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Fluid and Electrolyte Disorders

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Presentation on theme: "Fluid and Electrolyte Disorders"— Presentation transcript:

1 Fluid and Electrolyte Disorders

2 Functions of Body Fluids
Transports gases, nutrients, and wastes Help to generate the electrical activity needed to power body functions Takes part in the transforming of food into energy Maintains the overall function of the body

3 Distribution of Body Fluids
Intracellular compartment (ICF) Consists of fluid contained within all of the billions of cells in the body Larger of the two compartments, with approximately two thirds of the body water in healthy adults High concentration of K+ Extracellular compartment (ECF) Contains the remaining one third of body water Contains all the fluids outside the cells, including that in the interstitial or tissue spaces and blood vessels High concentration of Na+


5 Composition of the ECF, Plasma, and Interstitial Fluids
Large amounts of sodium and chloride Moderate amounts of bicarbonate Small quantities of potassium, magnesium, calcium, and phosphorus

6 Composition of the ICF Almost no calcium
Small amounts of sodium, chloride, bicarbonate, and phosphorus Moderate amounts of magnesium Large amounts of potassium


8 Question Which ion is in the highest concentration in the ICF? Na+ K+
Cl- Ca2+

9 Answer Na+ K+: Potassium is the most abundant ion of the ICF and is responsible for the membrane potential. Cl- Ca2+

10 Diffusion and Osmosis Concentration gradient Diffusion Osmosis
Difference in concentration over a distance Diffusion The movement of charged or uncharged particles along a concentration gradient from an area of higher concentration to one of lower concentration Osmosis The movement of water across a semi-permeable membrane from the side of the membrane with the lesser number of particles and greater concentration of water to the side with the greater number of particles and lesser concentration of water

11 Tonicity The osmotic pressure gradient of two solutions separated by a semipermeable membrane Solutions can be classified according to whether or not they cause cells to shrink. Isotonic: neither shrink nor swell Hypotonic: swell Hypertonic: shrink

12 Physiology of water balance
Na+ retention causes this volume to expand Na+ loss causes this volume to decrease Water moves freely within intracellular and extracellular compartments, keeping osmolality equal

13 Edema Edema = Accumulation of water in interstitial space
Collections of fluid in body cavities Hydrothorax – serous fluid in the thoracic cavity Hydroperitoneum (ascites) Hydropericardium fluid in the pericardial sac Anasarca = severe, generalized edema with profound subcutaneous edema

14 Pathophysiology of Edema
The normal flow of fluid through the interstitial space depends on four factors: Capillary hydrostatic pressure that filters fluid from the blood through the capillary wall Oncotic pressure exerted by the proteins in the blood plasma Permeability of the capillaries Presence of open lymphatic channels that collect some fluid forced out of the capillaries by the hydrostatic pressure of the blood and return the fluid to the circulation


16 Mechanism of Edema Formation
Increased hydrostatic pressure Reduced plasma oncotic pressure Decreased lymph outflow (lymphatic channel obstruction Increased capillary membrane permeability Retention of water and salts

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

18 Increased Hydrostatic Pressure

19 Decreased plasma oncotic pressure:
↓ plasma albumin • liver disease • protein malnutrition plasma proteins lost in: • glomerular diseases of kidney • hemorrhage, burns, open wounds idiopathic edema protein leakage from capillaries

20 Nephrotic Syndrome Ascites is the build up of fluid in the space between the lining of the abdomen and abdominal organs (the peritoneal cavity). Ascites results from high pressure in the blood vessels of the liver (portal hypertension) and low levels of a protein called albumin. Usually due to severe liver damage. Nephrotic syndrome is caused by different disorders that damage the kidneys. This damage leads to the release of too much protein in the urine. Cancer, diabetes, lupus, genetic disorders can all cause this syndrome.

