Parenteral fluid therapy

The major objective of parenteral fluid therapy is to provide pareneterally water that could replace physiological losses. Water loss from the body can be via urine / sweat /insensible means. Water losses from the body roughly parallels energy metabolism and is not related to body mass index.

Basic rules of parenteral fluid therapy include:

1. Never be generous with fluid administration
2. The source and amount of usual water out put from the body should be known
3. Amount of nutrients and electrolytes administered parenterally should be accurately known
4. The aim of fluid therapy should be clear
5. The same substance should not be given and removed at the same time
6. Commonly preferred parenteral fluid is isotonic solution
7. Kidney does'nt manufacture water / electrolytes
8. For short term fluid replacement water, glucose, sodium chloride, and phosphate alone needs to be given. Divalent ions like calcium and magnesium need not be replaced.
9. There are two types of parenteral fluids i.e crystalloids and colloids
10. Composition of various intravenous fluids should be accurately known

Main components of parenteral fluids:

1. Water
2. Electrolytes like sodium and chloride
3. Calcium ions
4. Magnesium ions
5. Bicarbonate
6. Phosphate

Types of parenteral fluids:

1. Isotonic
2. Hypertonic
3. Hypotonic

Classification of parenteral fluids:

1. Volume expanders
2. Blood / blood based products
3. Blood substitutes
4. Medications

Volume expanders:

There are two types of volume expanders i.e. Crystalloids and colloids. Crystalloids are aqueous solutions of mineral salts and other water soluble molecules.

Colloids contain large insoluble molecules. Gelatine is one classic example of such insoluble molecule.

Buffer solutions: These solutions are used to correct acidosis / alkalosis. Intravenous sodium bicarbonate is one such example of buffer solution. Commonly used buffer solution is Ringer lactate.

Parenteral nutrition: This helps in feeding a person bypassing the usual process of eating and digestion.

Intravenous route can be used to administer drugs.

Complications of fluid therapy:

1. Infection
2. Phlebitis
3. Extravasation to subcutaneous tissues
4. Fluid overload
5. Hypothermia
6. Electrolyte imbalance
7. Embolism