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FLUID THERAPY

FLUID THERAPY. JoAnne M. Roesner DVM, DABVP Loving Hands Animal Clinic Alpharetta, GA www.lovinghands.com joanne.roesner@lovinghands.com. Thanks to Schering-Plough for sponsoring this lecture!. Body Water and Fluid Compartments. TBW = 0.6 x kg TBW = ECF + ICF

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FLUID THERAPY

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  1. FLUID THERAPY JoAnne M. Roesner DVM, DABVP Loving Hands Animal Clinic Alpharetta, GA www.lovinghands.com joanne.roesner@lovinghands.com

  2. Thanks to Schering-Plough for sponsoring this lecture!

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

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

  5. Why give fluids? • Replace intravascular volume • Improve tissue perfusion • Replace fluid deficits (dehydration) • Meet maintenance in NPO patient • Replace ongoing losses (V, D, burns, etc.) • Fluid diuresis to eliminate toxins • Anesthetic and surgical support • Replacement of specific components (blood, plasma) • Nutritional support (TPN, PPN) (Mensach IVECCS, 2005)

  6. Examples of Fluid Loss • Puregastric vomiting: loss of HCl; volume causes hypochloremic metabolic alkalosis (Cl decrease limits re-adsorption of HCO3 in kidneys • Bilious vomiting: loss of K, HCO3, Na; causes hypokalemia, acidosis (Color of vomit is important!) • Panting: loss of free water; no electrolyte loss • PD: free water gain; dilution and diuresis promote ion loss • Diarrhea: volume; Na, K, HCO3

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

  8. Routes of Fluid Administration • Enteral: - 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 coloring • Intraperitoneal: - fairly rapid adsorption - aseptic technique - warm fluids (Mensach, IVECCS, 2005; Matthews, Vet Clinics, 1998.)

  9. Routes of Fluid Administration • Intraosseous: - similar to IV - useful especially in neonates and small patients • Intravenous: - 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)

  10. Maintenance Fluid Rates • Only an estimate • Consider sensible (urine, feces) and insensible fluid losses • Do not consider other potential losses (PUPD, V, D) • Calculations: 1 ml/lb/h 66 ml/kg/d for dogs 44 ml/kg/d for cats 30 ml/lb/day (30 x kg) + 70 (also = RER) Measure ins and outs and add 2 ml/kg/hr for insensible

  11. Fluid Deficits • Replace 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)

  12. Shock Fluid Rates • Goal is rapid repletion of vascular volume • Best to use physiologic endpoints rather than rote formula (BP, HR, CRT, etc.) • Dog: up to 90 ml/kg crystalloid Cat: up to 40 ml/kg crystalloid • Consider adding colloids, hypertonic saline

  13. Intra-operative Fluid Rates • 5 ml/kg/h for procedures involving minimal blood loss • 10 ml/kg/h for more extensive procedures or those with greater blood loss (Mensach, IVECCS, 2005)

  14. Monitoring Fluid Therapy • Serial exams: vascular fullness, membrane moisture, skin turgor, auscultation, CRT, pulse quality, HR, RR • Urine: specific gravity, volume • Blood pressure • Body weight • Labs: electrolytes, PCV, TS, BUN, Creatinine, lactate (tissue perfusion) • CVP (Mensach, IVECCS, 2005; Hughes, IVECCS, 2005)

  15. Serum Electrolytes SODIUM • Extracellular: 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 shrinking • ADH : released from posterior pituitary in response to increased plasma osmolarity, causes water re-adsorption in kidney • Aldosterone: released from adrenal gland, causes water re-adsorption in kidney, Na conservation, K excretion (Dibartola, Marks, Vet Clinics, 1998)

  16. Serum Electrolytes CHLORIDE • Primary extracellular anion • Levels typically parallel Na • Low Cl prevents HCO3 re-adsorption in kidney and exacerbates alkalosis (Dibartola, Marks, Vet Clinics, 1998)

  17. Serum Electrolytes POTASSIUM • Intracellular cation, Na K ATPase (Mg = cofactor) • Hypokalemia common, especially in cats • Maximum rate of administration 0.5 mEq/kg/h • Maintenace is 20 mEq/L of BES • Translocation alters serum levels (e.g. acidosis causes movement out of cells, insulin causes movement into cells) • Aldosterone promote K excretion (Na re-adsorption)

