Method and apparatus for calculating blood pressure of an artery

• US 5,797,850 A
• Filed: 02/16/1995
• Issued: 08/25/1998
• Est. Priority Date: 11/09/1993
• Status: Expired due to Fees

• Current Assignee: Medwave, Inc.
• Original Assignee: Medwave, Inc.
• Inventors: Thede, Roger C., Curran, Timothy G., Poliac, Marius O., Archibald, G. Kent, Danielson, Orland H.
• Primary Examiner(s): Lacyk, John P.
• Assistant Examiner(s): GILBERT, SAMUEL G
• Application Number:
  US08/388,751
• Time in Patent Office: 1,286 Days
• Field of Search: 128/672, 128/677, 128/678, 128/679, 128/680, 128/687-690, 600/485, 600/490, 600/491, 600/492-496, 600/500-503
• US Class Current: 600/494
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• 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 5/02141 Details of apparatus construction, e.g. pump units or housings therefor, cuff pressurising systems, arrangements of fluid conduits or circuits A61B5/02233, A61B5/0235 take precedence
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure

Abstract

The present invention is a method and apparatus for calculating blood pressure of an artery having a pulse. The method includes applying a varying pressure to the artery. Pressure waveforms are sensed to produce pressure waveform data. Waveform parameters are derived from the sensed pressure waveform data. Blood pressure is then determined using the derived parameters. The apparatus is a blood pressure monitoring device which includes pressure means for applying a varying pressure to the artery so that the artery exhibits pressure data, sensing means for sensing the pressure data, signal producing means connected to the sensing means for producing output signals corresponding to the sensed pressure data and processing means for receiving the output signals from the signal producing means, for deriving a plurality of parameters using sensed pressures and for determining a blood pressure value using the derived parameters.

Claims

1. A method for determining blood pressure of an artery having a pulse, the method comprising:

continuously varying a pressure applied to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data including at least one of the following;

(a) rise time of a selected portion of a waveform, (b) applied pressure corresponding to a starting point of a waveform, (c) applied pressure corresponding to an ending point of a waveform, (d) pressure of a waveform at a selected time, (e) a pressure corresponding to a selected point on a waveform, (f) a time value corresponding to a width of a selected portion of a waveform, (g) mean amplitude of a waveform, (h) mean of a curve generated from data taken from a plurality of waveforms; and

determining a blood pressure value based upon the parameters.

2. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data including at least one of the following;

(a) rise time of a selected portion of a waveform, (b) applied pressure corresponding to a starting point of a waveform, (c) applied pressure corresponding to an ending point of a waveform, (d) pressure of a waveform at a selected time, (e) a pressure corresponding to a selected point on a waveform, (f) a time value corresponding to a width of a selected portion of a waveform, (g) mean amplitude of a waveform, (h) mean of a curve generated from data taken from a plurality of waveforms; and

determining a blood pressure based upon the parameters;

wherein deriving a plurality of parameters from the sensed pressure data includes a relative amplitude value and at least one waveform shape parameter.

3. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data including at least one of the following;

(a) rise time of a selected portion of a waveform, (b) applied pressure corresponding to a starting point of a waveform, (c) applied pressure corresponding to an ending point of a waveform, (d) pressure of a waveform at a selected time, (e) a pressure corresponding to a selected point on a waveform, (f) a time value corresponding to a width of a selected portion of a waveform, (g) mean amplitude of a waveform, (h) mean of a curve generated from data taken from a plurality of waveforms; and

determining a blood pressure based upon the parameters;

wherein deriving a plurality of parameters includes deriving parameters of a curve generated from the sensed pressure data.

4. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data including at least one of the following;

(a) rise time of a selected portion of a waveform, (b) applied pressure corresponding to a starting point of a waveform, (c) applied pressure corresponding to an ending point of a waveform, (d) pressure of a waveform at a selected time, (e) a pressure corresponding to a selected point on a waveform, (f) a time corresponding to a width of a selected portion of a waveform, (g) mean amplitude of a waveform, (h) mean of a curve generated from data taken from a plurality of waveforms; and

determining a blood pressure based upon the parameters;

wherein the first pressure is applied to the artery at a starting point of a waveform and wherein a second pressure is applied to the artery at an ending point of the waveform and wherein deriving a plurality of parameters includes adjusting the waveform so that the starting point and the ending point of the waveform have equal pressure amplitudes.

5. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data including at least one of the following;

(a) rise time of a selected portion of a waveform, (b) applied pressure corresponding to a starting point of a waveform, (c) applied pressure corresponding to an ending point of a waveform, (d) pressure of a waveform at a selected time, (e) a pressure corresponding to a selected point on a waveform, (f) a time value corresponding to a width of a selected portion of a waveform, (g) mean amplitude of a waveform, (h) mean of a curve generated from data taken from a plurality of waveforms;

scaling a pressure waveform to eliminate gain, wherein the parameters are derived from the scaled pressure waveform; and

determining a blood pressure based upon the parameters.

