Fillers: the best technique for inserting a cannula
Bad cannula technique is a real bugbear in medical aesthetics. Often, aesthetic clinicians make too many insertion points, or place their pilot hole in the wrong place, and then insert the cannula too roughly. This poor practice causes unnecessary trauma for the patient.
In this blog, Dr Tim Pearce shares his tried and tested method for comfortably inserting a cannula that will improve your stability and technique, reduce pain and the risk of trauma and bruising for your patient, and ultimately make you a better injector.
Do you feel anxious about causing complications? Many clinicians feel so overwhelmed with the thought of causing a vascular occlusion that it stops them growing their aesthetics business. Dr Tim is currently hosting a webinar series to help you overcome your fear of complications so that you can uplevel your knowledge, and increase your CPD-certified learning to build a successful aesthetics business. Sign up here >>
How to create a pilot hole for your cannula
The pilot hole you create is the track you want your cannula to go down. Therefore, when you create it, have it clear in your mind that it must be congruent with the direction that your cannula is heading. There is no point in making a hole and then putting your cannula in at a different angle, explains Dr Tim.
It is also vital to remember that the needle (used for entry) is only required to go through the thicker connective tissue – only puncturing the dermis – and does not need to go all the way down the intended route of your cannula. Once you are into hypodermic fat the cannula will push the fat out the way, therefore, deep insertions with the pilot hole needle are unnecessary, causing more bruising (by puncturing vessels) for no additional benefit.
Next, you should ensure that you use a needle gauge that is equal to or slightly bigger than the cannula you will be using. It can be equal because the skin stretches a little, however, a slightly bigger entry hole makes it easier to guide in your cannula. Although, there is no requirement for an overly large or gaping entry hole.
When creating the pilot hole, you should only insert approximately a third of the needle in the direction that you want to treat with the cannula, stopping once through the dermis and extracting the needle, always maintaining the direction.
A word of caution from Dr Tim is to avoid doing certain additional steps that he regularly notices when watching other aesthetic injectors. Following entry, many attempt to make the hole bigger to make insertion of the cannula easier. This is usually practised with a stirring technique of the needle but is counter intuitive. If you stir or rotate the needle around once placed into the tissue, you will simply be dragging a sharp tip around in the fat or muscle causing unnecessary trauma. The hole that you need to get through with your cannula is surrounded by the non-sharp part of the needle, hence it will not make the hole larger. He also advises against the practice of dragging the needle out and flicking it to use the sharp end to create a small cut through the skin to make the entry slip larger. Despite being trained this way initially himself, he does not believe it is necessary.
To back up why he regards these two additional steps are unnecessary, Dr Tim explains how to put the cannula into the dermis once you are ready.
How to enter the cannula into the dermis
When placing the cannula into the tissue after creating the pilot hole, you must not simply jab until it goes in, cautions Dr Tim. This is a common practice he witnesses, practitioners ‘jabbing’ with the cannula hoping that it will hit the right spot eventually. All too often, this results in pushing against dermis that will not let you in. If you continue and just push harder, you eventually cause trauma from allowing a blunt needle to force its way into the skin.
You must find the easy access route and can achieve this by gently tapping around the hole, waiting for it to slide in. This technique works very well, and if there is a tiny drop of blood or some other lubrication, the cannula slides along the surface and when it finds the right space it will slip into the hole. Getting through the dermis is usually the hardest part when using a cannula.
How to navigate through the dermis
As you will recall, the aim is to be angled in the same way that you initially created the pilot hole. This should be in alignment with where you are going with your cannula.
Once you have slid the cannula through the dermis, the tip should be in the hypodermic fat. At this point, you can change the angle of insertion and stay in a single tissue layer as you pass your cannula gently into place. It is crucial to be gentle – if you are rough and tear through tissues rather than allowing them to be pushed out of the way gently, you will negate many of the benefits of using a cannula. Feel your way, look for that easy passage, and change directions in multiple ways until a track is found.
When navigating underneath the skin, you will occasionally come up against tissue that blocks your path with the cannula tip getting stuck against, or attached to, various types of connective tissue. If you do not pull the cannula outwards to free you up and allow you to change angle and find another path, you will likely drag the tissue with your tip as you try to move it left and right at the same depth. This means you will continue to find it impossible to navigate a way through.
If your attempts to reposition and find a new pathway do not work, you can try to create some negative pressure in the tissue to create a bit of space. This is achieved by grasping the skin from above your entry zone and lifting it. This action will also lift the tissue beneath slightly and provide additional opportunity for you to navigate through the tissue with your cannula.
Another top tip from Dr Tim – a semi-magical trick, as he jests – is to excrete a tiny bleb of filler. Upon finding tissue that you cannot push past, retract your cannula a little, and deposit a minute amount of filler. This often opens a space within the tissue that allows the cannula to slide through more readily to enable you to continue your journey or path until you reach the end point where you want to be with your cannula ready for the dermal filler treatment. At this point you can start to gently lay down filler in retrograde or entrograde injections; it is often appropriate to do both to gently fill the area.
Dr Tim concludes that with some patience in the early stages, you can usually dramatically reduce the level of discomfort for your patient and any post-procedural bruising that might occur when using some rougher techniques.
If you are unsure about using cannulas and the benefits of their use, have a read of some additional blogs from Dr Tim including, is needle or cannula safer for dermal fillers? and 6 ways to reduce severe vascular occlusion with cannulas.
Dr Tim loves to hear from his followers, so why not drop him a comment or question on social media; you can find Dr Tim Pearce on Instagram.
Aesthetics Mastery Show
The best method to insert a cannula
In this episode Dr Tim explains the tried and tested method for inserting a cannula that will improve stability and technique, reduce the risk of trauma & bruising for patients, and ultimately make life much easier as an injector! Watch the full Aesthetics Mastery Show here.
The video has been watched thousands of times already and has great comments from viewers, including patients as well as practitioners. Feedback on the youtube page includes:
“I really appreciate your video. All the techniques and tricks are the techniques I have used for years after being trained in diagnostic radiology and the “stirring”technique especially is one that made me cringe. I’m glad someone like you wants to help other injectors by posting.”
“I am so glad you posted this video. I see far too many clinicians causing more trauma than necessary with cannulas! Let’s remember the reason we use cannulas to begin with lol”
“Incredibly useful tips. Thank you”
“Great practical advice”
Read more comments and join in the debate on our YouTube channel.
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Dermal Filler eLearning Courses
If you want to increase your knowledge about safe and effective dermal filler injectable treatments, Dr Tim Pearce offers a series of fabulous courses. The foundation level is a popular starting point, with many delegates continuing to complications courses focused around safety, including how to minimise the risk and how to handle things if the worst occurs:
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Dr Tim Pearce eLearning
Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.
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