Fluids and electrolytes balance
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This document provides an overview of body fluids and electrolyte balance. It discusses the sources and composition of body fluids, how fluids move between compartments, and the regulation of fluid balance and electrolytes like sodium, potassium, calcium, and phosphate. Key points include that total body water is 50-70% of weight, fluids move via diffusion, osmosis, active transport and filtration, and homeostasis of fluids and electrolytes is maintained through mechanisms that regulate volumes and solute concentrations.
Fluids and electrolytes balance
- 2. B a l a n cB a l a n c ee H+ cl- Na+ - HCO 3 DR JJ 19/3/2015
- 3. ContentsIntroduction Body Fluids Source Functions Composition Movements of Body Fluids Fluid Balance Regulation of Body Water Electrolytes Electrolyte balance Homeostasis Imbalance disorders Acid –Base Balance conclusion
- 4. Introduction To achieve homeostasis, the body maintains strict control of water and electrolyte distribution and of acid-base balance. This control is a function of the complex interplay of cellular membrane forces, specific organ activities and systemic and local hormone actions. Pestana C:fluids and electolytes in surgical patients, 2nd ed Baltimore, williams and wilkins, 2001 pp 101-144
- 5. 5 Total body water (TBW)
- 6. • Water constitutes an average 50 to 70% of the total body weight. Young males - 60% of total body weight Older males – 52% Young females – 50% of total body weight Older females – 47% • Variation of ±15% in both groups is normal. • Obese have 25 to 30% less body water than lean people. • Infants 75 to 80% - gradual physiological loss of body water. - 65% at one year of age.
- 7. Sources of Body Fluids Preformed water represents about 2,300 ml/day of daily intake. Metabolic water is produced through the catabolic breakdown of nutrients occurring during cellular respiration. This amounts to about 200 ml/d. Combining preformed and metabolic water gives us total daily intake of 2,500 ml.
- 9. Functions 1 All chemical reactions occur in liquid medium. 2 It is crucial in regulating chemical and bioelectrical distributions within cells. 3 Transports substances such as hormones and nutrients. 4 O2 transport from lungs to body cells. 5 CO2 transport in the opposite direction. 6 Dilutes toxic substances and waste products and transports them to the kidneys and the liver. 7 Distributes heat around the body.
- 11. Composition of Body Fluids Nonelectrolytes include most organic molecules, do not dissociate in water, and carry no net electrical charge. Electrolytes dissociate in water to ions, and include inorganic salts, acids and bases, and some proteins. The major cation in extracellular fluids is sodium, and the major anion is chloride; in intracellular fluid the major cation is potassium, and the major anion is phosphate. Electrolytes are the most abundant solutes in body fluids, but proteins and some nonelectrolytes account for 60-–97% of dissolved solutes.
- 12. Principles of Body Water Distribution Body control systems regulate ingestion and excretion: - constant total body water - constant total body osmolarity Homeostatic mechanisms respond to changes in ECF. No receptors directly monitor fluid or electrolyte balance. - Respond to changes in plasma volume or osmotic concentrations
- 13. Fluid Movements
- 14. Movement of BODY FLUIDSMovement of BODY FLUIDS Diffusion Osmosis Active Transport Filtration
- 15. Osmosis FluidFluid High SolutionHigh Solution Concentration,Concentration, Low FluidLow Fluid ConcentrationConcentration Low SoluteLow Solute Concentration,Concentration, High FluidHigh Fluid ConcentrationConcentration
- 16. DiffusionDiffusion High SoluteHigh Solute ConcentrationConcentration Low SoluteLow Solute ConcentrationConcentration FluidFluid Solutes
- 17. Active transportActive transport K +K + KK ++ KK ++ KK ++ KK ++ KK ++ KK ++ KK ++KK ++ KK ++ KK ++ KK ++ KK ++ KK ++ K +K + K +K + K +K +ATPATP ATPATP ATPATP ATPATP Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + Na +Na + INTRACELLULAR FLUID EXTRACELLULAR FLUID
- 18. Filtration Filtration is the transport of water and dissolved materials through a membrane from an area of higher pressure to an area of lower pressure
- 19. Fluid Movement Among Compartments Compartmental exchange is regulated by osmotic and hydrostatic pressures. Net leakage of fluid from the blood is picked up by lymphatic vessels and returned to the bloodstream. Exchanges between interstitial and intracellular fluids are complex due to the selective permeability of the cellular membranes. Two-way water flow is substantial. Ion fluxes are restricted and move selectively by active transport. Nutrients, respiratory gases, and wastes move unidirectionally. Plasma is the only fluid that circulates throughout the body and links external and internal environments. Osmolalities of all body fluids are equal; changes in solute concentrations are quickly followed by osmotic changes.
