This is a UKMLA-centred article about intravenous cannulation.

Introduction

Intravenous cannulation is a common medical procedure that involves inserting a flexible catheter into a patient’s vein to administer medications, fluids or draw blood samples.  This guide will offer a comprehensive guide on how to carry out an intravenous cannulation effectively. 

Gather Equipment

Before beginning the procedure, ensure you have the necessary equipment readily available. This includes collecting a procedure tray that has been wiped clean with an alcohol swab. In this tray you should place:

• non-sterile gloves
• tourniquet
• cannula
• sterile dressing
• cannula dressing
• cannula extension set
• gauze swabs
• normal saline 0.9%
• syringe
• alcohol swabs (2% chlorhexidine gluconate in 70% isopropyl)

Preparation

Before you begin you must gain consent from the patient, confirm their name and date of birth and check if they have any allergies (e.g. latex). This involves explaining the procedure in lay man terms, its purpose and ensuring that they are are prepared. The patient should be adequately exposed, ideally sitting up with their arm propped up on a table or using a cushion. Their sleeves should be rolled up and arm exposed.

The next step is to wash your hands thoroughly with soap and water. Once dry, put on sterile gloves to maintain aseptic technique throughout the procedure.

1. Once you have donned gloves, open the dressing pack and place all the contents onto the field. 
2. Prepare the normal saline flush by drawing the saline into your syringe (if pre-filled syringes are available you can skip this step).
3. Attach the extension set to the flush and prime the line. 

Identifying a vein

Once you have prepared your equipment and adjusted the patient, you can ask them if they have any pain and if they have a preferred arm. Next, inspect the arm for an appropriate cannulation site. Commonly used sites for cannulation include the veins in the lower forearm, back of hand and upper arm. A suitable vein is one which is visible, palpable and suitable for the size of the cannula. 

Apply the tourniquet approximately 4-5 finger-widths above the planned cannulation site. To better visualise the vein you can ask the patient to clench their fists or tap gently over the site. 

Clean the site with an alcohol swab for 30 seconds and then allow to dry completely for 30 seconds. You must not touch the cleaned site to avoid contamination. 

Inserting the cannula

• Remove the cannula sheath and prepare the cannula by opening the wings and unscrewing the cap at the back of the cannula and placing it upright in the tray. 
• Apply traction to the patient’s vein by gently pulling on the skin using your non-dominant hand. Hold the cannula with your dominant hand and warn the patient they will experience a sharp scratch.
• Position the bevel of the cannula upward and insert it into the vein at a 15 to 30-degree angle. Apply gentle pressure until you observe a flashback of blood into the cannula.
• Lower the angle of the cannula to a few degrees and advance it further into the vein.
• Once the cannula is in the vein, advance it approximately 1-2 cm further to ensure it is securely positioned within the vessel. Partially withdraw the introducer needle, ensuring it is within the plastic tubing of the cannula.
• Release the tourniquet and place some sterile gauze directly underneath the cannula hub. Gently pull the introducer needle backwards whilst holding the cannula in position until its completely removed. 
• Immediately dispose of the introducer needle immediately into a sharps container.
• Secure the cannula by placing adhesive strips to secure the cannula wings to the skin. Take care in ensuring the insertion site is visible to allow early identification of phlebitis. 

Flushing the cannula

Inject normal saline into the cannula using the flush you prepared earlier. There should be minimal resistance and you should observe the insertion site for any swelling which could indicate that the needle has punctured through the vein into surrounding tissue. 

Secure the cannula with a dressing once the flush has been used. The dressing should have the date of the cannula insertion written on it so healthcare professionals are aware.

Completing the procedure

Explain to the patient that the procedure is now complete and they are able to move their arm freely however to take caution and seek attention if the site becomes painful or inflamed. 

Dispose of all equipment into the clinical waste bin. 

Wash your hands.

Conclusion

Intravenous cannulation is an essential skill that requires practice and precision. Following the step-by-step guide provided in this article, healthcare professionals can carry out the procedure effectively, maintaining patient safety and comfort. Remember to prioritize infection control measures, maintain open communication with the patient, and adhere to best practices throughout the process. 

References

1. https://teachmesurgery.com/skills/clinical/cannulation/#:~:text=Intravenous%20cannulation%20is%20a%20process,be%20obtained%20from%20the%20cannula.

2. https://www.chelwest.nhs.uk/your-visit/patient-leaflets/medicine-services/intravenous-cannulation

3. https://www.britishjournalofnursing.com/content/clinical/cannulation-in-adults/

Author – Mohona Sengupta  

Editor – James Mackintosh

Last updated 20/05/23