Fluids,Fluids, ElectrolytesElectrolytes andand AcidAcid--BaseBase BalanceBalance

Todd A. Nickloes, DO, FACOS Assistant Professor of Surgery Department of Surgery Division of Trauma/CriticalTrauma/Critical Care University of Tennessee Medical Center - Knoxville ObjectivesObjectives

„ DefineDefine normalnormal rangesranges ofof electrolyteselectrolytes „ Compare/contrastCompare/contrast intracellular,intracellular, extracellularextracellular,, andand intravascularintravascular volumesvolumes „ OutlineOutline methodsmethods ofof determiningdetermining fluidfluid andand acid/baseacid/base balancebalance „ DescribeDescribe thethe clinicalclinical manifestationsmanifestations ofof variousvarious electrolyteelectrolyte imbalances.imbalances. NormalNormal PlasmaPlasma RangesRanges ofof ElectrolytesElectrolytes

„ Cations „ Concentration „ Sodium „ 135-145 mEq/L „ Potassium „ 3.5-5.0 mEq/L „ Calcium „ 8.0-10.5 mEq/L „ Magnesium „ 1.5-2.5 mEq/L „ Anions „ Chloride „ 95-105 mEq/L „ Bicarbonate „ 24-30 mEq/L „ Phosphate „ 2.5-4.5 mEq/L „ Sulfate „ 1.0 mEq/L „ Organic Acids (Lactate) „ 2.0 mEq/L „ Total Protein „ 6.0-8.4 mEq/L NormalNormal RangesRanges ofof ElectrolytesElectrolytes

„ SodiumSodium (Na(Na+)) „ RangeRange 135135 -- 145145 mEqmEq/L/L inin serumserum „ TotalTotal bodybody volumevolume estimatedestimated atat 4040 mEqmEq/kg/kg „ 1/31/3 fixedfixed toto bone,bone, 2/32/3 extracellularextracellular andand availableavailable forfor transtrans--membranemembrane exchangeexchange „ NormalNormal dailydaily requirementrequirement 11--22 mEqmEq/kg/day/kg/day „ ChiefChief extracellularextracellular cationcation NormalNormal RangesRanges ofof ElectrolytesElectrolytes

„ PotassiumPotassium (K(K+)) „ RangeRange 3.53.5 -- 5.05.0 mEqmEq/L/L inin serumserum „ TotalTotal bodybody volumevolume estimatedestimated atat 5050 mEqmEq/kg/kg „ 98%98% intracellularintracellular „ concentration of 150 mEq/L „ extracellular concentration of 70 mEq/L „ NormalNormal dailydaily requirementrequirement 0.50.5 –– 0.80.8 mEqmEq/kg/day/kg/day „ ChiefChief intracellularintracellular cationcation NormalNormal RangesRanges ofof ElectrolytesElectrolytes

„ IntracellularIntracellular vv ExtracellularExtracellular „ Electrolyte composition is different + + - - „ Intracellular - K , Mg , PO4 , SO4 , and proteins + + + - - „ Extracellular - Na , Ca , Mg , Cl , HCO3 and lactate „ Compositions of ions are maintained „ selective permeability of cell membranes „ active ion pumps „ Movement of water is passive „ colloid osmotic gradients intravascular v interstitial spaces (extracellularly) „ osmolar gradients intracellularly v extracellularly FluidFluid BalanceBalance

„ CalculationCalculation ofof OsmolarityOsmolarity

„ OsmOsm == 22 xx [[NaNas]] ++ [[gluglu // 18]18] ++ [BUN[BUN // 2.8]2.8] „ NormalNormal osmolarityosmolarity isis 280280--300300 mOsmmOsm/L/L „ NaNa+ resorptionresorption andand excretionexcretion areare thethe drivingdriving forcesforces forfor osmolarityosmolarity „ CalculatingCalculating TBWTBW deficitdeficit „ TBWD males = [(140 – SNa+) x 0.6 x IBW (kg)]/ 140 „ TBWD females = [(140 – SNa+) x 0.5 x IBW (kg)]/ 140 FluidFluid BalanceBalance

