I.V Fuid therapy

The goals of (IV) therapy

1. Maintain or replace body stores of water, electrolytes, vitamins, proteins, fats, and calories in the patient who cannot maintain an adequate intake by mouth.
2-Restore acid–base balance.
3-Restore volume of blood components.
4-Provide avenues for the administration of medications.
5-Monitor central venous pressure (CVP).
6-Provide nutrition while resting the gastrointestinal tract.

Principles

1. Tissue cells (e.g., erythrocytes, neurons) are surrounded by a semipermeable membrane.
2. Osmotic pressure is the “pulling” pressure demonstrated when water moves through the semipermeable membrane of tissue cells from an area of weaker concentration to stronger concentration of solute (e.g., sodium ions, blood glucose). The end result is dilution and equilibration between the intracellular and extracellular compartments.
3. Extracellular compartment fluids primarily include plasma and interstitial fluid.

Types of Fluids

1. Isotonic—a solution that exerts the same osmotic pressure as that found in plasma.
a. Normal saline 0.9%
b. Lactated Ringer’s
c. Blood components
(1) Albumin 5%
(2) Plasma
d. 5% dextrose in water (D5W)

2. Hypotonic—a solution that exerts less osmotic pressure than that of blood plasma. Administration of this fluid generally causes dilution of plasma solute concentration and forces water movement into cells to reestablish intracellular and extracellular equilibrium; cells will then expand or swell.
a. Dextrose 2.5% in half-strength normal saline, 0.45%
b. Half-strength normal saline, 0.45%
c. Quarter-strength normal saline, 0.2%

3. Hypertonic—a solution that exerts a higher osmotic pressure than that of blood plasma. Administration of this fluid increases the solute concentration of plasma, drawing water out of the cells and into the extracellular compartment to restore osmotic equilibrium; cells will then shrink.
a. Dextrose 5% in normal saline 0.9%
b. Dextrose 5% in half-strength normal saline (only slightly hypertonic because dextrose is rapidly metabolized and renders only temporary osmotic pressure)
c. Dextrose 10% in water
d. Dextrose 20% in water
e. Saline, 3% and 5%
f. Hyperalimentation solutions
g. Dextrose 5% in lactated Ringer’s
h. Albumin 25%

Composition of Fluids

1. Saline solutions—water and electrolytes (Na+, Cl-)
2. Dextrose solutions—water or saline and calories
3. Lactated Ringer’s—water and electrolytes (Na+, K+, Cl-, Ca++, lactate)
4. Balanced isotonic—varies; water, electrolytes, some calories (Na+, K+, Mg++, Cl-, HCO-3, gluconate)
5. Whole blood and blood components
6. Plasma expanders—albumin, dextran, plasma protein fraction 5% (Plasmanate), hetastarch (Hespan) (exert increased oncotic pressure, pulling fluid from interstitium into the circulation and temporarily increasing blood volume)
7. Parenteral hyperalimentation—fluid, electrolytes, amino acids, and calories