Fluid Balance and Electrolyte Management

Fluid Balance

• Input: Fluid intake from oral/parenteral sources, hormonal regulation
• Output: Urine, feces, sweat, insensible losses (breathing, skin)
• Balance: Input = Output; maintains blood volume, blood pressure, and tissue perfusion

Electrolyte Imbalance

• Hypokalemia (K+ < 3.5 mmol/L): muscle weakness, fatigue, cardiac arrhythmias
• Hyperkalemia (K+ > 5.5 mmol/L): cardiac arrhythmias, muscle weakness
• Hyponatremia (Na+ < 135 mmol/L): headache, nausea, seizures
• Hypernatremia (Na+ > 145 mmol/L): thirst, dry mouth, seizures
• Hypocalcemia (Ca2+ < 2.2 mmol/L): muscle cramps, twitching, tetany
• Hypercalcemia (Ca2+ > 2.6 mmol/L): muscle weakness, polyuria, kidney stones

IV Fluid Administration

• Types of IV Fluids:
  • Isotonic (280-300 mOsm/L): normal saline, lactated Ringer's
  • Hypotonic (< 280 mOsm/L): 0.45% saline, 2.5% dextrose
  • Hypertonic (> 300 mOsm/L): 3% saline, 7.5% dextrose
• Indications:
  • Dehydration
  • Hypovolemic shock
  • Electrolyte imbalance
  • Medication administration
• Contraindications:
  • Fluid overload
  • Heart failure
  • Pulmonary edema

Dehydration Assessment

• Clinical Signs:
  • Dry mucous membranes
  • Decreased skin turgor
  • Decreased urine output
  • Sunken eyes
  • Thirst
• Laboratory Tests:
  • Blood urea nitrogen (BUN) and creatinine levels
  • Urine specific gravity
  • Serum osmolality
• Dehydration Classification:
  • Mild: 3-5% fluid loss
  • Moderate: 5-10% fluid loss
  • Severe: >10% fluid loss