Patent ID: 8644901

Claim:
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.