Fluid and Electrolytes Management Notes

Introduction to Fluid and Electrolytes Management

• Understanding body fluid composition and its importance in maintaining homeostasis.

Body Fluid Composition

• Water Content:

  • Adult: 50-60% of body weight.

  • Geriatric: 45-50% of body weight.

  • 1 liter of water = 2.2 pounds.

Key Concepts and Definitions

• Osmosis: Movement of water across a semipermeable membrane from areas of low solute concentration to high solute concentration.

• Diffusion: Movement of solutes from an area of higher concentration to lower concentration.

• Filtration: Movement of water and solutes across a membrane due to hydrostatic pressure differences.

• Active Transport: Movement of substances against their concentration gradient, requiring energy (ATP).

Hormonal Regulation of Fluids

• Antidiuretic Hormone (ADH): Regulates water retention in kidneys.

• Aldosterone: Promotes sodium retention and potassium excretion.

• Atrial Natriuretic Peptide (ANP): Helps in reducing blood volume and pressure by promoting sodium excretion.

Effects of Fluid Imbalance

• Hypovolemia: Low fluid volume leading to decreased perfusion and gas exchange, impacting cognition and mobility.

• Hypervolemia: Excess fluid causing edema and increased blood pressure.

Electrolyte Focus

Major Electrolytes

1. Cations:

   • Sodium (Na+)

   • Potassium (K+)

   • Calcium (Ca²+)

   • Magnesium (Mg²+)

2. Anions:

   • Bicarbonate (HCO3-)

   • Chloride (Cl-)

   • Phosphate (PO4³-)

Movement of Fluids

• Types of Solutions:

  • Isotonic: Equal concentration.

  • Hypotonic: Lower concentration outside the cell, causing swelling.

  • Hypertonic: Higher concentration outside the cell, causing shriveling.

• Calculating Plasma Osmolality: ext{Plasma osmolality} = (2 imes ext{Na}) + rac{ ext{BUN}}{2.8} + rac{ ext{Glucose}}{18}

  • Normal range: 280-295 mOsm/kg.

  • Over 295: Too little water.

  • Under 275: Too little solute (water excess).

Assessing Fluid Balance

• Methods:

  • Skin turgor

  • Urine output

  • Daily weight (most accurate)

  • Presence of edema

Interprofessional Care for Imbalances

• Fluid Volume Deficit (Hypovolemia):

  • Replace water and electrolytes orally or via IV fluids.

• Fluid Volume Excess (Hypervolemia):

  • Correct underlying causes and monitor lab values to adjust treatment.

Electrolyte Imbalances

Sodium Imbalance

• Hypernatremia:

  • Causes: Inadequate water intake, excess water loss.

  • Signs: Agitation, thirst, increased BP, dry tongue.

  • Treatment: IV fluids, diuretics.

• Hyponatremia:

  • Causes: Loss of sodium-rich fluids, water excess (e.g., SIADH).

  • Signs: Confusion, seizures, headache.

  • Treatment: Isotonic solutions, fluid restriction.

Calcium Imbalance

• Hypercalcemia:

  • Causes: Hyperparathyroidism, malignancy.

  • Signs: Bone pain, fractures, increased BP.

  • Treatment: Hydration, IV fluids.

• Hypocalcemia:

  • Causes: Blood transfusions, chronic alcoholism.

  • Signs: Muscle cramps, tetany, laryngeal stridor.

  • Treatment: IV calcium gluconate.

Magnesium Imbalance

• Hypermagnesemia:

  • Causes: Increased intake with renal failure.

  • Signs: Hypotension, decreased pulse.

  • Treatment: Avoid magnesium-rich drugs, increase fluid.

• Hypomagnesemia:

  • Causes: GI loss, prolonged fasting.

  • Signs: Muscle cramps, increased pulse.

  • Treatment: Oral intake and IV magnesium sulfate.

Potassium Imbalance

• Hyperkalemia:

  • Causes: Impaired renal excretion.

  • Signs: V-Fib, muscle weakness.

  • Treatment: Increase potassium elimination, IV insulin.

• Hypokalemia:

  • Causes: Loss of potassium, low magnesium levels.

  • Signs: Weak pulse, muscle weakness.

  • Treatment: IV KCL.

Phosphate Imbalance

• Hyperphosphatemia:

  • Causes: Acute kidney injury, laxative use.

  • Signs: Tetany, muscle cramps.

  • Treatment: Restrict phosphate intake, dialysis.

• Hypophosphatemia:

  • Causes: Decreased intestinal absorption.

  • Signs: Confusion, muscle weakness.

  • Treatment: Phosphate-rich diet, IV sodium phosphate.

IV Therapy Considerations

• Isotonic Solutions: e.g., 0.9% Normal Saline, Lactated Ringer's.

• Colloids: Albumin, contraindicated in heart failure.

• Blood Products: Used to improve tissue oxygenation after significant blood loss.

Conclusion

• Regular monitoring and adjustments are essential for maintaining fluid and electrolyte balance in clinical settings, based on individual patient needs and conditions.