Intravenous Fluids in Nursing

Intravenous (IV) Fluids

• IV fluids are used for resuscitation, replacing fluid loss, and maintaining hydration in patients unable or disallowed from drinking.
• Like medications, IV fluids have benefits and risks; careful administration is crucial to avoid fluid overload or acid-base imbalances.
• Crystalloid solutions contain small molecules readily crossing semi-permeable membranes.
• Crystalloids are categorized as isotonic, hypotonic, or hypertonic based on their relative tonicity to plasma.
• Isotonic solutions have similar dissolved particle concentration to plasma and osmolality (mOsm/L).
• Isotonic solutions are primarily used to correct fluid volume deficits, remaining within the extracellular compartment (blood vessels, interstitial spaces).

General Nursing Considerations

• Document baseline vital signs, body weight, lung and heart sounds, note edema presence. Continuous monitoring is necessary.
• Monitor for signs of hypovolemia: weak pulse, poor skin turgor, hypotension, urine output < 0.5 mL/kg/hour.
• Monitor for signs of hypervolemia: bounding pulse, hypertension, pulmonary crackles, dyspnea, peripheral edema, JVD, S3 heart sound.
• Daily serum metabolic panels are advised for patients on continuous IV fluids, monitoring sodium, potassium, glucose, and renal function.

I.V. Fluid Osmolarity/Composition

• 0.9% NaCl (Normal Saline Solution, NSS):
  • Used for resuscitation, hemorrhage, severe vomiting, diarrhea, GI drainage, fistulas, wounds, mild hyponatremia, metabolic acidosis, hypercalcemia.
  • 308 mOsm/L
  • Na+ 154 mmol/L
  • Cl- 154 mmol/L
  • Caution in cardiac or renal disease. Should only be administered with blood products.
  • Monitor for hyperchloremic acidosis with large volumes.
• Lactated Ringer's Solution (LR).
  • First-line fluid for burn and trauma patients, acute blood loss, hypovolemia, GI loss, metabolic acidosis.
  • Contraindicated for liver disease.
• 5% Dextrose in Water (D5W):
  • Isotonic/hypotonic.
  • Initially hypotonic (dilutes extracellular fluid).
  • Provides free water for kidneys.
  • Used in hypernatremia.
• Ringer's Solution:
  • Similar to LR, but without lactate.
  • Not for patients with metabolic acidosis.
• PlasmaLyte:
  • Electrolyte composition similar to plasma.
  • Less likely to cause dilutional or hyperchloremic acidosis.
• 0.33% NaCl:
  • Allows kidneys to retain water.
  • Caution in patients with heart failure or severe renal insufficiency; often administered with dextrose to increase osmolality.
• 0.45% NaCl (1/2 NS):
  • Used in hypernatremia.
  • Caution in patients with heart failure.

Additional Isotonic Solutions

• 0.45% NaCl:
  • Similar to LR but without lactate. Not for patients with metabolic acidosis.
• PlasmaLyte:
  • Electrolyte composition similar to plasma.
  • Less likely to cause electrolyte imbalances.

Hypotonic Solutions

• Hypotonic solutions have a lower concentration of dissolved particles than plasma (<250 mOsm/L).
• Fluid shifts from vascular space into cells, potentially worsening hypovolemia and hypotension.
• Generally used for intracellular dehydration (diabetic ketoacidosis).

Hypertonic Solutions

• Hypertonic solutions have a higher concentration of dissolved particles than plasma (>375 mOsm/L).
• Fluid shifts from cells into vascular space; used to treat hyponatremia and cerebral edema.
• Caution in patients with increased intracranial pressure (ICP), cardiac conditions, severe renal insufficiency.

Colloids

• Contain large molecules that remain within blood vessels. (e.g., albumin, starches)
• Expand intravascular volume through higher oncotic pressure.
• Used in situations needing rapid volume expansion (shock, significant blood loss).
• Monitor for fluid overload, edema.