6. A non-invasive blood pressure monitoring device, the monitoring device comprising:

pressure means for applying an increasing pressure to the artery so that the artery exhibits pressure data;

sensing means for sensing the pressure data;

wherein the sensing means includes;

a transducer;

sensor support;

a flexible diaphragm coupled to the sensor support and having an active portion for transmitting blood pressure pulses of the underlying artery; and

a fluid coupling medium coupled between the flexible diaphragm and the transducer for transmitting blood pressure pulses within the underlying artery from the flexible diaphragm to the transducer;

signal producing means connected to the sensing means for producing output signals corresponding to the sensed pressure data; and

processing means for receiving the output signal from the signal producing means, for deriving a plurality of parameters using sensed pressures including at least one parameter other than maximum pressure waveform amplitude and for determining a blood pressure value using the derived parameters.

7. A non-invasive blood pressure measurements system comprising:

means for applying a sweeping increasing pressure to an artery;

means for sensing pressure from the artery over time while the increasing pressure is applied to the artery to generate pressure data; and

means for deriving a pressure value based upon a waveform analysis of the pressure data.

8. A method of determining blood pressure, the method comprising:

applying a sweeping increasing pressure to an artery;

sensing pressure over time while the increasing pressure is applied to the artery to generate pressure waveform data for pressure waveforms representing a plurality of beats;

detecting onset of the beats from the waveform data;

extracting waveform parameters using a detected onset of one of the beats; and

determining a blood pressure value based upon the waveform parameters.

9. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying an increasing pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of different parameters from the sensed pressure data; and

determining a blood pressure value as a function of the plurality of different parameters.

10. The method of claim 9 wherein deriving a plurality of different parameters includes:

deriving at least one parameter other than pressure waveform amplitude from the sensed pressure data.

11. The method of claim 9 including:

controlling the increasing pressure being applied to the artery based upon the derived parameters.

12. The method of claim 9 including:

limiting the increasing pressure being applied to the artery based upon the derived parameter.

13. The method of claim 9 wherein the step of applying an increasing pressure to the artery includes:

intermittently varying the increasing pressure.

14. The method of claim 9 wherein the step of applying an increasing pressure to the artery includes:

sweeping the increasing pressure being applied to the artery.

15. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a first hold down pressure to the artery;

sensing a first set of pressure data produced by the artery at the first hold down pressure;

applying a second hold down pressure to the artery, wherein the second hold down pressure is larger than the first hold down pressure;

sensing a second set of pressure data produced by the artery at the second hold down pressure;

deriving a plurality of parameters from at least one of the first and second sets of the sensed pressure data; and

determining a blood pressure value based upon the parameters.

16. A method for determining blood pressure of an artery having a pulse, the method comprising:

sensing pressure data produced by the artery while applying a sweeping increasing pressure to the artery;

deriving parameters from the sensed pressure data; and

determining a blood pressure value based upon the parameters.

17. A method for determining blood pressure of an artery having a pulse, the method comprising:

continuously varying a pressure applied to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data; and

determining a blood pressure value based upon the plurality of parameters and a stored set of coefficients.

18. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

deriving a plurality of parameters from the sensed pressure data; and

determining a blood pressure value based upon the plurality of parameters and a stored set of coefficients;

wherein deriving a plurality of parameters includes deriving parameters of a curve generated from the sensed pressure data.

19. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data; and

determining a blood pressure value based upon the plurality of parameters and a stored coefficients;

wherein a first pressure is applied to the artery at a starting point of a waveform and wherein a second pressure is applied to the artery at an ending point of the waveform and wherein deriving a plurality of parameters includes adjusting the waveform so that the starting point and the ending point of the waveform have equal pressure amplitudes.

20. A method for determining blood pressure of an artery having a pulse, the method comprising:

sweeping a pressure being applied to the artery;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data; and

determining a blood pressure value based upon the plurality of parameters and a stored set of coefficients.

21. A method for determining blood pressure of an artery having a pulse, the method comprising:

applying a pressure to the artery;

creating pressure waveform data of pressure waveforms presenting a plurality of beats from the sensed pressure data;

detecting onset of the beats from the waveform data;

deriving at least one parameter using a detected onset of one of the beats;

sensing pressure data produced by the artery;

deriving a plurality of parameters from the sensed pressure data; and

determining a blood pressure value based upon the plurality of parameters and a stored set of coefficients.

22. A method for monitoring pressure waveform data produced by an artery, the method comprising:

applying a sweeping increasing pressure to the artery beginning with an initial pressure and ending with a final non-occluding pressure so that the artery exhibits a plurality of pressure waveforms; and

sensing pressure waveform data produced by the artery representing each of the plurality of pressure waveforms, wherein the final non-occluding pressure applied to the artery is determined based upon the pressure waveform data sensed while the sweeping increasing pressure is applied to the artery.

23. The method of claim 22 wherein the step of sensing pressure waveform data includes sensing a maximum pressure amplitude for each pressure waveform, wherein the final pressure applied to the artery is based upon the maximum pressure amplitudes.

24. The method of claim 22 including:

detecting an onset of each of the plurality of waveforms.

25. A method for monitoring blood pressure parameters of an artery, the method comprising:

sensing pressure data produced by the artery over time representing a plurality of arterial pressure waveforms;

determining a maximum pressure amplitude for each of the plurality of arterial pressure waveforms from the sensed pressure data; and

applying a sweeping increasing pressure to the artery while the pressure data is sensed based upon the maximum pressure amplitudes.

26. The method of claim 25 wherein the step of applying an increasing pressure to the artery includes:

applying the increasing pressure to the artery until at least one waveform has a maximum pressure amplitude less than a maximum pressure amplitude of a preceding waveform.