Ultrasound-Optical Doppler Hemometer and Technique for Using the Same

• US 20100081912A1
• Filed: 09/30/2008
• Published: 04/01/2010
• Est. Priority Date: 09/30/2008
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: McKenna, Edward M., Baker, Clark R. JR.
• Application Number:
  US12/242,401
• Publication Number:
  US 20100081912A1
• Time in Patent Office: Days
• US Class Current: 600/368
• CPC Class Codes: A61B 5/0097 by applying acoustic waves and detecting light, i.e. acoustooptic measurements
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 8/04 Measuring blood pressure
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: G01S 15/899 Combination of imaging systems with ancillary equipment

Abstract

According to embodiments, a sensor assembly and/or systems for ultrasound-optical measurements may provide information related to hemodynamic parameters. An ultrasound beam may be used to generate a Doppler field for optical elements of a sensor assembly. By combining information received from ultrasound and optical elements of the sensor assembly, more accurate values for hemodynamic parameters may be determined.

Claims

1. A monitoring system comprising:

a storage device storing routines for;

receiving a signal from a photodetector;

receiving a signal from an ultrasound transducer;

determining at least one of a blood flow velocity or a red blood cell level based at least in part on the photodetector signal;

determining a blood vessel size based at least on part on the ultrasound transducer signal;

determining a physiological parameter based at least in part on the blood vessel size and one or more of the flow velocity or the red blood cell level; and

a processor capable of executing the stored routines.

2. The system as set forth in claim 1, wherein the physiological parameter comprises a hemoglobin value, a hematocrit value, or a blood pressure value.

3. The system as set forth in claim 1, comprising an emitter capable of emitting light into a tissue and generating the signal at the photodetector.

4. The system as set forth in claim 3, wherein the emitter and the photodetector are spaced about 2 mm to about 3 mm apart from one another.

5. The system as set forth in claim 3, comprising the ultrasound transducer.

6. The system as set forth in claim 5, wherein the ultrasound transducer is capable of being focused at a depth of less than 5 mm from a surface of the tissue.

7. The system as set forth in claim 5, wherein the ultrasound transducer is capable of transmitting a frequency-modulated ultrasound wave.

8. The system as set forth in claim 5, wherein the ultrasound transducer is spaced apart less than 2 mm from either the emitter or the photodetector.

9. The system as set forth in claim 5, wherein the ultrasound transducer is capable of transmitting ultrasound waves into the tissue at the same time the emitter transmits light into the tissue.

10. A method, comprising:

receiving a signal from a photodetector;

receiving a signal from an ultrasound transducer;

determining at least one of a blood flow velocity or a red blood cell level based at least in part on the photodetector signal;

determining a blood vessel size based at least on part on the ultrasound transducer signal;

determining a physiological parameter based at least in part on the blood vessel size and one or more of the flow velocity or the red blood cell level.

11. The method as set forth in claim 10, wherein determining the physiological parameter comprises determining a hematocrit value.

12. The method as set forth in claim 10, wherein determining the physiological parameter comprises determining a blood pressure value.

13. A method comprising:

emitting photons into a blood vessel of a patient'"'"'s tissue;

focusing an ultrasonic beam into the blood vessel so that a portion of the photons in the blood vessel experience a Doppler shift;

generating a signal related to detected photons at a detector; and

processing the signal to isolate a signal component representative of photons that have undergone a Doppler shift of a magnitude greater than a predetermined threshold; and

analyzing the isolated signal component to determine one or more properties of the blood vessel.

14. The method as set forth in claim 13, comparing the isolated component to a reference signal comprising a different isolated signal component representative of photons that do not traverse the blood vessel.

15. The method as set forth in claim 14, comprising emitting photons into the tissue away from the direction of flow of the blood vessel to generate the reference signal.

16. The method as set forth in claim 13, wherein focusing an ultrasonic beam comprises focusing a frequency-modulated ultrasonic beam.

17. The method as set forth in claim 13, comprising analyzing a speckle pattern of the photons detected at the detector to determine information about the blood vessel.

18. The method as set forth in claim 15, comprising determining a vessel diameter based at least in part on the speckle pattern.

19. The method as set forth in claim 13, comprising determining a concentration of red blood cells based at least in part on the detected photons.

20. The method as set forth in claim 13, comprising determining a concentration of velocity of red blood cells based at least in part on the detected photons.