Foot ulceration usually precedes more serious foot complications such as infection, gangrene or amputation. The risk of developing foot ulcers has been estimated to be higher in individuals with kidney disease. Patients with kidney disease receiving dialysis have an increased prevalence of critical limb ischemia. Carbon dioxide (CO2) foot bathing has been reported to improve subcutaneous microcirculation. The proposed clinical study will evaluate the therapeutic potential of CO2 enriched water (produced by the Carbothera device) on treating foot ulcers in patients with critical limb ischemia and undergoing hemodialysis. Forty individuals how have a distal extremity ulcer who are currently undergoing hemodialysis will participate in this study.