IV line

Intravenous therapy
Infusion therapy: A person receiving medication via intravenous therapy.
Synonyms	IV therapy, iv therapy
ICD-9-CM	38.93
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Intravenous therapy is therapy that delivers liquid substances directly into a vein ( + + ). The intravenous (IV) route of administration can be used for injections (with a syringe at higher pressures) or infusions (typically using only the pressure supplied by gravity). Intravenous infusions are commonly referred to as drips. The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body, because the circulation carries them. Intravenous therapy may be used for fluid replacement (such as correcting dehydration), to correct electrolyte imbalances, to deliver medications, and for blood transfusions.

Intravenous systems can be categorized by which type of vein the inserted tube, called the catheter, empties into.

A peripheral line is used on peripheral veins (the veins in the arms, hands, legs and feet). This is the most common type of IV therapy used.

Central IV lines have their catheters that are advanced through a vein and empty into a large central vein (a vein within the torso), usually the superior vena cava, inferior vena cava or even the right atrium of the heart. Because these veins have a larger diameter than peripheral veins and have faster blood flow, central lines are commonly used to administer substances that could irritate the blood vessel lining, such as some chemotherapy drugs and total parenteral nutrition, whose high glucose content can damage blood vessels.

Other advantages are that because it empties near the heart, medications can also be quickly distributed to the rest of the body. As there is room for multiple parallel compartments (lumen) within the catheter, so that multiple medications can be delivered at once even if they would not be chemically compatible within a single tube. Caregivers can also measure central venous pressure and other physiological variables through the line. It is commonly believed that fluid can be pushed faster through a central venous catheter but as they are often divided into multiple lumens then the internal diameter is less than that of a large-bore peripheral cannula. They are also longer, which as reflected in Poiseuille's law, requires higher pressure to achieve the same flow, all other variables being equal.