Objective determination of the predefined duration of a constant-load diagnostic tests in arterial claudication

[Current aspects of performing treadmill test in patients with peripheral artery disease]

The protocols of performing treadmill tests (TMT) in patients presenting with peripheral artery disease have over the last decades undergone significant changes, with the alterations concerning not only the speed and time values of the load, but also the parameters measured. Currently, there is no unified generally accepted method of TMT, hence the need for an optimal protocol for carrying out this type of examination, which would help obtain reliable results in assessment of everyday life functional activity of patients and efficacy of various methods of treatment for peripheral atherosclerosis. The choice of an optimal methodology of performing a TMT in patients with intermittent claudication is extremely important because studying the haemodynamic parameters alone not always clearly reflect functional peculiarities of the course of the disease, since they depend not only on the presence of arterial stenoses or occlusions, but also on the activity of oxidative enzymes, endothelial and mitochondrial dysfunction, taking therapeutic agents, concomitant pathology and a series of other factors. The article is a review of the related literature contained in such databases as the Medline, PubMed, Russian Science Citation Index (RSCI) and Scopus and concerning TMT in patients with peripheral artery disease. The authors summarized the information from a total of 63 literature sources over the period from the 1970s to 2018.

Treadmill Measured vs. Questionnaire Estimated Changes in Walking Ability in Patients With Peripheral Artery Disease

OBJECTIVE

Determining the maximum walking time (MWT) using the treadmill test is the gold standard method for evaluating walking capacity and treatment effect in patients with peripheral arterial disease (PAD). However, self reported functional disability is important when assessing quality of life. Changes in the Walking Estimated Limitation Calculated by History (WELCH) questionnaire scores were compared with the MWT.

METHODS

A cross sectional study was performed in patients with intermittent claudication. The treadmill test (3.2 km/h; 10% gradient) and WELCH questionnaire were administered to all patients for objective evaluation of walking capacity. Given the log normal distribution of these parameters in patients with PAD, a log transformation was applied to the WELCH score (LnW) and maximum walking time (LnT). The responsiveness of the WELCH score was determined using mean changes and correlation coefficients of LnW and LnT changes. The effect of time on the "estimated minus real" (E - R) changes (LnW - change minus LnT - change) was assessed after categorisation of patients into various test-retest intervals. Patients who underwent lower limb revascularisation between the two tests and those who underwent medical treatment only were analysed.

RESULTS

Correlation coefficients between LnW and LnT for tests 1 and 2 were r = 0.514 and r = 0.503, respectively (p < .001, for both). Correlation for LnW change vs. LnT change was 0.384 (p < .001). E - R was positive only early after surgery. E - R was negative for all test-retest intervals >1 year in revascularised and non-revascularised patients.

CONCLUSION

Changes in WELCH scores correlated with changes observed on the treadmill in patients with intermittent claudication. For long test-retest intervals, WELCH changes tended to overestimate the worsening of walking impairment as compared with the measured difference observed in both revascularised and non-revascularised patients. A shortlived "honeymoon" (overestimation of the benefit for the shortest test-retest interval) was observed only in revascularised patients.

Application of exercise transcutaneous oxygen pressure measurements for detection of proximal lower extremity arterial disease: a case report

Proximal claudication is secondary to ischemia caused by peripheral artery disease (PAD), whereas proximal pseudo-claudication is secondary to other disease processes such as hip arthritis, spinal stenosis, neuropathy, and so forth. The differentiation between the two can be challenging. Exercise transcutaneous oxygen pressure measurement (exercise-TcPO2) allows noninvasive detection of flow-reducing lesions in the proximal arteries and tributaries of the lower extremity arterial tree. We present the first case report in the United States using an exercise-TcPO2 algorithm. A 71-year-old diabetic patient with proximal left-sided and right-calf claudication with indeterminate ankle-brachial indices underwent an exercise-TcPO2 study before and after endovascular intervention. Four TcPO2 probes were placed: one at chest level (reference probe), one on each buttock, and one on the symptomatic calf. The Delta from Resting Oxygen Pressure (DROP) index was calculated at each probe site using a previously validated protocol. Proximal left- and right-calf ischemia were confirmed by the initial exercise-TcPO2, and, after endovascular treatment of the left iliac artery lesion, improvements in proximal exercise-TcPO2 values were found. These data suggest that exercise-TcPO2 can be useful in PAD evaluation in patients with non-compressible arteries and/or proximal claudication.

The correlation of the "Walking Estimated-Limitation Calculated by History" (WELCH) questionnaire with treadmill maximal walking time is not impaired by age, in patients with claudication

PURPOSE

The "Walking Estimated-Limitation Calculated by History" (WELCH) questionnaire is a short four-item questionnaire that estimates the walking capacity of a patient in comparison with relatives, friends or people the same age. As such, it should be relatively insensitive to age, yet this has never been tested.

METHODS

A prospective study was performed among 525 patients presenting vascular-type claudication. Patients were grouped into quintiles of age-from quintile 1 for the youngest patients to quintile 5 for the oldest ones. Patients completed a self-administered questionnaire and then had their maximal walking time (MWT) measured on a treadmill. We estimated the coefficient of correlation, the slope and the intercept of the relationship between the WELCH score and the MWT, then the accuracy of a WELCH score under 25 to predict the ability to walk for 5 min on a treadmill.