- 20. Water — Two liters of water per day are generally sufficient for adults. Most of this minimum intake is usually derived from the water content of food and the water of oxidation, therefore. it has been estimated that only 500ml of water needs be imbibed given normal diet and no increased losses. These sources of water are markedly reduced in patients who are not eating and so must be replaced by maintenance fluids.
- 21. water requirements increase with: fever, sweating, burns, tachypnea, surgical drains, polyuria, or ongoing significant gastrointestinal losses.
- 23. 23 Fluid Balance
- 24. Fluid Balance The body tries to maintain homeostasis of fluids and electrolytes by regulating: Volumes Solute charge and osmotic load
- 25. Fluid balance Normally, there is a balance achieved between our total daily intake and output of water. Total fluid intake is modified by the induction of the sensation of thirst. This is produced by a reaction of cells in Hypothalamus to the increased osmotic pressure of the blood passing through this region. Another stimulus of thirst would be the degree of dryness of the oral mucosa.
- 26. Regulation of body water Any of the following: • Decreased amount of water in body • Increased amount of Na+ in the body • Increased blood osmolality • Decreased circulating blood volume Results in: • Stimulation of osmoreceptors in hypothalamus • Release of ADH from the posterior pituitary • Increased thirst
- 27. Regulation of Water Intake The thirst mechanism is triggered by a decrease in plasma osmolarity, which results in a dry mouth and excites the hypothalamic thirst center. Thirst is quenched as the mucosa of the mouth is moistened, and continues with distention of the stomach and intestines, resulting in inhibition of the hypothalamic thirst center.
- 28. Regulation of Water Output Drinking is necessary since there is obligatory water loss due to the insensible water losses. Beyond obligatory water losses, solute concentration and volume of urine depend on fluid intake.
- 29. Influence of ADH The amount of water reabsorbed in the renal collecting ducts is proportional to ADH release. When ADH levels are low, most water in the collecting ducts is not reabsorbed, resulting in large quantities of dilute urine. When ADH levels are high, filtered water is reabsorbed, resulting in a lower volume of concentrated urine. ADH secretion is promoted or inhibited by the hypothalamus in response to changes in solute concentration of extracellular fluid, large changes in blood volume or pressure, or vascular baroreceptors.
- 30. Problems of Fluid Balance Deficient fluid volume Hypovolemia Dehydration Excess fluid volume • Hypervolemia Water intoxication Electrolyte imbalance Deficit or excess of one or more electrolytes Acid-base imbalance
- 31. Factors Affecting Fluid Balance Lifestyle factors Nutrition Exercise Stress Physiological factors Cardiovascular Respiratory Gastrointestinal Renal Integumentary Trauma Developmental factors Infants and children Adolescents and middle-aged adults Older adults Clinical factors Surgery Chemotherapy Medications Gastrointestinal intubation Intravenous therapy Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc.
- 33. Electrolytes 33
- 34. Electrolyte balance Na+ Predominant extracellular cation • 136 -145 mEq / L • Pairs with Cl- , HCO3 - to neutralize charge • Most important ion in water balance • Important in nerve and muscle function Reabsorption in renal tubule regulated by: • Aldosterone • Renin/angiotensin • Atrial Natriuretic Peptide (ANP)
- 35. Electrolyte balance K + Major intracellular cation • 150- 160 mEq/ L • Regulates resting membrane potential • Regulates fluid, ion balance inside cell Regulation in kidney through: • Aldosterone • Insulin
- 36. Electrolyte balance Cl ˉ (Chloride) • Major extracellular anion • 105 mEq/ L • Regulates tonicity • Reabsorbed in the kidney with sodium Regulation in kidney through: • Reabsorption with sodium • Reciprocal relationship with bicarbonate
- 37. SODIUM HOMEOSTASIS Normal dietary intake is 6-15g/day. Sodium is excreted in urine, stool, and sweat. Urinary losses are tightly regulated by renal mechanisms.
- 38. Sodium abnormalities Hypernatremia: Defined as a serum sodium concentration that exceeds 150mEq/L. Always accompanied by hyperosmolarity.
