FLUID THERAPYJoAnne M. Roesner DVM, DABVPLoving Hands Animal ClinicAlpharetta, GAwww.lovinghands.comjoanne.roesner@lovinghands.com

Thanks to Schering-Plough for sponsoring this lecture!

Body Water and Fluid CompartmentsTBW = 0.6 x kgTBW = ECF + ICF (1/3) (2/3)ECF = extracellular, ICF = intracellularECF = Interstitial + Plasma (1/3) (1/4)Fluid spaces are iso-osmolar due to water movement(Greco, Vet Clinics, 1998)

Fluid Movement Net filtration at arteriolar end Net re-adsorption at venuli end Inflammation causes increased vascular permeability (Greco, Vet Clinics, 1998)

Why give fluids?Replace intravascular volumeImprove tissue perfusionReplace fluid deficits (dehydration)Meet maintenance in NPO patientReplace ongoing losses (V, D, burns, etc.)Fluid diuresis to eliminate toxinsAnesthetic and surgical supportReplacement of specific components (blood, plasma)Nutritional support (TPN, PPN)(Mensach IVECCS, 2005)

Examples of Fluid LossPuregastric vomiting: loss of HCl; volume causes hypochloremic metabolic alkalosis (Cl decrease limits re-adsorption of HCO3 in kidneysBilious vomiting: loss of K, HCO3, Na; causes hypokalemia, acidosis (Color of vomit is important!)Panting: loss of free water; no electrolyte lossPD: free water gain; dilution and diuresis promote ion lossDiarrhea: volume; Na, K, HCO3

Routes of Fluid AdministrationSubcutaneous: - not for sever dehydration or shock- not if potential vasoconstriction- crystalloids only- no dextrose- K+ is painful- 10-20 ml/kg/site- aseptic technique

Routes of Fluid AdministrationEnteral: - limited by patients ability to handle - can use to prevent gut-atrophy - trickle feeding- can combine with other methods (NG tube, etc.)- BES + K + dextrose + food coloringIntraperitoneal:- fairly rapid adsorption- aseptic technique- warm fluids(Mensach, IVECCS, 2005; Matthews, Vet Clinics, 1998.)

Routes of Fluid AdministrationIntraosseous:- similar to IV- useful especially in neonates and small patientsIntravenous:- peripheral vs. central line- moderate/severe dehydration, shock- cutdowns (20G needle technique)- change catheters every 72 hours- CVP ballparking it- bolus vs. CRI- crystalloids, colloids, blood products, IV feeding(Mensach, IVECCS, 2005; Matthews, Vet Clinics, 1998)

Maintenance Fluid RatesOnly an estimateConsider sensible (urine, feces) and insensible fluid lossesDo not consider other potential losses (PUPD, V, D)Calculations:1 ml/lb/h66 ml/kg/d for dogs44 ml/kg/d for cats30 ml/lb/day(30 x kg) + 70 (also = RER)Measure ins and outs and add 2 ml/kg/hr for insensible

Fluid DeficitsReplace with BES (type determined by source of losses)Replace over 24 hours (in addition to maintenace route)Rapid replacement can result in cerebral edema when losses are chronic (idiogenic osmoles)Deficit (ml) = % dehydration x kg x 1000(Matthews, Vet Clinics, 1998)

Shock Fluid RatesGoal is rapid repletion of vascular volumeBest to use physiologic endpoints rather than rote formula (BP, HR, CRT, etc.)Dog: up to 90 ml/kg crystalloidCat: up to 40 ml/kg crystalloidConsider adding colloids, hypertonic saline

Intra-operative Fluid Rates5 ml/kg/h for procedures involving minimal blood loss10 ml/kg/h for more extensive procedures or those with greater blood loss(Mensach, IVECCS, 2005)

Monitoring Fluid TherapySerial exams: vascular fullness, membrane moisture, skin turgor, auscultation, CRT, pulse quality, HR, RRUrine: specific gravity, volumeBlood pressureBody weightLabs: electrolytes, PCV, TS, BUN, Creatinine, lactate (tissue perfusion)CVP(Mensach, IVECCS, 2005; Hughes, IVECCS, 2005)

