O3 Regional Oximeter Chapter 1: Technology
www.masimo.com 14 Masimo
The human body is opaque to most visible light frequencies, yet it is more transparent to red
and infrared light. Moreover, light absorptions of oxygen-related chromophores, such as
oxygenated and deoxygenated hemoglobin, vary as a function of wavelength in the near
infrared spectrum, as shown in Figure 1. Therefore, if the level of oxygenation in the tissue
changes, optical characteristics of the tissue also change according to the concentrations of
oxygenated and deoxygenated hemoglobin. This absorption of light by the chromophore
concentrations forms the basis of measurement of oxygen saturation, defined as the ratio of
oxygenated hemoglobin to total hemoglobin.
Figure 1: Absorption coefficients of tissue chromophores in the NIR spectrum*
Masimo’s regional oximeter consists of a light emitter and multiple detectors. By emitting
multiple wavelengths of light (LEDs), which pass through the region of interest, and
measuring them (using photo-detectors) after they have traveled through the tissue, the
system calculates attenuation experienced by each wavelength. These optical attenuations
are then mapped to rSO
2
.
* Beard P. Biomedical photoacoustic imaging. Interface Focus 2011;1:602-631.
To Next Page
Loading...
Need help?
General
