FE-SDCA-HANDOUTS

Fluid and Electrolytes Overview

  • Comprises approximately 60% of body weight.

  • Electrolytes facilitate fluid movement across compartments.

    • Major Electrolytes:

      • Intracellular Fluid (ICF): Potassium (K), Phosphorus (P)

      • Extracellular Fluid (ECF): Sodium (Na), Chloride (Cl)

Key Concepts

  • Diffusion: Movement of solute from high to low concentration.

  • Osmosis: Movement of solvent from low to high concentration.

  • Homeostasis: Balance of fluid in the body.

  • Fluid Balance by Demographics:

    • Males: 60% fluid

    • Females: 50% fluid

    • Infants: 80% fluid

    • Elderly: Less muscle mass results in lower fluid percentage.

Laboratory Tests for Fluid Imbalance

  • Urine Specific Gravity: 1.010-1.030

  • Hematocrit:

    • Males: 39-49%

    • Females: 35-45%

  • Serum Osmolality: 275-295 mOsm/kg

  • Urine Osmolality: 50-1200 mOsm/kg

Common Electrolytes and Their Functions

  • Potassium (3.5-5.3 mEq/L): Regulates heart and muscle function.

  • Sodium (135-145 mEq/L): Maintains fluid balance.

  • Chloride (98-108 mEq/L): Maintains fluid balance.

  • Magnesium (1.5-2.5 mEq/L): Muscle and nerve function.

  • Calcium (4.5-5.5 mEq/L): Bone health, blood, and muscle functions.

  • Phosphate (1.7-2.6 mEq/L): Bone and teeth formation.

Hypokalemia (Low Potassium)

  • Causes: Potassium excretion, diarrhea, diuretics, low-K diet.

  • Cardiac Manifestations:

    • Flat T waves, ST depression, U wave, higher risk of atrial fibrillation.

  • Symptoms: Fatigue, palpitations, muscle weakness, nausea.

  • Management: Potassium never given by IV push, always diluted and infused.

Hyperkalemia (High Potassium)

  • Causes: Renal failure, increased potassium intake, potassium-sparing diuretics.

  • Symptoms: Peaked T waves, bradycardia, gastrointestinal disturbances.

  • Management: Monitor EKG, discontinue potassium, use potassium-excreting diuretics.

Sodium Imbalances

  • Hypernatremia: Excessive water loss, signs include dry skin, irritability.

    • Management: Administer IV fluids, restrict sodium.

  • Hyponatremia: Excess water retention; symptoms include headache, confusion.

    • Management: Administer NaCl, increase sodium intake.

Magnesium Imbalance

  • Hypermagnesemia: Causes include renal failure; symptoms include decreased DTR.

  • Hypomagnesemia: Symptoms include muscle weakness; management via magnesium sulfate.

Calcium Imbalances

  • Hypocalcemia: Causes include hypoparathyroidism; symptoms include muscle spasms.

    • Management: Calcium supplements.

  • Hypercalcemia: Causes include hyperparathyroidism; symptoms include constipation and lethargy.

    • Management: Increase fluid intake, limit calcium.

Phosphate Imbalance

  • Common Causes of Hypophosphatemia: Malnutrition, malabsorption syndromes.

  • Common Causes of Hyperphosphatemia: Renal insufficiency, hypoparathyroidism.

Dehydration

  • More severe in young clients; body water decreases with age.

IV Fluid Types

  • Isotonic Solutions: Same osmolarity as blood.

    • Examples: 0.9% sodium chloride, lactated Ringer's.

  • Hypertonic Solutions: Higher solute concentration; used for hyponatremia.

    • Examples: 3% saline, D10W.

  • Hypotonic Solutions: Lower solute concentration; used for hypernatremia.

    • Examples: 0.45% Saline, 5% Dextrose in water.

Important Concepts

  • Monitor urine output before potassium administration; assess for fluid overload in patients with CHF or renal failure.

  • SODIUM BICARBONATE neutralizes gastric acids and should not be taken with milk.