Fluid & electrolyte therapy

This presentation contains fluid & electrolyte therapy of animals.

1. FLUID & ELECTROLYTE THERAPY D r ARYA MOHAN 19-MVM-13

2. Body Fluids Water Solutes 2 TOTAL BODY WATER 60% of BW ICF (40%) ECF (20%) INTRAVASCULAR FLUID TRANSCELLULAR FLUID EXTRAVASCULAR FLUID INACCESSIBLE BONE FLUID Blood plasma Interstitial fluid Lymph Secretions from glandular secretion, GI fluid, respiratory fluid, CSF, aqueous humor, peritoneal fluid

3. Electrolyte Compounds which exist as charged particles in solution ECF contains mainly Na ⁺ as major cation and Cl⁻, HCO₃⁻ & HPO₄ 2 ⁻ as anions ICF contains K⁺ as major cation and HCO₃⁻, PO₄ 3 ⁻, SO₄ 2 ⁻ & citrate as anions Electrolytes are essential for various life processes ECF volume is mainly maintained by Na⁺ & ICF volume is a function of K⁺ content- maintained by Na⁺/K⁺ ATPase pumps 3

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5. Acid-base balance Balance between acidity & alkalinity Determined by H ⁺ ion concentration in various body fluids pH of ECF is maintained within narrow limits of 40nEq (pH-7.4) in arterial blood & 45nEq (pH- 7.35) in venous blood & interstitial fluid Most enzymatic reactions have narrowly defined range of pH optimum, a small variation in H ⁺ ion will affect the reaction rates & various biological processes pH of ECF above 7.8 & below 7.0 is incompatible with life Normally a pH of arterial blood below 7.4 is considered as acidosis/ acidemia & above 7.4 is considered as alkalosis/ alkaliemia 5

6. H ⁺ ion concentration is maintained by 6 Bicarbonate buffer Phosphate buffer Protein buffer

7. 7 DISTURBANCES IN WATER, ELECTROLYTE & ACID-BASE BALANCE

8. Water imbalance DEHYDRATION Hypertonic- Water loss with little or no electrolyte loss Treated with hypotonic solution Isotonic- Water loss with proportionate electrolyte loss Treated with isotonic fluids OVERHYDRATION Does not occur commonly in animals Over hydration is usually balanced through renal water excretion Treated with diuretics 8

9. ELECTROLYTE IMBALANCE 9 SODIUM Hyponatremia Hypernatremia Hypovolemic hyponatremia Hypervolemic hyponatremia Normovolemic hyponatremia Hypovolemic hypernatremia Hypervolemic hypernatremia Normovolemic hypernatremia

10. HYPONATREMIA Rapid in onset Acute hyponatremia Causes influx of water into CNS Early signs include lethargy, nausea & vomiting More severe signs include pulmonary & cerebral edema, coma, increase in body weight Seizures due to acute water intoxication Clinical signs absent in chronic loss of Na ⁺ HYPERNATREMIA Related to cerebral dehydration Depression, lethargy, muscle rigidity, tremors, myoclonus & hyper- reflexia Vomiting, diarrhea, polydipsia & polyuria Seizures, coma & death in severe cases 10 CL I N I CAL S I GNS

11. HYPONATREMIA Severe symptomatic hyponatremia - hypertonic saline solution (3-5% NaCl) Mild to moderate hyponatremia - isotonic saline solution (0.9% NaCl) Adrenocortical insufficiency – HRT Overhydrated patients- hypertonic saline + loop diuretics Normovolemic patients- water restricted, discontinue the AD drugs HYPERNATREMIA Hypermatremia with pure water loss, water is given orally or as 5% dextrose solution Hypotonic hypernatremia treated by 0.45% NaCl solution or other hypotonic fluids Hypertonic hypernatremia - saline solution + loop diuretics 11 TREATMEN T

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14. 14 POTASSIUM Hypokalemia Hyperkalemia Muscle weakness Arrhythmia Ileus Rhabdomyolysis Renal dysfunction Reluctance or inability to stand or walk Tremors Bradycardia Arrhythmia

15. HYPOKALEMIA Oral or parenteral replacement therapy KCl is preferred solution (concurrent alklaosis & Cl ⁻ deficiency) K phosphate also preferred; chance of hyperphosphatemia & hypocalcemia Should not administer not more than 0.5mEq/Kg/h iv – fatal cardiotoxicity HYPERKALEMIA Management of underlying cause Withhold K ⁺ rich foods Administer K ⁺ free fluids Na bicarbonate – increase pH- push K ⁺ into cells Ca slow iv- reduce cardiotoxic effect Careful use of diuretics Primary renal disease- exchange resins, peritoneal dialysis & hemodialysis 15 TREATMEN T

