Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Fluids and Electrolytes Chapter 4 – Part 1

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Distribution of Body Fluids  Total body water (TBW)  Intracellular fluid (2/3 TBW or 28 L)  Extracellular fluid (1/3 TBW or 14L) Interstitial fluid (about 11L) Interstitial fluid (about 11L) Intravascular fluid (about 3L) Intravascular fluid (about 3L) Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal, pericardial, and intraocular fluids (less than 1L) Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal, pericardial, and intraocular fluids (less than 1L)

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Distribution of Body Fluids  Pediatrics  At birth water is 75-80% of body weight. Infants have a high metabolic rate and greater body surface area than adults. Infants have a high metabolic rate and greater body surface area than adults. Thus they have a greater fluid intake and output in relation to their body size. Thus they have a greater fluid intake and output in relation to their body size.  This makes them more susceptible to significant changes in body fluids than adults. Dehydration is a major concern. Dehydration is a major concern.

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Distribution of Body Fluids  Aging  The percentage of total body weight that is fluid decreases due to: Increase adipose and decrease muscle mass Increase adipose and decrease muscle mass Renal decline Renal decline Diminished thirst perception Diminished thirst perception  This puts the elderly at greater risk of dehydration than younger adults.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Movement Between the Intravascular and Interstitial Spaces  Movement within the ECF  Determined by the net filtration pressure across the capillary wall.  Net filtration = forces favoring filtration minus forces opposing filtration (Starling’s hypothesis)

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Water Movement Between the Intravascular and Interstitial Spaces  Forces favoring filtration:  Capillary hydrostatic pressure Due to blood pressure Due to blood pressure  Interstitial oncotic pressure Due to proteins in fluid between tissue cells (water-pulling) Due to proteins in fluid between tissue cells (water-pulling)

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Movement Between the Intravascular and Interstitial Spaces  Forces favoring reabsorption:  Plasma oncotic pressure – Due to plasma proteins (water pulling) Due to plasma proteins (water pulling)  Interstitial hydrostatic pressure – D ue to pressure in tissues (pushes into blood and cells) D ue to pressure in tissues (pushes into blood and cells)

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Movement Between the ICF and ECF  Caused by changes in the concentration of ECF (osmotic pressure differences).

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Movement Between the ICF and ECF  If ECF becomes less concentrated water flows into cells and they swell.  Could occur if there is fluid excess or sodium deficit.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Movement Between the ICF and ECF  If ECF becomes more concentrated water flows out of cells and they shrink.  Could occur if there is fluid deficit or sodium excess.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity B = into blood I = into interstitial C = into cells Lower than normal sodium levels. Lower than normal sodium levels. Higher than normal sodium levels. Higher than normal sodium levels. High blood pressure. High blood pressure. Low blood pressure. Low blood pressure. Lower than normal levels of plasma proteins. Lower than normal levels of plasma proteins. Higher than normal levels of plasma proteins. Higher than normal levels of plasma proteins.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity - Key B = into blood I = into interstitial C = into cells C Lower than normal sodium levels. I Higher than normal sodium levels. I High blood pressure. B Low blood pressure. B Low blood pressure. I Lower than normal levels of plasma proteins. I Lower than normal levels of plasma proteins. B Higher than normal levels of plasma proteins. B Higher than normal levels of plasma proteins.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Edema  Accumulation of fluid within the interstitial spaces  Causes  Increase in capillary hydrostatic pressure Example - vasoconstriction Example - vasoconstriction  Decrease in plasma oncotic pressure Example - liver failure & decreased plasma proteins Example - liver failure & decreased plasma proteins  Increases in capillary permeability Example - inflammation Example - inflammation  Lymph obstruction Example - after surgical removal of lymph nodes Example - after surgical removal of lymph nodes

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Causes of Edema

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Balance  Regulated through thirst perception and ADH secretion.  Antidiuretic hormone (ADH)  Causes increased water reabsorption, primarily in the distal convoluted tubules of kidneys.  Secreted when plasma volume drops or plasma concentration (osmolality) increases.  Osmolality receptors sense increased plasma concentration and plasma volume depletion.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. ADH System

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Sodium and Chloride Balance  Sodium  Primary ECF cation  Regulates osmotic forces  Roles Neuromuscular irritability, acid-base balance, and cellular chemical reactions and membrane transport Neuromuscular irritability, acid-base balance, and cellular chemical reactions and membrane transport

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Sodium and Chloride Balance  Chloride  Primary ECF anion  Provides electroneutrality  Levels vary inversely with those of bicarbonate

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Sodium and Chloride Regulation  Renin-angiotensin-aldosterone system: Trigger: A decrease in blood pressure and blood flow to the kidneys (or increased K+) Step 1: Renin is released by juxtaglomerular cells of the kidney Step 2: Renin is an enzyme that converts angiotensinogen to angiotensin I (in the blood)

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Renin-angiotensin system

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Sodium and Chloride Regulation Step 3: Angiotensin I is converted to angiotensin II (occurs in the lungs; requires ACE [angiotensin converting enzyme]) Step 4: Angiotensin II causes vasoconstriction and release of aldosterone by the adrenal cortex Step 5: Aldosterone causes increased sodium and water retention in the kidneys End result: An increase in blood volume and blood pressure (and decreased K + ).

