Method for spectrophotometric blood oxygenation monitoring

1. A method for non-invasively determining a blood oxygen parameter value of a subject's tissue, comprising:

providing a spectrophotometric sensor that includes at least one processor and at least one transducer, which transducer is operable to transmit light at a first plurality of predetermined wavelengths in a range of about 600 nm to about 900 nm into the subject's tissue at a known initial intensity value, and to sense the transmitted light;

detecting at least a portion of the transmitted light after passage through the subject's tissue using the transducer, and producing initial signal data representative of a detected intensity value of the light sensed;

using the at least one processor to execute instructions stored in a memory device, which instructions cause the processor to:

determine a value representative of an attenuation between the known initial intensity value and the detected intensity value of at least one wavelength less than about 720 nm within the first plurality of predetermined wavelengths; and

determine whether the representative attenuation value is outside a predefined range of attenuation values; and

determine the blood oxygen parameter value using a subset of the first plurality of predetermined wavelengths, which subset consists of a second plurality of wavelengths in a range of about 720 nm to about 900 nm, if the representative attenuation value is outside the predefined range of attenuation values, or using the first plurality of predetermined wavelengths if the representative attenuation value is within the predefined range of attenuation values.

2. The method of claim 1 , wherein the method is performed over a period of time, and wherein the initial signal data is produced once during the period of time.

3. The method of claim 1 , wherein the method is performed over a period of time, and wherein the initial signal data is produced more than once during the period of time.

4. The method of claim 1 , wherein the initial signal data is produced periodically during the period of time.

5. The method of claim 1 , wherein the transducer includes a light source and a plurality of light detectors.

6. The method of claim 1 , wherein the representative attenuation value is indicative of an altered tissue condition independent of the blood oxygen parameter value.

7. The method of claim 6 , wherein the altered tissue condition includes one or more of a bruise, contusion, scarring, skull fracture, concussion, surgery scarring, infection, tissue discoloration, bone discoloration, dura pigmentation, bone marrow, or forehead hair follicles.

8. A method for non-invasively determining a blood oxygen parameter value of a subject's tissue, comprising:

providing a spectrophotometric sensor that includes at least one processor and at least one transducer, which transducer is operable to transmit light at a first plurality of predetermined wavelengths in a range of about 600 nm to about 900 nm into the subject's tissue at a known initial intensity value, and to sense the transmitted light;

detecting at least a portion of the transmitted light after passage through the subject's tissue using the transducer, and producing initial signal data representative of a detected intensity value of the light sensed;

using the at least one processor to execute instructions stored in a memory device, which instructions cause the processor to:

determine a value representative of an attenuation between the known initial intensity value and the detected intensity value of at least one wavelength less than about 720 nm within the first plurality of predetermined wavelengths; and

determine a value representative of a hemoglobin concentration within the tissue;

determine whether the representative attenuation value is outside a predefined range of attenuation values associated with the determined hemoglobin concentration; and

determine the blood oxygen parameter value using a subset of the first plurality of predetermined wavelengths, which subset consists of a second plurality of wavelengths in a range of about 720 nm to about 900 nm, if the representative attenuation value is outside the predefined range of attenuation values associated with the determined hemoglobin concentration, or using the first plurality of predetermined wavelengths if the representative attenuation value is within the predefined range of attenuation values associated with the determined hemoglobin concentration.

9. The method of claim 8 , wherein the instructions causing the processor to determine a value representative of the hemoglobin concentration within the tissue include instructions that cause the processor to determine an oxyhemoglobin (HbO2) value, or a deoxyhemoglobin (Hb) value, or both.

10. A method for non-invasively determining a blood oxygen parameter value of a subject's tissue, comprising:

providing a spectrophotometric sensor that includes at least one processor and at least one transducer, which transducer is operable to transmit light at a first plurality of predetermined wavelengths in a range of about 600 nm to about 900 nm into the subject's tissue at a known initial intensity value, and to sense the transmitted light;

detecting at least a portion of the transmitted light after passage through the subject's tissue using the transducer, and producing initial signal data representative of a detected intensity value of the light sensed;

using the at least one processor to execute instructions stored in a memory device, which instructions cause the processor to:

determine a value representative of an attenuation between the known initial intensity value and the detected intensity value of at least one wavelength less than 720 nm within the first plurality of predetermined wavelengths; and

determine a value representative of the oxygen saturation value of the tissue; and

determine whether the representative attenuation value is outside a predetermined range of attenuation values associated with the determined oxygen saturation value; and

determine the blood oxygen parameter value using a subset of the first plurality of predetermined wavelengths, which subset consists of a second plurality of wavelengths in a range of about 720 nm to about 900 nm, if the representative attenuation value is outside the predefined range of attenuation values associated with the determined oxygen saturation value, or using the first plurality of predetermined wavelengths if the representative attenuation value is within the predefined range of attenuation values associated with the determined oxygen saturation value.

11. An apparatus for non-invasively determining a blood oxygen parameter value of a subject's tissue, comprising:

a spectrophotometric sensor that includes at least one processor and at least one transducer, which transducer is operable to transmit light at a first plurality of predetermined wavelengths and at a known initial intensity value into the subject's tissue, and is operable to detect at least a portion of the transmitted light after passage through the subject's tissue using the transducer, and to produce initial signal data representative of a detected intensity value of the light sensed;

wherein the at least one processor is in communication with a non-transitory memory storing instructions, which instructions when executed cause the processor to selectively determine a value representative of an attenuation between the known initial intensity value and the detected intensity value of at least one wavelength less than about 720 nm within the first plurality of predetermined wavelengths, and to determine whether the representative attenuation value is outside a predefined range of attenuation values, and to determine the blood oxygen parameter value using a subset of the first plurality of predetermined wavelengths, which subset includes a second plurality of wavelengths in a range of about 720 nm to about 900 nm, if the representative attenuation value is outside the predefined range of attenuation values, or using the first plurality of predetermined wavelengths if the representative attenuation value is within the predefined range of attenuation values.