Reviewing radiofrequency

Though this column typically focuses on lights and lasers, mentioning radiofrequency (RF) is clearly indicated for many reasons.

The first is that RF devices emit waves within the electromagnetic spectrum, which is the same spectrum from which the lasers originate. The second is that these devices are now becoming so common in the aesthetic market that they deserve consideration.

When we mention radiofrequency we are essentially referring to what are commonly known as radio waves. These waves are part of the electromagnetic spectrum that we have discussed many times in the past. In everyday life, radio waves are used to transport information through the atmosphere. We use them every day with television, cellular phones, and AM and CB radios.

Providing nonspecific heat to deep dermis and subcutaneous tissues was the idea behind nonablative lasers.

Heating collagen resulted in the stimulation of collagen production, yet this did not consistently translate into visible clinical results.

The idea behind RF heating is similar, except that these devices have the ability to heat deeper into the subcutaneous tissues than we have seen with infrared lasers.

One group has also demonstrated that the heating results in contraction of the fibrous septae in the subcutaneous tissues, resulting in clinical tissue tightening and lifting. In fact, these devices are first on the market to make the claim of tissue "tightening."

A bit of history

RF first hit the dermatology literature in 2001 with the talk of RF ablative resurfacing.

Next came RF for hair removal, acne, scarring and rejuvenation. RF devices are now being touted as skin tighteners and cellulite reducers. RF energy comprises very long electrical waves. These waves can be delivered at different speeds (Hertz), fluence (J/cm²) and for different lengths of time (seconds). Increasing the Hz of a system would potentially increase the amount of heat generated in the target tissue. Increasing the length of delivery and the fluence also increases the heat delivered. The currently available RF devices come in monopolar (Thermage®), unipolar (Accent/Alma Lasers) and bipolar varieties (Aurora SR, Polaris WR/Syneron Medical; Accent/Alma Lasers; Aluma/Lumenis).

No one has yet decided which produces better clinical results for tissue tightening, deep (MRF/URF) or superficial (BRF) heating. In addition, the term URF is a new one, and the clinical difference between it and MRF remains to be shown. Yet, it seems fairly reasonable to assume that to alter fat and cellulite, deep subcutaneous heating would be required. MRF seems to be more painful to deliver than BRF, and frequently requires topical anesthesia or, in some cases, mild sedation.

Running hot and cold

The most important component to all deep-heating devices is adequate epidermal cooling. All types of RF systems do require cooling of the epidermis so as not to non-selectively heat and burn the skin.