16. 16 CHLORIDE Hypochloremia Hyperchloremia 0.9% NaCl (Saline solution) 0.9% Saline solution 5% Dextrose water

17. 17 CALCIUM Hypocalcemia Hypercalcemia MAGNESIUM Hypomagnesemia Hypermagnesemia PHOSPHOROUS

18. ACID BASE BALANCE 18

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20. Fluid therapy Therapy must be individualized & tailored to each patient Constantly re-evaluated & reformulated according to changes in status Fluid selection is dictated by Patient’s needs, including volume, rate, & fluid composition required, as well as location the fluid is needed (interstitial vs intravascular ) Factors to consider include the following: Acute versus chronic conditions Patient pathology (e.g., acid-base balance, oncotic pressure, electrolyte abnormalities) Comorbid conditions 20

21. Variety of conditions can be effectively managed using three types of fluids: Balanced isotonic electrolyte (e.g. crystalloid such as lactated Ringer’s solution [LRS]) Hypotonic solution (e.g. crystalloid such as 5% dextrose in water [D5W]) Synthetic colloid (e.g., hydroxyethyl starch such as hetastarch or tetrastarch 21

22. General principles Assess for the following three types of fluid disturbances: Changes in volume (e.g., dehydration, blood loss) Changes in content (e.g., hyperkalemia) Changes in distribution (e.g., pleural effusion ) 22

23. Type of fluid: - Choice of fluid depends on type & extent of fluid losses incurred Balanced crystalloids are preferred when replenishing hypovolemia in dehydrated patient Once rehydrated, maintenance solutions are preferred for long term fluid therapy Amount of fluid needed: - maintenance need, deficit & ongoing loss Fluid requirement in 24 hrs = Maintenance volume + Deficit (dehydrated) volume + Ongoing losses 23

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25. Estimation of dehydration 25

26. classification 28

27. CRYSTALLOIDS Mostly Na based electrolyte solutions with or without glucose in water Provide water, electrolyte, calorie & alkalising agents Effective both as maintenance & replacement solutions Replacement Fluids Mainly Na based fluids; have composition similar to plasma; given rapidly in large volumes do not drastically change constituents of intravascular fluids Maintenance Fluids Used as normal substitutes for normal intake of water & dietary electrolytes; provided after initial fluid balance is restored 29

28. Saline solution Normal saline solution/ isotonic saline solution/ NaCl solution/ Physiological Saline Solution Contains 0.9% w/v NaCl in water Most widely used replacement fluid; also used as maintenance fluid Mildly acidic in nature ~ 300 mOsm / Kg- isotonic with plasma; but not a balanced fluid Replaces Na ⁺ loss efficiently Can cause hyperchloremic metabolic alkalosis; contains more Cl ⁻ than that in plasma (diarrhea or kidney unable to excrete excess Cl ⁻ ) Contraindicated in patients with CHF & in restricted Na intake 30

29. Hypertonic saline solution Available commercially as 3%, 5% & 7.5% w/v NaCl in water Contain more osmotically active particles than intracellular fluid, water moves from the interstitial space Rapidly expand the plasma volume & help in maintaining perfusion- hypovolemia & hemorrhagic shock Indicated in hypervolemic hyponatremia, water intoxication syndrome Provide mild positive inotropic effect & provide pulmonary and systemic vasodilatation Contraindicated in dehydrated, hypernatremic or hyperchloremic patients Should be administered slow iv (adverse cardiac effects) 31

30. Hypotonic saline solution Contain 0.45% NaCl in water Contain NaCl half of that of isotonic saline – Half Normal Saline Solution Osmolality less than that of ECF As maintenance fluid Along with 2.5% dextrose solution 32

31. Ringer solution Prototype of replacement fluids Contain Na, K, Ca & Cl in appropriate concentrations Occasionally used as maintenance fluid High chloride content No bicarbonate precursor 33

32. Ringer lactate Hartmanns solution Ringer solution + lactate Ideal replacement fluid with plasma like electrolyte composition Supplies bicarbonate ions after hepatic metabolism of lactate Replacement of all fluid deficits & fluid delivery for all shocks except cardiogenic shock Here Na lactate in ringer lactate is replaced by Na acetate Bicarbonate generation occurs in muscles & peripheral tissues 34 Acetated ringers solution