21 Lymphatic channels blocked
Surgery Breast carcinoma with lymph node removal Blocked lymphatics Hematologic conditions Parasitoses

22 Lymphatic obstruction
Caused by thread-like parasitic worm – filaria (filariasis) transmitted by mosquitoes

23 Effects of Edema Swelling Pitting Increased body weight
Functional impairment Pain Impairment of arteriole circulation Other complications

24 Clinical Consequences of Edema
In skin edema may cause poor wound healing or poor clearance of infection Edema in a closed space such as the calvarium can cause increased pressure, which may cause herniation of the brain

25 Acute pulmonary edema Definition: An increase in pulmonary extravascular water, which occurs when transudation or exudation exceeds the capacity of lymphatic drainage. Transudation - the passage of a substance through a membrane as a result of a difference in hydrostatic pressure; same as exudation Exudation – oozing out; the slow escape of liquids from blood vessels through pores or breaks in the cell membranes

26 Stages of pulmonary edema
Interstitial pulmonary edema Cresentic alveolar filling Alveolar flooding Airway flooding With gradual onset these may be identifiable clinically, however with fulminant disease progression may be obscured There is usually prodromal stage in which lymphatic drainage is increase, though there is no detectable increase in lung water Crescentic – Interstitial edema increases and there is passage of fluid into the alveoli. However, the center of the alveoli and the most of the alveoli walls remain clear Alveolar Flooding - Fluid enters the alveoli in a crescentic fashion until the surface tension rises sharply and further fluid is drawn into the alveolus as the pressure gradient rises exponentially. Clearly no gas exchange can occur in flooded alveoli. Fulminante - is any event or process that occurs suddenly and quickly, and is intense and severe to the point of lethality Prodromal - An early symptom indicating the onset of an attack or a disease.

27 Cardioigenic pulmonary edema
Increased hydrostatic pressure secondary to elevated pulmonary venous pressure Interstitial edema Alveolar edema

28 Stages of Cardioigenic Pulmonary Edema
Elevated LA pressure causes distention and opening of small pulmonary vessels Stage 2 Fluid and colloid shift into the lung interstitium from the pulmonary capillaries, but an initial increase in lymphatic outflow efficiently removes the fluid.

29 Stages of Cardioigenic Pulmonary Edema
As fluid filtration continues to increase and the filling of interstitial space occurs, fluid accumulates in the relatively noncompliant interstitial space. At this stage, abnormalities in gas exchange are noticeable, vital capacity and other respiratory volumes are substantially reduced, and hypoxemia becomes more severe.

30 Toxic pulmonary edema Increased vascular permeability due to toxic damage of pulmonary capillaries.

31 High Altitude Pulmonary Edema (HAPE)
Hypoxic vasoconstriction Blood vessel leakage Fluid builds up in the lungs HAPE is a noncardiogenic form of pulmonary edema resulting from a leak in the alveolar capillary membrane. Autopsy studies performed on patients who died of HAPE have shown a proteinaceous exudate with hyaline membranes. Most reports mention capillary and arteriolar thrombi with deposits of fibrin, hemorrhage, and infarcts. The findings suggest a protein-rich edema with a possibility that clotting abnormalities may be partially responsible for this illness. The person usually notices fatigue, weakness, and dyspnea on exertion. The condition typically worsens at night, and tachycardia and tachypnea occur at rest. Periodic breathing during sleep is almost universal in sojourners at high altitude. Cough, frothy sputum, cyanosis, rales, and dyspnea progressing to severe respiratory distress are symptoms of the disease. A low-grade fever, respiratory alkalosis, and leukocytosis are other common features. In severe cases, an altered mental status, hypotension, and death may result.

32 Methods for Assessing Edema
Daily weight Visual assessment Measurement of the affected part Application of finger pressure to assess for pitting edema

33 Water and Na+ Balance Gain Water
Oral intake and metabolism of nutrients Na+ Loss Kidneys Skin Lungs Gastrointestinal tract Baroreceptors regulate effective volume Modulating sympathetic nervous system outflow and ADH secretion Atrial natriuretic peptide Renin-angiotensin-aldosterone system Angiotensin II Aldosterone

34 Regulators of Sodium The kidney is the main regulator of sodium.
Monitors arterial pressure; retains sodium when arterial pressure is decreased, and eliminates it when arterial pressure is increased The rate is coordinated by the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS). Atrial natriuretic peptide (ANP) may also regulate sodium excretion by the kidney.

