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.