The use of Near-Infrared Spectroscopy to evaluate the effect of exercise on peripheral muscle oxygenation in patients with lower-extremity artery disease: a systematic review
Abstract Funding Acknowledgements Type of funding sources: None. Background Near-Infrared Spectroscopy (NIRS) has been suggested as a new diagnostic tool in patients with lower-extremity artery disease (LEAD). The aim of this systematic review was i) to summarize the impact of exercise therapy on lower-limb muscle oxygenation, evaluated by means of NIRS, in patients with LEAD and ii) to give an overview on NIRS instruments and methodology. Methods A systematic search was conducted in MEDLINE and Embase, from the earliest date available until 16th of March 2020, to identify peer-reviewed studies involving the use of NIRS in the evaluation of exercise training on muscle oxygenation in patients with LEAD. Primary outcomes were NIRS-derived variables. Effect sizes were calculated as standardized mean differences. Assessment of methodological quality was done using a combined checklist from the Cochrane bias and the quality assessment tool for before-after studies without control group. Results Eleven original trials were included involving 16 exercise groups and 4 control groups. Tissue saturation index (TSI) at rest remained unchanged following the exercise interventions. Yet, exercise training increased time-to-minimum TSI during exercise (range effect sizes: +0.172 to +0.927). In addition, exercise training led to a faster recovery to half and full TSI rest values in most intervention groups (range effect sizes: -0.046 to -0.558 and -0.269 to -0.665 respectively). Finally, NIRS data reproducibility and analytic methods were underreported in the included studies. To illustrate, only four studies reported appropriate measures to ensure repeated reproducible probe positioning. The use of raw or filtered data for analysis was reported in none of the included articles. Conclusion The available NIRS data suggest that exercise training improves deoxygenation and reoxygenation patterns in patients with LEAD. Whereas NIRS is a promising tool in the evaluation of LEAD, the low number of RCT’s as well as large heterogeneity in NIRS assessment methods, outcome measures and instrumentation, warrants more research to better understand the role of muscle oxygenation associated with exercise-induced improvements in walking capacity. In particular the role of NIRS to study underlying mechanisms and determinants related to exercise progression in LEAD patients is appealing. Abstract Figure. NIRS during treadmill test
