Disrupted Homeostasis: Fluid and Electrolytes

Disrupted Homeostasis (Fluid and Electrolytes)

• This chapter focuses on disruptions in fluid and electrolyte balance.

Body Fluid Compartments

• Extracellular fluid (outside cells):
  • Plasma (5% of body weight), also called intravascular fluid
  • Interstitial fluid (15% of body weight), located between cells
  • Total extracellular fluid accounts for 60% of body weight
• Intracellular fluid (inside cells):
  • Accounts for 40% of body weight
  • Represents 2/3 of total body fluid

Fluid Regulation

• Osmolality (serum concentration of solutes):

  • Indicates water balance
  • Normal range is <275 mOsm/kg for water excess, ~275 mOsm/kg for balance
  • Higher values indicate greater water-pulling power.

• Regulation mechanisms:

  • Thirst: triggered by increased serum osmolality or decreased blood volume
  • Kidneys: Renin-Angiotensin-Aldosterone System (RAAS) and Antidiuretic Hormone (ADH) to regulate water and sodium reabsorption.

Fluid Volume Deficit

• Causes:

  • Vomiting and diarrhea
  • GI suctioning and intestinal fistulas
  • Diuretics
  • Renal disorders
  • Endocrine disorders
  • Burns
  • Hemorrhage
  • Hot environments

• Manifestations:

  • Weight loss
  • Thirst
  • Concentrated urine
  • Low urine volume
  • Dry skin and diminished skin turgor
  • Sunken eyeballs
  • Sunken or depressed fontanels
  • Hypotension
  • Decreased cardiac output
  • Tachypnea (rapid breathing)
  • Low-grade fever
  • Mental status changes.

Fluid Volume Excess

• Causes:

  • Heart or renal failure
  • Cirrhosis
  • Adrenal gland disorders
  • Corticosteroids
  • Stress conditions
  • Excessive sodium intake
  • Medications (side effects)
  • Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

• Manifestations:

  • Peripheral edema
  • High CVP (central venous pressure)
  • Pulmonary edema
  • Acute rapid weight gain
  • Altered urine output/concentration
  • Distended neck veins
  • Crackles
  • Tachycardia
  • Shortness of breath
  • Wheezing

Types of IV Fluids

• Isotonic: (e.g. 0.9% NaCl, Lactated Ringers (LR))
  • Fluid does not shift between compartments – “fills the tank evenly”.
• Hypotonic: (e.g. 0.45% NaCl)
  • Moves fluid from intravascular and interstitial spaces into cells
• Hypertonic: (e.g. D5NS, D5LR, D10, D50, 3% and 5% NaCl, albumin)
  • Moves fluid from cells to intravascular space

Sodium Disorders

• Hyponatremia (Na+ < 135 mEq/L):

  • Causes: Water gain or sodium loss
  • Manifestations: Osmolality changes, muscle cramps, weakness, HA, irritability, neurological changes, seizures, N/V, hypotension, shock
  • Medical Interventions: Fluid replacement, sodium replacement (hypertonic solutions), treat underlying cause
  • Nursing Interventions: Monitoring sodium levels, safety precautions (confusion), administering hypertonic solutions, monitoring neurological status, monitor pulmonary edema, monitor urine output.

• Hypernatremia (Na+ > 145 mEq/L):

  • Causes: Excess water loss, diabetes insipidus, osmotic diuretic, excess sodium intake
  • Manifestations: Dry, swollen tongue, sticky mucosa, oliguria, lightheadedness, weakness, seizures, coma, irritability, altered LOC
  • Medical Interventions: Labs, sodium, osmolality, oral rehydration, hypotonic solution
  • Nursing Interventions: Assess mental/neuro status, encourage fluids, H2O via tube feeding, administer hypotonic fluids slowly, sodium restriction, teach about low sodium foods.

Potassium Disorders

• Hypokalemia (K+ < 3.5 mEq/L)

  • Causes: GI loss, medications, metabolic alkalosis, sweating
  • Manifestations: Muscle weakness, nausea, vomiting, abdominal distension, muscle cramps, impaired renal function, constipation, ECG changes.
  • Medical Interventions: Potassium replacement (IV or PO), higher acuity setting for IV potassium replacement, eliminate cause
  • Nursing Interventions: Cardiac monitoring, Analyze ABGs, Potassium replacement therapy, monitor IV site, monitor kidney function

• Hyperkalemia (K+ > 5.3 mEq/L)

  • Causes: Metabolic acidosis, potassium-sparing diuretics, type I diabetes
  • Manifestations: ECG changes, chest pain, palpitations, muscle weakness, muscle cramping, diarrhea, anxiety or jitters, paresthesia, GI manifestations
  • Medical Interventions: Serial serum potassium, Kayexalate/diuretics, calcium gluconate, limit potassium, IV dextrose+insulin, dialysis
  • Nursing Interventions: Monitor ECGs, monitoring medications, educating on foods high in potassium

Magnesium Disorders

• Hypomagnesemia (Mg < 1.8 mg/dL):

  • Causes: Alcoholism, decreased absorption, medications
  • Manifestations: Neurological excitability, Chvostek’s sign, Trousseau’s sign, seizures, hypertension, tachycardia, dysrhythmias, personality changes
  • Medical Interventions: MgSO4 IV, oral magnesium, diet (increase magnesium intake)
  • Nursing Interventions: Assessment of neuro, respiratory, cardiovascular status, monitor labs, ensure patient safety, IV site care, patient education

• Hypermagnesemia (Mg > 3.0 mg/dL):

  • Causes: Excessive use of laxatives/antacids, renal failure, decreased renal function.
  • Manifestations: Lethargy, drowsiness, confusion, dizziness, decreased DTRs and decreased respiration, dysrhythmias
  • Medical Interventions: IV Calcium chloride, IV calcium gluconate, loop diuretics, isotonic fluids, hemodialysis
  • Nursing Interventions: Assessment of DTRs, respiratory rate, patient safety, teaching foods/medications high in magnesium

Calcium Disorders

• Hypocalcemia (Ca < 9 mg/dL):

  • Causes: Hypoparathyroidism, osteoporosis, kidney failure, bariatric surgery, malabsorption
  • Manifestations: Tetany, Seizures, circumoral numbness, muscle spasms, Chvostek’s sign, Trousseau’s sign, increased DTRs, dysrhythmias
  • Medical Interventions: IV calcium chloride, calcium gluconate, oral calcium/vitamin D, Calcium level labs, magnesium, phosphorus, vitamin D
  • Nursing Interventions: Assessment, medication administration, patient education (weight-bearing exercises, foods high in calcium).

• Hypercalcemia (Ca > 11 mg/dL):

  • Causes: Hyperparathyroidism, malignancies, lack of weight bearing, immobilization, renal failure, excess vitamin D, medications, hypophosphatemia.
  • Manifestations: Muscle weakness, fatigue, GI manifestations, decreased muscle tone, dysrhythmias, bone pain, kidney stones, depression
  • Medical Interventions: Phosphates, biphosphates, calcitonin, labs (ionized calcium), Isotonic solution, check current meds
  • Nursing Interventions: Assessment, encourage ambulation, increased fluids/UO monitoring, teaching about fiber, dietary limitations

Other Important Information

• Chest X-ray: Used to assess for pulmonary congestion and treatment effectiveness (daily comparisons).
• Other tests: Echocardiogram, ECG, CBC, electrolytes, LFT, ABGs.
• Assessment: Vital signs (VS), especially peripheral pulse, peripheral volume, CVP, and signs/symptoms; hydration status; mental status, and overall care to identify fluctuations, hydration status, and fluid imbalances