Intravenous saline is a medical treatment that provides the body with a sterile solution of water and sodium chloride (NaCl), also known as salt. This solution is administered through a tube directly into the patient's vein using an injection needle. In fact, the term "intravenous" means "into a vein." Intravenous saline is commonly used to rehydrate the body in order to improve or restore body function.
The human body naturally contains a percentage of sodium, chloride and water. Dehydration and blood loss can cause a fluid imbalance within the body that needs to be corrected through an intravenous infusion. Medical saline in the proper NaCl-to-water ratio can be utilized to rehydrate and restore the body while maintaining the balance necessary to avoid disturbance of the body's cells.
The human body contains sodium chloride and water both inside and outside the body cells. A mixture known as "normal saline" is a solution of 0.9 percent sodium chloride and most frequently is used in intravenous saline therapy for rehydration. It is balanced with the natural salinity of the human body.
Sodium chloride attracts water. Fluid containing too great a percentage of salt is known as hypertonic solution, and it will draw water out of the cells of the body. This mixture can trigger dehydration, which — unless it is controlled — eventually will result in the patient's death. Likewise, a hypotonic solution of fluid containing too low a percentage of NaCl will attract water into the cells, causing them to swell. Both hypertonic and hypotonic solutions do have a place in medical therapy, depending on the patient's condition and electrolyte balance.
In order to administer intravenous saline, a medical professional must place specialized equipment that provides access to the patient's vein. Saline most commonly is administered through what is known as a peripheral cannula. The cannula, a small flexible tube, is connected to a hollow needle. This needle is inserted into any vein outside of the chest or abdominal area, commonly in the hand or the arm.
After the cannula is established, it can be connected with a tube to the intravenous bag or bottle of fluids. The flow of intravenous saline can be controlled with the use of an infusion pump or a gravity drip. The infusion pump is an electronic piece of equipment, and the gravity drip consists of an intravenous pole and a clamp. Hospitals might require a peripheral cannula to be changed at regular intervals in order to prevent inflammation and infection.