Serum ElectrolytesSODIUMExtracellular: major determinant of plasma tonicity, low Na means too much free water in blood, high Na means too little free water, must address abnormalities to prevent brain swelling or shrinkingADH : released from posterior pituitary in response to increased plasma osmolarity, causes water re-adsorption in kidneyAldosterone: released from adrenal gland, causes water re-adsorption in kidney, Na conservation, K excretion(Dibartola, Marks, Vet Clinics, 1998)

Serum ElectrolytesCHLORIDEPrimary extracellular anionLevels typically parallel NaLow Cl prevents HCO3 re-adsorption in kidney and exacerbates alkalosis(Dibartola, Marks, Vet Clinics, 1998)

Serum ElectrolytesPOTASSIUMIntracellular cation, Na K ATPase (Mg = cofactor)Hypokalemia common, especially in catsMaximum rate of administration 0.5 mEq/kg/hMaintenace is 20 mEq/L of BESTranslocation alters serum levels (e.g. acidosis causes movement out of cells, insulin causes movement into cells)Aldosterone promote K excretion (Na re-adsorption)

Serum ElectrolytesPOTASSIUMLow Mg promotes K excretionSerum levels do not reflect body storesLow K: weakness, droopy neck, long QT, interval, decreased T wavesHigh K: weakness, spiked T waves, wide QRS, decreased P waves(Phillips and Polzin, Vet Clinics, 1998)

Serum ElectrolytesMAGNESIUMMost common electrolyte abnormality n hospitalized humans is hypomagnesimiaPrimarily intracellularLow Mg may be clinically silent but makes hypocalcemia and hypokalemia refractory to treatmentVitamin D controls Mg absorptionMay see high Mg in renal failure

Serum ElectrolytesMAGNESIUMNormosol and Plasmalyte contain MgVery low Mg may require treatment with IV MgSO4Cofactor for NaK ATPase(Martin, Vet Clinics, 1998; Dhupa and Proulx, Vet Clinics, 1998)

Serum ElectrolytesBICARBONATEMajor plasma buffer along with proteinsMetabolic component of acid/base disordersWill precipitate with Ca (do not add to LRS)Mild abnormalities resolve with fluid repletion and improved perfusionAlways under correct base deficits (organic acids are metabolized with improved perfusion i.e. dont need to neutralize)Normal dogs ~ 18-24(Bailey and Pablo, Vet Clinics, 1998)

Serum ElectrolytesPHOSPATEHyperphosphatemia: common in CRF, can occur with primary parathyroid disease and cancer (PTHrp)Hypophosphatemia: seen with diuresis, TPN, hepatic lipidosis, treated DKA (especially cats) alkalosisClinical signs may be profound:- neuro, cardiac, hemolysis (ATP, 2-3 DPG etc. mediated)- Therapy/prevention: replace half of daily K as K2PO4- Enteral cows milk

Types of FluidsCrystalloids: replacement solutions, maintenance solutions, hypertonic salineD5WColloidsBlood productsTPN and PPN(Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS Proceedings, 2005)

CrystalloidsWater with Na or glucose, base source, electrolytesShort intravascular retention equilibrate with intracellular and interstitial compartmentsBase source (Na++CO3-): lactate: liver metabolismacetate: muscle metabolismgluconate: metabolism in most body tissue(Matthews, Vet Clinics, May 1998; Mensach 11th IVECCS Proceedings, 2005)

TonicityIsotonic: approximate osmolarity of blood and ECF, does not cause swelling or shrinking of RBC when infused (e.g. LRS)Hypertonic: osmolarity higher than ECF and blood, can shrink RBC and dehydrate intracellular and interstitial fluidHypotonic: osmolarity lower than ECF and blood, may swell RBC and cause edema(Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS 2005)

Replacement SolutionsEither alkalinizing or acidifyingSolute concentration ~ plasma water concentrationUsed to rapidly replace intravascular fluid and electrolytes (e.g. GI disease, 3rd spacing, +/- hemmorrhage, shock), used to replace fluid deficits20-25% stays within vascular space 1 hour post infusion