35 Physiologic Mechanisms Assisting in Regulating Body Water
Thirst Primarily a regulator of water intake ADH A regulator of water output Both mechanisms respond to changes in extracellular osmolality and volume.

36 Question Which ion will have the greatest effect on the membrane potential? Bicarbonate K+ Cl- Mg2+

37 Answer Bicarbonate K+: Slight deviations in potassium concentration will directly change the membrane potential. Cl- Mg2+

38 Disorders of ADH Expression
Diabetes insipidus Deficiency of or a decreased response to ADH Unable to concentrate urine during periods of water restriction, leading to excretion of large volumes of urine Neurogenic diabetes insipidus Central diabetes insipidus Syndrome of inappropriate antidiuretic hormone (SIAH) Failure of the negative feedback system that regulates the release and inhibition of ADH

39 Types of Diabetes Insipidus
Central or neurogenic diabetes insipidus Occurs because of a defect in the synthesis or release of ADH by the Hypothalamus Usually Idiopathic but may be due to autoimmune disease such as Sarcoidosis, head trauma, or tumor Nephrogenic diabetes insipidus Occurs because the kidneys do not respond normally to ADH

40 Diabetes Insipidus Excessive Urination Extreme Thirst
Urine does NOT contain Glucose

41 The End

42 Mechanisms Protecting Extracellular Fluid Volume
Alterations in hemodynamic variables Vasoconstriction and an increase in heart rate Alterations in sodium and water balance Isotonic contraction or expansion of ECF volume Hypotonic dilution or hypertonic concentration of extracellular sodium brought about by changes in extracellular water

43 Causes of Fluid Volume Excess
Inadequate sodium and water elimination Excessive sodium intake in relation to output Excessive fluid intake in relation to output

44 Vitamin D, Calcitonin, and Parathyroid Hormone
Vitamin D acts to sustain normal plasma levels of calcium and phosphorus by increasing their absorption from the intestine. Calcitonin acts on the kidney and bone to remove calcium from the extracellular circulation.

45 Mechanisms Regulating Calcium, Phosphorus, and Magnesium Balance
Calcium, phosphorus, and magnesium are the major divalent cations in the body. They are: Ingested in the diet Absorbed from the intestine Filtered in the glomerulus of the kidney Reabsorbed in the renal tubules Eliminated in the urine

46 Physiologic Calcium ECF calcium exists in three forms Protein bound
40% of ECF calcium is bound to albumin. Complexed 10% is chelated with citrate, phosphate, and sulfate. Ionized 50% of ECF calcium is present in the ionized form.

47 Calcium Gain and Loss Gains Dietary dairy foods
Parathyroid hormone and vitamin D stimulate calcium reabsorption in the nephron. Losses Occur when dietary intake and calcium absorption are less than intestinal secretion

48 Causes and Symptoms of Hypercalcemia
Increased intestinal absorption Excessive vitamin D and calcium Milk-alkali syndrome Increased bone resorption Increased parathyroid hormone Malignant neoplasms Prolonged immobilization Decreased elimination Thiazide, lithium therapy Symptoms Changes in neural excitability Alterations in smooth and cardiac muscle function Exposure of the kidneys to high concentrations of calcium

49 Causes and Symptoms of Hypocalcemia
Impaired ability to mobilize calcium from bone stores Abnormal losses of calcium from the kidney Increased protein binding or chelation such that greater proportions of calcium are in the nonionized form Soft tissue sequestration Symptoms Increased neuromuscular excitability Cardiovascular effects Nerve cells less sensitive to stimuli

50 Role of Phosphorus in the Body
Plays a major role in bone formation Essential to certain metabolic processes The formation of ATP and the enzymes needed for metabolism of glucose, fat, and protein Necessary component of several vital parts of the cell Incorporated into the nucleic acids of DNA and RNA and the phospholipids of the cell membrane

