A/B & F/E Lecture 4

Fluid Replacement Agents

  • Purpose: Address fluid balance and acid-base disorders through IV solutions.
Classifications of IV Solutions:

  1. Crystalloids

    • Contain electrolytes, mimicking extracellular fluid.
    • No proteins; used for fluid replacement and urine output promotion.
    • Types: Isotonic, hypertonic, hypotonic.

  2. Colloids

    • Plasma expanders (proteins/starches), remain in circulation longer.
    • Increase plasma osmolarity, draw water into plasma.
    • Used for hypovolemic shock (burns, hemorrhage, surgery).
    • Example: Dextran; side effects include fluid overload and hypertension.

  3. Blood and Blood Products

    • Packed Red Blood Cells (PRBC), plasma, platelets, albumin.
    • Special administration protocols (19 gauge or larger IV, specific tubing, max transfusion time 4 hours).
Types of Crystalloids:

  • Isotonic Solutions

    • Expands intravascular volume without fluid shift; osmolarity 280-300.
    • Used for fluid loss from vomiting/diarrhea, surgery; examples:
    • Lactated Ringers
    • Normal Saline
    • D5W (Dextrose 5% in water).
    • Caution: Cardiac/renal patients at risk for fluid volume excess.

  • Hypertonic Solutions

    • Draw water out of cells (cell shrinkage); osmolarity > 300.
    • Treats cellular edema (e.g., cerebral edema); example: D5 half normal saline.

  • Hypotonic Solutions

    • Causes cells to swell; osmolarity < 280.
    • Moves water into cells; treats hypernatremia/dehydration; example: Half normal saline.
    • Effect on Blood Pressure: May cause hypotension.

Electrolyte Replacement

  • Potassium Chloride:

    • Prevents/treats hypokalemia; forms: tablets, liquids, IV.
    • Administer slowly IV (5-10 mEq/hr max); monitor heart function, avoid infiltration.
    • Side effects: nausea, vomiting, hyperkalemia signs.

  • Sodium Chloride:

    • Treats hyponatremia; forms: tablets, IV.
    • Risks: hypernatremia (signs: lethargy, confusion).

  • Calcium Gluconate:

    • For hypocalcemia; forms: IV, oral.
    • Administer with meals for better absorption; side effects: hypercalcemia.

  • Magnesium:

    • Treats hypomagnesemia; forms: IV, oral.
    • Monitor cardiac function; side effects: hypermagnesemia signs.

Acid-Base Correction

  • Sodium Bicarbonate:

    • Treats metabolic acidosis (base); IV/oral forms.
    • No mixing with calcium products; risk of metabolic alkalosis from over-administration.

  • Ammonium Chloride:

    • For metabolic alkalosis; administered slowly to avoid acidosis.

  • Ion Exchange Resin (K-exelate):

    • Treats hyperkalemia (removes excess potassium); mainly given as an enema.
    • Side effects: gastric irritation, nausea, hypokalemia.

Nursing Considerations

  • Assessment: Health history, medication review, physical exam (weight), lab tests.
  • Monitoring: Vital signs, fluid volume status, neurological status, urinary output, hypersensitivity reactions.
  • Administration: Follow protocols for IV fluids, monitor sites for infiltration/extravasation.