What is the proper technique for inserting a 14G cannula?

Proper Technique for Inserting a 14G Cannula

The proper technique for inserting a 14G cannula requires careful preparation, proper angle of insertion (45 degrees for AV grafts and 25 degrees for AV fistulae), and aseptic technique to minimize infection risk and ensure successful placement. 1

Preparation

• Perform a complete physical assessment of the access site and document findings 1
• Locate and palpate the cannulation sites prior to skin preparation 1
• Wash the access site using an antibacterial soap or scrub (e.g., 2% chlorhexidine) and water 1
• Cleanse the skin by applying 70% alcohol and/or 10% povidone iodine using a circular rubbing motion 1
  • Alcohol should be applied in a rubbing motion for 1 minute immediately prior to cannulation 1
  • If using povidone iodine, allow 2-3 minutes for full bacteriostatic action and let it dry before cannulation 1

Insertion Technique

• Put on clean gloves before cannulation 1

• After skin preparation, pull the skin taut in the opposite direction of needle insertion to compress peripheral nerve endings 1

• Grasp the needle wings and remove the tip protector 1

• Align the needle cannula with the bevel facing up over the cannulation site 1

• For AV grafts: Use approximately a 45-degree angle of insertion 1

• For AV fistulae: Use approximately a 25-degree angle of insertion 1

• Once the vessel has been penetrated, you have three options 1:

  1. Advance the needle slowly with cutting edge facing top of vessel without rotating
  2. Immediately rotate the axis of the needle 180 degrees and advance slowly with cutting edge facing bottom of vessel
  3. Advance the needle to desired position, then rotate the axis 180 degrees

• A flashback of blood indicates the needle is in the access 1

• Lower the angle of insertion and continue to advance the needle until appropriately positioned within the vessel 1

• Securely tape the needle at the same angle or similar to the angle of insertion 1

Post-Insertion Care

• Monitor the site for complications such as redness, swelling, hematoma, or infection 2
• When removing the needle, use the same or similar angle as insertion 1
• Never apply pressure before the needle is completely out to avoid trauma to the vessel 1

Common Pitfalls and How to Avoid Them

• Pressing the needle shaft flat against the skin can move the needle tip from the desired position within the vessel lumen 1
• Avoid dragging the cutting edge along the vessel intima during insertion or removal 1
• Steeper angles increase risk of perforating the underside of the vessel 1
• Inadequate fixation can lead to complications - ensure proper taping technique 2
• Leaving cannulae in place too long increases complication risk - complications become very distinct after 24 hours 2

Special Considerations for 14G Cannulae

• Larger gauge cannulae like 14G are typically used for procedures requiring high flow rates, such as blood transfusion 3
• The larger diameter requires careful attention to insertion technique to minimize trauma 4
• For internal jugular vein cannulation with large gauge needles, be aware that larger needles may require longer distances to reach the vein (15.0-21.5mm) 5