US-20260123891-A1 - Melanin-Corrected Oxygen Saturation

US20260123891A1US 20260123891 A1US20260123891 A1US 20260123891A1US-20260123891-A1

Abstract

An oximeter device takes into account tissue color (e.g., skin color or melanin content) to improve accuracy when determining oxygen saturation of tissue. Light is transmitted from a light source into tissue having melanin (e.g., eumelanin or pheomelanin). Light reflected from the tissue is received by a detector. A compensation factor is determined to account for absorption due to the melanin. The oximeter uses this compensation factor and determines a melanin-corrected oxygen saturation value.

Inventors

Kate Leeann Bechtel
Kimberly Merritt Shultz
Alex Michael Margiott
George Edward Kechter

Assignees

VIOPTIX, INC.

Dates

Publication Date: 20260507
Application Date: 20251219

Claims (20)

1 . A system comprising: an oximeter device comprising a sensor tip comprising source structures and detector structures at a distal end of the device, a processor, and a display associated with the oximeter device, wherein the processor of the oximeter device calculates a melanin-corrected oxygen saturation value, and displays the melanin-corrected oxygen saturation value on the display.
2 . The system of claim 1 wherein the processor of the oximeter device is configured to use the sensor tip to make a first measurement and a second measurement to determine the melanin-corrected oxygen saturation value; receive first information based on the first measurement of a first tissue at a first location when the sensor tip is positioned on the first tissue, wherein the melanin-corrected oxygen saturation value is unavailable for display after the first measurement is made and before the second measurement is made; receive second information based on the second measurement of a second tissue at a second location when the sensor tip is positioned on the second tissue, wherein the second location is different from the first location; and use the first information and second information to determine the melanin-corrected oxygen saturation value, wherein the melanin-corrected oxygen saturation value takes into account melanin components of the first tissue and second tissue, and the melanin components comprise eumelanin and pheomelanin.
3 . The system of claim 1 wherein the first location is at a first position of the body, the second location is at a second position of the body, and the first position and second position are contralateral with respect to each other.
4 . The system of claim 1 wherein the oximeter device is a handheld oximeter comprising a power source, and the processor is housed within an enclosure that also houses the source structures and detector structures of the sensor tip.
5 . The system of claim 1 wherein the oximeter device comprises a memory, and the memory stores first simulated reflectance curves for a first melanin content value, second simulated reflectance curves for a second melanin content value, and the first melanin content value is different from the second melanin content value.
6 . The system of claim 5 wherein the oximeter device is specially configured to: based on the first and second information, determine a melanin content value for the first tissue and second tissue; and use the determined melanin content value to select one of the first simulated reflectance curves or the second simulated reflectance curves stored in the memory by comparing the determined melanin content value against the melanin content value associated with each of the simulated reflectance curves.
7 . The system of claim 1 wherein the processor of the oximeter device is configured to: transmit first light through a source structure into a first tissue at a first location to be measured, wherein the first tissue comprises a first melanin component, and the first melanin component comprises at least one of eumelanin or pheomelanin; receive the first light at a detector structure that is reflected by the first tissue in response to the transmitted first light, wherein the received first light comprises a first melanin absorption component due to the first melanin component; transmit second light through a source structure into a second tissue at a second location to be measured, wherein the second location is different from the first location, and second tissue comprises a second melanin component, and the second melanin component comprises at least one of eumelanin or pheomelanin; receive the second light at a detector structure that is reflected by the second tissue in response to the transmitted light, wherein the received second light comprises a second melanin absorption component due to the second melanin component; determine a melanin compensation component for a melanin absorption component due to a melanin component of tissue, wherein the melanin absorption component comprises the first and second melanin components; and use the melanin compensation component, obtaining the melanin-corrected oxygen saturation value for the first tissue, wherein the melanin-corrected oxygen saturation value accounts for the melanin absorption component.
