Device for Continuous, Non-invasive Measurement of Arterial Blood Pressure and Uses Thereof

• US 20080200785A1
• Filed: 12/10/2007
• Published: 08/21/2008
• Est. Priority Date: 12/11/2006
• Status: Abandoned Application

• Current Assignee: CNSystems Medizintechnik GmbH (CNSystems Medizintechnik AG)
• Original Assignee: CNSystems Medizintechnik GmbH (CNSystems Medizintechnik AG)
• Inventors: Fortin, Juergen
• Application Number:
  US11/953,285
• Publication Number:
  US 20080200785A1
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/0235 Valves specially adapted therefor
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7425 Displaying combinations of multiple images regardless of image source, e.g. displaying a reference anatomical image with a live image geometric transforms for image registration G06T3/14; enhancement using image fusion G06T5/50; algorithms for registration of images G06T7/30

Abstract

The invention relates to methods and devices for continuous, non-invasive measurement of arterial blood pressure. One embodiment of the invention as illustrated in FIG. 1 comprises (a) a first radiation source (1) and at least one other radiation source (2); (b) at least one detector (4); (c) an air pressure generator, one or more valves, a manometer and a cuff (9, 10, 11, 12) for applying time-variable pressure on the body part, wherein a pressure signal p(t) corresponds to the arterial blood pressure; (d) a reference signal generator (6); and (e) a filter (7), which receives the reference signal and separates a supplementing signal from a favored signal.

Claims

1. A signal processing device comprising:

(a) at least one detector for generating at least one measurement signal from at least one measurement radiation, wherein the measurement radiation propagates along a propagation medium starting from at least one radiation source;

(b) an air pressure generator, one or more valves, a manometer and a cuff for applying a pressure on the propagation medium;

(c) a reference signal generator that accepts the signals generated by the detector and the pressure generated by the pressure generator to compute a reference signal; and

(d) a filter receiving the reference signal as an input, wherein the filter essentially separates a supplementing signal and a favored signal from the signals generated by the detector,

wherein the favored signal is a measure of the physiological characteristics.

2. The signal processing device according to claim 1, wherein each of the measurement radiation of (a) is of different wavelength.

3. The signal processing device according to claim 1, wherein the measurement radiation of (a) propagates wholly or partially along a propagation path situated in the propagation medium

4. The signal processing device according to claim 1, wherein the pressure of (b) is a time-variable pressure.

5. The signal processing device according to claim 1, wherein the propagation medium is a human body part.

6. A device for measuring one or more physiological characteristics, the device comprising

(a) at least one radiation source for generating at least one measurement radiation, wherein the measurement radiation propagates through a body part;

(b) at least one detector for generating at least one measurement signal from the measurement radiation;

(c) an air pressure generator, one or more valves, a manometer, and a cuff for applying a pressure to the body part;

(d) a reference signal generator, which computes a reference signal from the signal generated by the detector and the pressure signal from the pressure generator; and

(e) a filter receiving the reference signal, wherein the filter essentially separates a supplementing signal and a favored signal from the signals measured by the detector,

wherein the favored signal is a measure of the physiological characteristics.

7. The device according to claim 6, wherein each of the measurement radiation of (a) is of different wavelength.

8. The device according to claim 6, wherein the measurement radiation of (a) propagates wholly or partially along a propagation path situated in the body part.

9. The device according to claim 6, wherein the pressure of (c) is a time-variable pressure.

10. The device according to claim 6, wherein the physiological characteristics comprise blood characteristics.

11. The device according to claim 6, wherein the physiological characteristics comprise arterial and venous characteristics.

12. The device according to claim 6, wherein the physiological characteristics comprise blood pressure characteristics.

13. The device according to claim 6, wherein the physiological characteristics comprise arterial oxygen saturation.

14. The device according to claim 6, wherein the physiological characteristics comprise venous oxygen saturation.

15. The device according to claim 6, wherein each of the at least one measurement radiation of (a) is of defined, mutually differing wavelengths.

