The intra {Latin - within} venous {vein} route of administration is the fastest way to get drugs into your body and to feel the effects by injection. It is the most potent out of the following "common routes" - it allows the drug to act almost immediately, and can reach a high plasma concentration efficiently. Large volumes of drug or even just fluid can be given this way. Right into the bloodstream.

Unless you consider intrathecally - in the spinal cord. But that's another ball game.

Other common routes of injection (aka parenteral) drug administration are:
SC Subcutaneous and SM submucosal - under the skin and mucosa
IM Intramuscular - in the muscle

Some of the disadvantages of the IV route are:
Skill is required to insert the needle into a vein - a haematoma may be produced if the vein wall of torn.
Infection may be carried into the bloostream - a major hazard for IVDUs (intravenous drug users) aka drug addicts
The sudden entry of the drug into the blood can cause toxic or particularly severe allergic reaction.
Some drugs or their solvents are irritant to vessel walls and can cause thrombophlebitis - e.g. propylene glycol solvent for diazepam.

This literally translates as 'within the vein', and is a description of one of the methods used by clinicians to place drugs or fluids into a person's body. Often shortened to i.v. or IV. As a term, it is used in two different contexts.

Intravenous Infusion

Also called a 'drip' or an 'i.v. line', this is the introduction, in most cases slowly, of a volume of fluid into the blood stream. It is the fastest way of dispensing a fluid, e.g., saline or blood, into the body, as it instantly reaches the main circulation. The fluid travels from a suspended bag or bottle, down through tubing and into the patient's vein via a cannula. If necessary, drugs, such as morphine, can be mixed in with fluid to give a constant measured quantity of the drug over time to the patient.

The cannula is a small piece of plastic tubing that sits inside the patient's vein, and is placed using a trocar or a needle to pierce the skin and then sliding the cannula over into the vein itself while simultaneously pulling the trocar out. Cannulas come in various different sizes, from tiny 20G (gauge) 'kiddie-sized' ones to large 14G 'there's no way you're coming near me with that' torture devices.

Cannulas are usually sited in a patient's forearm. However, this can be difficult for some, such as those who receive regular dialysis, as the veins in their arms become so scarred from constant use that alternative sites are used, such as the veins in the leg. Another site that is used are the jugulars, which are the main veins of the neck. This is not common practice, but is incredibly useful when a patient who has suffered a large amount of blood loss is admitted to the hospital, as the veins are large enough to allow treating clinicians to practically pour blood and fluid into the patient's body to replace what's been lost.

It is standard procedure (in the UK at least), that all patients who enter hospital via A&E have a cannula sited. This is for the simple reason that, you never know when you're going to need them and that when you do need them, you need them. Patients who were but seconds ago happily walking around chatting to the wife can suddenly collapse, and a cannula offers a fast, convenient way to administer life saving drugs quickly.

Cannulas can often be left in place for several days while the patient is in hospital.

Another method of establishing intravenous access for the infusion of drugs and fluids is the placement of small flexible tubes (catheters) in the larger veins of the body . These are procedures performed when long-term access to the circulation is required, e.g., for patients on ICU wards or for the delivery of chemotherapy during treatment for cancer. One version is called central venous access, where the catheter is placed in one of the large veins of the chest or neck (e.g., subclavian vein) using ultrasound guidance. It will then be capped off using a port that will sit just below the skin, which will be visible as a small raised disk under the skin the size of a small coin. These are sometimes called 'portacaths'. A small needle is then pushed through the skin covering the port whenever blood needs to be drawn or drugs administered. An alternative to this is a peripherally inserted central catheter (PICC), where the catheter is inserted into a large vein in the arm, and then advanced up to the subclavian vein.

The use of these devices over cannulation offers several advantages for those receiving long term care. They avoid the inflammation and scarring that occurs in veins from being repeatedly stuck with needles. Also, some drugs are highly irritant to the veins, so by placing them in the larger veins of the body rather than the small veins of the arm, the patient feels less irritation and pain. Finally, they increase comfort and reduce anxiety in those patients that require frequent venous access over the course of their treatment.

Intravenous Injection

This is the brief placement of a needle into a vein to administer a drug to a patient via a syringe. This is the fastest way of introducing a drug to the body, but not necessarily the route of choice for many drugs. For instance, insulin needs to be absorbed by the body very slowly, and so is injected subcutaneously (under the skin). Other injection methods include intramuscular (into the muscle), intrathecal (into the spine) and intra-articular (into a joint).

In`tra*ve"nous (?), a.

Within the veins.

 

© Webster 1913.