ORLANDO – Short, fixed cannulas can deliver filler products to augment multiple areas of the face, including nasolabial folds, the dorsum of the nose, and under the eyes, according to Dr. Doris Hexsel.
The small caliber, short cannulas also offer greater precision for filler placement, compared with the longer, flexible cannulas currently on the market, said Dr. Hexsel of the department of dermatology at Pontificia Universidade Católica do Rio Grande (Brazil) do Sul.
Dr. Doris Hexsel
Cannulas are disposable, can be attached to different syringe types, and can replace needles for most facial filler indications, Dr. Hexsel said. One notable exception is in the treatment of superficial lines or defects, where she said she still recommends the use of a needle.
Cannulas can deliver a wide range of filler products. "Anything we inject with needles we can also inject with cannulas," Dr. Hexsel said at the annual meeting of the Florida Society of Dermatologic Surgeons.
All cannulas with a rounded end typically cause less bruising and trauma, compared with needles. Cannulas also help to avoid other needle-related adverse events, Dr. Hexsel said. Perforation of the veins or arteries and accidental injection of fillers into vessels are the most serious examples.
Facial augmentation via cannula is "particularly useful for patients taking anticoagulants or who cannot bruise because they have a social event," Dr. Hexsel said. Reduction of the risk of a sharps injury is a plus for physicians, she added.
Cannulas cannot puncture the skin, so a needle stick is still required to make an entry hole. Proponents of long cannulas will point to a need for only one entry point, Dr. Hexsel said, but "a single orifice and use of a long cannula cannot reach all indications." Nasolabial folds, for example, require at least two entry points to treat.
Dr. Hexsel designed a cannula that she and her colleagues compared with a standard needle in a prospective, randomized, phase II bilateral study of 25 women (Dermatol. Surg. 2011 Oct. 19 [doi:10.1111/j.1524-4725.2011.02195.x]). The metallic cannula safely and effectively delivered hyaluronic acid for nasolabial fold augmentation and was associated with less pain, edema, hematoma and redness at the site, compared with the side treated with a needle. At day 3, the mean Modified Fitzpatrick Wrinkle Scale was comparable for both treated sides of the face (from 2.40 at baseline to 1.46 on the cannula-injected side and from 2.40 to 1.48 on the needle-injected side).
Photos courtesy Dr. Doris Hexsel
Dr. Hexsel uses her cannula to deliver filler and improve the appearance of dark circles under a patient's eyes.
Another use for cannulas is to deliver filler products to correct any defects of the nasal dorsum after rhinoplasty, she said.
Cannulas can also deliver fillers to help improve the appearance of dark circles under the eyes. After Dr. Hexsel cleans and marks the area, she said she injects a small amount of lidocaine anesthetic. She said that she then makes a small hole with a regular needle and introduces the cannula. Only inject a small amount of filler product at a time, she said. "You can ask patients to participate. I can put in a little Restylane under the eyes, give the patient a mirror, and ask them where they want more." The patient leaves with nothing visible; a small micropore dressing can be placed over the entry points.
Dr. Hexsel disclosed holding design patents on cannula devices not yet available in the United States.