IV cannula subtypes include the peripheral IV cannula, the central IV cannula, and the draining cannulas. There are also several sizes of intravenous cannulas. The most common sizes range from 14 to 22 gauge. The higher the gauge number, the smaller the cannula. Different sized cannulas move liquid through them at different rates.
Peripheral IV Cannulas
Medical professionals typically use peripheral IV cannulas in the emergency room and during surgery in order to provide necessary fluids or to insert contrast when taking a radiological image. These cannulas are for short-term use and may be taped to the skin to prevent them from moving.
Central IV Cannulas
Medical professionals may use a central line cannula for an individual who needs long-term treatments that require weeks or months of IV medication or fluids. For example, an individual receiving chemotherapy might require a central IV cannula for the intravenous infusion of the drugs. Central IV cannulas can quickly deliver medication and fluids into the body via the jugular, femoral, or subclavian vein. They can get easily infected; therefore, if any signs of infection (e.g. erythema, swelling, induration, fever) occur, they are typically removed.
Draining Cannulas
Health care providers use draining cannulas to drain fluids or other substances from the body. They can be used in procedures such as extracorporeal membrane oxygenation (ECMO), which is typically only used in critically ill patients with severe pulmonary and/or cardiac failure. In ECMO, blood is drained from the venous system, oxygenated, and then returned to the body. Sometimes draining cannulas might be used during liposuction. In that case, the cannula is connected to a trocar, which is a sharp metal or plastic instrument that can puncture tissue and remove fluid from or insert fluid into a body cavity or organ.
When inserting an IV cannula in an individual’s vein (usually in their arm), the patient is asked to lie or sit down with one of their arms exposed and extended by their side. The healthcare professional performing the procedure will choose the insertion point, which is usually in the individual's non-dominant arm or hand. Then, the area is thoroughly cleaned with an antiseptic while a tourniquet is tied above the desired insertion point. When ready, the healthcare professional will insert the IV cannula into a vein. The needle is only required to puncture the skin and vein. Once the cannula is placed in the vein, the needle is withdrawn as the cannula slides over the needle and into the vein. The cannula is then secured in place with medical tapes, such as a wrap or a special bandage.