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How to perform intravenous cannulation?

Posted by Ann V. On 2016 Mar 11th

How to perform intravenous cannulation?

Intravenous (IV) cannulation is technical process to place a cannula, a flexible tube with crotar needle, inside a vein to gain venous access. The technique is commonly used in health institutions to perform various tests by sampling blood or to administer essential fluids, medications, parenteral nutrition and blood components in chemotherapy. It mainly involves puncturing vein at the right place so that an external duct could be inserted into the body fluid supply.

Performing Intravenous Cannulation

Health workers use different methods of cannulation depending on their individual preferences. But to find a method with which you are most comfortable with is the real thing.

Before touching the cannula, make sure that you follow certain steps to ensure complete hygiene. Do wash and sterilize your hands. Also, it would be better if the patient is politely informed that cannulation process is required. You are supposed to explain entire process to the subject, but just saying, “It’ll be a little uncomfortable, but don’t worry, there’ll be hardly any pain”, will do fine too. Also, you should ensure taking consent from the subject before proceeding with cannulation.

Ready Equipments

You need to ensure all required equipments are in place and readily accessible. Gather non sterile globes, apron, cannula, cannula dressing, saline and syringe (10ml), gauze, alcohol swab, and tourniquet.

Find Right Vein, Right Spot

Before puncturing, you need to make sure that you have selected most appropriate vein and spot. Apply a tourniquet, but avoid nipping the patient’s skin and palpate a vein. You should be able to feel a vein. A suitable vein would feel springy and would be ideally straight. Then, tap the vein and make the subject pump his/her fist. It’ll help in making veins clearly visible. Keep in mind that you never go for areas where two or more veins are joining.

Inserting Cannula

Make sure your gloves are on. Take an alcohol swab and clean the area with it for at least 30 seconds. You should swab it in outward circular motion. Before inserting cannula try to observe whether subject is mentally ready for it. If prepared, open winds of cannula and check whether top cap is working or not. Then withdraw needle very slightly to make it easier to glide. Take out cannual cap and place it upright in tray.

Now, remove the cannula sheath and use your non-dominant hand from below and let patient know about upcoming sharp scratch.


A cannula should be inserted at an angle of between 20-40 degree and the bevel should be facing upward direction.

Observe the subject and then advance the needle a further 1-2mm. Make sure that the cannula is in the veins lumen before you withdraw the needle slightly to insert the sharp point inside the plastic tubing. Now, advance cannula fully into the vein and release the tourniquet to reduce bleeding. Some gauze should be placed directly underneath the cannula and pressure should be applied over the vein from above.Now, you can remove the needle and dispose it into a bin.

Secure the cannula by putting some tape onto its wings before flushing. To flush the cannula, first set up flush. Open a 5-10ml syringe, get a 10ml bottle of saline 0.9%, withdraw fluid from the saline bottle into syringe, and make sure to remove every bubble within the syringe. Now, remove the top cap and insert syringe and inject the saline into cannula.

You should not experience much resistance if it’s being done right. Do look for signs of swelling around the site and stop immediately if you spot any. Confirm from the patient if he is feeling pain and stop if the answer is affirmative.

If everything is positive, you can close the cannula port and apply dressing to the site. Don’t forget to thank the subject for co-operating.