Non-invasive blood pressure monitoring device and methods

• US 7,601,123 B2
• Filed: 08/20/2004
• Issued: 10/13/2009
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: EPPCOR, INC.
• Inventors: Epstein, Paul, Tweed, David, Phillips, Patrick G.
• Primary Examiner(s): Nasser, Robert L
• Assistant Examiner(s): Toth, Karen E
• Application Number:
  US10/922,826
• Publication Number:
  US 20050148885A1
• Time in Patent Office: 1,880 Days
• Field of Search: 600/480, 600/481, 600/485, 600490-503
• US Class Current: 600/490
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence

Abstract

The apparatus and methods of the present invention provide a non-invasive measurement of blood pressure with a frequency that approximates a continuous measurement. Blood pressure measurement provides information that is both clinically and diagnostically significant. In accordance with an aspect of the present invention, a method for providing a non-invasive measurement of blood pressure, includes obtaining a first input signal and a second input signal indicative of systolic blood pressure and diastolic blood pressure, respectively; tracking a signal indicative of pulse pressure; continuously measuring a third signal indicative of mean blood pressure; and processing the signals to obtain a measurement indicative of systolic and diastolic blood pressure, wherein at least a portion of the measurement indicative of systolic and diastolic blood pressure is continuous. The second input signal indicative of diastolic blood pressure is analyzed to identify a maximum amplitude of the signal, the maximum amplitude being indicative of the diastolic blood pressure measurement.

Claims

1. A method for providing a non-invasive measurement of blood pressure, the method comprising the steps of:

obtaining a first input signal and a second input signal indicative of occlusive measurements of systolic blood pressure and diastolic blood pressure, respectively;

tracking a signal indicative of pulse pressure;

continuously measuring a third signal indicative of mean blood pressure; and

processing said signals to obtain a measurement indicative of systolic and diastolic blood pressure, wherein at least a portion of the measurement indicative of systolic and diastolic blood pressure is continuous wherein obtaining the second input signal indicative of diastolic blood pressure comprises analyzing the second input signal to identify a maximum amplitude of the signal, the maximum amplitude being indicative of the diastolic blood pressure measurement.

2. The method of claim 1, wherein the first input signal and the second input signal are obtained from a photo-plethysmograph.

3. The method of claim 2, wherein the photo-plethysmograph comprises a light source and a detector.

4. The method of claim 3, wherein the light source is a light emitting diode, a laser or an incandescent lamp.

5. The method of claim 3, wherein the detector is one of a photocell or a photo-resistive device.

6. The method of claim 1, wherein tracking a signal indicative of pulse pressure, pulse pressure characterized as the difference between a systolic pressure measurement and a diastolic pressure measurement, further comprises:

inducing a pulse signal into a region of interest, and

obtaining a resultant signal indicative of a combination of the induced pulse signal and a heart pulse signal.

7. The method of claim 6, wherein processing the resultant signal further comprises amplifying the resultant signal, separating the induced pulse signal from the heart pulse signal and calculating the pulse pressure from the relative amplitudes of the induced pulse signal and the heart pulse signal.

8. The method of claim 6, further comprising minimizing a venous response to the induced pulse signal.

9. The method of claim 8, wherein minimizing the venous response comprises at least one of selecting an appropriate frequency for the induced pulse signal and/or applying a constant pressure to the region of interest.

10. A method for providing a non-invasive measurement of blood pressure, the method comprising the steps of:

obtaining a first input signal and a second input signal indicative of occlusive measurements of systolic blood pressure and diastolic blood pressure, respectively;

tracking a signal indicative of pulse pressure;

continuously measuring a third signal indicative of mean blood pressure; and

processing said signals to obtain a measurement indicative of systolic and diastolic blood pressure, wherein at least a portion of the measurement indicative of systolic and diastolic blood pressure is continuous wherein the step of continuously measuring mean blood pressure further comprises continuously monitoring a voltage signal of a photo-plethysmograph and an amplitude signal of an induced pulse signal.

11. The method of claim 10, wherein the amplitude of the induced pulse signal is proportional to a compliance characteristic of an arterial vasculature.

12. The method of claim 10, further comprising:

calculating a function of the voltage signal and the amplitude signal, wherein the function is proportional to the mean blood pressure.

13. The method of claim 12, wherein the function is a geometric mean of the voltage signal and the amplitude signal.

14. The method of claim 12, further comprising determining a continuous measurement indicative of systolic blood pressure from the relationship defined by mean blood pressure added to a fraction of the pulse pressure.

15. The method of claim 14, wherein the fraction of the pulse pressure is two-thirds.

16. The method of claim 12, further comprising determining a continuous measurement indicative of diastolic blood pressure from the relationship governed by a fraction of the pulse pressure subtracted from mean blood pressure.

17. The method of claim 16, wherein the fraction of pulse pressure is one-third.

18. A method for providing a non-invasive measurement of blood pressure, the method comprising the steps of:

obtaining a first input signal and a second input signal indicative of occlusive measurements of systolic blood pressure and diastolic blood pressure, respectively;

tracking a signal indicative of pulse pressure;

continuously measuring a third signal indicative of mean blood pressure; and

processing said signals to obtain a measurement indicative of systolic and diastolic blood pressure, wherein at least a portion of the measurement indicative of systolic and diastolic blood pressure is continuous wherein obtaining the second input signal indicative of diastolic blood pressure comprises analyzing the second input signal to identify a maximum amplitude of the signal, the maximum amplitude being indicative of the diastolic blood pressure measurement, the method further comprises obtaining a new first input signal and a new second input signal and processing the first new input signal and the second new input signal to obtain a new measurement indicative of systolic and diastolic pressure.