„ HereHere’’ss aa tricktrick „ ForFor everyevery 3.53.5 mEqmEq thethe NaNa+ isis overover 140,140, therethere isis anan estimatedestimated freefree waterwater deficitdeficit ofof 11 L.L. NormalNormal PhysiologyPhysiology

„ TotalTotal bodybody waterwater „ 60% IBW of males „ 50-55% IBW of females „ directly related to muscle mass (70% water) „ inversely related to fat content (10% water) „ This is why witches float „ CompartmentsCompartments „ Intracellular „ Extracellular „ Interstitial 10 BodyBody FluidFluid CompartmentsCompartments

„„ 2/32/3 (65%)(65%) ofof TBWTBW isis intracellularintracellular (ICF)(ICF) „„ 1/31/3 extracellularextracellular waterwater „ 2525 %% interstitialinterstitial fluidfluid (ISF)(ISF) „ 55-- 88 %% inin plasmaplasma (IVF(IVF intravascularintravascular fluid)fluid) „ 11-- 22 %% inin transcellulartranscellular fluidsfluids –– CSF,CSF, intraocularintraocular fluids,fluids, serousserous membranes,membranes, andand inin GI,GI, respiratoryrespiratory andand urinaryurinary tractstracts (third(third space)space)

11 NormalNormal PhysiologyPhysiology

8% Intravascular water 25% Interstitial water

67% Intracellular water 13 NormalNormal PhysiologyPhysiology

„ TwoTwo mainmain compartmentscompartments „ Intracellular „ 2/3 of TBW „ 40% body weight 8% Intravascular water „ Extracellular 25% Interstitial water „ Intravascular and Interstitial compartments 67% Intracellular „ 1/3 of TBW water „ 20% body weight 15 „ FluidFluid compartmentscompartments areare separatedseparated byby membranesmembranes thatthat areare freelyfreely permeablepermeable toto water.water. „ MovementMovement ofof fluidsfluids duedue to:to: „ hydrostatichydrostatic pressurepressure „ osmoticosmotic pressurepressure „ CapillaryCapillary filtrationfiltration (hydrostatic)(hydrostatic) pressurepressure „ CapillaryCapillary colloidcolloid osmoticosmotic pressurepressure „ InterstitialInterstitial hydrostatichydrostatic pressurepressure „ TissueTissue colloidcolloid osmoticosmotic pressurepressure

16 17 Cell in a hypertonic solution

18 Cell in a hypotonic solution

19 20 BalanceBalance

„ FluidFluid andand electrolyteelectrolyte homeostasishomeostasis isis maintainedmaintained inin thethe bodybody „ NeutralNeutral balance:balance: inputinput == outputoutput „ PositivePositive balance:balance: inputinput >> outputoutput „ NegativeNegative balance:balance: inputinput << outputoutput

21 SolutesSolutes –– dissolveddissolved particlesparticles „„ ElectrolytesElectrolytes –– chargedcharged particlesparticles „ CationsCations –– positivelypositively chargedcharged ionsions „NaNa+,, KK+ ,, CaCa++,, HH+ „ AnionsAnions –– negativelynegatively chargedcharged ionsions - - 3- „ClCl ,, HCOHCO3 ,, POPO4 „„ NonNon--electrolyteselectrolytes -- UnchargedUncharged

„Proteins,Proteins, urea,urea, glucose,glucose, OO2,, COCO2

22 „ BodyBody fluidsfluids are:are: „ ElectricallyElectrically neutralneutral „ OsmoticallyOsmotically maintainedmaintained „SpecificSpecific numbernumber ofof particlesparticles perper volumevolume ofof fluidfluid

23 HomeostasisHomeostasis maintainedmaintained by:by:

„ IonIon transporttransport „ WaterWater movementmovement „ KidneyKidney functionfunction

24 Basic Definitions

MW (Molecular Weight) = sum of the weights of atoms in a molecule mEq (milliequivalents) = MW (in mg)/ valence mOsm (milliosmoles) = number of particles in a solution

25 Movement of body fluids “ Where sodium goes, water follows.”

Diffusion – movement of particles down a concentration gradient.

