Cerebral oxygenation monitor during head-up and -down tilt using near-infrared spatially resolved spectroscopy*

2003 ◽  
Vol 23 (4) ◽  
pp. 177-181 ◽  
Author(s):  
Koichi Kurihara ◽  
Azusa Kikukawa ◽  
Asao Kobayashi
Keyword(s):  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Spatially Resolved ◽  
Spatially Resolved Spectroscopy

Frontal cortical oxygenation changes during gravity-induced loss of consciousness in humans: a near-infrared spatially resolved spectroscopic study

2007 ◽  
Vol 103 (4) ◽  
pp. 1326-1331 ◽  
Author(s):  
Koichi Kurihara ◽  
Azusa Kikukawa ◽  
Asao Kobayashi ◽  
Toshio Nakadate
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Oxygenation Index ◽  
Loss Of Consciousness ◽  
Spatially Resolved ◽  
Hemoglobin Saturation ◽  
Significant Difference ◽  
Concentration Changes ◽  
Spatially Resolved Spectroscopy

Gravity (G)-induced loss of consciousness (G-LOC), which is presumably caused by a reduction of cerebral blood flow resulting in a decreased oxygen supply to the brain, is a major threat to pilots of high-performance fighter aircraft. The application of cerebral near-infrared spectroscopy (NIRS) to monitor gravity-induced cerebral oxygenation debt has generated concern over potential sources of extracranial contamination. The recently developed NIR spatially resolved spectroscopy (SRS-NIRS) has been confirmed to provide frontal cortical tissue hemoglobin saturation [tissue oxygenation index (TOI)]. In this study, we monitored the TOI and the standard NIRS measured chromophore concentration changes of oxygenated hemoglobin and deoxygenated hemoglobin in 141 healthy male pilots during various levels of +Gz (head-to-foot inertial forces) exposure to identify the differences between subjects who lose consciousness and those who do not during high +Gz exposure. Subjects were exposed to seven centrifuge profiles, with +Gz levels from 4 to 8 Gz and an onset rate from 0.1 to 6.0 Gz/s. The SRS-NIRS revealed an ∼15% decrease in the TOI in G-LOC. The present study also demonstrated the TOI to be a useful variable to evaluate the effect of the anti-G protection system. However, there was no significant difference found between conditions with and without G-LOC in subjects with terminated G exposure. Further studies that elucidate the mechanism(s) behind the wide variety of individual differences may be needed for a method of G-LOC prediction to be effectively realized.

scholarly journals Use of near–infrared spectroscopy in the adult

1997 ◽  
Vol 352 (1354) ◽  
pp. 701-705 ◽  
Author(s):  
Peter J. Kirkpatrick
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Haemoglobin Concentration ◽  
Potential Method ◽  
Adult Brain ◽  
Spatially Resolved ◽  
Clinical Scenarios ◽  
Spatially Resolved Spectroscopy

Adult near–infrared spectroscopy is a potential method for observing changes in cerebral oxygenation non–invasively. Access of light to the adult brain requires penetration through extracranial tissues; hence the detection of changes in cerebral chromophore concentration can only be achieved by using near–infrared spectroscopy in the reflectance–mode thereby adding variables which are difficult to control. These include the effects of variable anatomy, different intra–optode distances and the presence of an extra– to intracranial collateral blood supply. Although movements of oxygenated haemoglobin concentration following specific cerebral stimuli can be demonstrated, the challenge of separating changes which occur within the extracranial compartment from those occurring in the intracranial compartments remains. Our experience with near–infrared spectroscopy in the three adult clinical scenarios of carotid endarterectomy, head injury and carbon dioxide stress testing will be presented. The influence of extracranial contamination is demonstrated, as are the methods we have developed to help control for extracranial contamination. Provisional experience with spatially resolved spectroscopy technology will also be presented.

