Pressure modulation, motion detection, individualized geometry, and improved optic-skin coupling to improve long term clinical monitoring with diffuse optics
The present disclosure provides devices and methods for improved hemodynamic monitoring, including devices for characterizing hemodynamic activity within a tissue or region of interest.
1. A system, comprising:
a first device that comprises
a first illumination source-detector pair having a source and a detector separated by a first distance (a);
a second illumination source-detector pair having a source and a detector separated by a second distance (b),
distances (a) and (b) being different from one another such that the first illumination source-detector pair is configured to illuminate and detect scattered light from a deep tissue region of a tissue and the second illumination source-detector pair is configured to illuminate and detect scattered light from superficial tissue region disposed between the deep tissue region and the first illumination source-detector pair and the second illumination source-detector pair;
a first element configured to apply a varying perturbation to the surface of the tissue such that the deep tissue region is substantially unaffected; and
a processor configured to estimate at least one of regional blood flow, blood volume, and regional saturation in the deep tissue region from (i) signals related to scattered light collected by at least the first illumination source-detector pair and the second illumination source-detector pair during application of a first pressure to the tissue surface, and (ii) signals related to scattered light collected by the first illumination source-detector pair and the second illumination source-detector pair during application of a second pressure to the tissue surface.
2. The system of claim 1 , further comprising a second device configured to compute intensity correlation functions from photon counts, the second device being in electronic communication, optical communication, or both with at least one of the detectors of the source-detector pairs.
3. The system of claim 1 , further comprising a second element configured to isolate a hemodynamic superficial tissue signal from collected illumination.
4. The system of claim 1 , wherein the first element is configured to apply a pressure proximate to at least one of the source-detector pairs.
5. The system of claim 4 , wherein the first element comprises a balloon, a spring, a motor, a hydraulic element, or any combination thereof.
6. The system of claim 5 , wherein the first element comprises a balloon.
7. The system of claim 1 , wherein the first element is automated.
8. The system of claim 1 , wherein at least one detector of the first source-detector pair and the second source-detector pair is a single-mode or few-mode fiber.
9. The system of claim 1 , wherein at least one detector of the first source-detector pair and the second source-detector pair comprises a photon-counting detector.
10. The system of claim 1 , wherein at least one source of the first source-detector pair and the second source-detector pair and one detector of the first source-detector pair and the second source-detector pair share a prism.
11. The system of claim 1 , wherein the source of the first source-detector pair and the source of the second source-detector pair share a prism.
12. The system of claim 1 , wherein at least one detector of the first source-detector pair and the second source-detector pair is a Diffuse Optical Spectroscopy (DOS) detector and at least one detector of the first source-detector pair and the second source-detector pair is a Diffuse Correlation Spectroscopy (DCS) detector, and wherein the at least one DOS detector and the at least one DCS detector share a prism.
13. The system of claim 1 , the system further comprising a third element configured to maintain at least one source-detector pair in a position on a subject.
14. The system of claim 13 , wherein the third element comprises a band, a cap, a sleeve, or any combination thereof.
15. The system of claim 1 , wherein at least one source of the first source-detector pair and the second source-detector pair is configured to deliver illumination at between about 300 nm and 1500 nm in wavelength.
16. The system of claim 14 , wherein the at least one source of the first source-detector pair and the second source-detector pair is configured to deliver illumination at between about 660 nm and about 930 nm in wavelength.
17. The system of claim 1 , wherein the system further comprises a fiber optic connection to a source of the first source-detector pair and the second source-detector pair, a detector of the first source-detector pair and the second source-detector pair, or both.
18. The system of claim 1 , wherein the processor is configured to apply a DCS Lambert Law, a DOS/Near Infrared Spectroscopy (NIRS) Modified Beer-Lambert law, any combination thereof to the signal related to illumination collected by at least one of the source-detector pairs.
19. The system of claim 1 , further comprising an amount of scattering optical coupling gel configured to be placed between the optical elements and the tissue surface to minimize light reflected from the diffuse-non-diffuse boundary.
20. The system of claim 1 , further comprising a pressure sensor configured to monitor a pressure exerted by the first device against a subject.
21. The system of claim 1 , wherein the processor is configured to estimate a tissue blood flow from (i) a first signal related to illumination collected by at least one of the source-detector pairs during application of a first pressure to a subject's body, and (ii) a second signal related to illumination collected by at least one of the source-detector pairs during application of a second pressure to a subject's body.
22. The system of claim 1 , wherein the first element is configured to moveably advance a portion of the first element so as to increase a pressure between the first device and a subject's body.