16. A signal processing device comprising:

(a) at least one detector providing a first measurement signal s₁(t) from a measurement radiation of defined wavelength, which propagates along a propagation path starting from a first radiation source, and at least one other measurement signal s_N(t) from another measurement radiation of different wave-length, which propagates wholly or partially along the propagation path starting from at least one other radiation source, wherein at least a portion of the propagation path is situated in a propagation medium, wherein the first signal s₁(t) comprises a favored signal a₁(t) and a supplementing signal v₁(t) and the at least one other signal s_N(t) comprises a favored signal a_N(t) and a supplementing signal v_N(t), wherein the signals a₁(t) to a_N(t) result from a first, time-variable quantity a(t) in the propagating medium and the signals v₁(t) to v_N(t) result from a second, time-variable quantity v(t) in the propagation medium;

(b) an air pressure generator, one or more valves, a manometer and a cuff for applying time-variable pressure on the propagation medium, with a pressure signal p(t) being a function of the first, time-variable quantity a(t) of the propagation medium or a function of one or more signals s₁(t) to s_N(t) measured by the detector;

(c) a reference signal generator, which accepts the signals s₁(t) to s_N(t) measured by the detector and the pressure signal p(t) as inputs and computes from these inputs a reference signal Δ

n′

(t), which is a function of the second, time-variable quantity v(t) or of the supplementing signals v₁(t) to v_N(t); and

(d) a filter receiving the reference signal Δ

n′

(t) as an input, wherein the frequency properties of the filter essentially correlate with the reference signal Δ

n′

(t), and wherein the filter essentially separates from at least one of the signals s₁(t) to s_N(t) measured by the detector the supplementing signal v₁(t) to v_N(t) from the favored signal a₁(t) to a_N(t).

17. A device for the continuous, non-invasive measurement of the arterial blood flow comprising:

(a) a first radiation source and at least one other radiation source for generating a first and at least one other measurement radiation of defined, mutually differing wavelengths;

(b) at least one detector for generating a first measurement signal s₁(t) from the first measurement radiation and at least one other measurement signal s_N(t) from the at least one other measurement radiation of different wavelength, wherein the measurement radiations propagate wholly or partially along a propagation path and wherein at least a portion of this propagation path is located in a body part traversed by arterial and venous blood flows, and wherein the first signal s₁(t) has a first arterial signal component a₁(t) and a first venous signal component v₁(t) and wherein the at least one other signal s_N(t) has at least one other arterial signal component a_N(t) and at least one other venous signal component v_N(t), and wherein arterial signal components a₁(t) to a_N(t) result from a time-varying arterial blood flow a(t) in the body part, and the venous signal components v₁(t) to v_N(t) result from a time-varying venous blood flow v(t) in the body part;

(c) an air pressure generator, one or more valves, a manometer and a cuff for applying a time-varying pressure to the body part, wherein a pressure signal p(t) corresponding to an arterial blood pressure, is a function of the arterial blood flow a(t) in the body part or a function of one or more of the signals s₁(t) to s_N(t) measured by the detector;

(d) a reference signal generator, which has as inputs the signals s₁(t) to s_N(t) measured by the detector and the pressure signal p(t), and which computes from these inputs a reference signal Δ

n′

(t), which is a function of the venous blood flow v(t) or of the venous signal components v₁(t) to v_N(t); and

(e) a filter receiving the reference signal Δ

n′

(t) as an input, where the frequency properties of the filter essentially correlate with the reference signal Δ

n′

(t), and wherein the filter essentially separates from at least in one of the signals s₁(t) to s_N(t) measured by the detector the venous signal component v₁(t) to v_N(t) from the arterial signal component a₁(t) to a_N(t), wherein the arterial signal component is proportional to the arterial blood flow a(t).

18. A pulse oximeter comprising

(a) at least one radiation source for generating at least one measurement radiation, wherein the measurement radiation propagates through a body part;

(b) at least one detector for generating at least one measurement signal from the measurement radiation;

(c) an air pressure generator, one or more valves, a manometer, and a cuff for applying a time-varying pressure to the body part;

(d) a reference signal generator, which computes a reference signal from the signal generated by the detector and the pressure signal from the pressure generator; and

(e) a filter receiving the reference signal, wherein the filter essentially separates a supplementing signal and a favored signal from the signals measured by the detector,

wherein the favored signal is a measure of the physiological characteristics.

