Exercise Oximetry Correlates Better With Exercise-Induced Lactate Increase, than Ankle Brachial Index or Walking Time, in Vascular Claudicants.

In claudication, the correlation between walking-induced biomarkers and indices of clinical severity (e.g., walking distance or ankle brachial index (ABI)), is fair. We hypothesized that a correlation would be observed between the clinical estimation of ischemia severity with exercise transcutaneous oximetry (Ex-TcpO2) and lactate increase. A prospective study was performed among 377 patients with arterial claudication. We recorded age, sex, ABI, body mass index (BMI), systolic arterial blood pressure (SBP), and glycemia. Capillary blood lactate was measured at rest and 3 min after a constant load treadmill test. We recorded maximum walking time (MWT), heart rate (HRmax), the sum of minimal decrease from oxygen values for buttocks, thighs and calves Ex-TcpO2 (DROPmin), as well as the amplitude of chest-TcpO2 decrease. A multilinear regression model was used to assess the variables associated with lactate increase. BMI, SBP, HRmax, the amplitude of decrease in chest-TcpO2 and DROPmin, but not age, sex, ABI, MWT, diabetes mellitus nor glycemia, were significantly associated to lactate increase in the model. Because it accounts for the severity and diffusion of lower-limb exercise-induced ischemia and detects exercise induced hypoxemia, TcpO2 may be preferable to ABI or MWT to estimate the metabolic consequences of walking in claudicants.

The "Walking Estimated Limitation Stated by History" (WELSH) visual tool is applicable and accurate to determine walking capacity, even in people with low literacy level.

Determination of the self-reported walking capacity by interview or standardized questionnaire is important. However, the existing questionnaires require the patient to be able to read and write in a specific language. We recently proposed the WELSH (Walking Estimated Limitation Stated by History) tool to be administrable to illiterate people. The main objective was to assess the applicability of WELSH tool in the community and in a large group. We performed a prospective study in the city of Bobo-Dioulasso in Burkina Faso during June 2020. We recruited 630 interviewers among medical students. They were trained to administer the WELSH, and to conduct a 6-minute walk test. We performed a Pearson's "r" correlation between the WELSH and maximal walking distance (MWD). Of the 1723 participants available for the analysis, 757 (43.9%: 41.6-46.3) never went to school or attended only elementary school. The percentage of questionnaires with participant filling-in errors corrected by the investigator decreased with the decrease in educational level (p<0.001). The average WELSH score was 53 ± 22 and the average MWD was 383 ±142 meters. The Spearman correlation coefficient between the WELSH score and the MWD was r = 0.567 (p<0.001). Correlations ranged from 0.291 to 0.576 in males and females, (all p values < 0.05) and in different levels of education, with the highest coefficients found in illiterate people. The WELSH is feasible on the community by a wide variety of interviewers. It correlates with the MWD estimated by the 6-minutes' walk test even for people with little or no schooling.

Exercise-Induced Plasma Metabolomic Profiles in Patients With Peripheral Arterial Disease.

Aim: A better knowledge of the biological consequences in the blood of these exercise-induced ischemic events in lower extremity artery disease (LEAD) may improve the prospects of disease management. We explored the preminus postexercise metabolomic difference in 39 patients with LEAD referred for a treadmill oximetry test [transcutaneous oximetry (TcPO2)]. Methods: Ischemia was estimated through the sum of decrease from rest of oxygen pressure (DROPs) (limb TcPO2 changes minus chest TcPO2 changes) at buttocks, thighs, and calves regions. Targeted metabolomic analyses measuring 188 metabolites were performed on a few microliters blood samples taken at the earlobe at rest and 3 min after exercise. Results: Maximum walking distance (MWD) was 290 m (120-652 m) and ankle brachial index (ABI) was 0.67 ± 0.17. Supervised paired partial least squares discriminant analysis based on 23,345 models showed good predictive performance for test sets with a median area under the receiver operating characteristic (AUROC) curve value of 0.99 and a p-value of 0.00049. The best discriminant metabolites contributing to the model included a subset of 71 (47%) of the 150 accurately measured metabolites in the plasma, comprising 3 acylcarnitines, 3 amino acids, 5 biogenic amines, 9 sphingomyelin, 7 lysophosphatidylcholines, and 44 phosphatidylcholines. In addition, 16 of these metabolites were found to correlate with one or more severity scores of the LEAD. Conclusion: Our results provide new insights into the biological changes that accompany exercise in LEAD and contribute to a better understanding of walking impairment pathophysiology in LEAD, highlighting new candidate biomarkers.

Current-Induced Vasodilation Specifically Detects, and Correlates With the Time Since, Last Aspirin Intake: An Interventional Study of 830 Patients.

