Study of an algorithm based on model experiments and diffusion theory for a portable tissue oximeter

The aim of the present study was to compare the frequency of oxygenation determined in the vastus lateralis by near-infrared spectroscopy (NIRS) in light exercise with that at rest. A subject rested in a recumbent position for 5 min and changed body position to a sitting position on a cycle ergometer for 9 min. Then exercise with low intensity (work rate of 60% of maximal oxygen uptake) was carried out for 30 min. Total hemoglobin and myoglobin (THb/Mb) suddenly decreased after the start of exercise and gradually increased until 6 min. Oxygenated hemoglobin and myoglobin (Hb/MbO2) suddenly decreased and returned to a steady state after the start of exercise. The difference between Hb/MbO2 and THb/Mb showed a sudden decrease and then a steady state. This difference was analyzed by fast Fourier transform. The peak frequencies of the power spectrum density (PSD) were 0.0169 + 0.0076 Hz at rest and 0.0117 + 0.0042 Hz in exercise. The peak frequency of PSD was significantly decreased in exercise. In exercise, the range of frequencies was expanded. It is concluded that there are oscillations at rest as well as in exercise and that the frequency of peak PSD becomes lower in exercise than at rest

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“…In NIRS, THb/Mb, Hb/MbO 2 and deoxy hemoglobin and myoglobin (HHb/Mb) are obtained by the following equations (24).…”

Section: Discussionmentioning

confidence: 99%

Oscillation of oxygenation in skeletal muscle at rest and in light exercise

Yano

Cs²,

Arimitsu³

et al. 2013

Acta Physiologica Hungarica

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“…Realistic situations are particularly valuable when exploring human executive functions and fiberless fNIRS systems may provide a unique insight into human brain functions. The first fiberless systems were equipped only with a small number of channels (e.g., single channel 15 and 2 channels 16 ) limiting the investigation to small areas. More recently, multichannel wireless and wearable fNIRS devices have been developed 6,7,[17][18][19][20] giving the possibility to monitor larger portions of the head on freely moving participants.…”

Section: Introductionmentioning

confidence: 99%

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

Pinti

Aichelburg

Lind

et al. 2015

JoVE

127

146

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Functional Near Infrared Spectroscopy (fNIRS) is a neuroimaging technique that uses near-infrared light to monitor brain activity. Based on neurovascular coupling, fNIRS is able to measure the haemoglobin concentration changes secondary to neuronal activity. Compared to other neuroimaging techniques, fNIRS represents a good compromise in terms of spatial and temporal resolution. Moreover, it is portable, lightweight, less sensitive to motion artifacts and does not impose significant physical restraints. It is therefore appropriate to monitor a wide range of cognitive tasks (e.g., auditory, gait analysis, social interaction) and different age populations (e.g., new-borns, adults, elderly people). The recent development of fiberless fNIRS devices has opened the way to new applications in neuroscience research. This represents a unique opportunity to study functional activity during real-world tests, which can be more sensitive and accurate in assessing cognitive function and dysfunction than lab-based tests. This study explored the use of fiberless fNIRS to monitor brain activity during a real-world prospective memory task. This protocol is performed outside the lab and brain haemoglobin concentration changes are continuously measured over the prefrontal cortex while the subject walks around in order to accomplish several different tasks.

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“…The light can penetrate soft tissue up to approximately 2.0 cm when the detector is at a distance of 4 cm from the radiation source. Relative changes in oxygenated haemoglobin (oxy-Hb), deoxygenated Hb (deoxy-Hb), and total Hb (t-Hb) were calculated by the equation reported in a previous study (Shiga et al, 1997). However, continuous wave NIRS could not provide absolute values because of unknown physical properties such as the optical path length in tissue (Hamaoka et al, 2007;McCully & Hamaoka, 2000).…”

Section: The Difference Of Acupuncture On Autonomic System and Localimentioning

confidence: 99%

“…The light can penetrate soft tissue up to approximately 2.0 cm when the detector is at a distance of 4 cm from the radiation source. Relative changes in oxygenated haemoglobin (oxy-Hb), deoxygenated Hb (deoxy-Hb), and total Hb (t-Hb) were calculated by the equation reported in a previous study (Shiga et al, 1997). Corrected concentrations (mM) considering the subcutaneous adipose tissue thickness (ATT) for oxy-Hb, deoxy-Hb, and t-Hb were obtained by dividing the concentrations with normalized measurement sensitivity S as shown in the literature (Niwayama et al, 2002).…”

Section: The Effect Of Varying Acupuncture Techniques On Muscle Bloodmentioning

confidence: 99%