RESULTS

The slopes of the relationships and the correlation coefficients were not significantly different in each quintile, but a significant shift in the intercept of regressing lines was found with age. Nevertheless, the accuracy in predicting treadmill results from the WELCH score with a cut-off point of 25 was, respectively, 68.6, 72.4, 80.0, 72.4 and 73.3 % in quintiles 1, 2, 3, 4 and 5 (p = 0.45).

CONCLUSIONS

The relationship of MWT on a treadmill and the WELCH score is slightly influenced by age, but a score superior to 25 seems to be of equal discriminatory performance in different quintiles of age to predict the ability to walk for 5 min on a treadmill. This makes this cut-off limit of interest for routine use, regardless of age.

Applicability of global positioning system for the assessment of walking ability in patients with arterial claudication

OBJECTIVE

This study determined for the first time the clinical applicability of a global positioning system (GPS)-monitored community-based walking ability assessment in a large cohort of patients with peripheral artery disease (PAD).

METHODS

A multicenter study was conducted among PAD patients who complained of intermittent claudication. Patients equipped with a GPS device performed a community-based outdoor walk. We determined the number of technically satisfactory GPS recordings (attempt No. 1). Patients with unsatisfactory GPS recordings were asked to perform a second attempt (attempt No. 2). From the satisfactory recordings obtained after attempts No. 1 and No. 2, we analyzed several GPS parameters to provide clinical information on the patients' walking ability. Results are reported as median (interquartile range).

RESULTS

A total of 218 patients performed an outdoor walk. GPS recordings were technically satisfactory in 185 patients (85%) and in 203 (93%) after attempts No. 1 and No. 2, respectively. The highest measured distance between two stops during community walking was 678 m (IQR, 381-1333 m), whereas self-reported maximal walking distance was 250 m (IQR, 150-400 m; P < .001). Walking speed was 3.6 km/h (IQR, 3.1-3.9 km/h), with few variations during the walk. Among the patients who had to stop during the walk, the stop durations were <10 minutes in all but one individual.

CONCLUSIONS

GPS is applicable for the nonsupervised multicenter recording of walking ability in the community. In the future, it may facilitate objective community-based assessment of walking ability, allow for the adequate monitoring of home-based walking programs, and for the study of new dimensions of walking in PAD patients with intermittent claudication.

Limitations of self-reported estimates of functional capacity using the Walking Impairment Questionnaire

OBJECTIVE

A potential issue with the Walking Impairment Questionnaire (WIQ) is that it is relatively complex. We estimated the number of errors made by patients when self-completing the WIQ, and assessed the benefit of correcting missing, duplicate or paradoxical (i.e., reported lower difficulty for a higher-intensity task) answers.

DESIGN

Prospective non-interventional study.

MATERIALS

All consecutive new patients with claudication over a 3-month period.

METHODS

The WIQ was self-completed before patients performed a constant-load treadmill walking test (maximised to 750 m).

MAIN OUTCOME MEASURE

We analysed the coefficient of determination of the linear relationship between overall WIQ score (mean of the available subscales when at least two subscales are available) and treadmill maximal walking distance (MWD), before and after correction of errors.

RESULTS

We studied 73 patients. Thirty-seven questionnaires had to be corrected for one or more errors. The coefficient of determination between the overall WIQ score and MWD was R(2) = 0.391 (n = 56) and R(2) = 0.426 (n = 73) before and after correction, respectively.

CONCLUSION

Supervision of self-completed WIQs detects errors in almost half of the questionnaires, resulting in a missing overall WIQ score in 23% of cases among uncorrected questionnaires. The overall WIQ score correlates only moderately with MWD, even after correction.

CLINICAL TRIAL REGISTRATION

NIH database: NCT01114178.

Heart rate recovery after constant-load exercise tests is decreased in proportion to the importance (severity and diffusion) of exercise-induced lower-limb ischaemia

BACKGROUND

Conditions that may influence heart rate recovery at 1 min of recovery from exercise (HRR1: end-exercise heart rate minus heart rate 1 min after exercise) are not fully understood. We hypothesized that the 'importance' (both local severity and regional diffusion) of peripheral skeletal muscle ischaemia is associated with low HRR1.

DESIGN AND METHODS

In 529 patients with suspected or confirmed peripheral vascular disease not receiving beta-blockers (61·4 ± 11·3 years old), we retrospectively studied the relationship of HRR1 to exercise-induced changes in transcutaneous oxygen DROP index (limb changes minus chest changes from rest). The sum of DROP indices observed on both calves and both buttocks (DROPtot) provides the unique opportunity to estimate both the severity and the diffusion of exercise-induced ischaemia on the right and left side simultaneously. It was used during a constant-load treadmill test (3·2 km h(-1) ; 10% grade) to classify patients in quartiles, the fourth quartile representing the more 'important' ischaemias.

RESULTS

There was an inverse relationship between quartiles of DROPtot and HRR1, even after adjustment for heart rate reserve (Delta HR: end-exercise minus resting heart rate), age (≤ or >60 years), gender, body mass index, treadmill maximal walking distance and ankle brachial index: adjusted R = 0·629; P<0·0001.

CONCLUSIONS

During constant-load treadmill testing, DROPtot, an index of the 'importance' of exercise-induced lower-limb ischaemia, correlates with HRR1. Whether HRR1 is improved in proportion of DROPtot improvement in patients undergoing surgery or rehabilitation for peripheral artery disease is a fascinating issue for future studies.