TISSUE TEMPERATURES DURING ULTRASOUND-ASSISTED LIPOPLASTY

Removing excess subcutaneous fat with the assistance of ultrasonic ene rgy has recently become a technique of interest in the United States a fter nearly a decade of use in Europe. There are a number of reported advantages of ultrasound-assisted lipoplasty over traditional liposuct ion, and there are also some theoretical concerns. Ultrasound-assisted lipoplasty involves the conversion of electrical energy to mechanical energy and transfer to the tissues through acoustic pressure waves, w ith the formation of heat as a by-product. Heat generated in this proc ess dissipates through the body's own cooling mechanisms and conductio n to the surrounding tissues, and it does not contribute to the clinic al treatment of the adipose tissue. Reports of ''burns'' and ischemic skin injuries in the literature, and concerns for potential heat-relat ed problems, prompted us to investigate whether significant temperatur e elevations occur in the clinical setting. Subcutaneous tissue temper ature determinations during ultrasound-assisted lipoplasty were begun in February of 1996, and data were collected from 55 patients who had the procedure performed during a 6-month period. Intraoperatively, tem perature measurements were made with a data-logging instrument and a n eedle microprobe inserted into the subcutaneous tissues. Temperatures were taken in the area of liposuction before the infusion of tumescent fluid, after tumescent fluid infusion, and at 5-minute intervals unti l the end of the procedure. The patient's core body temperature remain ed stable during the procedure within a narrow range (35.7 degrees C t o 36.3 degrees C). There was a gradual increase in the temperature of the subcutaneous tissues over time during the application of ultrasoni c energy; however, average subcutaneous temperatures remained below th e core temperature (p < 0.05) at all time intervals. Room-temperature tumescent fluid further enhanced the thermal safety zone without lower ing core body temperature. There were no temperature related complicat ions in our study population and no untoward effects of performing tem perature measurements.We conclude that there is no clinically signific ant elevation of subcutaneous temperatures during ultrasound-assisted lipoplasty. Reported ischemic skin complications are more likely the r esult of injury to the subdermal plexus rather than a temperature-indu ced thermal injury. Although heat is a natural by-product of the energ y transfer involved in ultrasound-assisted lipoplasty, the risk of the rmal injury is negligible when the procedure is performed by experienc ed operators. Complete understanding of the technique along with stric t adherence to basic principles of flap vascularity will ensure safe a nd effective performance of ultrasound-assisted lipoplasty.