Clinical applications of StO 2 analysis

• US 8,208,983 B2
• Filed: 02/27/2007
• Issued: 06/26/2012
• Est. Priority Date: 02/27/2006
• Status: Expired due to Fees

• Current Assignee: Hutchinson Technology Incorporated (TDK Corporation)
• Original Assignee: Hutchinson Technology Incorporated (TDK Corporation)
• Inventors: Anderson, LeAnn, Myers, Dean E., Ortner, Joseph P., Wheatley, Gregory L.
• Primary Examiner(s): Winakur, Eric
• Assistant Examiner(s): Liu, Chu Chuan (JJ)
• Application Number:
  US11/679,592
• Publication Number:
  US 20070203406A1
• Time in Patent Office: 1,946 Days
• Field of Search: 600/322, 600/323, 600/324, 600/310, 600/326, 600/328, 600/300
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis

Abstract

Embodiments of the invention provide a method and apparatus for using StO₂ values to predict an outcome of a subject'"'"'s health status.

Claims

1. A method for predicting a health status of a subject, comprising:

measuring the levels of hemoglobin oxygenation (StO₂) in tissue of the subject;

comparing the measured levels to a hemoglobin oxygenation threshold value;

trending a plurality of StO₂ levels over a period of time;

determining the magnitude of a net tissue oxygenation cumulative area or cumulative ischemia score based on the trended StO₂ levels; and

predicting a change in the health status of the subject from a first health status to a second health status based on the magnitude of the net tissue oxygenation cumulative area or cumulative ischemia score associated with the trended StO₂ levels relative to the hemoglobin oxygenation threshold value.

2. The method of claim 1 wherein the measuring of StO₂ is measuring on a thenar eminence muscle of a hand.

3. The method of claim 1 wherein the measuring of the StO₂ is by spectroscopic radiation.

4. The method of claim 3 wherein the spectroscopic radiation is near infrared radiation.

5. The method of claim 1 wherein the first health status is a lower risk or probability of developing an adverse health outcome.

6. The method of claim 1 wherein the second health status is a higher risk or probability of developing an adverse health outcome.

7. The method of claim 6 wherein the adverse health outcome is ischemia, hypoperfusion, hypoxia, oxygen debt death, multiple organ dysfunction, ventilator-free days or number of hospitalization days.

8. The method of claim 1 wherein the threshold value is a minimum StO₂ value.

9. The method of claim 8 wherein the minimum StO₂ value is 75 percent.

10. The method of claim 1 wherein the net tissue oxygenation cumulative area or cumulative ischemia score is calculated using the equation:

11. The method of claim 1 wherein the threshold value is set by a physician or end user.

12. The method of claim 1 wherein the threshold value of 50 percent StO₂ indicates a highest probability of developing an adverse health outcome.

13. An apparatus for predicting a subject'"'"'s health status based on a measure of hemoglobin oxygen saturation (StO₂), comprising:

a subject interface comprising a light path for irradiating tissue of the subject with spectroscopic radiation and a detector for detecting a spectral response from the tissue responsive to irradiation with the spectroscopic radiation;

a display for displaying data;

a memory configured for storing a predetermined hemoglobin oxygenation threshold value or range;

a processor operatively connected to the memory and the subject interface such that the processor generates data from information comprising the spectral response of the tissue sample in a pre-selected format;

wherein the processor is configured to issue a signal to indicate when a measured StO₂ data is outside of the hemoglobin oxygenation threshold value or range; and

wherein the processor is configured to trend a plurality of StO₂ data measurements taken over a period of time and predict a change in the health status of the subject from a first health status to a second health status based on the magnitude of a net tissue oxygenation cumulative area or cumulative ischemia score associated with the trended StO₂ data measurements relative to the hemoglobin oxygenation threshold value or range.

14. The apparatus of claim 13 wherein the subject interface is placed on a thenar eminence.

15. The apparatus of claim 13 wherein the pre-determined threshold value is a minimum StO₂.

16. The apparatus of claim 15 wherein the minimum StO₂ value limit is 75 percent.

17. The apparatus of claim 15 wherein a threshold of 50 percent StO₂ signals a highest probability of developing an adverse health outcome.

18. The apparatus of claim 13 wherein the memory is configured for storing data representative of a correlation which provides the relative concentration of the oxygenated hemoglobin as a function of a scaled, second derivative spectrum value input, wherein the scaled second derivative value input is derived from the spectral response obtained from the tissue sample at a plurality of wavelengths within a wavelength range from 600 nm to 900 nm.

19. The apparatus of claim 13 wherein the apparatus further signals to indicate when StO₂ levels are generally trending above or below the threshold value.

20. The apparatus of claim 13 wherein the net tissue oxygenation cumulative area or cumulative ischemia score is calculated using the equation:

21. The apparatus of claim 13 wherein a threshold can be adjusted according to the end user.

22. A device for predicting a subject'"'"'s health status based on a measure of hemoglobin oxygen saturation (StO₂), comprising:

means for sensing including a light source assembly for generating spectroscopic radiation for irradiating a tissue and a spectroscopic detector for detecting a spectral response emitted by the tissue sample responsive to irradiation with the spectroscopic radiation;

means for displaying data;

means for providing a notice to a user upon the occurrence of a specified event;

means for storing, said means for storing including a predetermined hemoglobin oxygenation threshold value or range;

a means for generating data of the tissue sample from information comprising the spectral response of the tissue sample;

a means for characterizing the data in a pre-selected form including a control system interfaced with the means for storing and the means for sensing such that the control system generates data of the tissue sample;

a means to indicate when a measured StO₂ data is outside of the pre-determined hemoglobin oxygenation threshold value or range; and

a means for trending a plurality of StO₂ data measurements taken over a period of time and predicting a change in the health status of the subject from a first health status to a second health status based on the magnitude of a net tissue oxygenation cumulative area or cumulative ischemia score associated with the trended StO₂ data measurements relative to the hemoglobin oxygenation threshold value or range.

23. A method of determining a relationship between hemoglobin oxygenation (StO₂) and a health status of a subject, the method comprising;

monitoring the subject'"'"'s StO₂ for a period;

storing the subject'"'"'s StO₂ measurements versus time to form a StO₂ curve;

determining an area between the StO₂ curve and a hemoglobin oxygenation threshold value;

predicting whether the subject is likely to develop a first health status if the area is above the threshold value or generally trending above the threshold value, or likely to develop a second health status if the area is below the threshold value or generally trending below the threshold value; and

wherein the relationship between the StO₂ and the health status is determined based on the magnitude of a net tissue oxygenation cumulative area or cumulative ischemia score relative to the hemoglobin oxygenation threshold value.

24. The method of claim 23 wherein the first health status is a lower risk or probability of developing an adverse health outcome.

25. The method of claim 23 wherein the second health status is a higher risk or probability of developing an adverse health outcome.

26. The method of claim 23 wherein the threshold value is a minimum StO₂ value.

27. The method of claim 26 wherein the minimum StO₂ value is 75 percent.

28. The method of claim 23 wherein the net tissue oxygenation cumulative area or cumulative ischemia score is calculated using the equation:

29. The method of claim 23 wherein the threshold value is pre-set by a user.

30. The method of claim 23 wherein a physician or end-user treats the subject to affect or change the StO₂ depending on the health status of the subject.

31. The method of claim 23 wherein the storing is storing StO₂ in the form of graphs.