Osmosis – diffusion of water across a selectively permeable membrane

Active transport – movement of particles up a concentration gradient ; requires energy

26 27 NormalNormal PhysiologyPhysiology

„ NaNa+ resorptionresorption secondarysecondary toto aldosteronealdosterone „ OccursOccurs inin distaldistal convolutedconvoluted tubulestubules „ ActiveActive exchangeexchange forfor KK+ andand HH+ ionsions „ MaintainsMaintains extracellularextracellular volumevolume andand osmolarityosmolarity „ WaterWater resorptionresorption secondarysecondary toto antidiureticantidiuretic hormonehormone „ OccursOccurs inin collectingcollecting ductsducts „ ModulatedModulated byby intracranialintracranial osmoreceptorsosmoreceptors andand atrialatrial stretchstretch receptorsreceptors NormalNormal PhysiologyPhysiology NaNa++ modulationmodulation

Renal perfusion decreases JG apparatus secretes renin

Renin cleaves angiotensinogen Renin secretion ceases to angiotensin I

Angiotensin I converted to Renal perfusion increases II by ACE

Angiotensin II stimulates aldosterone Extracellular volume secretion from adrenal cortex expansion as water follows Na+ Aldosterone increases Na+ resorption in exchange for K+ in DCT 30 NormalNormal PhysiologyPhysiology Na+Na+ modulationmodulation Result: increased water consumption increased water conservation Increased water in body increased volume and decreased Na+ concentration

31 Dysfunction and/or Trauma

Leads to:

Decreased amount of water in body Increased amount of Na+ in the body Increased blood osmolality Decreased circulating blood volume

32 RegulationRegulation ofof bodybody waterwater „ ADHADH –– antidiureticantidiuretic hormonehormone ++ thirstthirst „ DecreasedDecreased amountamount ofof waterwater inin bodybody „ IncreasedIncreased amountamount ofof Na+Na+ inin thethe bodybody „ IncreasedIncreased bloodblood osmolalityosmolality „ DecreasedDecreased circulatingcirculating bloodblood volumevolume „ StimulateStimulate osmoreceptorsosmoreceptors inin hypothalamushypothalamus ADHADH releasedreleased fromfrom posteriorposterior pituitarypituitary IncreasedIncreased thirstthirst

33 NormalNormal PhysiologyPhysiology

FreeFree HH22OO modulationmodulation Intracranial osmoreceptors detect increased plasma osmolarity

Adenohypophysis (posterior Plasma osmolarity increases pituitary) secretes ADH

Renal collecting ducts become Renal collecting ducts become less permeable to water more permeable to water

Adenohypophysis ceases ADH Plasma osmolarity decreases secretion

Intracranial osmoreceptors detect decreased osmolarity Acid/BaseAcid/Base BalanceBalance

„ TheThe managementmanagement ofof HydrogenHydrogen ionsions „ measuredmeasured asas pHpH „ maintainedmaintained atat 7.47.4 +/+/-- 0.050.05 „ ThreeThree mechanismsmechanisms (differing(differing effectiveeffective intervals)intervals) „ bufferingbuffering systemssystems inin plasmaplasma

„ ventilatoryventilatory changeschanges forfor COCO2 excretionexcretion „ RenalRenal tubulartubular excretionexcretion ofof HydrogenHydrogen ionsions Acid/BaseAcid/Base BalanceBalance

„ HendersonHenderson--HasselbalchHasselbalch „ RememberRemember - + „ HH2OO ++ COCO2 == HH2COCO3 == HCOHCO3 ++ HH

- pHpH == 6.16.1 ++ log[HCOlog[HCO3 ]/0.03]/0.03 xx PaCOPaCO2

oror

+ - [H[H ]] == 2424 xx PaCOPaCO2// [HCO[HCO3 ]] Acid/BaseAcid/Base BalanceBalance ExtracellularExtracellular RegulationRegulation

PulmonaryPulmonary regulationregulation ofof PaCOPaCO2 andand renalrenal tubulartubular - regulationregulation ofof HCOHCO3 areare importantimportant determinantsdeterminants ofof extracellularextracellular pH.pH. Basically,Basically, thethe pHpH isis detedeterminedrmined byby thethe ratioratio ofof - [HCO[HCO3 /H/H2COCO3]]

