Near‐infrared diffuse correlation spectroscopy: the future of non‐invasive assessment of skeletal muscle oxygenation?

Central cardiorespiratory and gas exchange limitations imposed by chronic obstructive pulmonary disease (COPD) impair ambulatory skeletal muscle oxygenation during whole body exercise. This investigation tested the hypothesis that peripheral factors per se contribute to impaired contracting lower limb muscle oxygenation in COPD patients. Submaximal neuromuscular electrical stimulation (NMES; 30, 40, and 50 mA at 50 Hz) of the quadriceps femoris was employed to evaluate contracting skeletal muscle oxygenation while minimizing the influence of COPD-related central cardiorespiratory constraints. Fractional O2 extraction was estimated by near-infrared spectroscopy (deoxyhemoglobin/myoglobin concentration; deoxy-[Hb/Mb]), and torque output was measured by isokinetic dynamometry in 15 nonhypoxemic patients with moderate-to-severe COPD (SpO2 = 94 ± 2%; FEV1 = 46.4 ± 10.1%; GOLD II and III) and in 10 age- and gender-matched sedentary controls. COPD patients had lower leg muscle mass than controls (LMM = 8.0 ± 0.7 kg vs. 8.9 ± 1.0 kg, respectively; P < 0.05) and produced relatively lower absolute and LMM-normalized torque across the range of NMES intensities ( P < 0.05 for all). Despite producing less torque, COPD patients had similar deoxy-[Hb/Mb] amplitudes at 30 and 40 mA ( P > 0.05 for both) and higher deoxy-[Hb/Mb] amplitude at 50 mA ( P < 0.05). Further analysis indicated that COPD patients required greater fractional O2 extraction to produce torque (i.e., ↑Δdeoxy-[Hb/Mb]/torque) relative to controls ( P < 0.05 for 40 and 50 mA) and as a function of NMES intensity ( P < 0.05 for all). The present data obtained during submaximal NMES of small muscle mass indicate that peripheral abnormalities contribute mechanistically to impaired contracting skeletal muscle oxygenation in nonhypoxemic, moderate-to-severe COPD patients.

Download Full-text

Impact of Changes in Tissue Optical Properties on Near-Infrared Diffuse Correlation Spectroscopy Measures of Skeletal Muscle Blood Flow

Journal of Applied Physiology ◽

10.1152/japplphysiol.00857.2020 ◽

2021 ◽

Author(s):

Miles F. Bartlett ◽

Scott M. Jordan ◽

Dennis M. Hueber ◽

Michael D. Nelson

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Optical Properties ◽

Near Infrared ◽

Muscle Blood Flow ◽

Reactive Hyperemia ◽

Correlation Spectroscopy ◽

Skeletal Muscle Blood Flow ◽

Diffuse Correlation Spectroscopy ◽

Tissue Optical Properties

Near-infrared diffuse correlation spectroscopy (DCS) is increasingly utilized to study relative changes in skeletal muscle blood flow. However, most diffuse correlation spectrometers assume that tissue optical properties- such as absorption (μa) and reduced scattering (μ's) coefficients- remain constant during physiological provocations, which is untrue for skeletal muscle. Here, we interrogate how changes in tissue μa and μ's affect DCS calculations of blood flow index (BFI). We recalculated BFI using raw autocorrelation curves and μa/μ's values recorded during a reactive hyperemia protocol in 16 healthy young individuals. First, we show that incorrectly assuming baseline μa and μ's substantially affects peak BFI and BFI slope when expressed in absolute terms (cm2/s, p<0.01) but these differences are abolished when expressed in relative terms (% baseline). Next, to evaluate the impact of physiologic changes in μa and μ's, we compared peak BFI and BFI slope when μa and μ's were held constant throughout the reactive hyperemia protocol versus integrated from a 3s-rolling average. Regardless of approach, group means for peak BFI and BFI slope did not differ. Group means for peak BFI and BFI slope were also similar following ad absurdum analyses, where we simulated supraphysiologic changes in μa/μ's. In both cases, however, we identified individual cases where peak BFI and BFI slope were indeed affected, with this result being driven by relative changes in μa over μ's. Overall, these results provide support for past reports in which μa/μ's were held constant but also advocate for real-time incorporation of μa and μ's moving forward.

