Tissue Fluid Samples: Samples of subcutaneous tissue fluid will be obtained by liposuction of approximately 10 ml of subcutaneous fat and tumescent anesthetic solution using a hand-held syringe, the aspirate being centrifuged to obtain an aqueous infranate from which cefazolin, metronidazole and lidocaine concentration will be measured by HPLC. Clinical experience has shown that tumescent local anesthesia persists for at least 12 hours. If the patient experiences any significant discomfort during the aspiration of subcutaneous fat using a hand-held syringe, then no further subcutaneous tissue samples will be taken for the duration of that clinical procedure.