Comparison between transcutaneous oximetry and ankle-brachial pressure ratio in predicting runoff and outcome in patients who undergo aortobifemoral bypass.

In a prospective study, transcutaneous oxygen tension and ankle-brachial pressure index (ABI) were measured pre- and postoperatively in 105 symptomatic patients who underwent aortobifemoral bypass to compare the ability of these two measurements to reflect the runoff status, determined by angiography, and to predict the outcome of surgery. Postoperatively, ABI better reflected the runoff status. The difference in mean ABI for good versus poor runoff was 0.17 (p less than 0.05). The difference in mean transcutaneous oxygen tension below the knee for the two runoff categories was relatively small (6.3 mm Hg, p less than 0.05). Post-minus preoperative increases in ABI reflected the runoff status better than increases in transcutaneous oxygen tension. For good runoff, the mean ABI increase was 0.25 and for poor runoff it was only 0.14 (p less than 0.05). Runoff and transcutaneous oxygen tension were found to be the best predictors of symptomatic recurrence. Poor runoff was associated with a relative risk of 2.5 (p = 0.017) and transcutaneous oxygen pressure of less than 40 mm Hg implied a relative risk of 2.3 (p = 0.029) for symptomatic recurrence. The most important predictor of graft failure was preoperative ABI. Transcutaneous oxygen tension and the ankle-brachial pressure index appear to be valuable noninvasive techniques for vascular assessment, offering different insights and different predictions for management and prognosis of peripheral vascular disease.