„ NormallyNormally 20:120:1 (7.40)(7.40) „ AsAs oneone increases,increases, thethe otherother increasesincreases toto rere--establishestablish thethe 20:120:1 ratioratio Acid/BaseAcid/Base BalanceBalance IntracellularIntracellular RegulationRegulation „ IntracellularIntracellular bufferingbuffering „ Excessive CO2 retention or excretion „ 50% of fixed acid loads (lactate) „ 95% of hydrogen ion changes „ Reciprocal K+ ion exchange „ Alkalosis „ H+ moves extracellularly „ K+ moves intracellularly „ Acidosis „ H+ moves intracellularly „ K+ moves extracellularly „ This can have significant clinical effect, especially regarding myocardial function FluidsFluids andand ElectolytesElectolytes inin thethe PostoperativePostoperative PeriodPeriod

„ MaintenanceMaintenance „ ResuscitationResuscitation „ ReplacementReplacement ofof LossesLosses FluidsFluids andand ElectolytesElectolytes inin thethe PostoperativePostoperative PeriodPeriod „ MaintenanceMaintenance „ NormalNormal dailydaily outputsoutputs „ Urine = 12-15 cc/kg „ Stool = 3 cc/kg „ Sweat = 1.5 cc/kg „ Respiratory and Skin insensible losses = 10 cc/kg „ Increased by 8%/degree F for fever „ NormalNormal dailydaily endogenousendogenous inputinput „ Oxidation of carbohydrates and fat = 3 cc/kg „ StandardStandard nomogramsnomograms estimateestimate dailydaily requirementsrequirements 41 42 FluidsFluids andand ElectolytesElectolytes inin thethe PostoperativePostoperative PeriodPeriod

„ ThirdThird SpaceSpace FluidFluid LossesLosses „ Fluids sequestered into extracellular and intersitial spaces „ Peritonitis „ Intestinal obstruction „ Soft tissue inflammation/edema „ Traumatic losses „ Evidence of diminished volume „ Hemodynamic changes „ Tachycardia „ Narrowed pulse pressures „ Hypotension Edema The accumulation of fluid within the interstitial spaces. Leads to: increased hydrostatic pressure lowered plasma osmotic pressure increased capillary membrane permeability lymphatic channel obstruction

44 Hydrostatic pressure increases Venous obstruction: thrombophlebitis (inflammation of veins) hepatic obstruction tight clothing on extremities prolonged standing Salt or water retention congestive heart failure renal failure

45 Decreased plasma osmotic pressure ↓ plasma albumin (liver disease or protein malnutrition) plasma proteins lost in : glomerular diseases of kidney hemorrhage, burns, open wounds and cirrhosis of liver

46 Increased capillary permeability: Inflammation immune responses

Lymphatic channels blocked: surgical removal infection involving lymphatics lymphedema

47 ElectrolyteElectrolyte imbalances:imbalances: SodiumSodium

„„ HypernatremiaHypernatremia (high(high levelslevels ofof sodium)sodium) „ PlasmaPlasma Na+Na+ >> 145145 mEqmEq // LL „ DueDue toto ↑↑ NaNa ++ oror ↓↓ waterwater „ WaterWater movesmoves fromfrom ICFICF →→ ECFECF „ CellsCells dehydratedehydrate

48 49 HypernatremiaHypernatremia „„ CausesCauses „ HypertonicHypertonic IVIV solnsoln.. „ OversecretionOversecretion ofof aldosteronealdosterone „ LossLoss ofof purepure waterwater „LongLong termterm sweatingsweating withwith chronicchronic feverfever „RespiratoryRespiratory infectioninfection →→ waterwater vaporvapor lossloss „DiabetesDiabetes –– polyuriapolyuria „ InsufficientInsufficient intakeintake ofof waterwater ((hypodipsiahypodipsia))

50 ClinicalClinical manifestationsmanifestations ofof HypernatremiaHypernatremia

„ ThirstThirst „ LethargyLethargy „ NeurologicalNeurological dysfunctiondysfunction duedue toto dehydrationdehydration ofof brainbrain cellscells „ DecreasedDecreased vascularvascular volumevolume