Replacement SolutionsConsider source of loss (e.g. pure gastric vs. bilious vomiting) when choosing a fluidFluid deficit (liters) = % dehydration x kgExamples:LRS0.9% NaClPlasmalyte ANormosol-R(Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS 2005)

Lactated Ringers Solution (LRS)IsotonicAlakalinzing 28 mEq/L of bicarb precursorsNa+ lower than plasma (130 mEq/L)K+ is low (4 mEq/L)No Mg2+Cl- is relatively high (119 mEq/L0Ca2+ is 3 mEq/L(Matthews, Vet Clinics, May 1998, p. 483)

Lactated Ringers Solution (LRS)Lactate must be metabolized in liver, may already be high in patient with hypoperfusionCalcium will precipitate if add NaHCO3, chelating anticoagulants and some drugsConsider adding 16 mEq/L KCL if used as a maintenance fluid (i.e. total 20 mEq/L K+)Add free water source if used as maintenaceUseful choice for diuresis replacement of isotonic or slightly hypotonic fluid losses, vascular volume repletion(Matthews, Vet Clinics, May 1998, p. 483)

L-LRS vs. Raceemic (D-L) LRSMost LRS is racemicL-LRS is available from BaxterD-isomer is pro-inflammatoryL-isomer is not inflammatoryKetone Ringers (betahydroxybutyrate relace lactate as buffer) also less inflammatory(Wall, IVECCS, 2005)

Ringers Ethyl PyruvateBetter restoration of splanich flowDecreased intestinal hyperpermeabilityDecrease NF Kappa B activation(Wall, IVECCS, 2005)

Normal Saline (0.9% NaCl)Isotonic, acidifyingNa and Cl = 154 mEq/LNo Ca or MgCan add HCO3, PO4 safelyUseful to treat alkalosis (pure gastric vomiting, furosemide overdose)(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Normal Saline (0.9% NaCl)Useful to treat hypercalcemia and hyperkalemia (Addisons) and bodywide Na depletion (diabetes/DKA) and initially in sever hypernatremiaMay need potassium supplement contra-indicated in volume overload (CHF, hypertension, liver disease with Na retention)(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Normosol RIsotonic- Na = 140 mEq/L- K = 5 mEq/L- Cl = 98 mEq/L- Mg = 3 mEq/LMay add HCO3, PO4, some alkalinizing drugsAcetate is buffer (16 mEq/L)(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Normosol RUseful in a wide variety of situationsUseful in liver disease because acetate is metabolized in muscleNot enough Mg to treat hypomagnesemia but may prevent itUse cautiously with renal disease as Mg may already be high(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Maintenance SolutionsUse after fluid deficits have been replacedSolute concentration approximates ECF, meets normal maintenace lossesHypotonicLess than 10% remains in vascular space after 1 hourMost need potassium supplementatione.g. Normosol M, Plasmalyte 56, 0.45% NaCl and 1/2 D5W and LRS(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Hypertonic Saline7.5-23% NaClUsed to rapidly expand vascular volume (e.g. severe hypovolemia with impending death, low volume resuscitation in head trauma, GDV (cannot get fluids in fast enough))Dogs 4-8 ml/kg, cats 204 ml/kg at 1 ml/kg/minuteLasts 30 minutes intravascularlyFollow with crystalloids, colloids(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Hypertonic SalineContra-indications: dehydration, heart or liver disease, uncontrolled hemorrhageMonitor cardiovascular parameters (negative inotrope, lasts for approximately 10 minutes post-infusion)May decrease re-perfusion injury by reducing calcium entry into cellsDecreases endothelial swelling and dysfunctionCan combine with colloids(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

D5WIsotonicSource of free waterNOT balanced (No Na, K, Mg, Cl)No buffer sourceVehicle for drug infusionNot a significant calorie sourceUsed with mixed replacement solutions to create maintenace fluids(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

D5WFree water deficit:Liters = 0.6 x kg ((1-42)/Patient Na)Plasma osmolality = 2(Na + K) + BUN/18 + Glucose(DiBartola, Vet Clinics, 1998; Marks and Taboada, Vet Clinics, 1998.)