BACKGROUND: Galvanic current-induced vasodilation (CIV) is impaired in patients under low-dose aspirin (ASA; ≤ 500 mg/day), but potential covariates and the impact of the time since the last ASA intake are unknown. OBJECTIVES: We used tissue viability imaging (TiVi) in patients at risk of cardiovascular disease and examined its association with self-reported treatments. PATIENTS/METHODS: We recorded the age, gender, height, weight, smoking status, and use of 14 different drug categories in 822 patients either with known peripheral artery disease or at risk thereof. The difference between TiVi arbitrary units (TAUs) where stimulation was applied and an adjacent skin area was recorded, as well as the time since the last ASA intake. Step-by-step regression analysis was used to determine the factors that affect CIV amplitude. RESULTS AND CONCLUSIONS: CIV was 28.2 ± 22.9 vs. 14.6 ± 18.0 TAUs (P < 0.001) in patients treated with ASA (n = 287) and not treated with ASA (n = 535), respectively. The main determinants of CIV amplitude, by order of importance, were: aspirin intake, diabetes mellitus, age, and male sex. In ASA-treated patients, the main determinants were diabetes mellitus, time since the last ASA intake, male gender, and age. Non-invasive determination of the physiological effects of low-dose ASA is feasible in routine clinical practice. It could be a clinical approach to provide objective evidence of ASA intake, and potentially could be used to test adherence to treatment in ASA-treated patients.

Investigation of arterial claudication with transcutaneous oxygen pressure at exercise: Interests and limits.

Transcutaneous oxygen pressure (TcpO2) measurement has been used for years at rest in patients with lower extremity artery disease. It was proposed for exercise testing (Ex-TcpO2) in the 80ies to evaluate regional blood flow impairment (RBFI) at the proximal and distal levels simultaneously and on both sides, in case of claudication. It was suggested that the use of a chest electrode was mandatory to show that decreases in TcpO2 at the limb level result from limb RBFI and not from a systemic pO2 decrease of cardiopulmonary origin (exercise-induced hypoxemia). Unfortunately, a major pitfall of Ex-TcpO2 was the low absolute reliability of the regional perfusion index (RPI: ratio of limb to chest values) and the technique was almost abandoned until 2003, when the DROP index (Decrease from rest of oxygen pressure: limb changes minus chest changes from rest) was proposed. The DROP mathematical formula makes Tcpo2 results independent from the absolute pO2 starting values, improving reliability of Ex-TcpO2 as compared to the RPI. Since then, Ex-TcpO2 has been of renewed interest. The present paper addresses the physiology of Ex-TcpO2, interpretation of its results, and common misunderstandings about its use.

The hidden side of calf claudication: Hemodynamic and clinical results of treadmill testing in 584 patients complaining of isolated exertional calf pain.

BACKGROUND AND AIMS: Calf pain is the most frequent symptom of arterial claudication. We hypothesized that patients with self-reported isolated calf claudication have frequent exertional non-calf symptoms during objective laboratory testing, and that many would show not only distal, but also proximal ischemia. METHODS: We retrospectively analyzed the patients referred since 2016 for exercise transcutaneous oxygen pressure (Ex-tcpO2). The Edinburgh Claudication Questionnaire (ECQ) was self-completed before and during a treadmill test. For calf and non-calf (buttock and thigh) Ex-tcpO2, a lowest decrease of rest of oxygen pressure (DROP) < -15 mmHg was indicative of ischemia. We selected the patients that reported calf claudication only and analyzed minimal DROP and per-test ECQ observations. RESULTS: Exertional symptoms on a treadmill occurred in 526 (90.1%) of the 584 patients analyzed (65.6 ± 11.4 years old), with 391 (74.3%) of these symptoms affecting only the calf. Isolated calf ischemia with or without symptoms was found in only 139 (23.8%) patients. Overall, among the 584 patients self-reporting isolated calf symptoms, a perfect concordance between symptoms on a treadmill and Ex-tcpO2 (i.e. calf symptoms associated to calf ischemia) was observed in only 114 (19.5%) cases. CONCLUSIONS: Our study demonstrated that patients self-reporting exertional limb pain strictly limited to the calf may also have non-calf claudication on a treadmill and frequently show not-only-calf ischemia. These observations are important when planning reeducation or when studying the tissue consequences of ischemia in patients with claudication.

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

AIM: To compare the transcutaneous oxygen pressure results observed in patients with severe walking limitation during standard procedures (3.2 km/hr, 10% slope) versus during a test performed at a low speed (2 km/hr, 10% slope). METHODS: In 31 patients, the decrease from rest of oxygen pressure (DROP) index was measured on both buttocks, both thighs and both calves during two consecutive tests on treadmill. The maximal walking time (MWT) and the minimal DROP values (DROPmin ) observed during the 2 tests were compared with t test. Correlation of DROPmin values during the slow and standard procedure was performed with linear regression. The -15 mmHg cut-off value defined for standard test interpretation was used arbitrarily for the interpretation of slow test results. RESULTS: MWT was 80 ± 52 s versus 376 ± 269 s at standard and slow speed, respectively (p < .001). No difference on all recorded DROPmin values at a standard (-9.5 ± 6.9 mmHg) and slow (-10.5 ± 7.9 mmHg) speed was found; n = 186, p = .168. Coefficient of correlation between DROPmin s found at the two tests was r = 0.820 (p < .01), with regression line close to the line of identity. With the identical -15 mmHg cut-off, 166 (89.2%) of 186 the results were classified similarly after standard and slow procedures. CONCLUSION: Specific slow treadmill procedures are not mandatory in patients with extremely short test durations when performing standard (3.2 km/hr 10% slope) exercise oximetry. In patients expected to be unable to walk at standard speed, the -15 mmHg normal limit seems to be valid for the interpretation of tests with a slow procedure (2.0 km/hr).