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Dr Melody Hiew


When I learned how to use ultrasound, I thought - wow, now I have this tool, I’ll never miss an IV again! I mean, you can see what you’re doing in real time - what could possibly go awry?

Well… plenty, as it turns out. And through trial and error (not to mention the guidance of some people cleverer than myself), I’ve refined my technique… here are some tips that you may find useful.

1) Pick your patient

There are some patients who need central lines or PICC lines off the bat. For instance, if I see a IVDU patient who has one potentially usable vein 4cm below the surface, and they’re going to need antibiotics for more than 3 days… that patient needs a PICC.

A word of caution: sometimes getting the cannula in is the easiest part - getting it to STAY IN is the challenge. In patients with a lot of loose, fatty, or freely mobile subcutaneous tissue (ie, elderly patients, or patients with a lot of adipose tissue), by the time you’ve traversed 4cm of soft tissue, only a few millimetres of cannula is in the vein. As soon as the subcut tissue moves - that cannula will be pulled out of the vein. A PICC or long line is your best bet here.

2) Comfort is key

Set up your workspace to maximise comfort - yours and the patient’s! (Take a tip from our anaesthetic colleagues - they are the masters of a good set up, as they know it’s key to the success of any procedure). A comfortable patient will stay still and hold a required position for longer. A comfortable doctor will have better fine motor control and better chance at success.

For patient comfort - use towel rolls, pay attention to positioning and use an assistant to steady the limb if available. For doctor comfort - swing the screen of the ultrasound machine to an optimal position, sit down to do the procedure (or crank the bed up so you’re not having to lean over)... and, most important of all… eat and/or go to the bathroom before you start!

My preference is to use use local anaesthetic drawn up in an insulin syringe (or 1mL syringe with 25G needle) whenever I’m doing ultrasound-guided IV cannulae. Personally, I get very distracted by patient pain, and I can work better if the patient isn’t flinching, wincing or swearing. Also, I figure that by the time I come along, there have already been several attempts at cannulation, and it’s a nice thing to do. A word of warning - if you’re using local anaesthetic,ensure that you get all the air out of the syringe before your infiltrate. Any air introduced into your field will destroy your ultrasound picture!

3) Choose your weapons wisely

This is my list of equipment for inserting IV cannulae:

  • Probe cover - USE ONE. I could go on for ages about the pros and cons of different probe covers, infection control standards etc, but I’ll keep it quick and just say - you need some kind of sterile bag on that probe.

  • Non sterile ultrasound gel and sterile gel (standard sterile water soluble lubricant is fine). The non-sterile stuff goes between the probe and its cover, the sterile stuff goes between the probe cover and the patient’s skin

  • Aqueous chlorhexidine - for preparation of the skin, also doesn’t evaporate as fast as alcohol-based solutions (therefore allows the probe to glide better)

  • Local anaesthetic, insulin syringe

  • Long IV cannulae - unless the target vessel is within about 1cm of the surface, you’ll be needing the extra length. Remember that you need to get a decent amount of the cannulae inside the vessel in order for it to stay put! (And if your department doesn’t have any long cannulae - order them in!)

4) Use whatever view suits your needs

Long axis? Short axis? What’s the best approach to cannulation? In my mind - both! Here’s a description of my technique:

After my preparations are complete and I’m comfortably seated, I insert the needle and approach the vein using a short-axis approach, with my eyes on the screen until I reach the vessel. Once on top of the vessel, I bounce the needle a little so I can confirm that the needle is indenting the vessel. I then look down at the needle and advance it into the vessel, so I can spot a flashback as soon as it occurs. Once I get a flashback, I then rotate the probe into long axis view, and reduce the angle of the needle (ie, so it’s more shallow). I then advance a millimetre or so more, so I can see I’m in the centre of the vein, and watch on the screen as I slide the cannula off and into the vessel.

5) Secure that cannula!

You’ve got it in… now make sure it stays in: tape that sucker down! Dry off the area thoroughly and secure it like you would a paediatric cannula. Hint: a bit of Friar’s Balsam (tincture of benzoin) or Cavilon (™) is particularly useful on sweaty skin, to help things to stick down.

6) Practice, practice, practice!

This is just my technique - different things work best for different people. Practice this skill, ask people for tips, and try them out! It takes practice,a little experimentation and active learning to be a master at this skill.

Acknowledgements: Many thanks to Dr Adrian Goudie, Dr Leanne Hartnett and Dr Lindsay Bridgford, for their tips and tricks which have helped me refine my IV cannulation technique!


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