Chapter 15 Fluid and Electrolytes: Balance and Disturbance

1. Chapter 15Fluid and Electrolytes: Balance and Disturbance

2. Fluid and Electrolyte Balance • Necessary for life and homeostasis • Nursing role is to help prevent and treat fluid and electrolyte disturbances

3. Fluid • Approximately 60% of the typical adult is fluid • Varies with age, body size, and sex • Intracellular fluid • Extracellular fluid (ECF) • Intravascular • Interstitial • Transcellular • “Third spacing”: loss of ECF into a space that does not contribute to equilibrium

4. Electrolytes • Active chemicals that carry positive (cations) and negative (anions) electrical charges • Major cations: • Major anions: • Sodium • Potassium • Calcium • Magnesium • Hydrogen ions • Electrolyte concentrations differ in the fluid compartments • Chloride • Bicarbonate • Phosphate • Sulfate • Proteinate ions

5. Electrolytes cont’d • Major cation in ECF • Sodium • Major cation in ICF • Potassium See Table 15-1

6. Regulation of Fluid • Movement of fluid through capillary walls depends on: • Hydrostatic pressure • Pressure exerted on the walls of blood vessels • Osmotic pressure • Pressure exerted by the protein in the plasma • The direction of fluid movement depends on the differences of hydrostatic and osmotic pressures

7. Regulation of Fluid cont’d • Osmosis • Diffusion • Filtration • Active transport

8. Question Which of the following is the major cation in extracellular fluid? • Calcium • Sodium • Magnesium • Potassium

9. Answer • Sodium Rationale: Sodium is the most abundant electrolyte in the ECF; its concentration normally ranges from 135 to 145 mmol/L.

10. Fluid Balance • Fluid gain • Dietary intake of fluid and food or enteral feeding • Parenteral fluids • Fluid loss • Kidney: urine output • Skin loss: sensible and insensible losses • Lungs • GI tract • Laboratory tests of fluid balance • Homeostatic mechanisms

11. Gerontologic Considerations • Reduced homeostatic mechanisms: cardiac, renal, and respiratory function • Decreased body fluid percentage • Medication use • Presence of concomitant conditions

12. Fluid Volume Imbalances • Fluid volume deficit (FVD): hypovolemia • Fluid volume excess (FVE): hypervolemia

13. Fluid Volume Deficit • Loss of extracellular fluid exceeds intake ratio of water, and electrolytes are lost in the same proportion as they exist in normal body fluids • Dehydration refers to loss of water alone with increased serum sodium level • May occur in combination with other imbalances • Causes: fluid loss from vomiting, diarrhea, GI suctioning, sweating, decreased intake, and inability to gain access to fluid • Risk factors: diabetes insipidus, adrenal insufficiency, osmotic diuresis, hemorrhage, coma, and third space shifts

14. Fluid Volume Deficit cont’d • Manifestations: rapid weight loss, decreased skin turgor, oliguria, concentrated urine, postural hypotension, rapid and weak pulse, increased temperature, cool and clammy skin caused by vasoconstriction, lassitude, thirst, nausea, muscle weakness, and cramps • Laboratory data: elevated BUN in relation to serum creatinine, increased hematocrit, and possible serum electrolyte changes • Medical management: provide fluids to meet body needs • Oral fluids • IV solutions: see Table 15-3

15. Fluid Volume Deficit—Nursing Management • Monitor intake and output (I&O) and volumetric solution (VS) • Monitor for symptoms: skin and tongue turgor, mucosa, urinary output (UO), and mental status • Initiate measures to minimize fluid loss • Provide oral care • Administer oral fluids • Administer parenteral fluids

16. Fluid Volume Excess • Caused by fluid overload or diminished homeostatic mechanisms • Risk factors: heart failure, renal failure, and cirrhosis of the liver • Contributing factors: excessive dietary sodium or sodium-containing IV solutions • Manifestations: edema; distended neck veins; abnormal lung sounds (crackles); tachycardia; increased BP, pulse pressure, and CVP; increased weight; increased UO; shortness of breath; and wheezing • Medical management is directed at the cause, restriction of fluids and sodium, and the administration of diuretics

