What is Intravenous Cannulation?

Intravenous cannulation is a technique which is used to place a cannula inside a vein for the purpose of providing venous access. There are a number of reasons why a doctor or medical team might want venous access. Cannulation can be performed at the scene of an emergency by first responders who want to make sure that they will have access to a vein and it is also routinely done in hospital settings. Intravenous cannulation is one of the earliest skills learned by health care providers like doctors, nurses, and paramedics.

In the intravenous cannulation procedure, a needle is used to gain access to the target vein so that a cannula can be placed. When the cannula is stable, the needle is removed, and the cannula is taped in place so that it cannot slide out. Tubing can be attached to the cannula to deliver fluids, drugs, or nutrition. The cannula may be left in place as long as it is needed.

Typically, an upper extremity like an arm is chosen for intravenous cannulation. The size of the cannula varies, depending on the size of the patient, the condition of the veins, and the purpose for which the cannula is being used. The larger the tube, the faster things like fluids can be delivered, but if the tube is too large, it can be difficult to insert or may injure the patient. The care provider must balance the needs of the situation when selecting a cannula. These devices are usually color coded so that people know how big the cannula is by glancing at it.

Ideally, patient consent is obtained before placing an intravenous cannula. The doctor or nurse performing the procedure should quickly explain what it is, why it is being done, and how it will be done. A shot of local anesthetic may be given to make the cannula insertion more comfortable. A sterile environment must be maintained during intravenous cannulation to avoid introducing bacteria and other organisms into the cannulation site.

Cannulas periodically need to be flushed, and there are other steps which must be taken for maintenance to keep the tube clear and prevent infection. The longer the cannula remains in place, the higher the risk of infection. A doctor may switch cannulation sites if a cannula is needed in the long term, or consider installing a port for venous access. The intravenous cannula is removed as soon as it is no longer necessary, to increase patient comfort and minimize the possibility of infection.