Cannulation

A cannula (/ˈkænjᵿlə/; from Latin "little reed"; plural cannulae or cannulas) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data. In simple terms, a cannula can surround the inner or outer surfaces of a trocar needle thus extending the effective needle length by at least half the length of the original needle. It is also called an intravenous IV cannula. Its size mainly ranges from 14 to 24 gauge. Different-sized cannula have different colours as coded.

Decannulation is the permanent removal of a cannula (extubation), especially of a tracheostomy cannula, once a physician determines it is no longer needed for breathing.

Cannulae normally come with a trocar attached, which allows puncturing of the body in order to get into the intended space. Many types of cannulae exist:

Intravenous cannulae are the most common in hospital use. A variety of cannulae are used to establish cardiopulmonary bypass in cardiac surgery. A nasal cannula is a piece of plastic tubing that runs under the nose and is used to administer oxygen.

A venous cannula is inserted into a vein, primarily for the administration of intravenous fluids, for obtaining blood samples and for administering medicines. An arterial cannula is inserted into an artery, commonly the radial artery, and is used during major operations and in critical care areas to measure beat-to-beat blood pressure and to draw repeated blood samples. Insertion of the venous cannula is a painful procedure that can lead to anxiety and stress. Use of a vapocoolant immediately before cannulation reduces pain during the procedure, without increasing the difficulty of cannulation.

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