Download Full-text

Changes in skeletal muscle oxygenation during exercise measured by near-infrared spectroscopy on ascent to altitude

Critical Care ◽

10.1186/cc8005 ◽

2009 ◽

Vol 13 (Suppl 5) ◽

pp. S7 ◽

Cited By ~ 15

Author(s):

Daniel S Martin ◽

Denny ZH Levett ◽

Michael Mythen ◽

Mike PW Grocott ◽

Keyword(s):

Skeletal Muscle ◽

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Muscle Oxygenation ◽

Skeletal Muscle Oxygenation

Download Full-text

Quantitative measurement of skeletal muscle oxygenation by combined near infrared time resolved and unresolved spectroscopy

10.1117/12.2283780 ◽

1993 ◽

Author(s):

Marco Ferrari

Keyword(s):

Skeletal Muscle ◽

Quantitative Measurement ◽

Near Infrared ◽

Muscle Oxygenation ◽

Time Resolved ◽

Skeletal Muscle Oxygenation

Download Full-text

Monte-Carlo Lookup Table-based Inverse Model for Non-invasive Quantification of Cerebral Optical Properties in Small Animals Using Review of Time-domain Diffuse Correlation Spectroscopy: From Theoryrequency-domain Near-infrared Spectroscopy

Biophotonics Congress: Biomedical Optics Congress 2018 (Microscopy/Translational/Brain/OTS) ◽

10.1364/translational.2018.jtu3a.58 ◽

2018 ◽

Cited By ~ 1

Author(s):

Seung Yup Lee ◽

Corey Zheng ◽

Erin Buckley

Keyword(s):

Monte Carlo ◽

Optical Properties ◽

Infrared Spectroscopy ◽

Time Domain ◽

Near Infrared ◽

Correlation Spectroscopy ◽

Lookup Table ◽

Small Animals ◽

Diffuse Correlation Spectroscopy ◽

Non Invasive

Download Full-text

Near-infrared diffuse correlation spectroscopy tracks changes in oxygen delivery and utilization during exercise with and without isolated arterial compression

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00212.2019 ◽

2020 ◽

Vol 318 (1) ◽

pp. R81-R88

Author(s):

Wesley J. Tucker ◽

Ryan Rosenberry ◽

Darian Trojacek ◽

Belinda Sanchez ◽

Robert F. Bentley ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Radial Artery ◽

Brachial Artery ◽

Oxygen Delivery ◽

Near Infrared ◽

Correlation Spectroscopy ◽

Flow Index ◽

Artery Blood Flow ◽

Diffuse Correlation Spectroscopy

Near-infrared diffuse correlation spectroscopy (NIR-DCS) is an emerging technology for simultaneous measurement of skeletal muscle microvascular oxygen delivery and utilization during exercise. The extent to which NIR-DCS can track acute changes in oxygen delivery and utilization has not yet been fully established. To address this knowledge gap, 14 healthy men performed rhythmic handgrip exercise at 30% maximal voluntary contraction, with and without isolated brachial artery compression, designed to acutely reduce convective oxygen delivery to the exercising muscle. Radial artery blood flow (Duplex Ultrasound) and NIR-DCS derived variables [blood flow index (BFI), tissue oxygen saturation ([Formula: see text]), and metabolic rate of oxygen ([Formula: see text])] were simultaneously measured. During exercise, both radial artery blood flow (+51.6 ± 20.3 mL/min) and DCS-derived BFI (+155.0 ± 82.2%) increased significantly ( P < 0.001), whereas [Formula: see text] decreased −7.9 ± 6.2% ( P = 0.002) from rest. Brachial artery compression during exercise caused a significant reduction in both radial artery blood flow (−32.0 ± 19.5 mL/min, P = 0.001) and DCS-derived BFI (−57.3 ± 51.1%, P = 0.01) and a further reduction of [Formula: see text] (−5.6 ± 3.8%, P = 0.001) compared with exercise without compression. [Formula: see text] was not significantly reduced during arterial compression ( P = 0.83) due to compensatory reductions in [Formula: see text], driven by increases in deoxyhemoglobin/myoglobin (+7.1 ± 6.1 μM, P = 0.01; an index of oxygen extraction). Together, these proof-of-concept data help to further validate NIR-DCS as an effective tool to assess the determinants of skeletal muscle oxygen consumption at the level of the microvasculature during exercise.

Download Full-text