tackyUrine output SpGoliguria oliguria/anuriaCapillary Refill normaldelayed very delayed

For simple dehydrationDifference b/w current weight and recent weight = fluid deficit60% ECF loss, 40% ICF lossWithout recent weight, Current weight X % dehydration = probable weight loss = fluid loss

5.4 kg femaleDeficit of 400 mlMaintenance? 540 ml per dayTotal daily fluid requirement940 ml per dayWhat is your IV rate?940 24 = 40 ml/hr over 24 hoursTo replace in first 8 hours, rest over next 16 hours940 2 = 470 ml; 470 8 = 60 ml/hr for 8 hours, then 30 ml/hr for 16 hoursThis does not correct for ongoing losses!

Dont ignore the patient!Tachycardia, change in mental status, tachypnea, oliguria, thready pulses = unstable patientABCsSupport circulationBolus fluids and reevaluation

Isotonic solution0.9%NaCl10-20 ml/kg bolus run over 0-30 minutesShock requires rapid bolusesReevaluation, reassessmentMental, cardiovascular, respiratory status No change? Give another, and another May require up to 80 ml/kg-120ml/kg bolus fluidsSubtract bolus volume from first 8 hour fluid vol

Less expensive, lower complications vs IV fluids2006 Cochrane review - more paralytic ileus with ORT but equal successShould be used more in developed countries, especially with losses due to acute diarrheaMild dehydration - 50mL/kg of oral rehydration solution (ORS) within 4hr Moderate dehydration - 100mL/kg over 4hrWHO solution has highest [Na] of all rehydration solutions

* Rice syrup solids are the carbohydrate source.Behrman: Nelson Textbook of Pediatrics, 17th ed., Copyright 2004 Elseviern

Composition of Oral Rehydration SolutionsSolutionGlucose (mmol/L)Na (mEq/L)K (mEq/L)Cl (mEq/L)Base (mEq/L)Osmolality (mOsm/kg)WHO solution11190208030311Rehydralyte14075206530310Pedialyte14045203530250Pediatric Electrolyte14045203548250Infalyte70 * 50254534200Naturalyte14045203548238WHO = World Health Organization.

*Values vary slightly depending on source.

APPROXIMATE ELECTROLYTE COMPOSITION OF COMMONLY CONSUMED FLUIDS (NOT RECOMMENDED FOR ORT) * CHO (g/dL) Na+ (mEq/L) K+ (mEq/L) Cl (mEq/L) HCO3 (mEq/L) mOsm/kg H2 O Apple juice 11.9 0.426 700 Coca-Cola 10.9 4.30.1 13.4656 Gatorade 5.9 (327 mmol/L)212.5 17 377 Ginger ale 9 3.50.1 3.6565 Milk 4.9 2236 28 30260 Orange juice 10.40.2 49 50 654From Behrman RE, Kliegman RM, Arvin AM. Nelson textbook of pediatrics, 16th ed. Philadelphia: WB Saunders; 2000.CHO, carbohydrate.

WHO solution111 mmol/L90208030311

Term and preterm infants have a different total body water composition, which eventually changes due to both diuresis and cell growthNa is the primary extracellular cation with potassium the main intracellular cationOsmolality differences form the driving force between fluid shiftsThe body uses both osmolality changes and volume loss to maintain homeostasisHas limits as to how much it can control without proper external fluid supportTotal body fluid requirements for inpatient use are based upon weight, activity and fluid lossesAcute weight loss equals fluid loss for rehydration purposesActivity, environment and external support can chages daily maintenance requirementsD5 or NS with KCL is the best and safest rehydration solution for all simple casesHistory and physical exam skills are the key to initial and continued assessment of the patients hydration statusABCs!!!HyperNa and hypoNa dehydration present numerous pitfalls if not corrected with careWith healthy kids, oral rehydration is the best treatment for dehydration but the correct ingredients are important

We have been assuming simple dehydration no change in serum [Na]Isonatremia about 98% of casesECF decrease with mild ICF decreaseHyponatremia 1-2% Large ECF decrease with little ICF decreaseHypernatremia

