Intravenous drip

An intravenous drip (or IV for short) is the infusion of fluids into a vein, intravenous meaning "within veins." It is administered in medical situations either to replace fluid or to provide easy access to the bloodstream for drugs. It is usually a bag of fluid that is gravity fed (and thus hangs above the patient).

One common, cheap form of flow control is a visible drip chamber, which also removes air from adminsitration, and lets staff observe and control the flow rate.

A bag can also be placed into an inflatable cuff so that the liquid can be pushed into the patient; as the cuff is inflated fluid is infused at a higher flow rate. This is often done with a large bore IV, meaning that the cannula needle that is inserted into the patient´s vein is of a large diameter allowing a high flow rate.

Another method is to use an infusion pump.

Intravenous fluids are used in a great variety of medical conditions, ranging from dehydration (loss of water) to electrolyte imbalances and acute or chronic blood loss.

Beside blood transfusion and intravenous drugs, there are essentially two types of fluids that are used for intravenous drips: crystalloid and colloid fluids. "Crystalloids" are aqueous solutions of mineral salts such as isotonic saline or Ringer´s solution. "Colloids" are solutions of larger molecules such as gelatine.

IV drips have a number of hazards. More than 2 ml of air in a line can starve tissue of oxygen and food. The bubble can float to a body part (including the brain) and remain there. An "air embolism" of this sort is famously difficult to diagnose because it can cause so many different types of symptoms. A drip lower than the patient can cause reverse flow, literally siphoning the bood from a patient. A nonsterile (i.e. reused) administration set can cause a dangerous systemic blood-based infection. Finally, an unmeasured flow can be to a collapsed vein, or the tip of the needle can leave the vein, causing a failure to infuse, or localized edema.

Note that an intravenous drip is a sterile medical procedure that should only be performed by trained personnel under medical supervision, using proper equipment.

See also life support, medicine, total parenteral nutrition