33. 5% w/v dextrose in water Used a maintenance fluid & source of water Used in hypernatremia & primary water depletion states Should not be used as a replacement fluid Does not supply required electrolytes Not suitable for volume resuscitation, intravascular volume maintenance or interstitial volume replacement For treatment of hypoglycemia & ketosis 10%, 25% & 50% solutions 35 Isotonic dextrose solution hyper tonic dextrose solution

34. Hypotonic dextrose solution 2.5% w/v dextrose in water Used as maintenance fluid alone or in combination with other fluids 4.3% dextrose + 0.18% NaCl Maintenance of fluid & electrolyte levels Useful for hypertonic dehydration 36 iso tonic dextrose solution

35. Sodium bicarbonate solution Treatment of metabolic acidosis 1.5%, 5% & 8.4% solutions 1.5% solution is approximately isotonic Used to alkalinise urine Adjunct in hypercalcemia & hyperkalemia Administered slowly – overshoot alkalosis Incompatible with D5W & D5 RL solutions 37

36. Potassium chloride solution Available as 2mEq/mL & 3mEq/mL solutions Treatment of hypokalemia Slow iv (rapid- cardiotoxic) Contraindicated in renal failure, AV block & hyperkalemia Diluted with 50 times its volume of 0.9% NaCl solution Mixtures of monobasic & dibasic salt forms To correct hypokalemia or hypophosphatemia diabetic ketoacidosis 38 Potassium phosphate solution

37. Calcium gluconate & calcium borogluconate Most widely used salts of Ca Treatment of hypocalcemia in large & small animals Administered according to response of patient, intensity of clinical signs & blood analysis Not preferred therapeutically More likely to cause hypotension 39 Calcium chloride

38. Magnesium sulphate Available in 10, 12.5, 25 & 50 concentrations Used as source of Mg in hypomagnesemic tetany Overdosage cause CNS depression, cardiac depression, respiratory depression & muscular weakness Ventilatory support & Ca iv required for severe hypermagnesimia 40

39. Darrow’s solution Lactated K saline injection Consists of 0.4% NaCl + 0.27% KCl + 0.58% Na lactate Counters depletion of K in ICF in dehydration Na lactate – alkalinising agent Less used in veterinary therapeutics 41

40. colloids Plasma volume expanders High molecular weight synthetic colloidal substances; attract & hold water in vascular space Do not enhance O₂ carrying capacity of blood Natural colloids- plasma, albumin preparations & whole blood Synthetic colloids are more readily available & carry no risk of transmitting disease Effectiveness depends on molecular weight, colloid content & bioavailability, their ability to bind intravascular volume & maintain oncotic pressure 42

41. DESIRABLE PROPERTIES Should exert oncotic pressure comparable to plasma Should remain in circulation for required period & not readily leak out in tissues Pharmacologically inert Not pyrogenic or antigenic Not adversely affect any visceral organ Not interfere with grouping & cross matching of blood Longer storage period Easily sterilisable Readily available & economical 43

42. Useful in patients which are hypovolemic , hypoproteinemic & shock Often in combination with hypertonic saline (to increase effect of hypertonic saline & to reduce the volume of crystalloids needed to achieve & maintain adequate systemic arterial blood pressure & tissue perfusion) Dextran, Hetastarch , Oxypolygelatine / Gelatine 44

43. PLASMA Most commonly used colloid solution in veterinary medicine Its main advantage stems from the colloid osmotic pressure provided by plasma proteins It is useful for treating hypoproteinemic conditions such as chronic liver disease, protein-losing enteropathy , and glomerulopathy Main disadvantages of plasma are its limited availability, its effects are temporary & it is expensive 45

44. DEXTRANS Synthetic colloids derived from sugar beets Dextran 70 and 40 are available in 5% dextrose or saline solutions Dextran 40 has the advantage of retarding formation of rouleaux & sludging of RBC, thus improving microcirculation above & beyond simple volume expansion Disadvantages include coagulopathies as a result of decreased platelet function & altered fibrin clot formation Other problems include renal failure, anaphylaxis & depressed immune function 46

45. HETASTARCH Hydroxyethyl starch ( Hetastarch ) is a synthetic polymer derived from a waxy starch composed mostly of amylopectin Like albumin, it expands the circulating plasma volume Osmolality is approximately 310 mOsm /L expanded plasma volume may last for 24 hours or longer Hydroxyethyl starch is available as a 6% solution in saline 47