- 39. Etiology Excessive salt intake Excessive water loss Reduced salt excretion Reduced water intake Administration of loop diuretics Gastrointestinal losses
- 40. Treatment: Restore circulating volume with isotonic saline solution After intravascular vol. correction hypernatremia is corrected using free water.
- 41. Hyponatremia Serum sodium concentration less than 135mEq/L . Renal losses caused by diuretic excess, osmotic diuresis, salt- wasting nephropathy, adrenal insufficiency, proximal renal tubular acidosis, metabolic alkalosis, and pseudohypoaldosteronism result in a urine sodium concentration greater than 20 mEq/L Extrarenal losses caused by vomiting, diarrhea, sweat, and third spacing result in a urine sodium concentration less than 20 mEq/L
- 42. Etiology Excessive water intake Impaired renal water excretion Loss of renal diluting capacity
- 43. Treatment of Hyponatremia Correct serum Na by 1mEq/L/hr Use 3% saline in severe hyponatremia. Goal is serum Na 130. 43
- 44. Hypochloremia Most commonly from gastric losses Often presents as a contraction alkalosis with paradoxical aciduria (Na+ retained and H+ wasted in the kidney) Treatment : resuscitation with normal saline.
- 45. Hyperchloremia Most commonly from over-resuscitation with normal saline. Often presents as a hyperchloremic acidemia with paradoxical alkaluria. Rx: stop normal saline and replace with hypotonic crystalloid.
- 46. Hypokalemia Serum K+ < 3.5 mEq /L
- 47. Causes of Hypokalemia Decreased intake of K+ Increased K+ loss Chronic diuretics Severe vomiting/diarrhea Acid/base imbalance Trauma and stress Increased aldosterone Redistribution between ICF and ECF 47
- 48. Hyperkalemia Serum K+ > 5.5 mEq / L 48
- 49. Hyperkalemia Management 10% Calcium Gluconate or Calcium Chloride Insulin (0.1U/kg/hr) and IV Glucose Lasix 1mg/kg (if renal function is normal)
- 50. Hypokalemia: Serum potassium level<3.5mEq/L Etiology: GI losses from vomiting, diarrhea, or fistula and use of diuretics
- 51. Treatment: Correction of the underlying condition K should be given orally unless severe(<2.5mEq/L), patient is symptomatic or the enteral route is contraindicated Oral K supplements (60-80mEq/L) coupled with normal diet is sufficient. ECG monitoring along with frequent assessment of serum K level is reqiured
- 52. Calcium homeostasis Body contains approx. 1400gm of calcium Reduction in calcium level leads to increases calcium reabsorption from the bone. It increases calcium reabsorption and stimulates the formation of the active metabolite of vit. D that increases gut reabsorption of elemental calcium and facilitates the action on the bone.
- 53. Calcium abnormalities: Hypercalcemia: Ionized calcium conc. > 5.3mg/dL
- 55. Treatment: Severe hypercalcemia- Initial supportive therapy includes furosamide to increase calcium excretion. Calcitonin reduces bone resorption and has an immediate effect and lasts for 48 hrs. prolongation can be done by using corticosteroids
- 56. Hypocalcemia: Ionized calcium conc. < 4.4mg/dL
- 57. Etiology: Parathyroid or thyroid surgery Severe pancreatitis Magnesium deficiency Massive blood transfusion
- 58. Treatment: Asymptomatic Calcium supplementation is not required Symptomatic IV calcium therapy- initially 100mg elemental calcium over a period of 5-10mins.susequently, a calcium infusion of 0.5- 2mg/kg/hr is given.
- 59. Phosphate homeostasis Dietary intake-800-1200mg/day. Reabsorbed in the jejunum. Kidney acts as the principle regulator. Normal serum P conc. Is 2.5-4.5mg/dL.
- 60. Phosphate abnormalities: Hyperphosphatemia: Serum phosphate level>4.5mg/dL
- 62. Treatment: Treatment of the underlying renal failure. Chronic- phosphate binding antacids are effective. Acute- end stage renal disease. Dialysis is required.
