Klein further demonstrated the safety of the tumescent anesthesia by demonstrating that when lidocaine is used as a dilute solution of 0.05% lidocaine containing 1:1,000,000 epinephrine, does of up to 35 mg of lidocaine per kilogram of body weight
were safe and effective.This technique allowed increased amounts of fat to be safely and comfortably removed using only this local anesthetic technique.Studies by other liposuction surgeons detail that the maximum tumescent safe lidocaine dose is greater than 35 mg of lidocaine per kilogram of body weight. Ostad proposed that the maximum safe tumescent lidocaine dose was 55 mg/kg. Lilles felt that the maximum allowable dose was above 35 mg of lidocaine per kilogram of body weight. Butterwick showed that the rate of infusion of the tumescent anesthesia was independent of plasma lidocaine levels. There have been several studies that have demonstrated that modern tumescent liposuction, using only dilute solutions of local anesthesia, is an extremely safe procedure. There have been numerous reports documenting the safety of this technique. Studies directed by Hanke and Bernstein have shown very few complications when tumescent liposuction is performed correctly. A recent study by Housman has clearly documented the safety of tumescent liposuction. In this study, 505 dermatologic surgeons were surveyed, asking for their incidence of serious adverse events (SAEs).A total of 66,570 procedures were reported upon, and there was an SAE rate of 0.68/100 cases. No deaths were reported. This study clearly demonstrates that the procedure is safe and without risk if tumescent liposuction is performed properly.

There have been several reports of the dangers of liposuction and several reports reporting on fatalities from the technique. These cases very often were carried out under general anesthesia or when large volumes of fluid were used. It is the opinion of many liposuction surgeons that the dangers of liposuction are minimal when proper technique is used using only dilute solutions of local anesthesia. Complications may occur with heavy sedation or general anesthesia, large volumes of liposuction, large volumes of fluid, or when extensive liposuction (megaliposuction) is performed. When intravenous fluids or general anesthesia is used, patients may experience fluid overload with the possibility of pulmonary edema. Unconscious patients can experience pulmonary embolism and thrombophlebitis. Furthermore, tumescent liposuction performed in the outpatient setting appears to be safer than those procedures performed in the hospital environment.

Two variations in instrumentation have been developed. Ultrasonic liposuction was developed in Europe in the early 1990s, having been introduced by Zocchi.The concept was that adipose cells could be treated with ultrasound energy, presumably breaking up their cell walls and facilitating fat aspiration. The American Society of Plastic and Reconstructive Surgery quickly adopted ultrasonic liposuction; however, over time, problems were found with this technique. Internal ultrasound (ultrasound tips contained within cannulas) increased the risk of cutaneous burns and seroma formation. Many dermatologic surgeons have not found any additional benefit over standard liposuction. External ultrasound devices when used before or during a liposuction procedure have not been found to be of any benefit to the patient or the surgeon. It is the feeling of the author that unnecessary complications without benefit can result from the use of ultrasound in liposuction.