ColloidsContain large molecules which do not diffuse freely from intravascular compartmentOncotic pressure proportional to number of particlesExpand vascular volumeHypovolemic resuscitation (e.g. head trauma, 3rd spacing)(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

ColloidsInflammatory disease (pancreatitis, SIRS, sepsis, etc.)Synthetic and natural(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

ColloidsRelatively contra-indicated in CHF or oliguric/anuric RFMay decrease clotting factor activity with synthetic colloids, but low clinic risk with products available currentlyMonitor if use synthetic colloids in patients with pre-existing coagulopathy

Capillary Leak SyndromePresent in inflammationResults in tissue edema -> organ dysfunction -> MODSColloids help ameliorate via: plug endothelial gaps with large molecule, down regulate adhesins (e.g. ICAM-1, selectin)(Chan, IVECCS, 2005)

PlasmaMidwest Animal Blood Services Inc.(517)851-8244Feline FFP25 ml/unit$110 (4/05)Canine FFP210 ml/unit$165Canine Cryopoor P100ml/unit$66Shelf life is one year

PlasmaFFP: all clotting factors, ATIII alpha-2 macroglobulin, etc. + albuminCryopoor Plasma: lacks factor VIII etc., still has albumin, other clotting factors (ATIII)22.5 ml/kg of plasma will raise patient albumin 5g/LMay need to combine with sythetic colloids in inflammation(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

PlasmaControversial: incubate with heparin (10-100 u/kg) for 30 minutes in DICVolume: 20-30 ml/kg/dayInfuse over 4-24 hours(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

AlbuminSource of oncotic pressure in plasmaLeaks in inflammation1 g albumin retains 18 ml of fluid in intravascular spaceNormal distribution: 40% intravascular, 60% interstitialHepatic synthesis regulated by osmoreceptors in interstitium, not by blood levels(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Albumint = 8-9 days in manCarries drugs and endogenous substanecsScavenges free radicals, reactive oxygen species, FeHelps to maintain vascular integrity(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

25% Human Serum Albumin (HAS)May have anti-inflammatory benefit (decreased macrophage activation and PMN oxygen burst, CD 18 down regulation)Use peripheral or central lineOVC in Geulph 200 cases: 2-4 ml/kg at rate of 0.1-1.7 ml/kg/h, monitor BP, HR, RR, T, edema, anaphylaxisPlasbumin BayerLong-term effects still under investigation(Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

Hetastarch (HES)Synthetic colloid, plant starchDegraded by amylase, rate is proportional to degree of hydroxyl substitutionDogs at 20 ml/kg/day say changes in clotting tests but no clinical effectsUSA: 6% HES (450 KDa/0.7 C2:C6)Europe: lower MW higher substitution products less coagulation change, balanced electrolyte solution less inflammatory(Chan, IVECCS, 2005)

Hetastarch (HES)Dose:Dog 20 ml/kg/day (up to 40 ml/kg/day)Cat 5-10 ml/kg/dayAfter initial volume administration can mix with crystalloids in a ratio of 30% HES:70% crystalloid x rate of fluidsMonitor for overhydration with all synthetic colloids(Matthews, Vet Clinics, 1998; Chan, IVECCS, 2005.)

Hemoglobin Based Oxygen Carriers (HBOCs)Oxyglobin BiopureHemopure Biopure (future product?)PolyHeme Northfield Labs (under development)Sangart Product (under development)(Wall, IVECCS, 2005)

HBOC OxyglobinBovine Hb solutionUnloads O2 according to Cl tensionAccess to microcucultation (smaller than RBC)Potent colloid give slowly and at lower volume than in catsStable at room temperatureDo not freeze(Matthews, Vet Clinics, 1998; Mensach, IVECCS, 2005; Wall, IVECCS, 2005.)

