**8. Pearls**

#### **8.1 Surgery under local anesthesia with conscious sedation**

One of the greatest advantages to minimally invasive approaches to arm contouring is the ability to perform the procedure under local anesthesia safely and comfortably for both the patient and the surgeon. A complete medical history, physical examination, and review of patient's medications and allergies is integral to safe administration of any medication, including for procedures performed under local anesthesia with or without sedation.

#### *8.1.1 Nitrous oxide (Pronox)*

We commonly utilize Pro-Nox, which is a combination of 50% nitrous oxide and 50% oxygen delivered through a one-way valve. The patient holds the mouthpiece and inhales the gas for comfort as needed. The device inherently minimizes risk of overdose as the patient is unable to hold the mouthpiece if they become too drowsy. It is therefore important not to assist the patient in holding or controlling the mouthpiece device. The use of nitrous oxide is well-established in dental literature and has been adopted to many dermatologic and aesthetic procedures, including tumescent liposuction, as a safe analgesic adjunct [26–28]. Additional monitoring with a pulse oximeter is advised for longer procedures. Surgeons must be aware of contraindications to its use which include but are not limited to pregnancy, certain pulmonary diseases (COPD, cystic fibrosis), recent tympanic membrane surgery, claustrophobia, and intoxication, etc. Adverse effects are mild and infrequent and include emotional lability (most commonly laughter and euphoria), nausea, and dizziness. It has a quick onset and recovery times are 5 to 10 minutes allowing for patients to drive themselves home following smaller local procedures [26].

#### *8.1.2 Oral sedatives (lorazepam, MKO lozenges)*

In order to reduce any stress or anxiety associated with the procedure, we have traditionally administered sublingual lorazepam to patients undergoing procedures under local anesthesia lasting greater than 45 minutes or those with underlying anxiety. Recently, oral formulations of midazolam, ketamine, and ondansetron have become available as prefabricated lozenges (MKO Melt, ImprimisRx, San Diego, CA), which can also be prepared at any compound pharmacy (Midazolam 3 mg, Ketamine 25 mg, Ondansetron 2 mg). We have found this new oral combination to be highly effective for longer duration procedures under local anesthesia, including arm lipocontouring. The medication provides anesthetic, sedative, and antiemetic effects that set in within 15 minutes and 30 minutes to peak effect. Anesthetic and sedative effects can last up to 4 hours after administration [29] and, as with any form of sedation, the patient is monitored post procedure until discharge criteria are met and released to the care of a responsible adult for 24 hours.

#### **9. Pitfalls and complications**

The usual complications associated with liposuction can be seen in arm lipocontouring including infection, seroma, irregularities, sensory or motor nerve injury, the need for further liposuction enhancement, and loose skin requiring (additional) RF treatment or skin excision. The added complication of burns to the skin with any energy-device (UAL or RF) must also be discussed with the patient preoperatively.