46. Oral rehydration solutions Essentially contain Na ⁺ , K ⁺ , Cl ⁻ & glucose Widely used in man & small animals to correct water & electrolyte loss due to diarrhea & other conditions Normally made isotonic Base- bicarbonate or citrate or lactate – to correct acidosis Super ORS - ORS solution containing actively transported amino acids (alanine & glycine) 48

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48. 50 SOME SPECIAL FLUID THERAPY CONSIDERATIONS

49. ANEMIA Intravenous fluids are sometimes used excessively in the anemic patient when the decrease in red blood cell mass is misinterpreted as total blood volume depletion, when in fact the plasma volume might even be expanded To compensate for decreased tissue oxygen delivery, the heart rate increases, and if these patients are subjected to large fluid volumes over a short period of time, pulmonary edema can occur 51

50. Extracellular Fluid Volume Excess Associated with an increase in total body salt & water Occurs in a variety of clinical settings including congestive heart failure, glomerulopathies , liver fibrosis &protein-losing enteropathyThese conditions are Associated with a decrease in "effective arterial volume," which stimulates the renin-angiotensin-aldosterone cycle & the release of antidiuretic hormones to promote renal salt & water retention Increased venous pressure from heart failure and cirrhosis or because of decreased plasma oncotic pressure associated with hypoalbuminemia , the retained salt and water move into the interstitial and other body spaces, causing edema, ascites, or pleural effusion 52

51. Such patients are extremely sensitive to intravenous overload with crystalloid solutions Treatment should be directed toward improving the underlying primary pathologic process Fresh or fresh frozen plasma should be used to volume expand animals with hypoalbuminemia , although in glomerulopathies and protein-losing enteropathy , beneficial effects are usually temporary at best because of continued protein losses Heart failure patients receiving intravenous fluids should be closely observed for weight gain and respiratory distress caused by intravascular fluid overload 53

52. When parenteral fluid therapy is indicated in the cardiac patient, solutions containing little or no sodium are given after dehydration and hypovolemia are corrected with isotonic solutions Either 0.45% saline or D-5-W can be used Efforts should be made to avoid hypokalemia by adding potassium chloride solution to the fluids at a dose of 7 to 10 mEq /250 ml 54

53. Hypovolemic Shock Isotonic crystalloid solutions (NS, acetated Ringer's or LRS)are the most commonly used replacement fluids because they are usually effective, readily available, easily administered, and relatively inexpensive Severely hypotensive patients might require at least one whole blood volume of replacement fluids during the first hour of treatment Initial rapid infusion for dogs should be 20 to 40 ml/kg IV (one half this amount for cats) for 15 minutes, followed by 70 to 90 ml/kg (dogs) or 30 to 50 ml/kg (cats) administered over one hour Any signs of fluid overload necessitate prompt decreases in fluid delivery and consideration of diuretic therapy Useful for treating dogs and cats with trauma-induced peracute blood loss It has also been proved efficacious for treating other conditions in which plasma volume is depleted rapidly, such as the canine hemorrhagic gastroenteritis (HGE) syndrome 55

54. Vomiting Principle sign of gastric disease, but it can also accompany disorders of the small or large bowel, liver, and pancreas, as well as disorders occurring outside of the digestive system Deplete the body of a substantial volume of fluids and electrolytes Specific types of electrolyte deficiencies and acid-base abnormalities depend on the location of the primary disorder Vomiting caused by pyloric outflow obstructions typically can lead to dehydration, metabolic alkalosis, hypochloremia , hypokalemia, and hyponatremia NS supplemented with potassium chloride (3 to 10 mEq / kg BW  every 24-hours) is the fluid of choice Fluid losses through vomiting associated with systemic illness or intestinal disease are best replaced with lactated or acetated Ringer's solutions 56

55. Diarrhea Fluid deficit from massive diarrhea can be efficiently corrected with LRS or acetated Ringer's because In markedly hypotensive patients, the intravenous fluids should be given as per hypovolemic shock condition 57

56. ACIDOSIS Respiratory Ventilation, bronchodilators, intubation Use of Na bicarbonate is contraindicated Chronic acidosis is difficult to treat Metabolic Correction of primary metabolic effect Use of alkalinising agents- NaHCO ₃ 58

57. ALKALOSIS Respiratory Normalisation of ventilation Removal of primary cause O₂ therapy Mechanical respirators Sedative or tranquilisers if needed Metabolic Treat for primary cause Administration of Cl ⁻- Cl⁻ responsive alkalosis Correction of volume depletion- 0.9% NaCl solution KCl solution to treat hypokalemia Ammonium chloride- acidifying agents- Hypochloremic alkalosis 59

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