Aesthetic nurse prescriber Jackie Partridge shares her tips and technique advice for treating the perioral area using a cannula
Lips are one of the most important features of the face and youthful, plump, full lips are something many people aspire to. Lip augmentation has gained momentum in recent years and is one of the most popular facial volumisation treatments.1 Successful, natural lip augmentation is often about looking at the proportions of a patient’s face to determine which shape best complements their other facial features. There is no single technique that suits every lip, and each practitioner will have their own unique treatment approach to achieve the desired results. Many practitioners ask me whether I prefer to augment the perioral area using a needle or cannula. My answer is always that the decision depends on what is presented clinically, the area I am working on and the outcome I am looking for. However, the use of a cannula in this area does present its advantages.
Benefits of cannulas in the perioral area
Traditionally, dermal fillers were injected using sharp tip needles. I like to use Restylane Kysse in the lips and it comes pre-packaged with two needles, as do other dermal filler brands such as Juvéderm, but using a blunt-tipped cannula for the injection of dermal filler in the lip has many benefits.
Treatment with a cannula has been found to result in significantly fewer bruises and be less painful, so is gaining popularity with patients.2,3 A needle gives several sharp pricks, rather than just one or two pricks with a cannula, so this is very appealing for patients and increases patient retention rates; those who are less likely to bruise are more satisfied with their overall treatment and experience.2 There is also less downtime associated, meaning patients can return to work sooner. The perioral area is highly vascular and the labial artery has several branches coming off it, which makes it more prone to bruising than other areas of the face. In patients who are more likely to bruise or swell, using a cannula has been shown to lessen this risk.2 According to Manhattan-based dermatologist Dr Anne Chapas, who was an investigator for a mid-face cannula study in the US, none of the 60 patients treated experienced arterial occlusion and the cannula reduced post-injection bruising and swelling.4 The safety profile of cannulas is considered higher than needles because the blunt end is more likely to glide past a vessel or a ligament rather than penetrate it, resulting in less trauma and bruising.5 The facial arterial system represents a danger zone for filler injections, as intra-arterial injection can potentially lead to widespread necrosis and even blindness.6 Minimising the risk of intra-arterial injection of fillers is therefore of paramount importance. There are also far fewer entry points with a cannula. By making one entry point lateral to the corner of the mouth, manoeuvrability is improved, and you can treat the whole perioral area, including the lips, the nasolabial folds and the oral commissures. By treating all these areas from one access point, the risk of bleeding, bruising and infection is reduced because there are less breaks in the skin.5 Additionally, when using a cannula, the practitioner can feel resistance from the structures that the cannula passes through. This enables you to judge when and how to apply pressure, and to clearly determine the direction of the cannula, as well as indicating which plane you are working in. If you are too deep, you will be injecting into subcutaneous fat and the product will not give as much projection.7
Advice for successful injections
A thorough understanding of the anatomy is essential for any successful aesthetic procedure. When treating the perioral area, an awareness of position and depth of the inferior and superior labial arteries is vital. However, every patient has anatomical variations, so to help me establish the position of the arteries before treatment, I always palpate the labial arteries before injecting. As with any procedure that breaks the skin’s surface, dermal fillers present a risk of infection, so an aseptic technique must be adopted. The mouth presents a higher risk of bacterial load than other areas on the face, so it is important to make sure that the field you are working in is as clean as possible.8 Do not drag the cannula across hair or other unclean surfaces as this can lead to contamination. The entry point is usually lateral to the corners of the mouth and I inject into the deep dermis. Each plane feels different; fat is very smooth, whereas more superficial planes feel slightly more resistant in places. You know that you’re in the right plane because it should feel effortless, with no pain or at the very most, slight discomfort for the patient.
You know that you’re in the right plane because it should feel effortless, with no pain or at the very most, slight discomfort for the patient
Choosing a cannula
It is vital that the correct size and length of cannula is used. A cannula that is too fine will behave just like a needle, which can give the practitioner a false sense of security and could result in vessel penetration.10 I don’t use a cannula that is narrower than 25 gauge, and this is my standard approach for all areas. My length of choice is a 38mm cannula, which is slightly longer than a standard needle at around half an inch;9 however, I still feel that I can control it in a safe way. I find that a 25 gauge 38mm is less likely to puncture a vessel and is a good length to reach to the midline of the perioral area or lip from each side when entering from the side of the mouth. It is important to select the size of the access needle carefully – it must be the appropriate size to break the skin at the access point and should be a slightly larger gauge than the cannula; some companies supply both the cannula and the appropriate needle together. The length of the cannula doesn’t impact safety greatly, as its blunt tip coupled with a greater flexibility allows the cannula to glide under the dermis with less trauma.10 I would say that the most important factor for me is the confidence and the experience of the practitioner. However, if the cannula is too long it can change the plane into which you inject as it travels through the tissue.
There are a variety of different brands of cannula on the market, so it is important that practitioners are knowledgeable about the brand they are using. Some brands have the bevel on the side of the cannula, while others have the bevel at the very end of the tip. The bevel should be in an upright position when injecting as the product will sit more superficially, ensuring that you are getting the benefit of the lift of the product within the dermis or subcutaneous tissue.
Drawbacks of cannula use
Although cannula injection methods offer many benefits to both patients and practitioners when treating the perioral area, there are still cases when needles are the best option of delivery. I find that I have more precision and control with a needle; however, one cadaver study by Humzah et al, which looked at the differences between needles and cannulas, concluded that the cannula showed more precision in the placement of product and a lower risk of intra-arterial injection complications.6 It’s my belief that as long as the plane that the cannula is positioned in is correct, needles and cannulas behave in the same way. In my hands, I find that needles are more precise than cannulas because when using cannulas, due to the longer length and flexibility, you are able to place a product up to 90mm away from the insertion point in some cases, which perhaps allows for a change in depth.
It is also important to bear in mind the cost of cannulas. A cannula is around £7, while a needle will come free when purchasing the product. From a business point of view, practitioners need to remember to think about costs when putting together their treatment pricing structure. However, the patients’ needs and the safety benefits of using a cannula or a needle should always be at the forefront of our priorities.
There will always be a place for injection methods using both cannula and needle depending on the technique, product and patient choice. It is well known that many patients appreciate the benefits of the cannula delivery method since there are generally fewer associated risks, less bruising and reduced downtime than with a sharp needle.6 It is essential that practitioners equip themselves with the essential anatomical knowledge, as well as familiarity with product types and injection techniques. This, combined with a clear examination and a thorough patient consultation, will determine the most appropriate modality of treatment to achieve the best aesthetic goals.
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