What is a Cannula?
A cannula is a thin tube that is inserted into the body, most commonly into a vein or artery. As a general term, a cannula is a medical device made of plastic or metal that can be used for infusions, drainage of fluid, or drawing blood. Some common uses of cannulas include intravenous (IV) therapy, dialysis, and drawing blood samples.
Types of Cannulas
There are different types of cannulas used for various medical purposes:
- Intravenous (IV) Cannula: Cannula is the most common type inserted into a vein to deliver fluids, medications, blood products, nutrients, and other treatments. IV cannulas come in various sizes depending on the vein and purpose.
- Central Venous Cannula: Larger than a standard IV cannula, a central line is inserted into a larger central vein and threaded further into the body. This allows infusion of irritating substances or prolonged IV therapy.
- Arterial Cannula: Similar to a central line but inserted into an artery, arterial lines are used to monitor blood pressure, obtain blood gases, and other diagnostic tests.
- Hemodialysis Cannula: Two cannulas are needed for hemodialysis, one to remove blood from the body and one to return cleaned blood. These are surgically placed in an artery and vein in the arm or leg.
- Chest Drainage Cannula: Also called a thoracostomy tube, this type drains fluid from the pleural space around the lungs after surgery or trauma.
- Peritoneal Cannula: Used for peritoneal dialysis, a flexible tube is placed in the abdomen to drain and return dialysate fluid.
Cannula Insertion and Removal
IV cannulas are usually inserted into a vein in the hand, arm, or scalp depending on need and vein accessibility. The site is cleaned and often numbed with local anesthetic prior. Usingaseptic technique, the clinician feels for a suitable vein and gently inserts the hollow needle attached to the cannula. Once blood flashes back, indicating proper placement in the vein, the needle is withdrawn leaving the thin plastic cannula in place. Dressings and tape secure it.
Removal requires clamping the line, cleaning the site, and gently withdrawing the cannula while applying pressure. Larger cannulas like central lines have specialized insertion and removal protocols due to their size and location in larger central veins. Infection risk is higher so strict sterile procedure is vital during placement and care.
Cannula Benefits and Risks
When placed correctly by trained staff, cannulas provide important clinical benefits. They allow fluids, nutrition, medication and blood products to be safely administered or drainage of fluid from the body. This supports treatments like dialysis, management of shock, hydration, chemotherapy and more.
However, there are also risks involved with all cannulas:
- Infection: Bacterial contamination during placement or care can lead to local or bloodstream infection. Risk increases with duration of use.
- Injury: Improper technique carries risk of puncturing the vein, surrounding tissues, or organs during insertion. Veins can also later collapse.
- Bleeding: If the vessel is damaged or the cannula dislodges, bleeding may result. Hematomas can form.
- Phlebitis: Veins become inflamed and painful from chemical irritation or repeated cannulation. This may preclude further IV access at that site.
- Thrombosis: Blood clots can form in the vessel if irritation or injury causes endothelial damage. These increase risk of pulmonary embolism.
To minimize risks, proper training, sterile technique, site care, securing, and scheduled removal of cannulas by medical staff is important. Patients are also educated on signs of potential complications to report early. With correct use, cannulas provide vital clinical care far outweighing the risks.
Cannula Care and Monitoring
Once placed, cannulas require vigilant care and monitoring to prevent problems. The site is cleaned daily with antiseptic and checked for swelling, redness or pain which could signal infection or phlebitis starting. Dressings are replaced and tapeSecurely holds the cannula in place.
Occlusive dressings designed to minimize air/fluid entry are commonly used. Blood return is ensured periodically by removing clamps and observing for flashback in the line. Regular flushing with saline maintains patency. Tubing connections are secured and changed based on the facility protocol to prevent breaks or leaks.
For long-term cannulas like central lines, daily assessment of the insertion site, prompt treatment of any issues, and scheduled replacement help reduce complications. Constant monitoring for signs of infection, infiltration, blood clots or mechanical issues also catch problems early. With diligent care and hygiene practices, cannulas offer life-saving clinical access when used and maintained correctly.
In the cannulas are invaluable medical devices that allow therapies to be administered directly into the circulatory system. While risks exist with any foreign body, trained placement and rigorous sterile technique and monitoring can prevent complications. From simple IVs to intricate dialysis catheters, cannulas bridge treatment needs when oral intake is not possible or other non-invasive options will not suffice. With proper use, cannulas benefit patients greatly.
About Author:
Priya Pandey is a dynamic and passionate editor with over three years of expertise in content editing and proofreading. Holding a bachelor's degree in biotechnology, Priya has a knack for making the content engaging. Her diverse portfolio includes editing documents across different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. Priya's meticulous attention to detail and commitment to excellence make her an invaluable asset in the world of content creation and refinement. (LinkedIn- https://www.linkedin.com/in/priya-pandey-8417a8173/)