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Renin-angiotensin system

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Atrial Natriuretic Hormone System  Atrial natriuretic hormone (peptide) (ANH) – has the opposite effect of aldosterone  ANH is secreted by the atria in response to increased blood volume (stretching).  Function: ANH decreases sodium retention so more sodium and water are excreted in the urine. This decreases blood volume and blood pressure.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Atrial Natriuretic Hormone System

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity Match the hormones with their descriptions. a. ADH b. aldosterone c. ANH Causes increased retention of sodium and water when blood pressure falls. Causes increased retention of sodium and water when blood pressure falls. Causes more water to be reabsorbed when the plasma becomes too concentrated. Causes more water to be reabsorbed when the plasma becomes too concentrated. Causes excretion of sodium and water when blood volume becomes too great. Causes excretion of sodium and water when blood volume becomes too great.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity - Key Match the hormones with their descriptions. a. ADH b. aldosterone c. ANH B Causes increased retention of sodium and water when blood pressure falls. B Causes increased retention of sodium and water when blood pressure falls. A Causes more water to be reabsorbed when the plasma becomes too concentrated. A Causes more water to be reabsorbed when the plasma becomes too concentrated. C Causes excretion of sodium and water when blood volume becomes too great. C Causes excretion of sodium and water when blood volume becomes too great.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Alterations in Na +, Cl –, and Water Balance  Isotonic alterations  Isotonic fluid has the same water-to- electrolyte content as normal body fluid.  An isotonic alteration is a change in total body water in which there is a proportional change in electrolytes and water.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Alterations in Na +, Cl –, and Water Balance  Isotonic fluid loss  Isotonic fluid excess

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Isotonic Alterations  Isotonic fluid loss (isotonic dehydration)  Causes – hemorrhage, mild vomiting, mild diarrhea or excessive sweating  Manifestations - weight loss, dryness of skin and mucous membranes, decreased skin turgor, decreased urine output, and symptoms of hypovolemia (rapid heart rate, flattened neck veins, and normal or decreased blood pressure, and shock).

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Isotonic Alterations  Isotonic fluid excess  Causes - excessive administration of intravenous fluids, hypersecretion of aldosterone, or drugs such as cortisone.  Manifestations – symptoms of hypervolemia including weight gain, decreased hematocrit, distended neck veins, increase in BP, and edema.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypertonic Alterations Hypertonic Alterations  Fluid is more concentrated.  Hypernatremia  Serum sodium above 147 mEq/L  Water moves from the ICF to the ECF, causing intracellular dehydration including shrinkage of brain cells; but there is excess extracellular fluid.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hyperosmotic State

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypertonic Alterations  Hypernatremia (cont.)  Causes – Excess administration of hypertonic IV solutions Excess administration of hypertonic IV solutions Oversecretion of aldosterone Oversecretion of aldosterone

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypertonic Alterations  Hypernatremia  Manifestations Increased ECF causes edema and increased blood pressure. Increased ECF causes edema and increased blood pressure. High sodium level causes muscular weakness and hyperactive reflexes. High sodium level causes muscular weakness and hyperactive reflexes. Decreased ICF causes thirst, decreased urine output, confusion, and ultimately coma. Decreased ICF causes thirst, decreased urine output, confusion, and ultimately coma.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Pure Water Deficit  Hypertonic dehydration  Loss of water alone ECF becomes more concentrated, so water moves from ICF to ECF. ECF becomes more concentrated, so water moves from ICF to ECF. Both ECF and ICF become dehydrated and hypovolemia occurs. Both ECF and ICF become dehydrated and hypovolemia occurs.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Pure Water Deficit  Causes Inability to obtain water (ex. comatose patients) Inability to obtain water (ex. comatose patients) Extended hyperventilation Extended hyperventilation Increased renal free water clearance as with decreased ADH secretion (most common cause). Increased renal free water clearance as with decreased ADH secretion (most common cause).

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Pure Water Deficit  Manifestations Decreased ECF causes a weak pulse, postural hypotension, and tachycardia, elevated hematocrit and elevated serum sodium level. Decreased ECF causes a weak pulse, postural hypotension, and tachycardia, elevated hematocrit and elevated serum sodium level. Decreased ICF causes thirst, fever, decreased urine output, shrinkage of brain cells, confusion and coma. Decreased ICF causes thirst, fever, decreased urine output, shrinkage of brain cells, confusion and coma.