17. Fluid Volume Excess—Nursing Management • Take I&O and daily weights; assess for lung sounds, edema, and other symptoms; monitor responses to medications such as diuretics • Promote adherence to fluid restrictions and patient teaching related to sodium and fluid restrictions • Monitor and avoid sources of excessive sodium; include medications • Promote rest • Usesemi-Fowler’s position for orthopnea • Provide skin care and positioning or turning

18. Electrolyte Imbalances • Sodium: hyponatremia and hypernatremia • Potassium: hypokalemia and hyperkalemia • Calcium: hypocalcemia and hypercalcemia • Magnesium: hypomagnesemia and hypermagnesemia • Phosphorus: hypophosphatemia and hyperphosphatemia • Chloride: hypochloremia and hyperchloremia

19. Hyponatremia • Serum sodium less than 135 mEq/L • Causes: adrenal insufficiency, water intoxication, SIADH, and losses by vomiting, diarrhea, sweating, and diuretics • Manifestations: poor skin turgor, dry mucosa, headache, decreased salivation, decreased BP, nausea, abdominal cramping, and neurologic changes

20. Hyponatremia cont’d • Medical management: water restriction and sodium replacement • Nursing management: assessment and prevention, monitoring of dietary sodium and fluid intake, identification and monitoring of at-risk patients and the effects of medications (diuretics and lithium)

21. Hypernatremia • Serum sodium greater than 145 mEq/L • Causes: excess water loss, excess sodium administration, diabetes insipidus, heat stroke, and hypertonic IV solutions • Manifestations: thirst; elevated temperature; dry, swollen tongue; sticky mucosa; neurologic symptoms; restlessness; and weakness • Thirst may be impaired in the elderly or ill

22. Hypernatremia cont’d • Medical management: hypotonic electrolyte solution or D5W • Nursing management: assessment and prevention, assess for over-the-counter (OTC) sources of sodium, offer and encourage fluids to meet patient needs, and provide sufficient water with tube feedings

23. Question Which of the following is a contributing factor of hyponatremia? • Heat stroke • Impaired renal function • SIADH • Diabetes insipidus

24. Answer • SIADH Rationale: Potential contributing factors of hyponatremia include disease states associated with SIADH such as head trauma and oat-cell lung tumour, use of diuretics, renal disease, and adrenal insufficiency.

25. Hypokalemia • Below-normal serum potassium (<3.5 mmol/L) may occur with normal potassium levels in alkalosis owing to shift of serum potassium into cells • Causes: GI losses, medications, alterations of acid–base balance, hyperaldosteronism, and poor dietary intake • Manifestations: fatigue, anorexia, nausea, vomiting, dysrhythmias, muscle weakness, cramps, paresthesias, glucose intolerance, decreased muscle strength, and deep tendon reflexes (DTRs)

26. Hypokalemia cont’d • Medical management: increased dietary potassium, potassium replacement, and IV for severe deficit • Nursing management: assessment (severe hypokalemia is life-threatening), monitoring of electrocardiogram (ECG), arterial blood gases (ABGs), and dietary potassium, and providing nursing care related to IV potassium administration

27. Hyperkalemia • Serum potassium greater than 5.0 mmol/L • Causes: usually treatment-related, impaired renal function, hypoaldosteronism, tissue trauma, and acidosis • Manifestations: cardiac changes anddysrhythmias, muscle weakness with potential respiratory impairment, paresthesias, anxiety, and GI manifestations

28. Hyperkalemia cont’d • Medical management: monitor ECG, cation exchange resin (Kayexalate), IV sodium bicarbonate, IV calcium gluconate, regular insulin and hypertonic dextrose IV, and -2 agonists; limit dietary potassium; and perform dialysis • Nursing management: assess serum potassium levels, mix well IVs containing K+, monitor medication effects, and initiate dietary potassium restriction and dietary teaching for patients at risk