8 . The system of claim 1 wherein the processor of the oximeter device is configured to: transmit first light through a source structure into a first tissue at a first location to be measured, wherein the first tissue comprises a first melanin component, and the first melanin component comprises at least one of eumelanin or pheomelanin; receive the first light at a detector structure that is reflected by the first tissue in response to the transmitted first light, wherein the received first light comprises a first melanin absorption component due to the first melanin component; determine a melanin compensation component for a melanin absorption component due to a melanin component of tissue, wherein the melanin absorption component comprises the first and second melanin components, wherein the determining the melanin compensation component for the melanin absorption component due to the melanin component comprises: transmit second light through a source structure into a second tissue at a second location to be measured, wherein the second location is different from the first location, and the second tissue comprises a second melanin component, and the second melanin component comprises at least one of eumelanin or pheomelanin; receive the second light at the detector structure that is reflected by the first tissue in response to the transmitted light, wherein the received second light comprises a second melanin absorption component due to the second melanin component; determine a first plurality of absorption coefficients that are dependent on a plurality of wavelengths of the first light emitted into the first tissue when the measurement on the first tissue is performed; and determine a second plurality of absorption coefficients that are dependent on the first plurality of wavelengths of the second light emitted into the second tissue when the measurement on the second tissue is performed; and use the melanin compensation component, obtaining a melanin-corrected oxygen saturation value for the first tissue, wherein the melanin-corrected oxygen saturation value accounts for the melanin absorption component.
9 . The system of claim 8 wherein to determine the melanin compensation component for the melanin absorption component due to the melanin component comprises: calculate a first angular deviation and a second angular deviation of a curve for the first plurality of absorption coefficients for the first tissue; calculate a third angular deviation and a fourth angular deviation of a curve for the second plurality of absorption coefficients for the second tissue; calculate a first angular difference between the first and second angular deviations and a second angular difference between the third and fourth angular deviations; and calculate a relative change in oxygen saturation between the first and second tissues based on the first and second angular differences.
10 . The system of claim 8 comprising: adjust the absorption coefficients of the second plurality of absorption coefficients for each wavelength of the first light using the reflectance data for the first tissue, wherein the melanin compensation component comprises the adjusted absorption coefficients; and determine an oxygen saturation value for the second tissue using the adjusted absorption coefficients.
11 . The system of claim 9 comprising displaying on the display associated with the oximeter device, the melanin-corrected oxygen saturation value, wherein the melanin-corrected oxygen saturation value is a value for the relative change in oxygen saturation between the first and second tissues.
12 . The system of claim 11 wherein to determine the melanin compensation component for the melanin absorption component due to the melanin component comprises scaling the first and second angular differences with a scaling vector, and the scaling vector representing a 100 percent difference in oxygenation of a tissue phantom.
13 . The system of claim 8 wherein to determine the melanin compensation component for the melanin absorption component due to the melanin component comprises: generate a third absorption coefficient by adjusting at least one of the coefficients of the first plurality of absorption coefficients using at least one of the absorption coefficients of the second plurality of absorption coefficients; and generate the melanin-corrected oxygen saturation value for the first tissue using the third absorption coefficient.
14 . The system of claim 13 wherein to determine the melanin compensation component for the melanin absorption component due to the melanin component comprises: fit first reflectance data for the first light received at a detector structure for the first tissue to a plurality of simulated reflectance curves for determining the at least one of the absorption coefficients of the first plurality of absorption coefficients, wherein the simulated reflectance curves include modeling for melanin in simulated tissue; and determine the at least one of the absorption coefficients of the first plurality of absorption coefficients from one or more best fitting one of the simulated reflectance curves.
15 . The system of claim 14 wherein to determine the melanin compensation component for the melanin absorption component due to the melanin component comprises: fit second reflectance data for the second light received at a detector structure for the second tissue to the plurality of simulated reflectance curves for determining the at least one of the absorption coefficients of the second plurality of absorption coefficients; and determine the at least one of the absorption coefficients of the second plurality of absorption coefficients from one or more best fitting one of the simulated reflectance curves.
16 . The system of claim 7 comprising: determine a first plurality of absorption coefficients that are dependent on a plurality of wavelengths of the first light emitted from into the first tissue when the measurement on the first tissue is performed; determine a second plurality of absorption coefficients that are dependent on the plurality of wavelengths of the second light emitted into the second tissue when the measurement on the second tissue is performed; generate a third absorption coefficient by adjusting at least one of the absorption coefficients of the first plurality of absorption coefficients using at least one of the absorption coefficients of the second plurality of absorption coefficients; and generate the melanin-corrected oxygen saturation value for the first tissue using the third absorption coefficient.
