Are large diameter cannulas safe in nonsurgical rhinoplasty?

Nonsurgical filler rhinoplasty is among the fastest growing cosmetic procedures worldwide1 and is also the one with greatest risk of ocular complications.2 Although still rare, intravascular injections of the filler material can cause serious complications, culminating in amaurosis and skin necrosis.1,3– 6 Ischemic lesions result primarily from the insertion of the filler into the lumen of blood vessels, especially arterial ones, with subsequent vascular thrombosis. Blunt cannulas are suggested in highrisk regions in an attempt to reduce the possibility of vessel cannulation,7 as these require greater forces for intraarterial penetration (especially large diameter ones) compared to similarsized needles.8 In previous force assessments,9 22 gauge cannulas were unable to penetrate the angular branch of the facial artery. Altogether, this can induce a [false] perception of being riskfree merely by using a large— diameter cannula. Here, two rare cases are reported to exemplify and raise concern for severe vascular complications due to nonsurgical rhinoplasty using hyaluronic acid (HA) injected though 22 gauge cannulas.

Nonsurgical filler rhinoplasty is among the fastest growing cosmetic procedures worldwide 1 and is also the one with greatest risk of ocular complications. 2 Although still rare, intravascular injections of the filler material can cause serious complications, culminating in amaurosis and skin necrosis. 1,[3][4][5][6] Ischemic lesions result primarily from the insertion of the filler into the lumen of blood vessels, especially arterial ones, with subsequent vascular thrombosis.
Blunt cannulas are suggested in high-risk regions in an attempt to reduce the possibility of vessel cannulation, 7 as these require greater forces for intra-arterial penetration (especially large diameter ones) compared to similar-sized needles. 8 In previous force assessments, 9 22 gauge cannulas were unable to penetrate the angular branch of the facial artery. Altogether, this can induce a [false] perception of being risk-free merely by using a large-diameter cannula.
Here, two rare cases are reported to exemplify and raise concern for severe vascular complications due to nonsurgical rhinoplasty using hyaluronic acid (HA) injected though 22 gauge cannulas.    Practitioners are thus urged to understand that the keys to safety are diverse and not confined to the injection apparatus: not just using blunt cannulas, but also targeting only the midline of the nose, with precise, low-pressure, low-volume, and deep-layer filler injections. 12 A growing number of studies focusing on the nasal region demonstrate that injection into the supraperiosteal or supraperichondrial layers can significantly reduce the risk of complications. 2,13 Blunt by nature, cannulas can make it difficult to accurately determine the exact depth of product placement. 14 Still, using a sharp needle can potentially result in arterial embolization, even when the needle is in constant contact with the periosteum. 15 Regardless of the chosen device (cannula or needle), emphasis must be placed on proper injection techniques. 16 If safety is defined as the diminished ability to penetrate the arterial vasculature, it can still be stated that large diameter cannulas are safer than needles and thinner cannulas. The application of the filler using cannulas presents greater injection precision in the chosen plane, since the material tends not to recede into the more superficial layers, thus reducing the risk of vascular events and unsightly defects. 8 However, the cases reported here should alert injectors that choosing a safer injection instrument alone does not mean the procedure is exempt from intra-arterial filler deposition.

ACK N OWLED G M ENTS
The authors are grateful to Raisa Bento de Albuquerque, MD, for assistance with clinical case information that improved the article significantly.

FU N D I N G I N FO R M ATI O N
The authors received no financial support for the research, authorship, and publication of this article.

CO N FLI C T O F I NTE R E S T
Dr F.N. Magacho-Vieira is a regular speaker and participates in advisory boards for Galderma. A.P. Santana declares no potential conflict of interest in the subject matter or materials discussed in this article.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

E TH I C S S TATEM ENT
No institutional approval was required for this publication. The authors confirm that the ethical policies of the journal, as noted on the journal's author guidelines page, have been adhered to.

PH OTO CO N S ENT
The patients in this article have given written informed consent to publication of their case details and photos.