Aleksandar Mihaylov
MBP3302
Supervisors:
Ken Tichauer
Keith St. Lawrence

NIRS
 What is it?
 Why use it?

NIRS Methodology
 Data acquisition
 Fitting
 Filtering and Spectral analysis


Results
Conclusion

Objective
 Measure blood oxygenation using near-infrared
light
 Non-invasive methodology
 Real time monitoring

Applications
 Muscle metabolism
 Vascular disorder studies
 Functional brain imaging
METABOLISM
http://www.daviddarling.info/encyclopedia/P/pulse_oximetry.html
BRAIN FUNCTION
http://www.rtmagazine.com/issues/articles/2007-10_07.asp

Other Methods
 Blood gas analysis
 Oxygen sensors

NIRS benefits
 Non-invasive
 Allows for real time monitoring
 Easy to implement

Near-Infrared light
 Wavelengths of 600-900 nm
 Deep penetration
 Highly sensitive to Hb saturation

Probe Layout
 Discrete vs. Broadband
 Transmission vs. Reflectance
 Positioning
http://www.pages.drexel.edu/~kmg462/

Relative measure of volume
change
Franceschini, et al, 2002


Separate oxy from non-oxy haemoglobin data
Deep penetration – one data set for arterial, venous and
capillary compartments.

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
Single-Sided Amplitude Spectrum of Relative Oxy-Hemoglobin
|rHbO(f)|
0.15
0.1
0.05
0
0
0.5
1
1.5
2
2.5
Frequency (Hz)
3
3.5
4
4.5
5
4.5
5
Single-Sided Amplitude Spectrum of Relative NonOxy-Hemoglobin
0.2
|rHb(f)|
0.15
0.1
0.05
0
0
0.5
1
1.5
2
2.5
Frequency (Hz)
3
3.5
4


Accuracy (Unpublished Data)
Run#
1:SvO2[%]
2:SvO2[%]
3:SvO2[%]
Expected
87.5
67.25
26
Calculated
74.9
47.1
31.1
Error
14.4
29.9
-19.6
Improvements
 Higher sensitivity – allow for low SvO2
measurements
 Improved fitting algorithm
 Artifact Correction

NIRS methodology
 Non-invasive
 Easy to implement
 Real-time monitoring

Further work
 Artifact correction
 Probe sensitivity and bandwidth
 Increased accuracy

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