1/3/2008. Karen Burke Priscilla LeMone Elaine Mohn-Brown. Medical-Surgical Nursing Care, 2e Karen Burke, Priscilla LeMone, and Elaine Mohn-Brown

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1 Medical-Surgical Nursing Care Second Edition Karen Burke Priscilla LeMone Elaine Mohn-Brown Chapter 7 Caring for Clients with Altered Fluid, Electrolyte, or Acid-Base Balance Water Primary component of body fluids Transports nutrients and oxygen to cells and waste products from cells Provides medium for metabolic reactions within cells Insulates and helps regulate and maintain body temperature Water Provides for body structure and acts as shock absorber Is a lubricant To maintain fluid balance, intake should equal output 2500 ml/day 1

2 Electrolytes Substances that dissociate in solution to form ions Cations are positively charged; anions are negatively charged Help regulate water and acid base balance Contribute to enzyme reactions Essential to neuromuscular activity TABLE 7-1 Normal Laboratory Values for Electrolytes, Osmolality, and Urine Specific Gravity. Body Fluid Distribution 2

3 Body Fluid Movement Osmosis Osmolality concentration of solutes Osmotic pressure power power of a solution Tonicity effect of osmotic pressure of a solution on cell within a solution Diffusion Body Fluid Movement Body Fluid Movement Filtration Active transport 3

4 Body Fluid Regulation Thirst Regulator of water intake Kidneys Regulator of fluid volume and electrolyte balance Renin angiotensin aldosterone aldosterone system Maintains intravascular fluid balance and blood pressure Body Fluid Regulation Antidiuretic hormone (ADH) Regulates water excretion from the kidneys Diabetes insipidus ADH is not produced Syndrome of inappropriate ADH secretion Excess ADH is produced Body Fluid Regulation Atrial natriuretic factor (ANF) Hormone released by cells in atria of heart in response to fluid overload Inhibits renin secretion and blocks secretion and effects of aldosterone Promotes sodium and water loss and causes blood vessels to dilate 4

5 Fluid Volume Deficit Excessive fluid losses Insufficient fluid intake Results in hypovolemia BOX 7-1 Focus on Older Adults: Fluid Volume deficit in Older Adults. Fluid Volume Deficit Decrease in extracellular fluids Loss of water and electrolytes Interstitial fluid shifts into vascular space to maintain blood volume Third spacing Shift of fluid from vascular space into soft tissue or potential space, such as intraabdominal 5

6 Fluid Volume Excess Fluid Volume Excess Characterized by excess sodium that leads to water retention Results in hypervolemia and interstitial edema TABLE 7-2 Fluid Imbalances. Sodium Most plentiful electrolyte in extracellular fluid Serum sodium range 135 to 145 meq/l Regulates extracellular volume and distribution Contributes to neuromuscular activity and acid base balance Affects osmolality of extracellular fluid Kidneys work with the renin angiotensin aldosterone aldosterone system and atrial natriuretic factor to retain or excrete sodium 6

7 Potassium Serum potassium range 3.5 to 5 meq/l Regulates the transmission of nerve impulses and the normal contractility of smooth, skeletal, and cardiac muscle Imbalance can result in fatal dysrhythmias Calcium One of most abundant ions in body, mostly in bones and teeth with small amount in extracellular fluid Serum calcium range 8.5 to 10 mg/dl Calcium Regulation Parathyroid hormone Mobilizes calcium from bones Increases calcium absorption in intestines Promotes calcium reabsorption by the kidneys Cli Calcitriol il Assists parathyroid hormone processes Calcitonin Inhibits movement of calcium out of bone Reduces intestinal absorption of calcium Promotes urinary calcium excretion 7

8 Magnesium Found mostly in bones with some in the intracellular and extracellular fluid Serum magnesium range 1.3 to 2.1 meq/l or 1.6 to 2.6 mg/dl Extracellular magnesium affects neuromuscular irritability and contractility The kidneys control conservation or excretion of magnesium Phosphorus Found in all body tissues Primary anion in intracellular fluid with very small amount in extracellular fluid Serum phosphorus range 2.5 to 4.5 mg/dl Important for energy (ATP) production, metabolism, and red blood cell function Phosphate, ionized form of phosphorus, is responsible for its effects Phosphorus Imbalances An inverse relationship exists between phosphorus and calcium When one increases, the other decreases 8

