Transcutaneous oxygen tension and toe blood pressure as predictors for outcome of diabetic foot ulcers

OBJECTIVE - The present study was undertaken to compare the predictive values of transcutaneous oxygen tension (TcPo2) and toe blood pressure (TBP) measurements for ulcer healing in patients with diabetes and chronic foot ulcers. RESEARCH DESIGN AND METHODS - Investigated prospectively were 50 diabetic patients (37 men) with chronic foot ulcers. The age was 61 +/- 12 (mean +/- SD), and the diabetes duration was 26 +/- 14 years. TBP (mmHg) was measured in dig I and TcPo2 (mmHg) at the dorsum of the foot. Ulcer healing was continuously evaluated by measuring the ulcer area every 4-6 weeks. After a follow-up time of 12 months, the patients were divided into three groups according to clinical outcome: healed with intact skin, improved ulcer healing, or impaired ulcer healing. RESULTS - Of the 13 patients who deteriorated, 11 had TcPo2 <25 mmHg, while 34 of the 37 patients who improved had TcPo2 greater than or equal to 25 mmHg. The sensitivity and specificity for TcPo2 were 85 and 92%, respectively, when a cutoff level of 25 mmHg was used for determination of outcome of ulcer healing (healing or nonhealing). The corresponding values for TBP at 30 mmHg were 15 and 97%. Measurement of TcPo2 provided a higher positive predictive value (79%) than TBP (67%). CONCLUSIONS - The results indicate that TcPo2 is a better predictor for ulcer healing than TBP in diabetic patients with chronic foot ulcers, and that the probability of ulcer healing is low when TcPo2 is <25 mmHg.