We often picture a patient in a hospital with a drip running by the side. The drip contains fluids and sometimes electrolytes that are administered directly into a vein.
Body fluids have a delicate balance of water and electrolytes like sodium, potassium, bicarbonate and chloride. Fluids are present within the blood vessels in the form of blood, as well as outside the blood vessels within cells and surrounding tissues. There are certain situations when excess water and electrolytes are lost from the body. These include burns, severe vomiting and diarrhea, or trauma where blood is lost. If the amount of fluids in the blood vessels is reduced, the kidneys and other organs can shut down. Therefore, there is an urgent need to replace fluids in the body. This fluid replacement is achieved by intravenous fluid therapy. Intravenous fluids are particularly necessary when there is a major loss of fluid or the patient cannot take in fluids orally. Cases of blood loss should be treated with blood transfusion
; however, intravenous fluids may be administered till blood is made available.
Intravenous fluids are also administered when the balance between the water and electrolytes is lost. For example, if the sodium levels fall too low, intravenous fluid that contains sodium is given. If the potassium levels are low, a potassium-containing solution is administered.
Several drugs are also administered through IV fluids. These come either premixed with the fluid or have to be mixed before administration. It is important to note the instructions on the medication since some drugs cannot be given with certain IV fluids. Intravenous medications are particularly useful in emergencies because they act almost immediately.
Intravenous fluids are also used provide nutrition for those who cannot take in nutrition orally through a Ryles tube. They are administered during surgery to provide fluids and administer drugs.
What are the Types of Intravenous Fluids?
Intravenous fluids are of two types – crystalloids and colloids.
Crystalloids contain water, electrolytes and /or glucose in different proportions. Some of the crystalloids available include:
- 2.5%, 5%, 10% dextrose in water
- Isotonic, hypertonic or hypotonic sodium chloride / saline
- Dextrose in saline
- Ringer lactate
Crystalloids are usually useful to replace extravascular fluids. They do increase blood volume, but their effect is temporary, hence they are used for fluid replacement for short-term purposes only. Fluids containing dextrose provide energy, while saline fluids contain sodium chloride in varying concentrations. Hypertonic saline contains high amounts of salt and can be given to people with low sodium levels. On the other hand, hypotonic saline is given in those with high sodium levels. A hypertonic solution also extracts the excessive fluid and reduces brain swelling in patients with a head injury. Ringer lactate and Plasma-Lyte contain electrolytes like sodium and potassium and resemble body fluids to a greater extent.
Examples of colloids are:
- Hydroxyethyl starch
Colloids remain within blood vessels for a much longer time than crystalloids and help to increase the volume of fluid within blood vessels.
How is Intravenous Fluid Therapy Administered?
Intravenous fluids are usually administered in a hospital though they are also administered at home in some conditions. Some of the guidelines to administer intravenous fluid are as below:
- The ideal fluid for the particular situation is selected
- The amount of fluid necessary is calculated
- The intravenous set is set up. The fluid is passed through the tubing to replace the air in it
- The cannula for injection is introduced into a vein using aseptic precautions and secured in place. The injection is usually given in a peripheral vein in the arms or sometimes the legs. Irritant drugs cannot be administered into these veins. Injection into a larger vein closer to the heart is done in case long term IV fluids are required or the peripheral veins have collapsed
- The drip rate of the IV set is adjusted
- The IV fluid is labelled
- The fluid level should be regularly monitored. The fluid intake and output should also be recorded
What are the Complications Associated with Intravenous Fluid Therapy?
Complications due to intravenous fluid therapy include:
- Excess of fluid can result in fluid load. Due to this, the patient may suffer from pulmonary edema (fluid accumulation in the lungs) or heart failure
- Infections, if adequate sterile precautions are not taken
- Electrolyte imbalances, which can cause dangerous effects. For example, high potassium levels can affect the heart
- Bleeding, pain and /or inflammation at the site of injection
- Air embolism, if air goes through the tubing into the body. A clot may also be formed at the catheter site which can get detached and form an embolus. The embolus may travel to the heart or brain resulting in serious consequences
- Allergic reaction to the fluid or drug administered