Ultrasound-assisted lipolysis of the omentum in dwarf pigs.

Successful surgical treatment of medium degree obesity by subcutaneous liposuction has been reported in the literature. In obesity, most adipose tissue is visceral, mainly omental, and the resection of omentum is a mutilating procedure for the intestinal tract. Because of this, we planned to reduce omental adipose tissue by an apparently conservative approach: ultrasound-assisted lipolysis. The purpose of this study was to assess the feasibility and safety of this procedure in an animal experimental model, drawing clinical and autoptic patterns. We chose pigs because they are functionally analogous to humans, although they store less fat in the omentum, whose structure looks like a veil. Four male dwarf pigs were fed, since weaning, with hyperlipidic fodder. When they were eight months old, they were operated on under general anesthesia in our laboratory for experimental surgery. After laparotomy, the omentum was delivered and treated with ultrasound for 1 hour. Before and just after the sonication, biopsies were drawn from omentum and processed for histologic findings. After 50 days, the surviving animals were sacrificed and autopsied; specimens from omentum, liver, and spleen were histologically processed. Two animals died during the operation, while the two surviving animals were in good general condition. Macro and microscopic observations demonstrated that the ultrasound can liquefy omental fat, sparing its fibrous network in the immediate time; during the postoperative period, an intense inflammatory reaction developed; macroscopic observation evidenced fibrous adhesions of the omentum to the surrounding organs; the connective tissue network was thickened and the whole omentum was twisted on itself. The high mortality rate could be due either to the surgical learning curve or to casualty or to lethal effects of ultrasound on the cardiac conductive system; the inflammatory peritoneal reaction could be specifically due to ultrasound or to surgical handling.