System and method of resolving outliers in NIRS cerebral oximetry
First Claim
1. A system for assessing tissue blood oxygen saturation levels, comprising:
- a computing device;
a sensor in communication with said computing device, said sensor being configured to be attached to a human subject and having;
a light source capable of selectively emitting at least four different wavelengths of light, one wavelength at a time; and
a first light detector positioned a first distance from said light source and a second light detector positioned a second distance from said light source, said second distance being greater than said first distance;
said computing device having a memory for storing an algorithm and a processor for executing instructions associated with said algorithm, said algorithm comprising the following steps;
causing said light source to emit light of at least four different wavelengths, one wavelength at a time, into a human subject;
receiving optical density measurements from said first and second light detectors for each of the four wavelengths;
calculating a space contrasted ratio of the wavelength contrast difference of the optical density based on the optical density measurements from said first and second light detectors for three of said wavelengths emitted by said light source;
estimating a first tissue blood oxygen saturation value based on said space contrasted ratio of the wavelength contrast difference of the optical density;
calculating a second order contrasted optical density ratio based on the optical density measurements from said first and second light detectors for at least four of said wavelengths emitted by said light source;
estimating a second tissue blood oxygen saturation value based on said second order contrasted optical density ratio; and
determining if said first tissue blood oxygen saturation value is a valid estimate of an actual tissue blood oxygen saturation level in said human subject based upon a comparison of said first blood oxygen saturation value and said second blood oxygen saturation value.
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Abstract
A system and method for non-invasively estimating the tissue blood oxygen saturation level of a human subject, including so-called “outliers”, whose physiological make-up causes previously-known techniques to generate invalid tissue blood oxygen saturation estimations. The system includes a computing device and a sensor. The sensor includes a light source configured to emit light of at least four different wavelengths, one at a time. The sensor also includes two light detectors, each positioned a different distances from the light source. Optical density measurements are taken by the light detectors and provided to the computing device. A first tissue blood oxygen saturation value is computed using the optical density measurements associated with three of the four wavelengths, and a second tissue blood oxygen saturation value is computed using the optical density measurements associated with four of the wavelengths. The first and second tissue blood oxygen saturation values are compared, and the human subject is identified as an “outlier” based upon that comparison.
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Citations
10 Claims
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1. A system for assessing tissue blood oxygen saturation levels, comprising:
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a computing device; a sensor in communication with said computing device, said sensor being configured to be attached to a human subject and having; a light source capable of selectively emitting at least four different wavelengths of light, one wavelength at a time; and a first light detector positioned a first distance from said light source and a second light detector positioned a second distance from said light source, said second distance being greater than said first distance; said computing device having a memory for storing an algorithm and a processor for executing instructions associated with said algorithm, said algorithm comprising the following steps; causing said light source to emit light of at least four different wavelengths, one wavelength at a time, into a human subject; receiving optical density measurements from said first and second light detectors for each of the four wavelengths; calculating a space contrasted ratio of the wavelength contrast difference of the optical density based on the optical density measurements from said first and second light detectors for three of said wavelengths emitted by said light source; estimating a first tissue blood oxygen saturation value based on said space contrasted ratio of the wavelength contrast difference of the optical density; calculating a second order contrasted optical density ratio based on the optical density measurements from said first and second light detectors for at least four of said wavelengths emitted by said light source; estimating a second tissue blood oxygen saturation value based on said second order contrasted optical density ratio; and determining if said first tissue blood oxygen saturation value is a valid estimate of an actual tissue blood oxygen saturation level in said human subject based upon a comparison of said first blood oxygen saturation value and said second blood oxygen saturation value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification