Regional Differences of Hemodynamics and Oxygenation in the Human Calf Muscle Detected with Near-Infrared Spectrophotometry

Abstract

PURPOSE: Measurements in muscle tissue are often performed at a selected single location over the muscle of interest. The hypothesis is that the values obtained reflect the status within the entire muscle or muscle group. This, however, may not be the case. The study was performed to investigate whether this hypothesis is true for hemodynamics and oxygenation in the healthy human calf muscle at rest. MATERIALS AND METHODS:Hemoglobin flow, blood flow, oxygen consumption, and venous hemoglobin oxygen saturation were mapped at 22 locations in 30 legs of 15 healthy subjects (nine women, six men aged 26 -37 years) simultaneously by using frequency-domain near-infrared spectrophotometry with a specially designed probe during venous occlusion. RESULTS: For all parameters, spatial heterogeneity was found between subjects and within individual legs. All parameters were highly significantly different when comparing proximal and distal regions. Differences were also found between medial and lateral regions. The global mean values (؎standard deviation) over all measurements were as follows: hemoglobin flow, 1.27 mol per 100 mL/min ؎ 0.88; blood flow, 0.56 mL per 100 g/min ؎ 0.38; oxygen consumption, 0.016 mL per 100 g/min ؎ 0.011; and venous oxygen saturation, 77.6% ؎ 5.9. The thickness of the overlying adipose tissue had an influence on the measurements and must be considered. CONCLUSION: Highly significant spatial heterogeneity of hemodynamics and oxygenation was found in the healthy human calf muscle. J Vasc Interv Radiol 2007; 18:1094 -1101Abbreviations: ATT ϭ adipose tissue thickness, DPF ϭ differential pathlength factor, NIRS ϭ near-infrared spectrophotometry, SvO 2 ϭ venous oxygen saturation, TRV ϭ test-retest variability, VO 2 ϭ oxygen consumption NEAR-INFRARED spectrophotometry (NIRS) is a valuable tool for measuring hemodynamics and oxygenation in human tissue. NIRS is noninvasive, provides real-time measurements, is costeffective, is feasible at the bedside, and is easily repeatable and reproducible and, therefore, suitable for use in the clinical setting. Because NIRS provides measurements at the level of arterioles, capillaries, and venules (1) several centimeters deep in the tissue, it is a complementary method to Doppler, which probes larger blood vessels, laser Doppler flowmetry, which measures superficial blood vessels, and imaging techniques such as magnetic resonance (MR) imaging, positron emission tomography (PET), and radiography, which depend on the use of ionizing radiation and/or contrast media. NIRS has been applied to infants and adults to measure hemodynamics and oxygenation in many fields such as the brain, but one particularly promising field is the skeletal muscle (2-5). Studies in the skeletal muscle have included measurements in sports medicine (6,7) and in patients with peripheral vascular disease (8 -17), myopathies (18 -20), and heart failure (21-23).Measurements in muscle tissue are often performed at a selected single location over the muscle of interest. The values obtained are consider...

Textile integrated sensors and actuators for near-infrared spectroscopy

“…The average StO 2 value of 92% is within the StO 2 range of 82% ± 17% reported in [35] for lower legs obtained with an source/detector spacing of 20 mm. The venous oxygen saturation SvO 2 was 88%, which is again somewhat higher than the value of 77.6% ± 5.9% [33]. Our setup is more sensitive to the adipose tissue layer, which has a smaller light absorption, and by its nature a higher oxygenation [36], which explains our results.…”

“…[17,32,33]. However, it is to note that the changes in HHb, O 2 Hb and tHb are by trend smaller than the average values given in [33]. The smaller values arise from the different source/detector spacing used in this study (17 mm short distance between source and detector and 22 mm long distance, cf.…”

“…11, an exemplary measurement result is shown, with the occlusion period marked in grey. [17,32,33]. However, it is to note that the changes in HHb, O 2 Hb and tHb are by trend smaller than the average values given in [33].…”

“…The smaller values arise from the different source/detector spacing used in this study (17 mm short distance between source and detector and 22 mm long distance, cf. Figure 3) and in [33] where the spacing was between 24 mm and 35 mm. An increased spacing between source and detector allows a deeper penetration of the infrared light into the tissue and therefore more light absorption in the muscles [34].…”

Frequency domain near-infrared multiwavelength imager design using high-speed, direct analog-to-digital conversion

“…Such data acquired at multiple near-infrared wavelengths allow quantification of tissue chromophore concentrations, such as oxy-and deoxy-hemoglobin, water, and lipids. 3,4 Numerous applications of FD-NIRS techniques have been reported, including breast, 5,6 brain, 7,8 and muscle 9,10 tissues to name a few.…”