HBOC OxyglobinForms methemoglobin with storage after openingDose: 10-30 ml/kg (dog)Discolors urine and patientInterferes with some lab tests(Matthews, Vet Clinics, 1998; Mensach, IVECCS, 2005; Wall, IVECCS, 2005)

Total Parenteral Nutrition (TPN)Meet total caloric needs via IV solutionsMust use central lineAbsolute aseptic techniqueGut atrophy and bacterial/toxin translocatorsHypertonic solutions, lipid containingComplications: vasculitis, thrombosisEbb and flow phases of stressed starvation (hypermetabolism)(Mazzaferro, Multidisciplinary Review, 2004)

Partial Parenteral Nutrition (PPN)Use to meet part of RERAminoacids, electrolytes (K, Mg, PO4) carbohydrates +/- lipidsPeripheral line if < 5.50 mOsm/L dedicated line is best (my preference is BES 1 line PPN in 2nd line at maintenance rate)Need to monitor electrolytesAdd B vitamins(Mazzaferro, 2004; Matthews, Vet Clinics, 1998; Mensach, IVECCS, 2005)

Partial Parenteral Nutrition (PPN)RER = (30 x kg) + 70, goal 25-50% RERGive energy via Dextrose (80-100%) lipids (20%)Dog: 3g protein per 100 KcalCat: 4 g protein per 100 Kcal, add taurineConsider adding Mg (0.75 mEq/kg/day), PO4 (add of supplemental K requirements as K2PO4) and K+5% Dextrose (100 ml 50% ex to 900 ml BES = 0.17 Kcal/ml)Lipid 20% = 2 Kcal/mo, 8.5% amino acid = .085 g/ml(Mazzaferro, 2004)

PPN Products10% Aminosyn: $13.64/500 mlamino acid only, need to dilute in maintenace fluids to give peripherally, need to add CHO source and diluteProcalamine: amino acids, some electrolytes and glycerol, hard to find (old price ~ $40/L)Freeamine: amino acids and electrolytes (NOT BES, low NaCl), can add 50% dextrose to make a 5% solution(Mensach, IVECCS, 2005. Matthews, Vet Clinics, 1998)

PPN RecipeRemove 100 ml from 1 L bag of Normosol MAdd 100 cc 50% dextrose to yield ~ 5% dextrose in Normosol MRemove 330 ml of fluid from aboveAdd 330 ml of amino acid solution to above (e.g. Travasol)Final solution is:3.3% amino acid (33g protein)50 mEq/L Cl3.3% dextrose (33g dextrose)20 mEq/L PO430 mEq/L KCl5 mEq/L Mg45 mEq/L Na650 mOsm/L(Matthews, Vet Clinics, 1998)

ReferencesVet Clinics of North America Advances in Fluid Therapy, May 1998a. Distribution of Body Water and General Approach to the Patient. Greco, p. 473.b. Various Types of Parenteral Fluids and Their Indicators. Matthews, p. 483.c. Fluid Therapy in Shock. Mandell and King, p. 623.d. Hyponatremia. DiBartola, p. 515.e. Hypernatremia. Marks and Taboada, p. 533.

Referencesf. Clinical Disorders of Potassium Homeostasis. Phillips and Polzin, p. 545.g. Hypercalcemia and Hypermagnesimia. Martin, p. 565.h. Hypocalcemia and Hypomagnesimia. Dhupa and Proulx, p. 587.2. Proceedings 11th IVECCS Symposium, Sept. 2005.a. Fluid Therapy: Options and Rational Selection. Mensach, p. 389.

Referencesb. Update on Synthetic and Natural Colloids. Chan, p. 395.c. Designer Fluid Therapy. Wall, p. 405.d. Clinical Use of 25% Human Serum Albumin in Veterinary Patients. Mathews, p. 411.e. Clinical Use of Serum Lactate. Hughes, p. 173.3. Multidisciplinary Systems Review, Proceedings 10th IVECCS Symposium, September 8, 2004.a. Nutritional Requirements of the Critically Ill Patient. Mazzaferro, p. 1.