29. Effect of Potassium on ECG

30. Hyperkalemia • Hemolysis of blood specimen or drawing of blood above IV site may result in false laboratory result • Salt substitutes and medications may contain potassium • Potassium-sparing diuretics may cause elevation of potassium and should not be used in patients with renal dysfunction

31. Hypocalcemia • Causes: hypoparathyroidism, malabsorption, pancreatitis, alkalosis, massive transfusion of citrated blood, renal failure, medications, other • Manifestations: tetany, circumoral numbness, paresthesias, hyperactive DTRs, Trousseau’s sign, Chovstek's sign, seizures, respiratory symptoms of dyspnea and laryngospasm, abnormal clotting, and anxiety

32. Hypocalcemia cont’d • Medical management: IV of calcium gluconate, calcium and vitamin D supplements, diet • Nursing management: assessment as severe hypocalcemia is life-threatening, weight-bearing exercises to decrease bone calcium loss, patient teaching related to diet and medications, and nursing care related to IV calcium administration

33. Trousseau’s Sign

34. Hypercalcemia • Causes: malignancy and hyperparathyroidism, bone loss related to immobility • Manifestations: muscle weakness, incoordination, anorexia, constipation, nausea and vomiting, abdominal and bone pain, polyuria, thirst, ECG changes, and dysrhythmias

35. Hypercalcemia cont’d • Medical management: treat underlying cause, administer fluids, furosemide, phosphates, calcitonin, and bisphosphonates • Nursing management: assessment as hypercalcemic crisis has high mortality, encourage ambulation, fluids of 3 to 4 L/d, provide fluids containing sodium unless contraindicated and fibre for constipation, and ensure safety

36. Question Of which electrolyte is the following true: 98% of it is found intracellularly? • Calcium • Potassium • Sodium • Magnesium

37. Answer • Potassium Rationale: Potassium is the major intracellular electrolyte. 98% of the body’s potassium is inside the cells. Potassium influences both skeletal and cardiac muscle activity.

38. Hypomagnesemia • Causes: alcoholism, GI losses, enteral or parenteral feeding deficient in magnesium, medications, rapid administration of citrated blood; contributing causes include diabetic ketoacidosis, sepsis, burns, and hypothermia • Manifestations: neuromuscular irritability, muscle weakness, tremors, athetoid movements, ECG changes and dysrhythmias, and alterations in mood and level of consciousness

39. Hypomagnesemia cont’d • Medical management: diet, oral magnesium, and magnesium sulfate IV • Nursing management: assessment, ensure safety, patient teaching related to diet, medications, alcohol use, and nursing care related to IV magnesium sulfate • Hypomagnesemia is often accompanied by hypocalcemia • Monitor and treat potential hypocalcemia • Dysphagia is common in magnesium-depleted patients; assess ability to swallow with water before administering food or medications

40. Hypermagnesemia • Causes: renal failure, diabetic ketoacidosis, and excessive administration of magnesium • Manifestations: flushing, lowered BP, nausea, vomiting, hypoactive reflexes, drowsiness, muscle weakness, depressed respirations, ECG changes, and dysrhythmias • Medical management: IV calcium gluconate, loop diuretics, IV NS or RL, hemodialysis • Nursing management: assessment, avoid administering medications containing magnesium, and provide patient teaching regarding magnesium-containing OTC medications

41. Hypophosphatemia • Causes: alcoholism, refeeding of patients after starvation, pain, heat stroke, respiratory alkalosis, hyperventilation, diabetic ketoacidosis, hepatic encephalopathy, major burns, hyperparathyroidism, low magnesium, low potassium, diarrhea, vitamin D deficiency, and diuretic and antacid use • Manifestations: neurologic symptoms, confusion, muscle weakness, tissue hypoxia, muscle and bone pain, and increased susceptibility to infection • Medical management: oral or IV phosphorus replacement • Nursing management: assessment, encourage foods high in phosphorus, and gradually introduce calories for malnourished patients receiving parenteral nutrition