19. A method for measuring one or more physiological characteristics, the device comprises

(a) providing a first and at least one other measurement radiation;

(b) detecting a first measurement signal from the first measurement radiation and at least one other measurement signal from the at least one other measurement radiation of different wavelength, where the two measurement radiations propagate wholly or partially along the same propagation path in a body part;

(c) applying a pressure to the body part;

(d) computing a reference signal from the first and the at least one measurement signals of (b) and the pressure of (c); and

(e) separating a supplementing signal component and a favored signal component from the measurement signals of (b) by using a filter that receives a reference signal as an input, wherein the reference signal is computed from the measurement signal of (b) and the pressure signal of (c),

wherein the favored signal component is a measure of the physiological characteristics.

20. The method according to claim 19, wherein each of the measurement radiation of (a) is of different wavelength.

21. The method according to claim 19, wherein the measurement radiation of (a) propagates wholly or partially along a propagation path situated in the body part.

22. The method according to claim 19, wherein the pressure of (c) is a time-variable pressure.

23. The method according to claim 19, wherein the physiological characteristics comprise blood characteristics.

24. The method according to claim 19, wherein the physiological characteristics comprise blood characteristics.

25. The method according to claim 19, wherein the physiological characteristics comprise arterial and venous characteristics.

26. The method according to claim 19, wherein the physiological characteristics comprise blood pressure characteristics.

27. The method according to claim 19, wherein the physiological characteristics comprise arterial oxygen saturation.

28. The method according to claim 19, wherein the physiological characteristics comprise venous oxygen saturation.

29. The method according to claim 19, wherein each of the at least one measurement radiation of (a) is of defined, mutually differing wavelengths.

30. A method for the continuous, non-invasive measurement of arterial blood pressure in a body part with arterial and venous blood flow comprising:

(a) providing a first and at least one other measurement radiation of defined, mutually differing wavelengths;

(b) detecting a first measurement signal s₁(t) from the first measurement radiation and at least one other measurement signal s_N(t) from the at least one other measurement radiation of different wavelength, where the two measurement radiations propagate wholly or partially along the same propagation path and wherein part of this propagation path is located in the body part in which arterial and venous blood flows, and wherein the first signal s₁(t) has a first favored signal component a₁(t) and a first supplementing signal component v₁(t), and wherein the at least one other signal s_N(t) has a favored signal component a_N(t) and a supplementing signal component v_N(t), and wherein the first and all other favored signal components a₁(t) to a_N(t) result from a time-varying arterial blood flow a(t) in the body part and the first and all other supplementing signal components v₁(t) to v_N(t) result from a time-varying venous blood flow v(t) in the body part;

(c) applying a time-varying pressure to the body part, wherein a pressure signal p(t) corresponding to the arterial blood pressure is a function of the arterial blood flow a(t) in the body part or a function of one or more of the signals s₁(t) to s_N(t);

(d) computing a reference signal Δ

n′

(t) from the signals s₁(t) to s_N(t) and the pressure signal p(t), which is a function of venous blood flow v(t) or of the supplementing signal components v₁(t) to v_N(t); and

(e) separating the supplementing signal component v₁(t) to v_N(t) from the favored signal component a₁(t) to a_N(t) of the signals s₁(t) to s_N(t) measured by a detector by means of a filter receiving the reference signal Δ

n′

(t) as an input, wherein the frequency properties of the filter essentially correlates with the reference signal Δ

n′

(t), and wherein the favored signal component a₁(t) to a_N(t) is proportional to the arterial blood flow a(t).

31. The method according to claim 30, wherein the frequency properties of the filter are adaptively modified during signal analysis by means of the reference signal.

32. The method according to claim 30 or 31, wherein from the frequency properties obtained by measuring the blood pressure, the arterial oxygen saturation aSpO2 and/or the venous oxygen saturation vSpO2, are derived and displayed.

33. The method according to any of claims 30 or 31, wherein red light is used as the first measurement radiation and infrared light is used as the second measurement radiation.

34. The method according to claim 32, wherein red light is used as the first measurement radiation and infrared light is used as the second measurement radiation.

35. The method according to claim 33, wherein the red light is of wavelength 660 nm and the infrared light is of wavelength 940 nm.

36. The method according to claim 34, wherein the red light is of wavelength 660 nm and the infrared light is of wavelength 940 nm.