METHOD AND APPARATUS FOR HEMOMETRY

• US 20130035569A1
• Filed: 07/16/2012
• Published: 02/07/2013
• Est. Priority Date: 05/03/2006
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Heanue, Joseph Anthony, Lloyd, Lester John, Bechtel, Kate Leeann, Wilfley, Brian Patrick, Heanue, John Frederick
• Application Number:
  US13/550,276
• Publication Number:
  US 20130035569A1
• Time in Patent Office: Days
• US Class Current: 600/322
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0053 by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/418 lymph vessels, ducts or nodes
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/4406 Fluorescence spectrometry
• CPC Class Codes: G01N 2021/4797 time resolved, e.g. analysis of ballistic photons
• CPC Class Codes: G01N 21/4795 : spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 2201/0826 : Fibre array at source, distributing
• CPC Class Codes: G01N 2201/0833 : Fibre array at detector, resolving

Abstract

The present invention pertains to a method and apparatus for hemometry in humans. Pressure is applied proximal to a target area in human tissue. A modulated optical signal based on a digital code sequence is transmitted to the target area. A temporal transfer characteristic is derived from the modulated optical signal. Concentration of an analyte is determined based on the temporal transfer characteristic.

Claims

1. A method for hemometry in humans comprising:

applying a first amount of pressure to a first region proximal to a target area in a human tissue;

applying a second amount of pressure to a second region, said second region located between said first region and said target area;

generating a digital modulation signal associated with a code sequence;

generating a modulated optical signal based on said digital modulation signal;

transmitting said modulated optical signal to said target area;

receiving a modified version of said modulated optical signal after transmission through said target area; and

calculating a concentration of an analyte based on said temporal transfer characteristic.

2. The method for hemometry of claim 1 wherein said first region encircles a human arm.

3. The method for hemometry of claim 1 wherein said first region encircles a human finger.

4. The method for hemometry of claim 1 wherein said second amount of pressure is equal to said first amount of pressure.

5. The method for hemometry of claim 1 wherein said second amount of pressure is less than said first amount of pressure.

6. The method for hemometry of claim 1 wherein said analyte is total hemoglobin.

7. The method for hemometry of claim 1 further comprising:

releasing said first amount of pressure and said second amount of pressure;

repeating transmission of said modulated optical signal to said target area;

receiving a second modified version of said modulated optical signal after transmission through said target area;

deriving a second temporal transfer characteristic for said second modified version of said modulated optical signal; and

calculating an arterial blood concentration of said analyte by comparing said second temporal transfer characteristic with said temporal transfer characteristic.

8. A system for hemometry in humans comprising:

A signal generator for generating a digital modulation signal representing a code sequence;

an optical illumination source coupled to said signal generator for receiving said digital modulation signal and for transmitting a modulated optical signal along an optical transmission path to a target area in human tissue in response to said digital modulation signal;

a detector optically coupled to said human tissue for receiving said modulated optical signal after transmission through an optical transmission path through said target area;

a processor coupled to said detector for deriving a temporal transfer characteristic for said optical signal received by said detector and for determining a concentration of an analyte based in said temporal transfer characteristic; and

a pressure-applying device located proximal to said target area for applying pressure to said human tissue.

9. The system for hemometry of claim 8 wherein said pressure-applying device is a linear actuator.

10. The system for hemometry of claim 9 wherein said linear actuator is a piezo-electric actuator.

11. The system for hemometry of claim 9 wherein said linear actuator is an electromechanical actuator.

12. The system for hemometry of claim 9 wherein said linear actuator is a pneumatic actuator.

13. The system for hemometry of claim 9 wherein said linear actuator is a lead screw actuator.

14. The system for hemometry of claim 8 wherein said pressure-applying device is a band of electroactive polymer.

15. The system for hemometry of claim 8 wherein said pressure-applying device is a tourniquet.

16. The system for hemometry of claim 8 further comprising:

a heating element coupled to said human tissue for controlling temperature in said target area; and

temperature measurement and feedback electronics coupled to said human tissue and said heating element.

17. The system for hemometry of claim 8:

a second pressure-applying device located between said pressure-applying device and said target area.

18. The system for hemometry of claim 17 wherein said pressure-applying device comprises a first chamber of a segmented pressure cuff and said second pressure-applying device comprises a second chamber of said segmented pressure cuff.

19. The system for hemometry of claim 8 further comprising:

a second detector optically coupled to said human tissue located a greater distance from said optical illumination source than said detector, for receiving said modulated optical signal after transmission through an additional optical transmission path through said target area.