- 63. Electrolyte Disorders Signs and Symptoms ElectrolyteElectrolyte ExcessExcess DeficitDeficit Sodium (Na)Sodium (Na) •HypernatremiaHypernatremia •ThirstThirst •CNS deteriorationCNS deterioration •Increased interstitial fluidIncreased interstitial fluid •HyponatremiaHyponatremia •CNS deteriorationCNS deterioration Potassium (K)Potassium (K) •HyperkalemiaHyperkalemia •Ventricular fibrillationVentricular fibrillation •ECG changesECG changes •CNS changesCNS changes •HypokalemiaHypokalemia •BradycardiaBradycardia •ECG changesECG changes •CNS changesCNS changes
- 64. Electrolyte Disorders Signs and Symptoms ElectrolyteElectrolyte ExcessExcess DeficitDeficit Calcium (Ca)Calcium (Ca) •HypercalcemiaHypercalcemia •ThirstThirst •CNS deteriorationCNS deterioration •Increased interstitial fluidIncreased interstitial fluid •HypocalcemiaHypocalcemia •TetanyTetany •Chvostek’s, Trousseau’sChvostek’s, Trousseau’s signssigns •Muscle twitchingMuscle twitching •CNS changesCNS changes •ECG changesECG changes Magnesium (Mg)Magnesium (Mg) • HypermagnesemiaHypermagnesemia • Loss of deep tendonLoss of deep tendon reflexes (DTRs)reflexes (DTRs) • Depression of CNSDepression of CNS • Depression ofDepression of neuromuscular functionneuromuscular function •HypomagnesemiaHypomagnesemia •Hyperactive DTRsHyperactive DTRs •CNS changesCNS changes
- 65. Acid-Base Balance Usually present clinically as Tissue malfunction due to disturbed pH 20 changes in respiration as a response to the underlying metabolic changes. Clinical picture is dominated by the cause of the acid-base change.
- 66. Chlorine plays a major role in acid-base balance because of its production of hydrochloric acid (HCl). Water contains equal components of both an acid and a base . Pure water is considered a neutral solution.
- 67. Acid Base Imbalance Metabolic Acidosis Etiology and assessment Occurs when acids other than carbonic acid accumulates in the body resulting in ↓ plasma bicarbonate.
- 68. Management: Identify and correct the cause. IV fluid resuscitation is needed due to associated water and sodium depletion. Bicarbonate infusions can be started in cases where the underlying cause cannot be identified and the acidosis level is critical.
- 69. Metabolic alkalosis It’s the inability of the kidney to excrete the excess bicarbonate ions or to retain hygrogen ion. Usually accompanied by respiratory compensation.
- 70. Etiology: Chloride responsive metabolic alkalosis Chloride-unresponsive metabolic alkalosis
- 71. Treatment: Correction of the underlying defect Contraction alkalosis treated with saline
- 72. Respiratory acidosis Present when the pH is low and the PCO2 is elevated. Two types based upon etiology, time of evolution of the disorder and the degree of renal compensation - Acute Chronic
- 73. Etiology : Due to ineffective alveolar ventilation Decompensation of pre existing respiratory disease Asthma Neuromuscular disorders CNS depression Airway obstruction
- 74. Treatment: Improve alveolar ventilation By intubation By mechanical ventilation
- 75. Respiratory alkalosis Present when the pH is high and PCO2 is low. May be acute or chronic.
- 76. Etiology: Alveolar hyperventilation In surgical patients Hypoxia CNS lesions Pain Hepatic encephalopathy Mechanical ventilation
- 77. Treatment: Correction of the underlying problem.
- 78. Conclusion • Fluid movements in the body and Fluid – electrolyte balance are the inevitable process for normal body function. • Assessment of body fluid is important to determine causes of imbalance disorders.
- 79. References – Text Books • Oral and maxillofacial surgery-Daniel M Laskin Essentials of surgery-Becker and Stucchi Human physiology Mahabatra General surgery - Shenoy Human physiology(from cells to system – lauralee Sherwood. Human physiology – Vanders Principles of Surgery – Das Principles of Human Anatomy & Physiology – Tortora Grabowski Human Physiology – Shembulingam
- 80. References - Articles • Adrogue H, madias N: management of life threatening acid base disorders. N Engl J Med 338:26-34, 2008 • Gennari F:serum osmolality, N Engl J Med 310:102-105, 2004 • Kobrin S, goldfarb s: hypocalcemia and hypercalcemia. In adrogue H acid base and electrolyte disorders. Newyork, churchill, livingstone, 1999, pp69-96 • Pestana C:fluids and electolytes in surgical patients, 2nd ed Baltimore, williams and wilkins, 2001 pp 101-144
- 81. PREVIOUS YEAR QUESTIONS Osmosis (RGUHS 2010, 10 marks)