51 TreatmentTreatment ofof HypernatremiaHypernatremia

„ LowerLower serumserum Na+Na+ „ IsotonicIsotonic saltsalt--freefree IVIV fluidfluid „ OralOral solutionssolutions preferablepreferable

52 HyponatremiaHyponatremia

„ OverallOverall decreasedecrease inin Na+Na+ inin ECFECF „ TwoTwo types:types: depletionaldepletional andand dilutionaldilutional „ DepletionalDepletional HyponatremiaHyponatremia Na+Na+ loss:loss: „ diuretics,diuretics, chronicchronic vomitingvomiting „ ChronicChronic diarrheadiarrhea „ DecreasedDecreased aldosteronealdosterone „ DecreasedDecreased Na+Na+ intakeintake

53 „ DilutionalDilutional HyponatremiaHyponatremia:: „ RenalRenal dysfunctiondysfunction withwith ↑↑ intakeintake ofof hypotonichypotonic fluidsfluids „ ExcessiveExcessive sweatingsweating→→ increasedincreased thirstthirst →→ intakeintake ofof excessiveexcessive amountsamounts ofof purepure waterwater „ SyndromeSyndrome ofof InappropriateInappropriate ADHADH (SIADH)(SIADH) oror oliguricoliguric renalrenal failure,failure, severesevere congestivecongestive heartheart failure,failure, cirrhosiscirrhosis allall leadlead to:to: „ ImpairedImpaired renalrenal excretionexcretion ofof waterwater „ HyperglycemiaHyperglycemia –– attractsattracts waterwater

54 ClinicalClinical manifestationsmanifestations ofof HyponatremiaHyponatremia „ NeurologicalNeurological symptomssymptoms „ Lethargy,Lethargy, headache,headache, confusion,confusion, apprehension,apprehension, depresseddepressed reflexes,reflexes, seizuresseizures andand comacoma „„ MuscleMuscle symptomssymptoms „ Cramps,Cramps, weakness,weakness, fatiguefatigue „ GastrointestinalGastrointestinal symptomssymptoms „ Nausea,Nausea, vomiting,vomiting, abdominalabdominal cramps,cramps, andand diarrheadiarrhea „ TxTx –– limitlimit waterwater intakeintake oror discontinuediscontinue medsmeds

55 HypokalemiaHypokalemia

„ SerumSerum KK+ << 3.53.5 mEqmEq /L/L „ BewareBeware ifif diabeticdiabetic „ InsulinInsulin getsgets KK+ intointo cellcell „ KetoacidosisKetoacidosis –– HH+ replacesreplaces KK+,, whichwhich isis lostlost inin urineurine „„ ββ –– adrenergicadrenergic drugsdrugs oror epinephrineepinephrine

56 CausesCauses ofof HypokalemiaHypokalemia

„ DecreasedDecreased intakeintake ofof KK+ „ IncreasedIncreased KK+ lossloss „ ChronicChronic diureticsdiuretics „ Acid/baseAcid/base imbalanceimbalance „ TraumaTrauma andand stressstress „ IncreasedIncreased aldosteronealdosterone „ RedistributionRedistribution betweenbetween ICFICF andand ECFECF

57 ClinicalClinical manifestationsmanifestations ofof HypokalemiaHypokalemia „ NeuromuscularNeuromuscular disordersdisorders „ Weakness,Weakness, flaccidflaccid paralysis,paralysis, respiratoryrespiratory arrest,arrest, constipationconstipation „ DysrhythmiasDysrhythmias,, appearanceappearance ofof UU wavewave „ PosturalPostural hypotensionhypotension „ CardiacCardiac arrestarrest „ OthersOthers –– tabletable 66--55 „ TreatmentTreatment-- „ IncreaseIncrease KK+ intake,intake, butbut slowlyslowly,, preferablypreferably byby foodsfoods

