Chest tcpO₂changes during constant-load treadmill walking tests in patients with claudication

Abstract

Changes in chest transcutaneous-pO 2 at rest ( tcpO 2 ) mimic absolute changes in arterial-pO 2 during moderate exercise, although the absolute starting values may dramatically differ. We retrospectively studied 485 patients (group 1), prospectively studied 292 new patients (group 2) and estimated the intra-test and the test-retest reproducibility of tcpO 2 during constant-load treadmill tests: 3.2 km h −1 , 10% grade, using the cross correlation technique. Patients were classified into groups according to their best fit to nine pre-defined mathematic models. Respectively, 71% and 76% of patients of groups 1 and 2 fitted with a model showing a tcpO 2 increase during and a decrease following exercise. Another 18% and 12% of the patients of groups 1 and 2 respectively fitted with a model that showed an abrupt decrease at exercise onset, a slow increase during walking and an overshoot in the recovery period, referred here as a walking-induced transcutaneous hack (WITH) profile. The mean r max value for the cross-correlation analysis was 0.919 ± 0.091 and 0.800 ± 0.129 for intra-test and test-retest reproducibility. Most profiles show the expected tcpO 2 exercise-induced increase. Future studies are needed to confirm and explain the WITH profiles that we found, and screen for potential-associated diseases.

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

“…As previously discussed, systemic arterial oxygen pressure influences absolute tcPO2, and changes throughout exercise in arterial partial oxygen pressure may be estimated by changes in tcPO2. 7,8 Assuming that the C and D profiles reflect exercise-induced hypoxemia, we hypothesized that systemic hypoxemia may worsen the tissue oxygen imbalance at exercise and result in a non-vascular contribution to walking limitation. Although the relationship between abnormal chest profile and cardiorespiratory disease is not yet established, we generally refer such patients for cardiopulmonary investigations and repeat Ex-tcPO2 after treatment of frequently detected cardiopulmonary disease.…”

“…9 The profiles A or B were considered normal, while classification into profiles C or D indicated abnormal systemic oxygenation during exercise (Figure 1). 8 In patients with C or D profiles, it is assumed that respiratory limitation might impair walking ability and limit exercise before a measurable significant ischemia occurs at the limb level. years, and 81% were male.…”

“…8 Using clustering analysis, we previously showed that chest-tcPO2 changes could be classified into 4 different profiles (A-D). 9 The first 2 are normal, while the latter 2 are abnormal and are associated with exercise-induced systemic hypoxemia.…”

The Walking-Induced Transient Hack Concept Is Valid & Relies on a Transient Early-Exercise Hypoxemia

“…The use of exercise transcutaneous pO 2 has recently gained interest in claudication, specifically in case of atypical claudication or claudication of questionable vascular origin [3]–[5]. We recently reported that, in patients with claudication and assumed peripheral artery disease referred for constant-load walking tests, the transcutaneous pO 2 changes while walking could be automatically classified into 4 empirically predefined types [6]. Two of them mimic the expected physiological walking-induced increase in arterial pO 2 (type A & B).…”

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

“…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. Ex-tcPO2 was initially performed in highly selected patients for whom usual techniques and/or post-exercise ABI were negative or impossible.…”