Comparison of exercise oximetry and ankle pressure measurements for patients with intermittent claudication: an observational study of 433 patients.

To study the concordance of exercise-oximetry and of ankle-brachial pressure index (ABI) and ankle pressure (AP) at rest, and after exercise, in patients complaining of vascular-type claudication to diagnose lower extremity artery disease (LEAD). Treadmill test in 433 patients with exercise-oximetry included constant load (3.2 km/h, 10% slope) phase for up to 15 min followed by an increment phase, if necessary. The presence (TcpO2e+) or absence (TcpO2e-) of ischemia was a decrease of limb minus chest oxygen pressure change greater than or less than - 15 mmHg. The post-exercise ABI and AP were measured after another test of a maximum of 5 min except if resting-ABI < 0.90. LEAD was diagnosed (+) based on resting-ABI < 0.90, post-exercise ABI < 0.8∙resting-ABI, or a difference of 30 mmHg between post-exercise and resting AP, or diagnosis was considered negative for all other cases (-). The discrepancies between the exercise-oximetry and pressure results were analyzed. We found 351 patients with resting-ABI+, of whom 52 were classified as TcpO2e-. Of the 82 patients with resting-ABI-, 25 had post-exercise ABI+ or AP+, of whom, 10 had TcpO2e-, while 57 had post-exercise ABI- and AP-, of whom, 28 had TcpO2e+. Discrepancies arose mainly from nonvascular limitations, isolated proximal ischemia, and detection of LEAD in the incremental phase of the exercise-oximetry. Post-exercise pressure measurements were easy and useful, but exercise-oximetry provided additional information for both resting-ABI- and resting-ABI+ patients and can help to prove the vascular origin of walking limitation of LEAD patients.