Exercise Transcutaneous Oximetry of the Buttocks　― External Validation With Computed Tomography Angiography ―

Abstract

Background: Exercise transcutaneous oximetry (Ex-tcPO2) is a non-invasive test for exercise-induced buttock ischemia. Prior study defined Ex-tcPO2 normal/abnormal cut-offs against arteriography but no external validation was available. The aims of this study were therefore to (1) determine the diagnostic performance of Ex-tcPO2 against CTA; (2) determine the cut-off point for detection of stenosis >75% in arteries toward the hypogastric circulation; and (3) determine the effect of chest profile classification on the diagnostic performance of Ex-tcPO2. Methods and Results:A total of 207 patients referred for Ex-tcPO2 were analyzed. DROP during Ex-tcPO2 was compared with the CTA results. Chest-tcPO2 changes were automatically classified into pre-defined profiles representing normal or abnormal responses. Using DROP <−15 mmHg as a cut-off, Ex-tcPO2 had 80.2% sensitivity, 72.3% specificity, 43.1% PPV, 93.3% NPV and 73.9% accuracy, to detect 1 stenosis >75% in arteries toward the hypogastric circulation. Optimal DROP to detect stenosis was: −15 mmHg. The overall diagnostic performance of Ex-tcPO2 was independent of chest profile classification. Conclusions:Ex-tcPO2 has satisfactory diagnostic performance to detect arterial stenoses towards the hypogastric circulation. Abnormal chest-tcPO2 profile does not impair the overall diagnostic performance of the test.

Discordance of peripheral artery disease diagnosis using exercise transcutaneous oxygen pressure measurement and post-exercise ankle-brachial index

“…This standardized methodology associated with the use of the delta from rest of oxygen pressure (DROP) cut-off has improved the reliability of this procedure that was confirmed by two studies 17,18 . Finally, two different teams found similar cut-off values of the DROP 8,10,12,19 8 .…”

Specific slow tests are not mandatory in patients with extremely short standard (3.2 km/hr 10% slope) test durations during exercise oximetry

“…A minimal DROP value (DROP min ) under – 15 mmHg is considered as indicating regional blood flow impairment. It has been validated as a sensitive and specific indicator for arterial lesions, in a population with proximal or distal claudication (Abraham et al, 2003, 2005; Audonnet et al, 2017). From October 2018, all the patients (whatever their usual speed and time required to walk 10 m in the corridor) had a standard treadmill protocol that included a 1‐min progressive increase in speed and slope to 3.2 km/hr and 10%, respectively.…”

“…Unfortunately, some patients are slow walkers and are likely unable to walk for at least one minute at the standard speed and slope. This has led us since 2003 and until September 2018, to submit patients unable to walk 10 m within 12 s, to a slow speed protocol (2.0 km/hr, 10% slope) although no proof was available that the results of this slow speed protocol were the same as those of a normal standard procedure (Audonnet et al, 2017; Mahe et al, 2010). This was based on the hypothesis that a very brief walking period could be too short to allow ischaemia to occur and might result in a high rate of false‐negative tests at a standard speed compared to a slower speed but longer period of walking.…”

Transcutaneous Exercise Oximetry for Patients With Claudication ― A Retrospective Review of Approximately 5,000 Consecutive Tests Over 15 Years ―

“…11, 12 We defined normal limits to be used and validated the technique against gold-standard arteriography at the calf and buttock level, 11,12 or computed tomography angiography. 13 We showed that Ex-tcPO2 also accounts for eventual systemic arterial oxygen pressure changes through the use of the chest electrode. 14 Since 2000 we have progressively integrated Ex-tcPO2 in our diagnostic routine of claudication as a tool to argue for the vascular origin of exercise-induced pain, specifically at the proximal level.…”