58 HyperkalemiaHyperkalemia

„ SerumSerum K+K+ >> 5.55.5 mEqmEq // LL „ CheckCheck forfor renalrenal diseasedisease „ MassiveMassive cellularcellular traumatrauma „ InsulinInsulin deficiencydeficiency „ AddisonAddison’’ss diseasedisease „ PotassiumPotassium sparingsparing diureticsdiuretics „ DecreasedDecreased bloodblood pHpH „ ExerciseExercise causescauses K+K+ toto movemove outout ofof cellscells 59 ClinicalClinical manifestationsmanifestations ofof HyperkalemiaHyperkalemia

„ EarlyEarly –– hyperactivehyperactive musclesmuscles ,, paresthesiaparesthesia „ LateLate -- MuscleMuscle weakness,weakness, flaccidflaccid paralysisparalysis „ ChangeChange inin ECGECG patternpattern „ DysrhythmiasDysrhythmias „ BradycardiaBradycardia ,, heartheart block,block, cardiaccardiac arrestarrest

60 TreatmentTreatment ofof HyperkalemiaHyperkalemia

„ IfIf time,time, decreasedecrease intakeintake andand increaseincrease renalrenal excretionexcretion „ InsulinInsulin ++ glucoseglucose „ BicarbonateBicarbonate „ CaCa++ counterscounters effecteffect onon heartheart

61 CalciumCalcium ImbalancesImbalances

„ MostMost inin ECFECF „ RegulatedRegulated by:by: „ ParathyroidParathyroid hormonehormone „↑↑BloodBlood CaCa++ byby stimulatingstimulating osteoclastsosteoclasts „↑↑GIGI absorptionabsorption andand renalrenal retentionretention „ CalcitoninCalcitonin fromfrom thethe thyroidthyroid glandgland „PromotesPromotes bonebone formationformation „↑↑ renalrenal excretionexcretion

62 HypercalcemiaHypercalcemia „ ResultsResults from:from: „ HyperparathyroidismHyperparathyroidism „ HypothyroidHypothyroid statesstates „ RenalRenal diseasedisease „ ExcessiveExcessive intakeintake ofof vitaminvitamin DD „ MilkMilk--alkalialkali syndromesyndrome „ CertainCertain drugsdrugs „ MalignantMalignant tumorstumors –– hypercalcemiahypercalcemia ofof malignancymalignancy „ TumorTumor productsproducts promotepromote bonebone breakdownbreakdown „ TumorTumor growthgrowth inin bonebone causingcausing CaCa++ releaserelease

63 HypercalcemiaHypercalcemia „ UsuallyUsually alsoalso seesee hypophosphatemiahypophosphatemia „ Effects:Effects: „ ManyMany nonspecificnonspecific –– fatigue,fatigue, weakness,weakness, lethargylethargy „ IncreasesIncreases formationformation ofof kidneykidney stonesstones andand pancreaticpancreatic stonesstones „ MuscleMuscle crampscramps „ BradycardiaBradycardia,, cardiaccardiac arrestarrest „ PainPain „ GIGI activityactivity alsoalso commoncommon „ Nausea, abdominal cramps „ Diarrhea / constipation „ MetastaticMetastatic calcificationcalcification 64 HypocalcemiaHypocalcemia „ HyperactiveHyperactive neuromuscularneuromuscular reflexesreflexes andand tetanytetany differentiatedifferentiate itit fromfrom hypercalcemiahypercalcemia „ ConvulsionsConvulsions inin severesevere casescases „ CausedCaused by:by: „ RenalRenal failurefailure „ LackLack ofof vitaminvitamin DD „ SuppressionSuppression ofof parathyroidparathyroid functionfunction „ HypersecretionHypersecretion ofof calcitonincalcitonin „ MalabsorptionMalabsorption statesstates „ AbnormalAbnormal intestinalintestinal acidityacidity andand acid/acid/ basebase bal.bal.

„ WidespreadWidespread infectioninfection oror peritonealperitoneal inflammationinflammation 65 HypocalcemiaHypocalcemia

„ Diagnosis:Diagnosis: „ ChvostekChvostek’’ss signsign „ TrousseauTrousseau’’ss signsign „ TreatmentTreatment „ IVIV calciumcalcium forfor acuteacute „ OralOral calciumcalcium andand vitaminvitamin DD forfor chronicchronic

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