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Hypotonic Alterations  Fluid is less concentrated  Hyponatremia Serum sodium level below135 mEq/L Serum sodium level below135 mEq/L Sodium deficit decreases the ECF osmotic pressure, and water moves into the cells. Sodium deficit decreases the ECF osmotic pressure, and water moves into the cells. Water movement causes symptoms related to hypovolemia and cellular swelling. Water movement causes symptoms related to hypovolemia and cellular swelling.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypoosmotic State

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypotonic Alterations Hyponatremia (cont.)  Causes – inadequate intake of Na+; hypoaldosteronism; increased loss of Na+ through diuresis, profuse sweating, or gastrointestinal losses.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypotonic Alterations Hyponatremia (cont.)  Manifestations – Increased ICF causes edema, brain cell swelling, irritability, depression, confusion, weakness, muscle cramps, anorexia, nausea, and diarrhea.  Pure sodium deficits cause hypotension, tachycardia, and decreased urine output.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Excess  Free water excess causes symptoms of hypervolemia and water intoxication  Causes – excessive administration of hypotonic intravenous solutions, drinking water to replace isotonic fluid losses, tap water enemas, psychogenic polydipsia, renal water retention, or increased antidiuretic hormone secretion.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Water Excess  Manifestations: Acute excesses cause confusion and convulsions. Acute excesses cause confusion and convulsions. Long-term water accumulation causes weakness, nausea, muscle twitching, headache, and weight gain. Long-term water accumulation causes weakness, nausea, muscle twitching, headache, and weight gain.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity

Activity - Key

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Potassium  Major intracellular cation  Concentration maintained by Na + /K + pump  Regulates intracellular electrical neutrality in relation to Na + and H +  Essential for transmission and conduction of nerve impulses, normal cardiac rhythms, and skeletal and smooth muscle contraction  Serum levels regulated by kidney excretion of potassium.

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Potassium Levels  Changes in pH affect K + balance  Hydrogen ions accumulate in the ICF during states of acidosis.  K+ shifts out to maintain a balance of cations across the membrane.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Interactions between K+ and H+

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Potassium Levels  Aldosterone and insulin influence serum potassium levels  Aldosterone – secreted in response to high K + levels; causes increased movement of K + into urine in exchange for Na +.  Insulin – stimulates cellular uptake of K +.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypokalemia  Potassium level below 3.5 mEq/L  Potassium balance is described by changes in plasma potassium levels  Causes  Reduced intake of potassium  Increased entry of potassium into body cells (as during alkalosis)  Increased loss of potassium Diarrhea Diarrhea From kidneys From kidneys

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypokalemia  Loop diuretics (like Lasix tm )  Inhibit Na + reabsorption in the loop of Henle, and so put an excess demand on the exchange of K + for Na + in the distal tubule of the nephron, thus resulting in K + loss.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Effects of Loop Diuretics Aldosterone: Na+ K+ = Stimulated

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hypokalemia  Manifestations - membrane hyperpolarization causes :  Decrease in neuromuscular excitability  Skeletal muscle weakness  Smooth muscle atony  Cardiac dysrhythmias

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hyperkalemia  Potassium level above 5.5 mEq/L  Hyperkalemia is rare because of efficient renal excretion  Caused by –  Increased intake  Shift of K + from ICF (as during acidosis)  Decreased renal excretion  Insulin deficiency  Cell trauma

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Hyperkalemia Manifestations:  Mild attacks  Increased neuromuscular irritability Tingling of lips and fingers, restlessness, intestinal cramping, and diarrhea Tingling of lips and fingers, restlessness, intestinal cramping, and diarrhea  Severe attacks  The cell is not able to repolarize, resulting in muscle weakness, loss of muscle tone, flaccid paralysis, and even cardiac arrest.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Electrocardiogram Changes with Potassium Imbalance

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity Indicate which are associated with: Hypokalemia (-) Hyperkalemia (+). Acidosis. Acidosis. Alkalosis. Alkalosis. Excess aldosterone. Excess aldosterone. Use of loop diuretics. Use of loop diuretics. Trauma to cells. Trauma to cells. Injection of insulin. Injection of insulin. Renal failure. Renal failure. Increased neuromuscular irritability. Increased neuromuscular irritability.

Elsevier items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Activity Indicate which are associated with: Hypokalemia (-) Hyperkalemia (+). + Acidosis. - Alkalosis. - Excess aldosterone. - Use of loop diuretics. + Trauma to cells. - Injection of insulin. + Renal failure. + Increased neuromuscular irritability.