9 Laboratory Tests (Fluid Balance, Sodium, and Potassium) Serum electrolytes Serum osmolality Hematocrit and hemoglobin Urine specific gravity and osmolality Liver and kidney function tests for fluid volume excess 24-hour urine specimen to evaluate sodium excretion Arterial blood gases Serum glucose Laboratory Tests (Calcium, Phosphorus, and Magnesium) Total serum calcium Serum magnesium Serum phosphate Serum parathyroid hormone Diagnostic Studies and Invasive Monitoring Central venous pressure (CVP) Electrocardiogram 9

10 Laboratory/Diagnostic Studies Acid-Base Imbalances Arterial blood gas studies Serum electrolytes Serum creatinine and BUN Electrocardiogram TABLE 7-12 Normal Arterial Blood Gas Values. Hyponatremia Loss of sodium or water gain that dilutes extracellular fluid Serum sodium < 135 meq/l Affects functioning of voluntary and involuntary muscles Brain cells swell Leading to neurologic manifestations and possible brain damage 10

11 Hypernatremia Gain of sodium in excess of water or loss of water in excess of sodium Serum sodium > 145 meq/l Dehydration of brain cells Leads to neurologic manifestations and dry, sticky mucous membranes TABLE 7-5 Sodium Imbalances. Hypokalemia Excess potassium loss or insufficient intake Serum potassium level < 3.5 meq/l Loss through the kidneys Loss through the gastrointestinal tract Shift into the intracellular space as result of: Alkalosis Rapid tissue repair High insulin levels 11

12 Hypokalemia Affects transmission of nerve impulses Affects normal contractility of smooth, skeletal, and cardiac muscle Results in cardiac dysrhythmias Hyperkalemia Abnormally high serum potassium Serum potassium > 5 meq/l Inadequate potassium excretion Excessive potassium intake Shift of potassium from intracellular to extracellular fluid Hyperkalemia Alters neuromuscular function Results in decreased cardiac contractility Weakness of skeletal muscles Gastrointestinal symptoms 12

13 TABLE 7-6 Potassium Imbalances. Hypocalcemia Serum calcium < 8.5 mg/dl At risk: Removal of parathyroid glands Older adults (especially women) Alcoholics Insufficient ionized calcium in the extracellular fluid causes neuromuscular excitability or tetany Critically low levels can cause respiratory or cardiac arrest or convulsions Hypercalcemia Serum calcium > 10.0 mg/dl High calcium levels due to: Increased calcium release (resorption) from bones Increased calcium intake Decreased renal excretion of calcium 13

14 Hypercalcemia Increased resorption of calcium from bones may result from: Hyperparathyroidism and excess hormone secretion Prolonged immobilization Malignancies (lung, breast, multiple myeloma) Impaired renal excretion of calcium Hypercalcemia Sedative effect on neuromuscular transmission Behavior is disturbed with excess calcium in cerebrospinal fluid Kidney stones occur from excess calcium in urine Critically high levels cause heart block and cardiac arrest TABLE 7-8 Calcium Imbalances. 14

15 Hypomagnesemia Serum magnesium < 1.3 meq/l or 1.6 mg/dl Total body deficit of magnesium Increases neuromuscular excitability Affects electrical conduction of the heart and the central nervous system Affects potassium and calcium metabolism Common in chronic alcoholism Hypermagnesemia Serum magnesium > 2.1 meq/l or 2.6 mg/dl Renal insufficiency or failure Excessive intake of magnesium-containing antacids or laxatives Magnesium treatments in complications of pregnancy Elevated levels interfere with neuromuscular transmission and depress the central nervous system Affects cardiovascular and respiratory functioning TABLE 7-10 Magnesium Imbalances. 15

16 Hypophosphatemia Serum phosphate < 2.5 mg/dl Decreased absorption of phosphate from gastrointestinal tract Increased excretion by the kidneys Depletion of cellular energy resources Tissue hypoxia due to decreased ability of red blood cells to transport oxygen Alcoholism can cause severe hypophosphatemia Hyperphosphatemia Serum phosphate > 4.5 mg/dl Acute or chronic renal failure Impaired renal excretion Increased phosphate intake or absorption Phosphate is released into extracellular fluid when cells are damaged or destroyed, resulting in excess serum levels TABLE 7-11 Phosphorus Imbalances. 16

