Relationship between transcutaneous oxygen tension, ankle blood pressure, and clinical outcome of vascular surgery in diabetic and nondiabetic patients.

We measured ankle systolic blood pressure (ABP) and limb transcutaneous oxygen tension (TcPO2) before and after 53 vascular procedures performed to relieve limb-threatening ischemia. We compared changes in ABP and TcPO2 and also compared these measurements of limb hemodynamics with the clinical outcome of the vascular procedures. For the procedures performed on patients without diabetes, both ABP and TcPO2 registered similar changes after surgery. Furthermore, those nondiabetic patients who had a postoperative ABP greater than 75 mm Hg or TcPO2 greater than 20 mm Hg showed resolution of the clinical symptoms within 60 days after surgery. All patients falling below these levels underwent a subsequent limb amputation. The results differed somewhat for procedures performed on patients with diabetes. First, a number of diabetic patients showed high ABP in conjunction with low TcPO2. We attribute these observations to the high incidence in diabetic patients of calcific medial stenosis leading to artificially elevated ABP measurements. Second, the clinical outcome among diabetic patients was uncorrelated with the postoperative ABP and was poorly correlated with postoperative TcPO2. Those diabetic patients with postoperative TcPO2 below 20 mm Hg showed unfavorable clinical outcomes, but many patients with postoperative TcPO2 greater than 20 mm Hg and postoperative ABP greater than 75 mm Hg also showed unfavorable clinical outcome (slow healing of ulcers, persistence of rest pain, and/or an amputation on the limb). These data suggest that among our patients with diabetes, simple relief of limb ischemia was not sufficient to result in a trouble-free clinical course. We conclude that TcPO2 is a useful replacement or adjunct to ABP measurements for evaluating the hemodynamic outcome of vascular surgery. Our results also suggest that it is extremely important to evaluate the outcome of such surgeries separately in patients with and without diabetes.