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Liposuction provides the most effective method of body contouring that we currently know. Its invasive approach is the direct subcutaneous disruption of fatty deposits followed by their vacuum extraction. The final result is a combination of the fat removed and how the overlying skin shrinks and adapts to its reduced underlying support structure. While effective, it is fairly traumatic to the tissues and substantial recovery is required in most cases.

Because of the desire to avoid liposuction surgery, the field of non-invasive body contouring has emerged in the past decade as an alternative treatment option. These are device-driven technologies that direct and drive various types of energies into the underlying tissues in an effort to either shrink fat, tighten skin or both. One of these energy technologies is that of radiofrequency. Known by the acronym RF, radiofrequency is the oscillation of electrical currents at radio frequencies. In essence, it is another name for radio waves which is one form of electromagnetic energy. Radiofrequency energy has been used in medicine for well over fifty years in such applications as radiofrequency ablation of tumors and magnetic resonance imaging to create images of internal structures of the human body.

The power of RF and its ability to penetrate tissues is a function of its wavelength (distance covered by one cycle of the wave) and its frequency. (the number of waves passing a given point in a second) The wavelength multipled by the frequency equals the speed of light. The frequency of RF energy is expressed in Hertz Units. (one Hz = one wave/second)  One thousand waves equals one kilohertz (KHz), one million waves equals one megahertz (MHz) and one billion waves equals one gigahertz. (GHz) Most RF waves are in the range of about 3 KHz to 300 GHz. As a common comparison, microwaves have radiowaves in the frequencies of 300 MHZ to 3 GHz. Exilis has RF energies in the 2 MHz range which can be seen to be just a fraction of the energy emitted by a standard kitchen microwave. Such wave oscillations affect underlying tissues by causing their molecules to vibrate creating a heating effect. The depth of wave penetration is ultimately controlled by the amount of power (watts), wavelength and the heat generated by the treated tissues. The Exilis device has been shown to penetrate up to 2.5 cms (one inch) below the skin.

Exilis treatments are delivered through a handheld wand device known as a transducer. It is a monopolar RF device that will rapidly heat up tissues, known as the therapeutic thermal temperature. The safety of the device is the real time monitoring of the skin’s temperature so it does not become too hot/burned. This allows the maximum of power to be delivered with reasonable comfort. A liquid gel interface between the skin and transducer is critical as well as the technician keeping the transducer head in motion based on the skin’s temperature.  The software of the Exlis device has a unique energy flow control feature so that it eliminates energy peaks to ensure more uniform energy distribution. It is these energy peaks, which if uncontrolled, that can lead to intermittent patient discomfort.

RF wave stimulation breaks down the well known triple-helix structure of collagen in the dermis of the skin. This unraveling by the focused energy is followed by healing of the dermis through the creation of new collagen by fibroblast production. This accounts for the skin thickening and skin tightening effect. It is not yet known whether thinner or thicker skin is more influenced by this RF-induced collagen remodeling. Fat within an inch of the undersurface of the skin is affected by cell breakdown of the adipocyte walls. The RF waves cause weakening of the fat cell walls which results in extrusion of their fatty acid content. The released lipids are naturally absorbed and eliminated by the lymphatic system which is why high daily water intake is recommended during the treatment period. With loss of some of their content, the fat cells shrink reducing the overlying skin contour. With this penetration distance limitation, areas of thinner fat will respond more rapidly and effectvely than thicker areas to Exilis treatments.

The key to getting skin tightening and far reduction effects with RF energy is the periodic ‘re-injury’  of the target tissues. This means that multiple treatment sessions are needed that are not spaced too far apart. (one to two weeks) For both skin and fat it is important to not give them adequate time to completely heal their structures. The fat cell walls need to be repeatedly weakened for maximal content release. The fibroblasts of the skin dermis benefit by repeated heat stimulation for collagen production. Exilis effects are continuous meaning that their full benefits can take several months to see. Although many patients report see benfits as early as after the first treatment.

Dr. Barry Eppley

Indianapolis, Indiana

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