Evaluation variables , including changes in the ankle-brachial index ( ABI ) of ischemic limbs , ulcer area , severity of rest pain , transcutaneous oxygen pressure ( T ( C ) PO2 ) , and 6-min walk distance from baseline to week 8 and 16 , as well as angiographic scores for new collateral vessel formation at week 16 , were used to compare the benefits of these 2 treatment approaches .