42. Hyperphosphatemia • Causes: renal failure, excess phosphorus, excess vitamin D, acidosis, hypoparathyroidism, and chemotherapy • Manifestations: few symptoms, soft-tissue calcifications, symptoms occur owing to associated hypocalcemia • Medical management: treat underlying disorder; use vitamin D preparations, calcium-binding antacids, phosphate-binding gels or antacids, loop diuretics, NS IV, and dialysis • Nursing management: assessment, avoid high-phosphorus foods, and provide patient teaching related to diet, phosphate-containing substances, and signs of hypocalcemia

43. Hypochloremia • Causes: Addison’s disease, reduced chloride intake, GI loss, diabetic ketoacidosis, excessive sweating, fever, burns, medications, and metabolic alkalosis • Loss of chloride occurs with loss of other electrolytes, potassium, and sodium • Manifestations: agitation, irritability, weakness, hyperexcitability of muscles, dysrhythmias, seizures, and coma

44. Hypochloremia cont’d • Medical management: replace chloride—IV NS or 0.45% NS • Nursing management: assessment, avoid free water, encourage high-chloride foods, and provide patient teaching related to high-chloride foods • Causes: excess sodium chloride infusions with water loss, head injury, hypernatremia, dehydration, severe diarrhea, respiratory alkalosis, metabolic acidosis, hyperparathyroidism, and medications

45. Hyperchloremia • Manifestations: tachypnea, lethargy, weakness, rapid, deep respirations, hypertension, and cognitive changes • Normal serum anion gap • Medical management: restore electrolyte and fluid balance, LR, sodium bicarbonate, and diuretics • Nursing management: assessment, provide patient teaching related to diet and hydration

46. Maintaining Acid–Base Balance • Normal plasma pH is 7.35 to 7.45: hydrogen ion concentration • Major extracellular fluid buffer system; bicarbonate-carbonic acid buffer system • Kidneys regulate bicarbonate in ECF • Lungs under the control of the medulla regulate CO2 and, therefore, carbonic acid in ECF • Other buffer systems • ECF: inorganic phosphates and plasma proteins • ICF: proteins, organic and inorganic phosphates • Hemoglobin

47. Metabolic Acidosis • Low pH <7.35 • Low bicarbonate <22 mEq/L • Most commonly caused by renal failure • Manifestations: headache, confusion, drowsiness, increased respiratory rate and depth, decreased blood pressure, decreased cardiac output, dysrhythmias, shock; if decrease is slow, patient may be asymptomatic until bicarbonate is 15 mEq/L or less • Correct the underlying problem and correct the imbalance; bicarbonate may be administered

48. Metabolic Acidosis cont’d • With acidosis, hyperkalemia may occur as potassium shifts out of the cell • As acidosis is corrected, potassium shifts back into the cell and potassium levels decrease • Monitor potassium levels • Serum calcium levels may be low with chronic metabolic acidosis and must be corrected before treating the acidosis

49. Metabolic Alkalosis • High pH >7.45 • High bicarbonate >26 mEq/L • Most commonly caused by vomiting or gastric suction; may also be caused by medications, especially long-term diuretic use • Hypokalemia will produce alkalosis • Manifestations: symptoms related to decreased calcium, respiratory depression, tachycardia, and symptoms of hypokalemia • Correct underlying disorder, supply chloride to allow excretion of excess bicarbonate, and restore fluid volume with sodium chloride solutions

50. Respiratory Acidosis • Low pH <7.35 • PaCO2 >42 mm Hg • Always caused by a respiratory problem with inadequate excretion of CO2 • With chronic respiratory acidosis, the body may compensate and may be asymptomatic; symptoms may include a suddenly increased pulse, respiratory rate, and BP; mental changes; feeling of fullness in the head • Potential increased intracranial pressure • Treatment is aimed at improving ventilation