Ischemic preconditioning is defined as protection from cell damage induced by prolonged ischemia by preceding cycles of short ischemia. Hence, ischemic preconditioning could reduce ischemic lesion during clamping a femoral artery for vascular surgery. In this prospective, randomized pilot study is investigated if clamping of the femoral artery leads to ischemia of the calf measurable by near-infrared spectroscopy. In addition to this, the effect of sevoflurane preconditioning on ischemia of the calf is measured.