17 minute read
Using Cannulas
Dr Marcus Mehta explores the use of cannulas for dermal filler placement and provides his tips for success for those newer to aesthetic medicine
The use of blunt-ended cannulas has increased in the last five years, with more evidence emerging showing that they allow for a safer dermal filler treatment of key areas of the face. Studies have indicated that blunt-ended cannulas are able to reduce trauma to tissues, decrease the risk of vascular injury and also lessen bruising, meaning lower downtime for patients.
In my practice, I now use cannulas for more than 80% of my patient cases, and as the industry advances, I have seen more and more practitioners switch to cannula use for most areas of the face.
One of the fears practitioners have when switching from needle to cannula is the technicality involved, which requires extra training and practice to become competent at. Aesthetic medicine education has traditionally focused around needle use rather than cannula because it is easier to teach and learn when starting out. In this article, I will explore the pros and cons of cannula use, explain how I use cannulas in my practice and provide some of my top tips to get the most out of them.
Why use cannulas?
There are many benefits to using cannulas for your dermal filler treatments, which include: lowered risk, less downtime and accurate and different product placement.
Lowered risk When injecting filler, one of the most severe risks is causing obstruction to a blood vessel. Vascular occlusion can occur as a result of compression or direct occlusion when filler blocks a blood vessel due to inadvertent puncture of the vessel wall.1,2 Injections with a cannula have been shown in the literature to be less likely to cause vascular occlusion due to them being blunt (Figure 1).3
Although cannulas have a lowered risk of causing a vascular occlusion, it is important to note that it is not impossible. When we are speaking about gauge of needles or cannulas, the larger the number the smaller the diameter of the instrument. Cannulas that are 27 gauge and smaller have the same arterial penetration force as a needle, so offer no safer advantage.4 One clinical study examined 294 penetration procedures of the facial and superficial temporal arteries performed in four fresh frozen cephalic specimens using both needles (20, 22, 25, and 27 gauge) and cannulas (22, 25, and 27 gauge). The study showed that all measured sizes of cannulas except 27 gauge required greater forces for intra-arterial penetration compared with correspondingly sized needles. The authors stated that this confirmed the safety of 22 and 25 gauge cannulas for the use of facial soft-tissue fillers; however, they found that 27 gauge cannulas required similar forces as 27 gauge needles, indicating that an artery could be penetrated with a similar force independent of whether the injector used a 27 gauge needle or a 27 gauge cannula.4
Different product placement Using a cannula for filler allows for longer threads of product to be injected, meaning the practitioner is able to treat larger areas and ensure a smoother result, especially when injecting in the subcutaneous fat. In my experience, this allows for a cosmetic result that is better for the patient as it reduces the risk of aggregation of the filler which can cause lumps.
When using a cannula, you get tactile feedback when moving through facial layers, especially when pushing through the superficial musculoaponeurotic system (SMAS). This allows you to accurately know that you are sub-SMAS and in deep fat when injecting. This is not possible with a needle when the only real feedback you get is when you touch the periosteum, denoting you are supra-periosteal with the needle tip.
A 2017 study where 10 fresh-frozen cephalic foreheads (nine male, one female) were injected with radiopaque material using both needles and cannulas demonstrated the accuracy of cannula use.5 In this study, the needle injection relied on a perpendicular transcutaneous approach, whereas cannulas were moved in the supra-periosteal plane until reaching the same location as the needle – here, radio opaque material was injected. In this study, the authors noted that in 60% of injections using a needle, the implanted material changed its plane; this was not observed when using the cannula (0%; P=0.003). They went on to say that if precision in filler injection is defined as the filler material remaining in the plane of intended implantation, then using cannulas resulted in a more precise injection of material as compared to needles. Applications with needles resulted in the distribution of material into more superficial layers, which was not noted for cannulas.5
Another 2017 study involved the injection of cadaver heads with dye material and soft-tissue fillers at multiple aesthetic facial sites on the supraperiosteum.6 The authors concluded that although direct extrapolation from cadavers to the in vivo situation cannot be made, the use of a cannula resulted in more precision in product placement. This was because with the sharp needle, the material was injected on the periosteum, and then migrated in a retrograde direction along the trajectory of the needle path, ending up in multiple anatomic layers.6
The downsides of cannula use
Although there are many benefits to using cannulas, there are also considerations to be mindful of. As mentioned above, much like aspiration with a needle,
