10. Contraindications

Patients who should not be treated include:


### 11. Operative technique

Patients are marked in an upright position. Depressions are marked, and protuberances are highlighted. The patient is asked to look down and note what she or he sees as the most important set of goals as far as fat reduction and skin tightening. This perspective may be somewhat different from the evaluating surgeon's view.

Steps in treatment include evaluation and marking, sterile prep and drape, and administration of anesthesia, which always includes tumescent infusion and can also include oral sedation, IV sedation, or general anesthesia. Liposuction, if indicated, of the treatment region is then performed. Treatment with subcutaneous heating of the Renuvion device follows. "Strokes" are considered as an insertion and slow withdrawal of the device. Ideally, the speed of withdrawal should be about 1.5 cm/s. A "pass" is considered to be a series of strokes performed from a single access point at the same depth. Lab studies show that in the typical treatment region, a series of three multidepth passes is required in order to see significant soft tissue and skin contraction within 24 h. In areas with a small surface area or limited amount of localized fat, two passes may be sufficient. Of course, in regions where adipose thickness is 3 cm or more, up to five passes at multiple depths may be needed in order to achieve the optimal outcome. Unless the treatment region is very thick, more than five passes in one region may be overtreatment.

Clinical endpoints with the Renuvion device are different from those with bulk heating treatment. There will be little localized warmth or erythema, because it is not a bulk heating device. A visible contraction of the skin surface with the handpiece slightly angled up upon withdrawal is an indicator of good response. Because there is not an energy expended measurement on the current generator, a good indicator is activated time on the tissue. I usually treat a 10 ˜ 15 cm segment of the tissue with 5 kJ, which correlates to 5 min of handpiece activation time per region.

Some controversy exists regarding "cross-hatching" or creating a perpendicular series of passes in the same treatment zone. Because the device seeks out low impedance tissue to briefly heat, the "woven" or "crisscross" method is not routinely needed. However, in large areas or in regions needing optimal soft tissue contraction, this approach is recommended.

Cross-hatching is contraindicated in areas such as the lower face, jowls, jawline, submentum, or decollete. Thin upper arm skin may also not need two perpendicular approaches.

Treatment depths generally include the deep suprafascial zone, the midlevel of the adipose layer which corresponds to Scarpa's fascia, and the immediate subdermal region. In patients with thin skin, striae, or a previous procedure in the treatment zone, a conservative two layer approach is recommended. In necks, a supraplatysmal and a subdermal approach are recommended.

Multiple treatment levels are recommended to reduce the amount of adipose gliding that is seen with age, a decrease in the stromal collagen binding of fat, and hormonal change [37].

Patients who note a disconnection of the soft tissue from the rectus fascia when leaning forward can gain some readherence with multilevel treatment. Suprafascial heating of the abdominal midline can decrease diastasis recti up to 1 cm. Further studies are needed to show the duration of this response.

Enhancement of tissue response can be achieved by reducing local impedance with infusion of tumescent fluid and by removing the insulating adipose tissue. Undertumescing will decrease tissue response. An infusion ratio of 1:1 is recommended for most regions. By optimizing treatment temperature, the stromal fibrous collagen bands will contract more intensely and more quickly. A variety of optimal temperatures are shown in the biomechanical literature, ranging from 60 to 80°C. At lower temperatures, tissue contraction is slower. Perfusion is the most influential factor, as well as the most difficult to measure and influence. Good perfusion can be enhanced by avoiding overtumescing as the closing venous pressure will be exceeded. Using warm fluid is helpful. Vasodilators are not indicated. Perfusion can be compromised by mechanical factors such as tissue location in a fibrous area (flanks and bra roll). A frequently overlooked consideration is

treatment in secondary cases. The presence of scar tissue in a patient who has undergone a previous procedure should be noted. The use of another energy-based device prior to the use of the primary heating device adds risk, such as liposuction using PAL or Vaser.

It is important to consider the effect of adding pressurized gas when treating the secondary patient. Fibrosis, whether induced by previous minimally invasive procedures or by surgery, will change the direction of the gas, which will follow the path of least resistance. While not clinically dangerous, the creation of temporary subcutaneous crepitus can be disconcerting to the patient. Careful and thorough tunneling of the treatment region will allow for gas egress in these cases. The use of more than one access port is imperative. Tunnels should be created in such a way that they communicate with one another, and aspiration of gas at the end of the procedure will improve patient comfort.