17 Acid-Base Regulation Acids are produced by metabolic processes in the body Volatile acids (carbonic acid) can be eliminated as gas Nonvolatile acids (i.e., lactic acid, hydrochloric acid) must be metabolized or excreted from the body in fluid Buffer System Prevents changes in ph by attaching to or releasing hydrogen ions Major buffer systems are: Bicarbonate-carbonic carbonic acid buffer system Phosphate buffer system Protein buffers Hemoglobin acts as a buffer in red blood cells Buffer System Normal serum bicarbonate level: 24 meq/l Normal carbonic acid serum level: 1.2 meq/l Bicarbonate-to-carbonic acid ratio of 20:1 maintains a ph of 7.35 to

18 Respiratory System Regulates carbonic acid by eliminating or retaining carbon dioxide Increase in carbon dioxide or hydrogen ions stimulates respiratory center in brain to increase rate and depth of respirations Eliminates carbon dioxide, carbonic acid levels fall, and ph becomes normal Respiratory System Alkalosis depresses the respiratory center Causes rate and depth of respirations to decrease Carbon dioxide is retained Retained carbon dioxide combines with water Carbonic acid levels and ph return to normal Renal System Regulates bicarbonate levels in extracellular fluid to excrete or retain hydrogen ions Excessive hydrogen ions cause ph to fall Kidneys excrete hydrogen ions and retain bicarbonate Excessive bicarbonate levels cause the kidneys to retain hydrogen ions and excrete bicarbonate to restore acid base balance 18

19 Acid-Base Imbalances Acidosis Hydrogen ion concentration increases above normal ph falls below 7.35 Alkalosis Hydrogen ion concentration decreases below normal ph rises above 7.45 Acidosis Metabolic acidosis Bicarbonate is decreased ph < 7.35, bicarbonate < 22 meq/l, PaCO 2 < 35 mm Hg Respiratory acidosis Carbon dioxide is retained Increases carbonic acid Metabolic alkalosis Excessive bicarbonate Respiratory alkalosis Carbon dioxide decreases Carbonic acid decreases Alkalosis 19

20 Acid-Base Disorders Primary or simple disorders One cause respiratory or metabolic Compensated by amount of change in ph Kidneys alter bicarbonate and hydrogen Lungs change rate and depth of respirations Mixed disorders Metabolic and respiratory imbalances are present BOX 7-15 Nursing Care Checklist: Interpreting Arterial Blood Gases. Fluid Volume Deficit Priority of care is restoring blood and fluid volume Teach ways to prevent fluid volume deficit: recommended fluid intake, avoid overexposure to heat and exercise, and monitor weight Replace fluid and electrolytes enterally or intravenously 20

21 TABLE 7-3 Commonly Administered Intravenous Fluids. Fluid Volume Excess Sodium-restricted diet Fluid Volume Excess Restricted fluid intake 21

22 Medications Diuretics Fluid Volume Excess BOX 7-10 Assessment: Assessing for Fluid Volume Excess. Fluid Volume Excess Priorities of care: Decrease excess fluid volume and hypervolemia Teach fluid and sodium restrictions and medication administration 22

23 Hyponatremia Intake of foods high in sodium Restrict oral fluids Administer sodium-containing intravenous fluids Medications Administer loop diuretic and sodium replacement to remove excess water Priority of care is to increase sodium intake or decrease excess water Hyponatremia Teach importance of drinking liquids containing sodium and other electrolytes: When perspiring heavily In hot environment When experiencing prolonged watery diarrhea Hypernatremia Correct water deficit Medications Administer diuretics to increase sodium excretion Prescribe low-sodium diet Priorities of care are to decrease sodium intake and increase water intake Teach low-sodium diet and sufficient water intake 23

24 Hypokalemia Potassium replacement orally or intravenously Increased intake of foods high in potassium Hypokalemia Priorities of care are early identification and monitoring of cardiac status Teach high-potassium diet, administering potassium supplements, and regular follow-up assessment Hyperkalemia Medications Administer loop diuretics, sodium polystyrene sulfonate (Kayexalate) Administer intravenous insulin, glucose, sodium bicarbonate, and calcium gluconate Administer hemodialysis or peritoneal dialysis Priorities of care are early detection and monitoring of cardiac status Teach administration of medications, low-potassium diet, obtaining regular laboratory tests, and follow-up care 24

25 Hypocalcemia Medications Administer oral calcium replacements and vitamin D Administer intravenous calcium chloride, calcium gluconate, or calcium gluceptate via slow IV push or infusion i Hypocalcemia Increase dietary intake of calcium Priority of care is to replace deficient calcium to prevent dysrhythmias and seizures. Teach dietary intake of calcium foods and vitamin D, administration of medications, and follow-up care Hypercalcemia Medications Administer intravenous normal saline solution Administer diuretics Administer biphosphonates, calcitonin, intravenous plicamycin, glucocorticoids 25