HypoNa IsoNa HyperNaTurgorvery poor poor fairSkinclammy drydoughyMMdry parched moistCNScoma lethargic irritable/comaPulserapid rapidmoderateBPvery low lowmod-low

Your clinical history should guide youPoor oral intake, trying Pedialyte unsuccessfully?IsonatremicLarge GI or urine losses and drinking water?HyponatremicCan see with adrenal insufficiency, CFUsually will have CV instability out of proportion to degree of presentationExcessive sweating or hyper-dilute urination (concentrating defect)HypernatremicSee with high solute intakeCNS abnormalities

Usually caused by Na loss and relative water retentionMost fluid lost is low in sodium in general, but oral fluids also low in sodiumWill become much worse if high solute fluids lostRenal salt wasting, third-spacing, cholera induced-diarrhea (most non-secretory diarrhea is low in sodium)Water shifts into the cells to balance for loss of intravascular solute large ECF losses

Goal of therapy is first to correct intravascular volume with 0.9% NaCl (isotonic fluid)Then replace sodium and water deficitsSodium deficit = ([Na]d [Na]m) x weight x 0.6Main risk with overcorrection or rapid correction is for developing central pontine myelinolysisNon-inflammatory destruction of myelin sheath in pons oligodendrocytes in vulnerable areas are in more vascular region, more prone to fluid shifts; *Chronic hyponatremia presents more riskIn most cases D5 normal saline with 20 mEq KCl/L is adequateCorrect by no more than 12 mEq/L per dayNeurologic changes from low Na (seizures) require 3% saline infusions to raise Na by 5-10 mEq/L abruptlyCan result in encephalopathy and cerebral edema

Pseudohyponatremia Due To Some Common SolutesFor every unit increase inthis solutemeasured sodium is decreased by1 g/dLTriglycerides2 mEq/L100 mg/dLGlucose1.6 mEq/L

Most dangerous form due to both actual disturbance and treatment complicationsIntracranial hemorrhage, thrombosis fluid shifts from brain cells to vasculature causing cell shrinking and vessel tearingBrain cells form idiogenic osmoles to increase intracellular osmolalityCerebral edema seizures, herniation, deathCorrection should be less than 10-12 mEq Na/L per day & can sometimes take 2-4 days to fully correct depending on labsAgain, correct initially with 0.9% NaCl (Ringers lactate is too hypotonic) and any developing deficitsDeficit and maintenance are corrected over two days in first 24 hrs, in second 24 hrsChoose D5 NS with 20 mEq KCl/L with most uncomplicated casesFollow labs!

Inability to provide sufficient tissue perfusion with oxygenated blood

Oxygen delivery directly related to O2 contentand cardiac output (SV,HR,& SVR)

HypovolemicMost common cause in childrenLoss of fluid secondary to diarrhea and vomiting, blood loss ,and third spacing

Distributive Shock

Abnormality in distribution of blood floodSeptic shock most common typeSystemic inflammatory response syndromeAnaphylaxis

Cardiogenic shockAbnormality in myocardial functionDepressed contractility and cardiac output

Obstructive Inability to produce adequate output in spite of adequate volume and contractility.Tension Pneumothorax

All shock presents with evidence that tissue perfusion is inadequate. The type may alter the initial presentation.

Recognize early shock and intervention is life and organ saving

CompensatedDecreased cardiac out put with increased sympathetic discharge causing increased HR and contractility yielding Increased cardiac output andBP

Compensated shock lasts for only a brief time unless intervention occursDecompensated shock will occur Decreased myocardial perfusion Increased myocardial oxygen consumptionYields decreased cardiac output with decreased blood pressure, poor perfusion, poor capillary refill

TreatmentEarly recognition and interventionABCs as neededFluid resuscitation20cc/kg as much as 160-200 mL/kg may be neededNS, LR, Colloid, BloodVasopressors

Behrman: Nelson Textbook of Pediatrics, Chapters 52-55; 19th ed., Copyright 2011 Elsevier Dehydration in Infancy and Childhood; Finberg, L; Pediatrics in Review, Vol.23 No.8 August 2002, 277 Fluid and Electrolyte Therapy; Mahan, J; Ohio State University, Columbus Childrens Hospital, Department of Nephrology