51 Role of Phosphorus in the Body (cont.)
Serves as an acid–base buffer in the extracellular fluid and in the renal excretion of hydrogen ions Necessary for delivery of oxygen by the red blood cells Needed for normal function of other blood cells White blood cells and platelets

52 Common Causes of Hypophosphatemia and Hyperphosphatemia
Depletion of phosphorus due to insufficient intestinal absorption Transcompartmental shifts Increased renal losses Hyperphosphatemia Failure of the kidneys to excrete excess phosphate Rapid redistribution of intracellular phosphate to the ECF compartment Excessive intake of phosphorus

53 Magnesium Balance Essential to all reactions that require ATP
Regulation at kidney level Magnesium absorption in the thick ascending loop of Henle is the positive voltage gradient created in the tubular lumen by the Na+-K+-2Cl– cotransport system Ingested in the diet Absorbed from the intestine Excreted by the kidneys

54 Manifestations of Hypomagnesemia
Laboratory values Serum magnesium level less than l.8 mg/dL Neuromuscular manifestations Personality changes, athetoid or choreiform movements, nystagmus, tetany, positive Babinski Chvostek, and Trousseau signs Cardiovascular manifestations Tachycardia, hypertension, cardiac dysrhythmias

55 Causes of Hypermagnesemia
Excessive intake Intravenous administration of magnesium for treatment of preeclampsia Excessive use of oral magnesium-containing medications Decreased excretion Kidney disease Acute renal failure

56 Question Alterations in ________________ may result in hypercalcemia.
ADH Na+ Vitamin D K+

57 Answer Alterations in ________________ may result in hypercalcemia.
ADH Na+ Vitamin D: When increased, vitamin D will result in higher retention of calcium. K+

58 Assessment of Body Fluid Loss
History of conditions that predispose to sodium and water losses, weight loss, and observations of altered physiologic function indicative of decreased fluid volume Heart rate Blood pressure Venous volume/filling Capillary refill rate

59 Psychogenic Polydipsia
Compulsive water drinking Psychiatric disorders Schizophrenia Drink large amounts of water and excrete large amounts of urine. Cigarette smoking ADH Interferes with water excretion by the kidneys Antipsychotic medications increase ADH levels

60 Isotonic Fluid Volume Excess
Isotonic expansion of the ECF compartment with increases in both interstitial and vascular volumes Increase in total body sodium that is accompanied by a proportionate increase in body water Causes of decreased sodium and water elimination Renal function Heart failure Liver failure Corticosteroid excess

61 Potassium Distribution and Regulation
Intracellular concentration of 140 to 150 mEq/L The extracellular concentration of 3.5 to 5.0 mEq/L Body stores of potassium are related to body size and muscle mass. Normally derived from dietary sources Plasma potassium is regulated through two mechanisms: Renal mechanisms that conserve or eliminate potassium A transcellular shift between the ICF and ICF compartments

62 Abnormal Potassium Hypokalemia refers to a decrease in plasma potassium levels below mEq/L. Inadequate intake Excessive gastrointestinal, renal, and skin losses Redistribution between the ICF and ECF compartments Hyperkalemia refers to an increase in plasma levels of potassium in excess of 5.0 mEq/L. Decreased renal elimination Excessively rapid administration Movement of potassium from the ICF to ECF compartment

63 Diagnosis and Treatment of Potassium Disorders
Diagnosis is based on complete history, physical examination to detect muscle weakness and signs of volume depletion, plasma potassium levels, and ECG findings. Treatment Calcium antagonizes the potassium-induced decrease in membrane excitability. Sodium bicarbonate will cause K+ to move into the ICF. Insulin will decrease ECF K+ concentration Curtail intake or absorption, increase renal excretion, and increase cellular uptake

64 ADH and Aquaporin-2 Channels
V1 receptors Vasoconstriction V2 receptors Control water reabsorption Aquaporins

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