Systems and methods for pedal revascularization assessment

• US 9,636,025 B2
• Filed: 08/14/2013
• Issued: 05/02/2017
• Est. Priority Date: 08/15/2012
• Status: Active Grant

• Current Assignee: Pedra Technology Pte Ltd.
• Original Assignee: Nanyang Technology University
• Inventors: Lee, Kijoon, Dong, Jing, Bi, Renzhe
• Primary Examiner(s): Cook, Christopher
• Assistant Examiner(s): Pehlke, Carolyn
• Application Number:
  US13/967,298
• Publication Number:
  US 20140052006A1
• Time in Patent Office: 1,357 Days
• Field of Search: None
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/6825 Hand
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/683 Means for maintaining contact with the body A61B5/6802 takes precedence
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/74 Details of notification to user or communication with user or patient indicating measured values G01D7/00; user input means input or output arrangements for computers G06F3/00
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7455 characterised by tactile indication, e.g. vibration or electrical stimulation

Abstract

Diffuse optical flow (DOF) sensors can be used to assess deep tissue flow. DOF sensors positioned on a foot can provide fluctuating light intensity data to an analyzer, which can then determine absolute and/or relative blood flow. The determined absolute and/or relative blood flow can be signaled to an operator, for example a surgeon for intra-operative use. DOF sensors may be utilized to assess pedal revascularization, for example to guide interventional procedures and to evaluate their efficacy. A support structure can carry a plurality of DOF sensors, such that when the support structure is placed onto a patient'"'"'s foot, the DOF sensors are disposed adjacent different locations on the foot. The different locations may correspond to different topographical regions of the foot, for example different pedal angiosomes.

Claims

1. A system for assessment of peripheral blood flow characteristics in deep tissue, the system comprising:

a support structure configured to be positioned onto a patient'"'"'s foot;

at least one diffuse optical flow (DOF) sensor carried by the support structure and configured to be positioned in optical communication with the skin surface of the patient'"'"'s foot, the DOF sensor comprising a return optical conduit, and at least one input optical fiber comprising an end configured to be positioned proximate the skin surface of the patient'"'"'s foot, the input optical fiber in optical communication with a coherent laser light source;

a photodetector operably connected to the at least one DOF sensor;

a software or hardware processor configured to analyze data from the at least one DOF sensor to determine blood flow characteristics at a location near the at least one DOF sensor when the support structure is positioned onto the patient'"'"'s foot, the hardware or software processor configured to determine blood perfusion characteristics in the patient'"'"'s arterioles and capillaries by determining the spatial speckle contrast ratio (K_s) or the temporal speckle contrast ratio (K_t) and determining 1/K_s² or 1/K_t² from intensity fluctuations, and correlating 1/K_t² or 1/K_t² values with blood flow; and

a display configured to provide audible, visual, or tactile feedback indicative of the blood flow characteristics determined by the hardware or software processor,

wherein the at least one DOF sensor is configured to capture light scattered diffusively into tissue and transmitted at a depth of penetration of between 5 mm and 50 mm.

2. The system of claim 1, wherein the support structure comprises a retention ring and an adhesive material.

3. The system of claim 1, wherein the support structure comprises a strap having the at least one DOF sensor attached thereto.

4. The system of claim 1, wherein the support structure comprises surgical tape.

5. The system of claim 1, wherein the at least one DOF sensor comprises a plurality of DOF sensors, wherein the plurality of DOF sensors are arranged such that when the support structure is positioned onto the patient'"'"'s foot, at least two of the DOF sensors are over different topographical locations in the foot including different pedal angiosomes.

6. The system of claim 5, wherein the plurality of DOF sensors comprise at least four DOF sensors, wherein the at least four DOF sensors are arranged such that when the support structure is positioned over the patient'"'"'s foot, wherein the at least four DOF sensors are over different topographical locations in the foot including different pedal angiosomes.

7. The system of claim 1, wherein the system is configured to provide the feedback indicative of the blood flow characteristics in real-time.

8. The system of claim 1, wherein the system is configured to provide the feedback indicative of the blood flow characteristics within 10 seconds from measurement.

9. The system of claim 1, wherein the photodetector comprises a multi-pixel image sensor or at least one photodiode.

10. The system of claim 9, comprising an multi-pixel image sensor, wherein the multi-pixel image sensor is a CCD or CMOS image sensor.

11. A method for real-time assessment of peripheral blood flow characteristics, the method comprising:

disposing at least one diffuse optical flow (DOF) sensor proximate a skin surface of a patient in optical communication with a first location on a foot of the patient, the DOF sensor comprising a return optical conduit;

transmitting light from a coherent laser light source through at least one input optical fiber of the at least one DOF sensor, the at least one input optical fiber comprising an end positioned proximate a second location on the foot of the patient;

obtaining measurements of intensity fluctuation from a depth of penetration of between 5 mm and 50 mm within a patient'"'"'s microcirculatory channels from the at least one DOF sensor;

analyzing the obtained measurements via a hardware or software processor to determine blood flow characteristics at the location, wherein analyzing comprises determining the spatial speckle contrast ratio (K_s) or the temporal speckle contrast ratio (K_t) and determining 1/K_s² or 1/K_t² from intensity fluctuations, and correlating 1/K_s² or 1/K_t² values with blood flow; and

signaling the determined blood flow characteristics to an operator.

12. The method of claim 11, wherein disposing the at least one DOF sensor comprises placing a support structure onto the foot of the patient, the at least one DOF sensor being carried by the support structure.

13. The method of claim 11, wherein disposing at least one DOF sensor comprises disposing a plurality of DOF sensors at a respective plurality of locations on the foot of the patient.

14. The method of claim 13, wherein the plurality of locations comprises at least two locations corresponding to different topographical locations in the foot including different pedal angiosomes.

15. The method of claim 14, wherein the plurality of locations comprises at least four locations corresponding to four different topographical locations in the foot including different pedal angiosomes.

16. The method of claim 11, wherein the signaling comprises providing visual, audible, or tactile indicia of blood flow characteristics.

17. The method of claim 11, wherein the assessment of peripheral blood flow characteristics occurs during a peripheral vascular intervention procedure.

18. A method for assessment of peripheral blood flow characteristics, the method comprising:

disposing a plurality of diffuse optical flow (DOF) sensors each comprising a return optical conduit at a respective plurality of locations in optical communication with the skin surface of an extremity of a patient, wherein at least two of the plurality of locations correspond to different topographical locations in the extremity including different angiosomes;

transmitting light from a coherent laser light source through at least one input optical fiber of each of the plurality of DOF sensors, each of the at least one input optical fibers comprising an end positioned proximate the skin surface of the extremity of the patient;

determining blood flow characteristics at each of the plurality of locations in the extremity of the patient via hardware or software by analyzing detected scattered coherent light at from depth of penetration of between 5 mm and 50 mm from within a patient'"'"'s microcirculatory channels, wherein analyzing comprises determining the spatial speckle contrast ratio (K_s) or the temporal speckle contrast ratio (K_t) and determining 1/K_s² or 1/K_t² from intensity fluctuations, and correlating 1/K_s² or 1/K_t² values with blood flow; and

signaling the determined blood flow characteristics to an operator.

19. The method of claim 18, wherein the extremity is a foot.

20. The method of claim 18, wherein the extremity is a hand.

21. The method of claim 18, wherein the signaling is performed in real-time.

22. The method of claim 18, further comprising utilizing the determined blood flow characteristics to assess the efficacy of a peripheral vascular interventional procedure.