  18. Serum Electrolytes POTASSIUM • Low Mg promotes K excretion • Serum levels do not reflect body stores • Low K: weakness, droopy neck, long QT, interval, decreased T waves High K: weakness, spiked T waves, wide QRS, decreased P waves (Phillips and Polzin, Vet Clinics, 1998)

  19. Serum Electrolytes MAGNESIUM • Most common electrolyte abnormality n hospitalized humans is hypomagnesimia • Primarily intracellular • Low Mg may be clinically silent but makes hypocalcemia and hypokalemia refractory to treatment • Vitamin D controls Mg absorption • May see high Mg in renal failure

  20. Serum Electrolytes MAGNESIUM • Normosol and Plasmalyte contain Mg • Very low Mg may require treatment with IV MgSO4 • Cofactor for NaK ATPase (Martin, Vet Clinics, 1998; Dhupa and Proulx, Vet Clinics, 1998)

  21. Serum Electrolytes BICARBONATE • Major plasma buffer along with proteins • “Metabolic” component of acid/base disorders • Will precipitate with Ca (do not add to LRS) • Mild abnormalities resolve with fluid repletion and improved perfusion • Always under correct base deficits (organic acids are metabolized with improved perfusion i.e. don’t need to neutralize) • Normal dogs ~ 18-24 (Bailey and Pablo, Vet Clinics, 1998)

  22. Serum Electrolytes PHOSPATE • Hyperphosphatemia: common in CRF, can occur with primary parathyroid disease and cancer (PTHrp) • Hypophosphatemia: seen with diuresis, TPN, hepatic lipidosis, treated DKA (especially cats) alkalosis Clinical 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

  23. Types of Fluids • Crystalloids: replacement solutions, maintenance solutions, hypertonic saline • D5W • Colloids • Blood products • TPN and PPN (Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS Proceedings, 2005)

  24. Crystalloids • Water with Na or glucose, base source, electrolytes • Short intravascular retention equilibrate with intracellular and interstitial compartments • Base source (Na++CO3-): lactate: liver metabolism acetate: muscle metabolism gluconate: metabolism in most body tissue (Matthews, Vet Clinics, May 1998; Mensach 11th IVECCS Proceedings, 2005)

  25. Tonicity • Isotonic: 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 fluid • Hypotonic: osmolarity lower than ECF and blood, may swell RBC and cause edema (Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS 2005)

  26. Replacement Solutions • Either alkalinizing or acidifying • Solute concentration ~ plasma water concentration • Used to rapidly replace intravascular fluid and electrolytes (e.g. GI disease, 3rd spacing, +/- hemmorrhage, shock), used to replace fluid deficits • 20-25% stays within vascular space 1 hour post infusion

  27. Replacement Solutions • Consider source of loss (e.g. pure gastric vs. bilious vomiting) when choosing a fluid • Fluid deficit (liters) = % dehydration x kg • Examples: LRS 0.9% NaCl Plasmalyte A Normosol-R (Matthews, Vet Clinics, May 1998; Mensach, 11th IVECCS 2005)

  28. Lactated Ringers Solution (LRS) • Isotonic • Alakalinzing 28 mEq/L of bicarb precursors • Na+ lower than plasma (130 mEq/L) • K+ is low (4 mEq/L) • No Mg2+ • Cl- is relatively high (119 mEq/L0 • Ca2+ is 3 mEq/L (Matthews, Vet Clinics, May 1998, p. 483)

  29. Lactated Ringers Solution (LRS) • Lactate must be metabolized in liver, may already be high in patient with hypoperfusion • Calcium will precipitate if add NaHCO3, chelating anticoagulants and some drugs • Consider 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 maintenace • Useful choice for diuresis replacement of isotonic or slightly hypotonic fluid losses, vascular volume repletion (Matthews, Vet Clinics, May 1998, p. 483)

  30. L-LRS vs. Raceemic (D-L) LRS • Most LRS is racemic • L-LRS is available from Baxter • D-isomer is pro-inflammatory L-isomer is not inflammatory • Ketone Ringers (betahydroxybutyrate relace lactate as buffer) also less inflammatory (Wall, IVECCS, 2005)