17 . The system of claim 16 comprising: fit first reflectance data, for the first light received at a detector structure for the first tissue, to a plurality of simulated reflectance curves for determining the at least one of the absorption coefficients of the first plurality of absorption coefficients, wherein the simulated reflectance curves include modeling for melanin in simulated tissue; and determine the at least one of the absorption coefficients of the first plurality of absorption coefficients from one or more best fitting ones of the simulated reflectance curves.
18 . The system of claim 17 comprising: fit second reflectance data, for the second light received at a detector structure for the second tissue, to the plurality of simulated reflectance curves for determining the at least one of the absorption coefficients of the second plurality of absorption coefficient; and determine the at least one of the absorption coefficients of the second plurality of absorption coefficients from one or more best fitting one of the simulated reflectance curves.
19 . The system of claim 1 wherein a user provides to the oximeter an indication of a skin color of the tissue.
20 . The system of claim 2 wherein a user provides to the oximeter an indication of a skin color of the tissue.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/503,119, filed Nov. 6, 2023, issued as U.S. Pat. No. 12,502,140 on Dec. 23, 2025, which is a continuation of U.S. patent application Ser. No. 17/088,520, filed Nov. 3, 2020, issued as U.S. Pat. No. 11,806,170 on Nov. 7, 2023, which is a divisional of U.S. patent application Ser. No. 15/494,444, filed Apr. 21, 2017, issued as U.S. Pat. No. 10,820,863 on Nov. 3, 2020, which claims the benefit of the following U.S. patent applications 62/325,919, filed Apr. 21, 2016, 62/326,630, 62/326,644, and 62/326,673, filed Apr. 22, 2016. These applications and U.S. patent application 62/363,562, filed Jul. 18, 2016, are incorporated by reference along with all other references cited in these applications. BACKGROUND OF THE INVENTION The present invention relates generally to optical systems that monitor oxygen levels in tissue. More specifically, the present invention relates to optical probes, such as oximeters, that include sources and detectors on sensor heads of the optical probes and that use locally stored simulated reflectance curves for determining oxygen saturation of tissue. Oximeters are medical devices used to measure oxygen saturation of tissue in humans and living things for various purposes. For example, oximeters are used for medical and diagnostic purposes in hospitals and other medical facilities (e.g., surgery, patient monitoring, or ambulance or other mobile monitoring for, e.g., hypoxia); sports and athletics purposes at a sports arena (e.g., professional athlete monitoring); personal or at-home monitoring of individuals (e.g., general health monitoring, or person training for a marathon); and veterinary purposes (e.g., animal monitoring). Pulse oximeters and tissue oximeters are two types of oximeters that operate on different principles. A pulse oximeter requires a pulse in order to function. A pulse oximeter typically measures the absorbance of light due to pulsing arterial blood. In contrast, a tissue oximeter does not require a pulse in order to function, and can be used to make oxygen saturation measurements of a tissue flap that has been disconnected from a blood supply. Human tissue, as an example, includes a variety of light-absorbing molecules. Such chromophores include oxygenated hemoglobin, deoxygenated hemoglobin, melanin, water, lipid, and cytochrome. Oxygenated hemoglobin, deoxygenated hemoglobin, and melanin are the most dominant chromophores in tissue for much of the visible and near-infrared spectral range. Light absorption differs significantly for oxygenated and deoxygenated hemoglobins at certain wavelengths of light. Tissue oximeters can measure oxygen levels in human tissue by exploiting these light-absorption differences. Despite the success of existing oximeters, there is a continuing desire to improve oximeters by, for example, improving measurement accuracy; reducing measurement time; lowering cost; reducing size, weight, or form factor; reducing power consumption; and for other reasons, and any combination of these measurements. In particular, assessing a patient's oxygenation state, at both the regional and local level, is important as it is an indicator of the state of the patient's local tissue health. Thus, oximeters are often used in clinical settings, such as during surgery and recovery, where it may be suspected that the patient's tissue oxygenation state is unstable. For example, during surgery, oximeters should be able to quickly deliver accurate oxygen saturation measurements under a variety of nonideal conditions. While existing oximeters have been sufficient for post-operative tissue monitoring where absolute accuracy is not critical and trending data alone is sufficient, accuracy is, however, required during surgery in which spot-checking can be used to determine whether tissue might remain viable or needs to be removed. Therefore, there is a need for improved tissue oximeter probes and methods of making measurements using these probes. BRIEF SUMMARY OF THE INVENTION An oximeter device takes into account tissue color (e.g., skin color or melanin content) to improve accuracy when determining oxygen saturation of tissue. Light is transmitted from a light source into tissue having melanin (e.g., eumelanin or pheomelanin). Light reflected from the tissue is received by a detector. A compensation factor is determined to account for absorption due to the melanin. The oximeter uses this compensation factor and determines a melanin-corrected oxygen saturation value. In an implementation, to calculate oxygen saturation, an oximeter probe utilizes a relatively large number of simulated reflectance curves to quickly determine the optical properties of tissue under investigation. The optical properties of the tissue allow for the further determination of the oxygenated hemoglobin and deoxygenated hemoglobin concentrations of the tissue as well as the oxygen sa