Figure 1: Needle vs cannula for reducing risk of vascular occlusion1,2 using a cannula is not a fail-safe option for preventing vascular occlusion. It is still possible to penetrate a vessel and cause damage with a cannula.4 In my practice I use 22 gauge and 25 gauge cannulas, but never a 27 gauge or anything smaller to reduce the risk of vessel penetration. The other consideration is the patient fear surrounding cannulas, which can be difficult for practitioners to navigate. In my experience, patients are often more fearful of cannulas due to the fact that they appear to be longer/larger than needles. I find new patients who have seen cannula treatment on social media, for example, are quite scared as it can look more painful on video despite often being more comfortable than needles. I always try to educate my patients, and explain what a cannula is and the benefits before beginning treatment, and I try to avoid showing them the instrument itself. As mentioned above, introductory dermal filler courses usually focus on using needles, so before you get started with cannulas you would require additional training (and a lot of practice) which takes time and is a cost to you and your business. However, this is integral to ensure you are skilled and knowledgeable in using this instrument. The other downsides which relate more to your business are that using cannulas might take slightly more treatment time than using a needle, and it’s an additional expense as dermal fillers often do not automatically come with a cannula. Top tips for success
Choosing a cannula The length of cannulas can range from short 13mm cannulas up to much longer 90mm cannulas. The area of the face you are treating will determine the cannula length best suited. For example, in the jawline I often use a 50mm cannula to help reach the chin tip, and along the jawline itself and in the lips and mid-face a 25mm or 30mm. When I started injecting with a cannula around four years ago, I found longer cannulas harder to use. My advice would be to get familiar with a shorter length before progressing on to longer cannula sizes such as a 50mm. When it comes to cannula brands, there are many brands available including TSK, Silkann and SoftFil. I personally use the SoftFil cannulas as I find the EasyGuide tool, which is a pre-hole needle guide, means I know where the insertion point is and I can get to the required depth easily. Other ways to help not lose the entry hole is to gently squeeze the skin so a small dot of blood forms on the skin, or better still, have an assistant pass you the cannula whilst you are still looking at where the insertion point has been made.
Practice makes perfect It’s important to take your time and practise using a cannula in different areas of the face. Sometimes, when you first insert a cannula you will find it difficult to progress from the insertion point. My advice would be to not panic, but spend time slowly attempting to progress the cannula gently; sometimes spinning the cannula can help move past this initial point. One of the key things I learnt when using a cannula was being able to feel the layers as you go through them. When treating the mid-face for example – deep medial cheek fat or pre-zygomatic space – you want to be below the SMAS to access the deep fat. To get there you must pass through the SMAS with the cannula, and you will consciously feel a pop when you do. Practising this sensation allows you to be sure you’re in the correct plane – going on a cadaver training course is a great way to do this.
Think about new treatment areas You should start to consider different areas where you could use a cannula, for example, the lips. For many new and even experienced practitioners who have been in the industry for a while, they are used to treating the lips with a needle, and the transition to using a cannula here is challenging as it takes some time to feel confident. My patient demographic is between 40 and 70 and I use a cannula to treat almost every lip I see in clinic. I find it volumises much more evenly, reduces pain and gives a result with much less downtime than a needle.
Consider cannulas in practice
Cannulas form an important part of modern aesthetic practice, and learning to use them competently is a key skill in developing as a practitioner. The main benefit is reduced risk to key structures beneath the skin and allowing for different product placement; however, it is important to be mindful that vascular injury can still occur with a cannula.
As with all things in aesthetic medicine, combining treatment techniques as well as modalities is one of the best ways to achieve good results for your patients. I often use a needle alongside cannulas, for example, when treating the lips I use a cannula in the lip body and a needle in the vermillion border, or when treating the mid-face I use supraperiosteal boluses with a needle combined with cannula in the deep medial cheek fat. Having a good understanding of treatment techniques which often combine needle and cannula use allows for us to offer treatments that are the most effective and ‘above all’ safe for our patients.
Dr Marcus Mehta is an aesthetic practitioner with a background in medicine and a post-graduate training in dermatology. He is the director of Harley Academy and the co-founder of STORY Clinics and Comma. Qual: BSc (hons), MBBS, PgDip (Derm)
REFERENCES
1. Martyn King, Lee Walker, Cormac Convery, and Emma Davies,
Management of a Vascular Occlusion Associated with Cosmetic
Injections, J Clin Aesthet Dermatol. 2020 Jan; 13(1): E53–E58. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7028373/> 2. Murray G, Convery C, Walker L, Davies E. Guideline for the
Management of Hyaluronic Acid Filler-induced Vascular
Occlusion. J Clin Aesthet Dermatol. 2021 May;14(5):E61-E69.
