Excessive free radicals are not produced during ultrasound-assisted liposuction

Abstract

High-intensity ultrasound energy has been used since the 1970s, when phacoemulsification was introduced. This technique was later extended to neurosurgery, with increased energy and dosages. Barnett et al. [1] concluded in 1997 that "there is at present, no indication that medical ultrasound is capable of inducing mutations in mammalian tissue in vivo." Still, highintensity ultrasound energy carries the risk for oxidative stress, which has been shown to be involved in the pathogenesis of a variety of diseases, such as atherosclerosis and cancer [2-4]. With the application of ultrasound-assisted liposuction (UAL) in breast surgery, surgeons inevitably are approaching a tissue that is very susceptible to DNA damage, particularly because undetected premalignant lesions, such as carcinoma lobular in situ, are found in up to 4% of women. Still, until now, there is no clinical proof of a direct malignant effect of UAL and breast tissue. Several clinical studies have confirmed that UAL is an effective and safe technique with few or no complications when performed by experienced hands [5, 6]. In 1998 and 1999 Topaz et al. [7, 8] expressed their concern about the complicating negative effects of UAL, especially the formation of large quantities of free radicals in vitro resulting from the cavitation phenomenon. Cavitation phenomena are produced in liquid media subjected to high-intensity ultrasound with the rapid formation and collapse of gas or vapor microbubbles when the pressure during the rarefaction phase of the cycle reduces the total pressure to a specific threshold value [9]. Collapse of these bubbles is the suspected cause for the breakdown of adipocyte membranes and the physical explanation of the effectiveness of UAL [9]. Topaz et al. noticed the formation of free radicals, which are a by-product of the brief high-temperature peaks and are created by the bubble collapse in vitro. They also postulated that the high-energy shock is able to break chemical bonds in a variety of molecules. This effect is called sonochemistry. The reaction of free radicals with RNA and DNA, resulting in mutations, may have long-term-effects. Herr et al, [10] investigated whether these highly reactive radicals were also formed during in vivo liposuction in the presence of the living defense system. The concern was that large numbers of free radicals generated in the direct neighborhood of unsaturated fatty acids may be expected to overwhelm the natural local antioxidant capacity, inevitably leading to lipid peroxidation. The resulting lipid hydroperoxides are metabolized to toxic secondary products, such as malondialdehyde, 4-hydroxynonenal, and other aldehydes. Measurement of malondialdehyde, for example, in aspirates of patients undergoing UAL, can be considered a measurement of relevant lipid peroxidation. © 2006 Springer-Verlag Berlin Heidelberg.