Medical devices for measuring tissue properties and methods of use

Patent metadata

Field	Value
Publication number	US-11857294-B2
Application number	US-202217980737-A
Country	US
Kind code	B2
Filing date	Nov 4, 2022
Priority date	Nov 4, 2021
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

Provided herein are medical devices, systems and platforms to monitor tissue properties such as oxygen saturation, temperature and degree of tissue edema for diagnosis and post-operative patient monitoring. The medical devices may be handheld or portable or may be removable patches. The medical devices utilize light of various visible and near-infrared wavelengths to interrogate a tissue where the intensities of reflected light correlate to one or more tissue property. Also provided are methods for measuring tissue properties, for detecting pressure ulcers and for remotely monitoring in real time a surgical flap on a post-operative subject via the medical devices.

First claim

What is claimed:

1. A medical device for measuring tissue properties in a subject, comprising:
a light-guiding cone comprising an opaque, anti-reflective, sloped surface and having optical properties that direct light along an optical excitation path into a homogeneous field on a tissue of interest in the subject;
a plurality of excitation light sources disposed at an open end of the light-guiding cone, each of said plurality emitting light at a wavelength from visible to near infrared;
an image sensor configured to measure intensities of light with different wavelengths reflected from the tissue of interest;
a radially extruded lip at the end of the light-guiding cone disposed to cover an area of the tissue of interest under interrogation and to prevent ambient light from impinging on the area;
at least one pressure sensor configured to sense conformal attachment of the medical device to the surface of the tissue of interest;
and
a processor and a memory in electronic communication with the device and tangibly storing an algorithm for processing the reflected wavelengths as a measurement of tissue properties, said algorithm comprising processor-executable instructions that perform all of the following to:
predict an Ankle Brachial Index from measurements of tissue oxygenation, tissue temperature, or perfusion index or a combination thereof at at least one wavelength;
correlate tissue oxygenation measurements from an upper limb and a lower limb of the subject to the Ankle Brachial Index;
measure a photoplethysmography signal; and
predict peripheral artery disease in the subject.

2. The medical device of claim 1 , further comprising:
a removable optically clear cap comprising a sterile barrier and disposed between the device and the tissue of interest;
an optical diffuser positioned on the optical excitation path configured to direct the light into the homogeneous field on the tissue of interest;
a temperature sensor to measure a surface temperature of the tissue of interest,
at least one accelerometer to remove effects of tissue or device movement during data calibration or during data acquisition; or
a display to monitor tissue properties; or
a combination thereof.

3. The medical device of claim 1 , wherein the light-guiding cone further comprises an impedance sensor for detecting moisture content in the tissue.

4. The medical device of claim 1 , wherein the light-guiding cone comprises at least one reflective material and is configured for automatic self-calibration.

5. The medical device of claim 1 , wherein the image sensor comprises a photodiode or an array of photodiodes.

6. The medical device of claim 1 , further comprising a printed circuit board in operable communication with the device, said printed circuit board comprising at least one accelerometer therewithin to quantify movements of the device.

7. The medical device of claim 1 , wherein one of the wavelengths emitted from the plurality of excitation light sources is an isosbestic point, that ranges from 800 nm to 805 nm, in a ratiometric image sensor measurement of a non-isosbestic wavelength to the isosbestic wavelength.

8. The medical device of claim 1 , wherein the algorithm further comprises processor-executable instructions configured to:
calculate distance from the image sensor to the tissue of interest via an analysis of patterns of light formed on the surface of the tissue of interest;
predict the stage of at least one pressure ulcer in the subject as stage 1, stage 2, stage 3, or stage 4; or
predict sub-clinical stage 1 pressure ulcers in the subject; or
a combination thereof.

9. A method for measuring tissue properties in a subject, comprising the steps of:
a) illuminating a tissue of interest in the subject with a non-isosbestic wavelength emitted from the plurality of excitation light sources comprising the medical device of claim 1 ;
b) measuring a reflected non-isosbestic wavelength via the image sensor comprising the device;
c) illuminating the tissue of interest with an isosbestic wavelength;
d) measuring a reflected isosbestic wavelength;
e) determining a ratiometric image sensor measurement of the reflected non-isosbestic wavelength to the reflected isosbestic wavelength via the algorithm comprising the medical device;
f) correlating the ratiometric image sensor measurement with at least one tissue property of the tissue of interest; and
g) repeating steps a) to f) at least once with another non-isosbestic wavelength and the isobestic wavelength.

10. The method of claim 9 , further comprising:
measuring the tissue properties to determine a baseline;
measuring the tissue properties as the subject exercises;
measuring the tissue properties during a recovery period after exercise is completed;
measuring a recovery time of the tissue properties; and
correlating, via the algorithm, the recovery time with an ankle brachial index in the subject or to predict severity of peripheral arterial disease in the subject.

11. The method of claim 9 , wherein steps a) to d) comprise:
illuminating sequentially the tissue of interest with a plurality of non-isosbestic wavelengths of differing wavelengths; and
measuring sequentially the plurality of reflected isosbestic wavelengths;
illuminating sequentially the tissue of interest with a plurality of isosbestic wavelengths of differing wavelengths; and
measuring sequentially the plurality of reflected isosbestic wavelengths.

Assignees

• Texas A&M Univ
• Texas A & M Univ Sys

Inventors

• Hanks John
• Zavareh Amir Tofighi
• Saint-Cyr Michel

Classifications

• A61B5/02055 Primary

  Simultaneously evaluating both cardiovascular condition and temperature · CPC title

• A61B5/0022

  Monitoring a patient using a global network, e.g. telephone networks, internet · CPC title

• A61B5/0261

  using optical means, e.g. infrared light · CPC title

• A61B5/0537

  Measuring body composition by impedance, e.g. tissue hydration or fat content · CPC title

• A61B5/14551

  for measuring blood gases · CPC title