Epub 2021 May 1. 3. Alam, M., Kakar, R., Dover, J.S., Harikumar, V., Kang, B.Y.,
Wan, H.T., Poon, E. and Jones, D.H. (2021). Rates of Vascular
Occlusion Associated With Using Needles vs Cannulas for Filler
Injection. JAMA Dermatology, 157(2), p.174. 4. Pavicic, T., Webb, K.L., Frank, K., Gotkin, R.H., Tamura, B. and
Cotofana, S. (2019). Arterial Wall Penetration Forces in Needles versus Cannulas. Plastic and Reconstructive Surgery, 143(3), pp.504e512e. 5. Erlbacher, K. (2017). Precision in Dermal Filling: A Comparison
Between Needle and Cannula When Using Soft Tissue Fillers. [online] JDDonline - Journal of Drugs in Dermatology. <https:// jddonline.com/articles/precision-in-dermal-filling-a-comparisonbetween-needle-and-cannula-when-using-soft-tissue-fillers-
S1545961617P0866X/> 6. Van Loghem, J.A.J., Humzah, D. and Kerscher, M. (2017). Cannula
Versus Sharp Needle for Placement of Soft Tissue Fillers: An
Observational Cadaver Study. Aesthetic surgery journal, [online] 38(1), pp.73–88.
Your patients with excess weight have the will. You can offer them the way.
Patients achieved signifi cant and sustained weight loss, in conjunction with reduced calorie intake and increased physical activity, in 1-year and 3-year trials vs placebo 1,2*
Similar to natural glucagon-like peptide-1, Saxenda® works to decrease appetite and thereby reduce food intake3†
This is not a real patient but only an illustration.
This material relates to the adult indication only. Please refer to SmPC for full indication.
Adults: Saxenda® is indicated as an adjunct to a reduced-calorie diet and increased physical activity for weight management in adult patients with an initial Body Mass Index (BMI) of ≥ 30 kg/m2 (obesity) or ≥ 27 kg/m2 to < 30 kg/m2 (overweight) in the presence of at least one weight-related comorbidity such as dysglycaemia (pre-diabetes or type 2 diabetes mellitus), hypertension, dyslipidaemia or obstructive sleep apnoea. Treatment with Saxenda® should be discontinued after 12 weeks on the 3.0 mg/day dose if patients have not lost at least 5% of their initial body weight. If you would like to request a visit from a representative please contact us on obesityuk@novonordisk.com For all product related enquiries please contact Novo Nordisk Customer Care Centre on 0800 023 2573.
†The exact mechanism of action of liraglutide is not entirely clear.
Prescribing Information
Please refer to the Saxenda® summary of product characteristics for full information. Saxenda® Liraglutide injection 3 mg. Saxenda® 6 mg/mL solution for injection in a pre-fi lled pen. One pre-fi lled pen contains 18mg liraglutide in 3mL. Indication: Adults: Saxenda® is indicated as an adjunct to a reduced-calorie diet and increased physical activity for weight management in adult patients with an initial Body Mass Index (BMI) of ≥ 30 kg/m2 (obesity) or ≥ 27 kg/m2 to < 30 kg/m2 (overweight) in the presence of at least one weight-related comorbidity such as dysglycaemia (pre-diabetes or type 2 diabetes mellitus), hypertension, dyslipidaemia or obstructive sleep apnoea. Adolescents (≥12 years): Saxenda® can be used as an adjunct to a healthy nutrition and increased physical activity for weight management in adolescent patients from the age of 12 years and above with obesity (BMI corresponding to ≥30 kg/m2 for adults by international cut-off points) and body weight above 60 kg. Posology and administration: Saxenda® is for once daily subcutaneous use only. Is administered once daily at any time, independent of meals. It is preferable that Saxenda® is injected around the same time of the day. Recommended starting dose is 0.6 mg once daily. Dose should be increased to 3.0 mg once daily in increments of 0.6 mg with at least one week intervals to improve gastro-intestinal (GI) tolerability. Treatment with Saxenda® in adults should be discontinued after 12 weeks on the 3.0 mg/day dose if patients have not lost at least 5% of their initial body weight. Daily doses higher than 3.0 mg are not recommended. No dose adjustment is required based on age but therapeutic experience in patients ≥75 years is limited and not recommended. No dose adjustment required for patients with mild or moderate renal impairment or mild or moderate hepatic impairment but it should be used with caution. Saxenda® for adolescents from the age of 12 to below 18 years old a similar dose escalation schedule as for adults should be applied. Treatment with Saxenda® in adolescents should be discontinued and re-evaluated if patients have not lost at least 4% of their BMI or BMI z score after 12 weeks on the 3.0mg/day or maximum tolerated dose. Saxenda® is not recommended for use in patients with severe renal impairment including endstage renal disease, or severe hepatic impairment or