26 Hypercalcemia Decrease dietary intake of calcium Hypercalcemia Priorities of care Monitor mental status Monitor respiratory and cardiac status Protect against injury due to falls from muscular weakness and fatigue Decrease incidence of kidney stones Teach administration of medications, decreased dietary intake of calcium, increased dietary intake of fiber, and encourage weight-bearing activities Hypomagnesemia Medications Administer oral magnesium supplements, such as antacids Administer magnesium via IV or deep intramuscular injection 26

27 Hypomagnesemia Increase dietary intake of foods high in magnesium Hypomagnesemia Priorities of care Monitor deep tendon reflexes and serum magnesium levels Teach administration of magnesium supplements, dietary intake of magnesium foods, and referrals for alcohol problems Hypermagnesemia Medications Withhold all medications and solutions containing magnesium Administer IV calcium to counteract cardiac effects Perform hemodialysis or peritoneal dialysis if renal failure Mechanical ventilation 27

28 Hypermagnesemia Priorities of care Monitor cardiac and respiratory status Monitor changes in neuromuscular excitability Monitor gastrointestinal function Teach to avoid magnesium-containing medications and to decrease dietary intake of magnesium foods Hypophosphatemia Increase phosphorus in the diet, especially milk and milk products Medications Administer oral phosphorus p supplements Administer intravenous phosphate solutions Priorities of care Monitor for signs of phosphate imbalance and serum phosphate levels Protect from infection Hypophosphatemia Teach administration of medications, dietary intake of phosphorus, effects of phosphorus-binding antacids, referrals for alcohol use 28

29 Hyperphosphatemia Decrease phosphorus in the diet Medications Administer aluminum hydroxide (Amphogel) Administer IV normal saline Administer glucose and insulin to drive phosphate into cells Perform dialysis Hyperphosphatemia Priorities of care Monitor and report signs of phosphate imbalance Monitor phosphate levels Teach to recognize signs of imbalance, avoid phosphate-containing laxatives and enemas, avoid dietary intake of phosphorus, and to take medications as ordered Metabolic Acidosis 29

30 Metabolic Acidosis Insufficient oxygen leads to lactic acidosis Affects the central nervous system, gastrointestinal tract, cardiovascular function Kussmaul s s respirations Priorities of care are to treat the underlying cause and monitor cardiac and neurologic functioning Medications Administer bicarbonate, lactate, acetate, or citrate solutions Metabolic Acidosis Teach proper diabetes mellitus care to prevent ketoacidosis Obtain treatment for alcoholism with proper diet and medications Manage renal failure with diet and dialysis Prevent or treat diarrhea Metabolic Alkalosis 30

31 Metabolic Alkalosis Loss of acid or excess bicarbonate in the body Respiratory system attempts to return ph to normal by slowing respiratory rate Priorities of care Treat underlying cause Restore normal fluid volume Monitor respirations Metabolic Alkalosis Medications Administer potassium chloride and sodium chloride solutions Administer dilute hydrochloric acid or ammonium chloride for critically i high h ph Teach how to prevent and manage acute gastroenteritis or vomiting, the advantages of a potassium-rich diet or potassium supplements, and to avoid use of antacids Respiratory Acidosis 31

32 Respiratory Acidosis Excess of dissolved carbon dioxide or carbonic acid Alveolar hypoventilation leads to carbon dioxide retention Kidneys compensate by retaining bicarbonate Priorities of care Administer oxygen Clear the airways Support ventilation Provide adequate hydration Respiratory Acidosis Medications Administer bronchodilator medications Administer antibiotics Administer medications to reverse narcotic and anesthetic effects Teach to avoid respiratory infections, to immunize against pneumococcal pneumonia and influenza, and to obtain treatment for narcotic or drug abuse Respiratory Alkalosis 32

33 Respiratory Alkalosis Hyperventilation leads to carbon dioxide deficit Low carbon dioxide levels cause cerebral blood vessels to constrict Causes decrease in calcium ionization Priorities of care Breathe slowly into a paper bag or rebreather mask to prevent excess loss of carbon dioxide Respiratory Alkalosis Medications Administer a sedative or antianxiety medication Teach to decrease anxiety, to seek counseling, and to identify hyperventilation and how to treat it 33