Cold air combo knocks out nerve blocks

San Antonio - A small study suggests that cold air anesthesia in combination with lidocaine outperforms lidocaine alone in patients receiving Restylane (hyaluronic acid, Q-Med) and Botox (botulinum toxin A, Allergan) injections.

"Most dermatologists use nerve blocks (dental blocks) for anesthesia prior to injecting Restylane, because Restylane hurts more than collagen. However, doing nerve blocks offers its own drawbacks - it's a painful procedure, and the patient is numb for many hours afterwards. And it distorts the facial anatomy a little bit," says Philip Hughes, M.D., a dermatologist in private practice in San Antonio and the study's author.

To determine whether forced cold air could provide adequate anesthesia for injection procedures, Dr. Hughes tested a Cryo 5 unit (Zimmer) on a total of 23 female patients in a non-blinded comparison study.

As part of his analysis, he gave seven patients receiving botulinum toxin A injections topical LMX 5 (ELA-Max/lidocaine 5 percent, Ferndale Laboratories), applied for 30 minutes, on one side of the face and cold air anesthesia on the other. As measured with a MiniTemp noncontact laser temperature device (Raytek), the cold air produced surface temperatures of 18 degrees to 20 degrees C. The injections themselves consisted of four units of botulinum toxin reconstituted with normal saline plus preservative in two lateral canthal injections.

In this trial, Dr. Hughes says, "Patients were equally divided as to whether they preferred the topical lidocaine or the cold air. Cold air was about equivalent to topical lidocaine in terms of pain relief." Specifically, three patients reported less pain with the lidocaine; two reported less pain with cold air; and two reported equal discomfort (p>0.1).

Dr. Hughes also used the same type of botulinum toxin injections in seven additional patients, whom he gave topical lidocaine alone on one side and lidocaine plus cold air on the other.

"Most of these patients preferred the combination," he reports. In particular, five preferred the combination, while two preferred lidocaine alone (p>0.1).

Similarly, Dr. Hughes compared topical lidocaine alone versus topical lidocaine plus cold air in nine additional patients whom he was treating with nasolabial fold dermal injections of hyaluronic acid.

"With the Restylane injections," he says, "the preference leaned significantly towards the combination in terms of pain relief (p = 0.05). The Restylane findings are the big news, because botulinum toxin injections aren't that unpleasant as long as one uses a topical anesthetic."

In the hyaluronic acid trial, eight patients preferred the combination of topical lidocaine and cold air, versus just one who preferred lidocaine alone. Dr. Hughes also asked patients to rate their discomfort levels on an ascending 10-point scale. In this analysis, six of the nine hyaluronic acid patients said the discomfort with the analgesic combination was minimal (a score of 1). Dr. Hughes observed no adverse side effects in these trials.

"When first applying the cold air, using a noncontact laser temperature device is important to avoid overcooling the patient's skin or even causing frostbite, as the cold air machine blows air at minus 34 degrees C," he says. "With experience, we found that if one sets the cold air blower at a fan setting of 2, 6 inches away from the skin, for a few seconds, this achieves the desired endpoint," namely, a skin surface temperature of 20 C.

"There's a whole series of procedures for which cold air anesthesia provides satisfactory pain relief. These include chemical peels, sclerotherapy, scissors excision of skin tags, steroid injections, local anesthetic injections, pulsed dye laser procedures and laser hair removal. However, cold air anesthesia does not work well with ablative laser procedures like the erbium YAG or CO² laser. Since it blows the laser plume all over the place, it makes it difficult for the suction device to suck up the plume," adds Dr. Hughes, who has used cold air anesthesia in several hundred procedures to date.