Apparatus and Method for Monitoring Tissue Vitality Parameters

• US 20070179366A1
• Filed: 10/10/2006
• Published: 08/02/2007
• Est. Priority Date: 09/25/2000
• Status: Abandoned Application

• Current Assignee: CritiSense Ltd.
• Original Assignee: CritiSense Ltd.
• Inventors: Pewzner, Eliahu, Mayevsky, Avraham
• Application Number:
  US11/539,949
• Publication Number:
  US 20070179366A1
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue

Abstract

Apparatus for determining the oxygenation state of at least one tissue element, comprising: a) illumination means for illuminating said tissue element with an illuminating radiation at a predetermined wavelength via at least one illumination location with respect to said tissue element, said illuminating radiation being at a wavelength within the NADH excitation spectrum or the Fp excitation spectrum; b) radiation receiving means and detection means for measuring the intensity of the corresponding NADH fluorescence or Fp fluorescence emitted by the tissue element at at least two predetermined wavelengths within the range of wavelengths comprised within the corresponding fluorescence emission spectrum.

Claims

1. Apparatus for determining the oxygenation state of at least one tissue element, comprising:

a) illumination means for illuminating said tissue element with an illuminating radiation at a predetermined wavelength via at least one illumination location with respect to said tissue element, said illuminating radiation being at a wavelength within the NADH excitation spectrum or the Fp excitation spectrum;

b) radiation receiving means and detection means for measuring the intensity of the corresponding NADH fluorescence or Fp fluorescence emitted by the tissue element at at least two predetermined wavelengths within the range of wavelengths comprised within the corresponding fluorescence emission spectrum.

2. Apparatus as claimed in claim 1, wherein the detection means comprises a spectrometer.

3. Apparatus as claimed in claim 1, further comprising suitable means adapted for comparing the intensities measured in (b) to provide an estimate of the relative levels of oxygenated blood to deoxygenated blood in said tissue.

4. Apparatus as claimed in claim 1, wherein said receiving means and said detection means are adapted for measuring said intensity at said at least two fluorescent wavelengths such that one of said fluorescent wavelengths is at an oxy-deoxy fluorescence emission isosbestic point in the fluorescent emission spectrum.

5. Apparatus as claimed in claim 1, wherein said receiving means and said detection means are adapted for measuring said intensity at said at least two fluorescent wavelengths, such that one of said fluorescent wavelengths is higher than, and another one of said at least two fluorescent wavelengths is smaller than, a wavelength corresponding to an oxy-deoxy fluorescence emission isosbestic point in the fluorescent emission spectrum.

6. Apparatus as claimed in claim 1, wherein said predetermined wavelength of said illuminating radiation corresponds to an isosbestic point of the blood oxy de-oxy absorption spectrum and being within the fluorescence excitation spectrum of NADH or Fp.

7. Apparatus as claimed in claim 1, wherein said illumination location is provided by at least one excitation optical fiber capable of being brought into registry with said tissue element.

8. Apparatus as claimed in claim 7, wherein said radiation receiving means comprises at least one suitable receiving optical fiber capable of being brought into registry with said tissue element.

9. Apparatus as claimed in claim 8, comprising at least one probe which houses said at least one excitation optical fiber, and said at least one receiving optical fiber.

10. Apparatus as claimed in claim 9, wherein the at least one probes comprise a plurality of probes, each probe housing at least one of the at least one excitation fibers and at least one of the at least one receiving fibers for determining the oxygenation state of one of the at least one tissue elements.

11. Apparatus as claimed in claim 10, wherein the illumination means comprises a UV monochromatic light source, adapted to provide said illuminating radiation to the plurality of probes, in pulses of predetermined duration and intensity.

12. A system as claimed in claim 11, further comprising suitable control means for controlling the frequency of pulsing of said pulses.

13. A system as claimed in claim 12, wherein said control means is adapted for selectively directing discrete said pulses to any one of said probes.

14. Apparatus as claimed in claim 12, further comprising coupling means for optically connecting said at least two probes to said detection means, wherein said control means is operatively connected to said detection means.

15. A system as claimed in claim 14, wherein said control means is selectively responsive to previously detected signals corresponding to the detection of said fluorescence detected by said detection means of a prior monitoring cycle.

16. Method for determining the oxygenation state of a tissue element, comprising:

(a) providing an illuminating radiation to the tissue element, said illuminating radiation being at a wavelength within one of the NADH fluorescence excitation spectrum or the Fp fluorescence excitation spectrum;

(b) measuring the intensity of the corresponding NADH fluorescence or Fp fluorescence, respectively, emitted by the tissue element at least at two predetermined wavelengths within the range of wavelengths comprised in the corresponding fluorescence emission;

(c) comparing the intensities measured in (b) to provide an estimate of the relative levels of oxygenated blood to deoxygenated blood in said tissue element.

17. Method as claimed in claim 16, wherein one of said wavelengths in step (b) is chosen to lie at a suitable NADH oxy-deoxy fluoresence emission isosbestic point or Fp oxy-deoxy fluoresence emission isosbestic point, respectively.

18. Method as claimed in claim 16, wherein in step (c) the fluorescence intensity at each wavelength in (b) is normalised by a normalising fluorescence intensity measured at a suitable corresponding NADH or Fp oxy-deoxy fluorescence emission isosbestic wavelength within the fluorescence emission spectrum.

19. Method as claimed in claim 16, wherein said illuminating radiation is provided at a suitable NADH oxy-deoxy fluoresence excitation isosbestic wavelength or a suitable Fp oxy-deoxy fluoresence excitation isosbestic wavelength, respectively within the corresponding NADH fluorescence excitation spectrum or Fp fluorescence excitation spectrum, respectively.

20. Method as claimed in claim 18, wherein said illuminating radiation in step (a) is within the range of wavelengths comprised in the NADH excitation spectrum, and said normalising fluorescence intensity is measured at an NADH oxy-deoxy fluorescence emission isosbestic wavelength within the fluorescence emission spectrum of about 455 nm±

5 nm.

21. Method as claimed in claim 18, wherein said illuminating radiation in step (a) is within the range of wavelengths comprised in the Fp excitation spectrum, and said normalising fluorescence intensity is measured at an Fp oxy-deoxy fluorescence emission isosbestic wavelength within the fluorescence emission spectrum of about 530 nm±

5 nm.