  31. Ringers Ethyl Pyruvate • Better restoration of splanich flow • Decreased intestinal hyperpermeability • Decrease NF Kappa B activation (Wall, IVECCS, 2005)

  32. Normal Saline (0.9% NaCl) • Isotonic, acidifying • Na and Cl = 154 mEq/L • No Ca or Mg • Can add HCO3, PO4 safely • Useful to treat alkalosis (pure gastric vomiting, furosemide overdose) (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

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

  34. Normosol R • Isotonic - Na = 140 mEq/L - K = 5 mEq/L - Cl = 98 mEq/L - Mg = 3 mEq/L • May add HCO3, PO4, some alkalinizing drugs • Acetate is buffer (16 mEq/L) (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  35. Normosol R • Useful in a wide variety of situations • Useful in liver disease because acetate is metabolized in muscle • Not enough Mg to treat hypomagnesemia but may prevent it • Use cautiously with renal disease as Mg may already be high (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  36. Maintenance Solutions • Use after fluid deficits have been replaced • Solute concentration approximates ECF, meets normal maintenace losses • Hypotonic • Less than 10% remains in vascular space after 1 hour • Most need potassium supplementation • e.g. Normosol M, Plasmalyte 56, 0.45% NaCl and 1/2 D5W and LRS (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  37. Hypertonic Saline • 7.5-23% NaCl • Used 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/minute • Lasts 30 minutes intravascularly • Follow with crystalloids, colloids (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  38. Hypertonic Saline • Contra-indications: dehydration, heart or liver disease, uncontrolled hemorrhage • Monitor cardiovascular parameters (negative inotrope, lasts for approximately 10 minutes post-infusion) • May decrease re-perfusion injury by reducing calcium entry into cells • Decreases endothelial swelling and dysfunction • Can combine with colloids (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  39. D5W • Isotonic • Source of free water • NOT balanced (No Na, K, Mg, Cl) • No buffer source • Vehicle for drug infusion • Not a significant calorie source • Used with mixed replacement solutions to create maintenace fluids (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  40. D5W • Free 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.)

  41. Colloids • Contain large molecules which do not diffuse freely from intravascular compartment • Oncotic pressure proportional to number of particles • Expand vascular volume • Hypovolemic resuscitation (e.g. head trauma, 3rd spacing) (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

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

  43. Colloids • Relatively contra-indicated in CHF or oliguric/anuric RF • May decrease clotting factor activity with synthetic colloids, but low clinic risk with products available currently • Monitor if use synthetic colloids in patients with pre-existing coagulopathy

  44. Capillary Leak Syndrome • Present in inflammation • Results in tissue edema -> organ dysfunction -> MODS • Colloids help ameliorate via: plug endothelial gaps with large molecule, down regulate adhesins (e.g. ICAM-1, ∑ selectin) (Chan, IVECCS, 2005)

  45. Plasma • Midwest Animal Blood Services Inc. (517)851-8244 • Feline FFP 25 ml/unit $110 (4/05) Canine FFP 210 ml/unit $165 Canine Cryopoor P 100ml/unit $66 • Shelf life is one year

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

  47. Plasma • Controversial: incubate with heparin (10-100 u/kg) for 30 minutes in DIC • Volume: 20-30 ml/kg/day • Infuse over 4-24 hours (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  48. Albumin • Source of oncotic pressure in plasma • Leaks in inflammation • 1 g albumin retains 18 ml of fluid in intravascular space • Normal distribution: 40% intravascular, 60% interstitial • Hepatic synthesis regulated by osmoreceptors in interstitium, not by blood levels (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  49. Albumin • t ½ = 8-9 days in man • Carries drugs and endogenous substanecs • Scavenges free radicals, reactive oxygen species, Fe • Helps to maintain vascular integrity (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

  50. 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 line • OVC in Geulph 200 cases: 2-4 ml/kg at rate of 0.1-1.7 ml/kg/h, monitor BP, HR, RR, T, edema, anaphylaxis • Plasbumin® Bayer • Long-term effects still under investigation (Matthews, Vet Clinics, May 1998; Mensach, IVECCS, 2005)

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