Cannula


A cannula is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. 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 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, especially of a tracheostomy cannula, once a physician determines it is no longer needed for breathing.

Medicine

Cannulae normally come with a trocar inside. The trocar is a needle, which punctures 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.

Intravenous (IV) cannulation

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.
Complications may arise in the vein as a result of the cannulation procedure, the four main groups of complication are:
A nasal cannula or an oral–nasal cannula consists of a flexible tube, usually with multiple short, open-ended branches for comfortable insertion into the nostrils and/or mouth, and may be used for the delivery of a gas, a gas mixture, or to measure airflow into and out of the nose and/or mouth.

Tracheotomy tube

The removal of a tracheotomy tube is referred to as decannulation.

Veterinary use

A cannula is used in an emergency procedure to relieve pressure and bloating in cattle and sheep with ruminal tympany, due most commonly to their accidentally grazing wilted legume or legume-dominant pastures, particularly alfalfa, ladino, and red and white clover.
Cannulas are a component used in the insertion of the Verichip.
Much larger cannulas are used to research about the digestive system of cows.

Aesthetic medicine and anti-ageing

In aesthetic medicine, a blunt-tip cannula or microcannula is a small tube with an edge that is not sharp and an extrusion port or pore near the tip which is designed for atraumatic subdermal injections of fluids or gels.
Depending on the size of the internal diameter, it can be used either for the injection of cosmetic wrinkle fillers like hyaluronic acid, collagen, poly-L-lactic acid, CaHA, etc., or for fat transfer. The advantage of using these is that they are less painful, have less risk of bruising, have less swelling, and a better safety profile. Accidental intravascular injections are more difficult with blunt-tip microcannulas, reducing the risk of skin necrosis, ulcers, and embolization to the retinal artery which can result in blindness. Indeed, in May 2015, the USA issued a warning of these risks as an FDA Safety Communication on the "Unintentional Injection of Soft Tissue Filler Into Blood Vessels In the Face".
In January 2012, the "Dermasculpt" microcannula was approved by the FDA for use in the United States for use with soft tissue fillers followed by the "Magic Needle", "Softfil", "TSK by Air-Tite", and "Sculpt-face". The primary structural differences between microcannulas is the distance of the extrusion port or pore from the tip, the bluntness of the tip, and the flexibility of the shaft was described on the use of microcannula to inject local anesthesia with less pain, bruising, and swelling. Also introduced were Accelerated Healing After Platelet-Rich Plasma, Accelerated Healing After Platelet-Rich Fibrin Matrix, and the use of microcannula to dissolve Sculptra nodules.

Body piercing

Cannulae are used in body piercing when using a standard IV needle, and for inserting hooks for suspensions.
During piercing, the fistula is created by inserting the needle. The needle is then removed, leaving the cannula in place, which is sometimes trimmed down. The cannula is then removed and sterile jewelry is inserted into the fistula simultaneously, in order to minimise trauma to the fresh fistula caused by insertion of blunt-ended jewelry.

Non-medical use

In biological research, a push-pull cannula, which both withdraws and injects fluid, can be used to determine the effect of a certain chemical on a specific cell. The push part of the cannula is filled with a physiological solution plus the chemical of interest and is then injected slowly into the local cellular environment of a cell. The pull cannula then draws liquid from the extracellular medium, thus measuring the cellular response to the chemical of interest. This technique is especially used for neuroscience.
In general aviation, a cannula refers to a piece of plastic tubing that runs under the nose and is used to administer oxygen in non-pressurized aircraft flying above 10,000 feet sea level.
In synthetic chemistry, a cannula refers to a piece of stainless steel or plastic tubing used to transfer liquids or gases from one vessel to another without exposure to air. See more at Cannula transfer.