Adequate hydration is essential in ensuring continued organ perfusion and normal organ function. It is also essential in ensuring stable blood pressure.
The human body is made up of about 60% of water. Water in our body contains electrolytes such as sodium, potassium, calcium, magnesium and bicarbonate. Iv fluids restore fluid balance when water is lost from the body.
Some functions of water in the human body include
- nutrients absorbtion and transport
- interfere in the chemical and metabolic reactions
- regulate the body temperature
- elimination of waste products through urine
- essential for cell life
Types of IV Fluids:
Crystalloids
Crystalloids contain small molecules that flow easily across semipermeable membranes. They are the most commonly used iv solutions for fluid replacement.
Crystalloids iv solutions are devided into three types:
Isotonic solutions
Isotonic solutions have the same concentration of solutes as blood plasma. They increased the fluid volume of patient when administered without a fluid shift. They are given to replace extracellular fluid losses and to expand intravascular volume.
Example of isotonic solutions:
- 0.9% normal saline
- lactated ringers
- 5% dextrose in water
Hypotonic solutions
Hypotonic solutions have lesser concentration of solutes than plasma. Fluid shifts out of the bloodstream to the area of higher concentration in the interstitial and intracellular spaces when hypotonic solution is administered.
Example of hypotonic solutions:
- 0.45% normal saline
- 0.225% saline
- 0.33% saline
Hypertonic solutions
Hypertonic solutions have a higher concentration of electrolytes than plasma. Fluid shifts from the interstitial and intracellular spaces into the bloodstream to dilute the electrolytes when a hypertonic solution is administered.
Example of hypertonic solution:
- 3% saline
- 5% saline
- 10% dextrose in water
- 5% dextrose in 0.9% saline
- 5% dextrose in 0.45% saline
- 5% dextrose in lactated ringers
Colloids
Colloids solutions contain large molecules that do not pass through semipermeable membranes and therefore remain in the blood vessels. They contain large proteins that generally do not cross capillary walls. Colloids expand intravascular volume by drawing fluid from the interstitial space into the vessels through higher oncotic pressure.
Example of colloids solution:
- albumin (5%)
- albumin (25%)
- dextran
- hydroxyethyl starch
- haemaccel and gelofusine
Caution should be used when administering colloids solutions