Measuring The Tensile Strain of Wood By Visible And Near-Infrared Spatially Resolved Spectroscopy

2021 ◽  
Author(s):  
Ma Te ◽  
Tetsuya Inagaki ◽  
Masato Yoshida ◽  
Mayumi Ichino ◽  
Satoru Tsuchikawa
Keyword(s):  
Light Scattering ◽  
Prediction Accuracy ◽  
Tensile Strain ◽  
Near Infrared ◽  
Mean Squared Error ◽  
Calibration Model ◽  
Spatially Resolved ◽  
Squared Error ◽  
Stiffness Evaluation ◽  
Spatially Resolved Spectroscopy

Abstract Wood has various mechanical properties, so stiffness evaluation is critical for quality management. Using conventional strain gauges constantly is high cost, also challenging to measure precious wood materials due to the use of strong adhesive. This study demonstrates the correlation between light scattering changes inside the wood cell walls and tensile strain. A multifiber-based visible-near-infrared (Vis–NIR) spatially resolved spectroscopy (SRS) system was designed to rapidly and conventiently acquire such light scattering changes. For the preliminary experiment, samples with different thicknesses were measured to evaluate the influence of thickness. The differences in Vis–NIR SRS spectral data diminish with an increase in sample thickness, which suggests that the SRS method can successfully measure the whole strain (i.e., surface and inside) of wood samples. Then, for the primary experiment, 18 wood samples with the same thickness (2 mm) were tested to construct a strain calibration model. The prediction accuracy was characterized by a determination coefficient (R2) of 0.86 with a root mean squared error (RMSE) of 297.89 με for five-fold cross-validation; for test validation, The prediction accuracy was characterized by an R2 of 0.82 and an RMSE of 345.44 με.

scholarly journals Measuring the tensile strain of wood by visible and near-infrared spatially resolved spectroscopy

Cellulose ◽  
2021 ◽  
Author(s):  
Te Ma ◽  
Tetsuya Inagaki ◽  
Masato Yoshida ◽  
Mayumi Ichino ◽  
Satoru Tsuchikawa
Keyword(s):  
Tensile Strain ◽  
Near Infrared ◽  
Spatially Resolved ◽  
Spatially Resolved Spectroscopy

A portable wireless near-infrared spatially resolved spectroscopy system for use on brain and muscle

2013 ◽  
Vol 35 (11) ◽  
pp. 1692-1697 ◽  
Author(s):  
N.L. Everdell ◽  
D. Airantzis ◽  
C. Kolvya ◽  
T. Suzuki ◽  
C.E. Elwell
Keyword(s):  
Near Infrared ◽  
Spatially Resolved ◽  
Spectroscopy System ◽  
Spatially Resolved Spectroscopy

scholarly journals Phantom testing of two clinical spatially-resolved NIRS instruments

2005 ◽  
Vol 19 (3) ◽  
pp. 165-169 ◽  
Author(s):  
A. J. Macnab ◽  
R. E. Gagnon
Keyword(s):  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Full Range ◽  
Hemoglobin Concentration ◽  
Bone Thickness ◽  
Technical Design ◽  
Spatially Resolved ◽  
Hemoglobin Saturation ◽  
Oxygenation Status ◽  
Total Hemoglobin Concentration

We used a living biological phantom to evaluate whether previously observed clinical differences in data collection between two similar near infrared spectrophotometers were due to technical design differences. A Somanetics INVOS-5100 was compared to a Hamamatsu NIRO-300. Both express the ratio of oxygenated hemoglobin to total hemoglobin concentration as a percentage, and both are intended for monitoring cerebral oxygenation status at the bedside. The living phantom simulated different bone densities and contained a low haematocrit solution of blood, intra-lipid, and saline, to which was added grower's yeast to alter oxygenation status. Results: In all trials, oxygen saturation decreased from 100% to 0 % as the yeast consumed the available oxygen. In all trials the spectrometers were significantly correlated (range: r2=0.815 to 0.995, p2>0.232). The NIRO-300 indicated oxygenation change 1 minute after addition of yeast, whereas the INVOS-5100 showed change after 5 minutes. Simulated bone thickness had almost no effect upon the NIRO-300, but did affect the INVOS-5100. Conclusion: In this study, the spectrophotometers had similar results consistent with the technical design differences: the INVOS-5100 does not report hemoglobin saturation change above 95% or below 15% while the NIRO-300 reports the full range from 100% to 0%.

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