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Near-Infrared Spiroximetry

Aleksandar Mihaylov MBP3302 Supervisors: Ken Tichauer Keith St. Lawrence. Near-Infrared Spiroximetry. Overview. NIRS What is it? Why use it? NIRS Methodology Data acquisition Fitting Filtering and Spectral analysis Results Conclusion. What is NIRS?. Objective

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Near-Infrared Spiroximetry

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  1. Aleksandar Mihaylov MBP3302 Supervisors: Ken Tichauer Keith St. Lawrence Near-Infrared Spiroximetry

  2. Overview • NIRS • What is it? • Why use it? • NIRS Methodology • Data acquisition • Fitting • Filtering and Spectral analysis • Results • Conclusion

  3. What is NIRS? • Objective • Measure blood oxygenation using near-infrared light • Non-invasive methodology • Real time monitoring • Applications • Muscle metabolism • Vascular disorder studies • Functional brain imaging

  4. Applications cont’d Metabolism Brain Function http://www.daviddarling.info/encyclopedia/P/pulse_oximetry.html http://www.rtmagazine.com/issues/articles/2007-10_07.asp

  5. Why use NIRS? • Other Methods • Blood gas analysis • Oxygen sensors • NIRS benefits • Non-invasive • Allows for real time monitoring • Easy to implement

  6. Methodology - Data Acquisition • Near-Infrared light • Wavelengths of 600-900 nm • Deep penetration • Highly sensitive to Hb saturation • Probe Layout • Discrete vs. Broadband • Transmission vs. Reflectance • Positioning • Relative measure of volume change http://www.pages.drexel.edu/~kmg462/

  7. Methodology - Fitting • Separate oxy from non-oxy haemoglobin data • Deep penetration – one data set for arterial, venous and capillary compartments. Franceschini, et al, 2002

  8. Methodology – Spectral Analysis • Pulsatile nature of blood vessels • Arterial – pulsations at the heart rate • Venous – pulsations at the respiratory frequency • Fourier Domain analysis • Further separation into compartments • Power in spectrum relative to concentration of HbO2 or Hb

  9. Results

  10. Results cont’d • Accuracy (Unpublished Data) • Improvements • Higher sensitivity – allow for low SvO2 measurements • Improved fitting algorithm • Artifact Correction

  11. Conclusion • NIRS methodology • Non-invasive • Easy to implement • Real-time monitoring • Further work • Artifact correction • Probe sensitivity and bandwidth • Increased accuracy

  12. References • Maria Angela Franceschini, et al, Near-infrared spiroximetry: noninvasive measurements of venous saturation in piglets and human subjects, J Appl Physiol 92: 372-384, 2002. • B. L. Horecker, The absorption spectra of hemoglobin and its derivatieves in the visible and near infra-red regions, ASBMB, 1942 • Willem G. Zijlstra, Anneke Buursma, O. W. van Assendelft, Visible and near infrared absorption spectra of human and animal haemoglobin: determination and application, VSP 2000 • Kenneth M. Tichauer, Derek W. Brown, Jennifer Hadway, Ting-Yim Lee, Keith St. Lawrence, Near-infrared spectroscopy measurements of cerebral blood flow and oxygen consumption following hypoxia-ischemia in newborn piglets, J Appl Physiol 2006

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