children below 12 years of age. Contraindications: Hypersensitivity to the active substance or to any of the excipients. Special warnings and precautions for use: There is no clinical experience in patients with congestive heart failure New York Heart Association (NYHA) class IV and Saxenda® is not recommended for use in these patients. It is also not recommended in patients with eating disorders or treatment with medicinal products that may cause weight gain. Use of Saxenda® is not recommended in patients with infl ammatory bowel disease and diabetic gastroparesis since it is associated with transient GI adverse reactions including nausea, diarrhoea and vomiting. Acute pancreatitis has been observed with the use of GLP-1 receptor agonists, patients should be informed of the characteristic symptoms. If pancreatitis is suspected, Saxenda® should be discontinued. If acute pancreatitis is confi rmed, Saxenda® should not be restarted. In weight management clinical trials, a higher rate of cholelithiasis and cholecystitis was observed in patients on Saxenda® than those on placebo, therefore patients should be informed of characteristic symptoms. Thyroid adverse events such as goitre have been reported in particular in patients with pre-existing thyroid disease. Saxenda® should be used with caution in patients with thyroid disease. An increase in heart rate was observed in clinical trials. For patients who experience a clinically relevant sustained increase in resting heart rate, treatment with Saxenda® should be discontinued. There is a risk of dehydration in relation to GI side effects associated with GLP-1 receptor agonists. Precautions should be taken to avoid fl uid depletion. Patients with type 2 diabetes mellitus receiving Saxenda® in combination with insulin and/or sulfonylurea may have an increased risk of hypoglycaemia. Episodes of clinically signifi cant hypoglycaemia have been reported in adolescents (≥12 years) treated with liraglutide. Adolescents should be informed about the characteristic symptoms of hypoglycaemia and the appropriate actions. Fertility, pregnancy and lactation: Saxenda® should not be used during pregnancy. If a patient wishes to become pregnant, or pregnancy occurs, treatment with Saxenda® should be discontinued. It should not be used during breast-feeding. Undesirable effects: Very common (≥1/10); nausea, vomiting, diarrhoea, constipation, headache. Common (≥1/100 to <1/10); hypoglycaemia, insomnia, dizziness, dysgeusia, dry mouth, dyspepsia, gastritis, gastro-oesophageal refl ux disease, abdominal pain upper, fl atulence, eructation, abdominal distension, cholelithiasis, injection site reactions, asthenia, fatigue, increased lipase, increased amylase. Uncommon (≥1/1,000 to <1/100); dehydration, tachycardia, pancreatitis, cholecystitis, urticaria, malaise, delayed gastric emptying Rare (≥1/10,000 to <1/1,000); anaphylactic reaction, acute renal failure, renal impairment. The Summary of Product Characteristics should be consulted for a full list of side effects.
MA numbers and Basic NHS Price:
NI: EU/1/15/992/003. 5 x 3 ml pre-fi lled pens £196.20. GB: PLGB 04668/0409. 5 x 3 ml pre-fi lled pens £196.20. 3 x 3 ml pre-fi lled pens £117.72. Legal category: POM. Full prescribing information can be obtained from: Novo Nordisk Limited, 3 City Place, Beehive Ring Road, Gatwick, West Sussex, RH6 0PA. Marketing Authorisation Holder: Novo Nordisk A/S, Novo Allé, DK-2880 Bagsværd, Denmark. Date last revised: March 2022
* In the 1 year trial patients taking Saxenda® (n=2487) had a baseline body weight of 106.2 kg. Completers’ (n=2437) mean weight loss at week 56 of treatment was 8.4 kg. Patients taking placebo (n=1244) had a baseline body weight of 106.2 kg. Completers’ (n=1225) mean weight loss at week 56 of treatment was 2.8 kg1, p<0.001. In the 3 year trial Patients taking Saxenda® (n=1505) had a baseline body weight of 107.5 kg. Completers’ (n=1472) mean weight loss at week 160 of treatment was 6.5 kg. Patients taking placebo (n=749) had a baseline body weight of 107.9 kg. Completers’ (n=738) mean weight loss at week 160 of treatment was 2.0kg2, p<0.0001. References: 1. Pi-Sunyer X, Astrup A, Fujioka K, et al; for the SCALE Obesity and Prediabetes NN8022-1839 Study Group. A randomised, controlled trial of 3.0 mg of liraglutide in weight management. N Engl J Med. 2015;373(1):11-22. 2. le Roux CW, Astrup A, Fujioka K, et al; for the SCALE Obesity and Prediabetes NN8022-1839 Study Group. 3 years of liraglutide versus placebo for type 2 diabetes risk reduction and weight management in individuals with prediabetes: a randomised, double-blind trial. Lancet. 2017;389(10077):1399-1409. 3. Saxenda® Summary of product characteristics, NI&GB. Bagsvard, Denmark: Novo Nordisk A/S.
