Transcutaneous oxygen (TcPO2) estimates probability of healing in the ischemic extremity

The severity of arterial ischemia is a major variable affecting healing of extremity wounds. By relating risk of failure to severity of ischemia, the probability of wound healing may be stratified along with assessment of general medical risks. Transcutaneous oxygen tension (TcPO2) arterial segmental pressure (ASP), and arterial segmental indices (ASI) were obtained in 204 ischemic lower extremity sites; 63% of the sites were in patients with diabetes mellitus (DM), 11% in patients with chronic renal failure (CRF), and 37% in patients with neither DM nor CRF (ND). Wounds included 126 amputations and 78 gangrenous ulcerations of the foot or toes. Healing (n = 112) was defined as complete wound closure, without regard to the time required. Failure (n = 92) was defined by the requirement for either arterial reconstruction (n = 45) or proximal amputation (n = 47). Stepwise multiple regression analysis was used to assess the relative contribution of each measurement and to predict the probability of healing; TcP02 was superior to ASP and ASI in all categories. TcP02 was the only test meeting the P < 0.05 entry criteria modeled by the regression. An accuracy of 83% was achieved. However, when each test was evaluated by univariate analysis, ASP and ASI did meet the criteria for the ND group. However, the accuracy was 68 and 72%, respectively. Predictive accuracy of TcP02 was unaffected by DM or CRF. ASP and ASI were satisfactory in the ND group, although of slightly reduced accuracy. ASP and ASI were misleading and inaccurate in DM and CRF. Thus, of the noninvasive tests, TcP02 alone is sufficient for objective risk stratification of arterial ischemia in the lower extremity.