*1.5.1 BodyTite radiofrequency (InMode)*

The InMode devices (Invasix, Yokneam, Israel) are bipolar radiofrequency devices that contain both an internal and external temperature monitor. The tip of the handpiece delivers RF energy which travels to an external electrode that slides on the surface of the skin in line with the internal electrode. The RF energy creates a zone of thermal coagulative necrosis leading to adipocyte injury and FSN contraction [34]. BodyTite has been shown to lead to improved skin and soft tissue contraction when compared with traditional SAL (35% versus 8%) [35]. Complications after BodyTite include bruising, contour irregularities, pain, and thermal burns [36–38].

## *1.5.2 Renuvion helium plasma-driven radiofrequency (Apyx)*

Renuvion was originally developed as a laparoscopic cautery device for general, gynecologic, and urologic surgeries [39]. Renuvion (Apyx Medical, Clearwater, FL, USA) combines radiofrequency energy and helium plasma to create subdermal tissue contraction. The device reaches the optimal temperature for subdermal tissue contraction (85°C) quickly with minimal thermal spread and cools to baseline temperatures in less than a second [40–45].

Helium plasma is created when helium gas is passed over the energized electrode at the tip of the handpiece. Heat is generated by the plasma beam itself and through the RF energy that passes from the handpiece to the patient's tissues [5].

The device is used after liposuction but can also be used alone to create skin tightening. The handpiece is passed through the subdermal plane and deeper subcutaneous tissues while slowly withdrawing the device. The amount of energy applied is recorded. In our experience, applying at least 10 kJ to the anterior abdomen is necessary.

Immediate results can be seen when using this device with visible improvement at 24 hours postoperatively and continued improvement for up to 12 months [5].

The advantages of the Renuvion system are decreased procedure times, decreased pain, and decreased risk of complications [39, 45–49]. The measured skin temperature rarely exceeds 38°C, leading to its increased safety profile. The risks associated with this device include helium embolism, thermal burns, pneumothorax, transient or permanent nerve injury, and helium gas buildup and crepitus.

### **1.6 Cannula selection**

## *1.6.1 Cannula size*

The larger the diameter of the cannula, the more rapidly the fat is removed. Larger diameter cannulas may be prone to creating contour irregularities from oversuctioning. Therefore, a balance exists between efficiency and postoperative complications. For abdominal and trunk contouring, we typically utilize 4 mm cannulas. The exception is for patients with extreme adiposity or minimal adiposity. A 5 mm cannula may be used during the initial debulking of the deeper fat compartments in patients with large adipose stores. In contrast, 3 mm cannulas may be appropriate for patients who are extremely thin to help prevent postoperative contour irregularities.

#### *1.6.2 Cannula type*

Caution has been placed on using basket cannulas for suctioning [2, 3], but we have not noted any untoward effects. On the contrary, we have found that suctioning with a 4 mm basket-tip cannula is more efficient than suctioning with the same diameter Mercedes-tip cannula. We utilize basket-tip cannulas for fat separation and fat equalization. Multi-holed cannulas are used for abdominal etching to remove all the fat between the fascia and dermis.
