Passive/non-invasive systemic and pulmonary blood pressure measurement

• US 6,152,879 A
• Filed: 10/06/1998
• Issued: 11/28/2000
• Est. Priority Date: 12/18/1996
• Status: Expired due to Term

• Current Assignee: AusculSciences, Inc.
• Original Assignee: Primedica
• Inventors: Mohler, Sailor
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/167,242
• Time in Patent Office: 784 Days
• Field of Search: 600/485, 600/490, 600/493-497, 600/503, 600/528, 600/586
• US Class Current: 600/485
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

An apparatus, operation and method for measurement of systemic and/or pulmonic blood pressure. The present invention offers a passive non-invasive method and system that can be used where measurement of systemic pressure with a traditional blood pressure cuff is contraindicated. The present invention also affords a means for early diagnosis and opportunity for intervention in patients with no symptoms or signs of elevated pulmonary blood pressure that can be performed as part of a routine physical exam. The present invention accomplishes this non-invasive measurement through detection, identification and characterization of the second heart sound acoustic signature associated with heart valve closure. An apparatus for measuring systemic and/or pulmonic blood pressure in accordance with the present invention includes a sensor assembly comprising a housing, an electronic module, a shock dampener, a mounting means, a transducer, an acoustic coupling and a back cover. The sensor assembly is connected to a data acquisition module which in turn is connected to a signal processing means, a remote connection means and a monitor. An improved acoustic coupling is disclosed that provides low-loss acoustic transmission coupling between the skin of the patient and the detector.

Claims

1. A method of determining blood pressure comprising:

performing initialization procedures;

filtering physiologic signals, using a filter having a logarithmic characteristic, to create filtered physiologic signals;

acquiring the filtered physiologic signals;

acquiring background signals;

subtracting the background signals from the filtered physiologic signals, creating physiologic data;

processing the physiologic data forming a time domain output and a frequency domain output;

comparing the time domain output and the frequency domain output with a reference pattern and feature library; and

determining if an elevated blood pressure modality is indicated.

2. The method of determining blood pressure as claimed in claim 1, wherein performing initialization further comprises:

initializing a system;

calibrating the system;

selecting sensors in the system;

inputting patient parameters into the system; and

clearing system buffers.

3. The method of determining blood pressure as claimed in claim 1, wherein acquiring the filtered physiologic signals comprises acquiring filtered physiologic acoustic signals.

4. The method of determining blood pressure as claimed in claim 3, wherein electric signals are acquired in conjunction with the filtered physiologic acoustic signals.

5. The method of determining blood pressure as claimed in claim 1, wherein the filtered physiologic signals are in an analog form, the method further comprising:

converting, the filtered physiologic signals from the analog form to a digital form.

6. The method of determining blood pressure as claimed in claim 1, wherein the background signals are in an analog form, the method further comprising:

converting the background signals from the analog form to a digital form.

7. The method of determining blood pressure as claimed in claim 1, wherein processing the physiologic data comprises:

applying signal conditioning and time domain averaging to the physiologic data forming conditioned and averaged data;

formatting the conditioned and averaged data in an array creating formatted data;

transforming the formatted data to create transformed data;

integrating conditioned and averaged data with the transformed data, creating integrated data, wherein said integrated data has time domain components and frequency domain components;

passing the time domain components of the integrated data through a time domain correlator and feature extraction process, creating the time domain output; and

passing the frequency domain components of the integrated data through a frequency domain correlator and feature extractor, creating the frequency domain output.

8. The method of determining blood pressure as claimed in claim 7, further comprising:

displaying the integrated data on a monitor.

9. The method of determining blood pressure as claimed in claim 1, further comprising:

updating the reference pattern and feature library.

10. A method of determining systemic blood pressure comprising:

monitoring the frequency of acoustic signals emitted by a valve selected from the group consisting of the pulmonary semilunar valve and the aortic semilunar valve, wherein the acoustic signals are detected using a sensor assembly, the sensor assembly comprising;

a housing having a front and a back;

an electronic module connected to the housing;

a shock dampener connected to the front of the housing;

a means for mounting connected to the housing;

an acoustic coupler connected to the mounting means, the acoustic coupler filtering out low frequency signals according to a logarithmic characteristic;

a transducer connected to the acoustic coupler; and

a cover connected to the back of the housing;

processing the acoustic signals, the processing comprising;

applying signal conditioning and time domain averaging to the acoustic signals to form conditioned and averaged data;

formatting the conditioned and averaged data in an array to create formatted data;

transforming the formatted data to create transformed data;

integrating the conditioned and averaged data with the transformed data, to create integrated data that has time domain components and frequency domain components;

passing the time domain components of the integrated data through a time domain correlator and feature extraction process to create a time domain output;

passing the frequency domain components of the integrated data through a frequency domain correlator and feature extractor, to create a frequency domain output;

comparing the time domain output and the frequency domain output with a reference pattern and feature library; and

determining if an elevated blood pressure modality is indicated.

11. The method of determining systemic blood pressure using sonospectrography analysis as claimed in claim 10, further comprising:

acquiring background signals; and

subtracting background signals from physiologic signals.

12. A sensor assembly for detecting physiological sounds comprising:

a housing having a front and a back;

an electronic module connected to the housing;

a shock dampener connected to the front of the housing;

a means for mounting connected to the shock dampener;

an acoustic coupler connected to the mounting means, the acoustic coupler filtering out low frequency signals according to a logarithmic characteristic;

a transducer connected to the acoustic coupler; and

a cover connected to the back of the housing.

13. The sensor assembly as claimed in claim 12, wherein the housing further comprises a sound deadening material.

14. The sensor assembly as claimed in claim 13, wherein the housing further comprises nickel plated aluminum.

15. The sensor assembly as claimed in claim 12, wherein the housing further comprises:

a rim having an inside and an outside, that is located on the periphery of the front of the housing;

a first indentation having an inside and an outside, that runs parallel and adjacent to the inside of the rim;

a second indentation that runs parallel and adjacent to the inside of the first indentation; and

a bore, that is approximately centrally located within the second indentation.

16. The sensor assembly as claimed in claim 15, wherein the electronic module nests within the bore.

17. The sensor assembly as claimed in claim 12, wherein the shock dampener is an "O" ring.

18. The sensor assembly as claimed in claim 12, wherein the mounting means is a plastic mounting ring.

19. The sensor assembly as claimed in claim 12, wherein the transducer is a piezoelement.

20. A sensor assembly for detecting physiological sounds comprising:

a housing, having a front, a back, and an interior;

an electronic module that nests in the interior of the housing;

a first shock dampener connected to the front of the housing;

a first mounting means connected to the first shock dampener;

a first transducer connected to the first mounting means;

a first acoustic coupling connected to the first transducer, the first acoustic coupling filtering out low frequency signals according to a logarithmic characteristic;

a second shock dampener connected to the back of the housing;

a second mounting means connected to the second shock dampener;

a second transducer connected to the second mounting means; and

a second acoustic coupling connected to the second transducer, the second acoustic coupling filtering out low frequency signals according to a logarithmic characteristic.

21. The sensor assembly as claimed in claim 20, wherein the housing further comprises a sound deadening material.

22. The sensor assembly as claimed in claim 21, wherein the housing further comprises nickel plated aluminum.

23. The sensor assembly as claimed in claim 20, wherein the housing further comprises:

a first rim having an inside and an outside, that is located on the periphery of the front of the housing;

a first indentation having an inside and an outside, that runs parallel and adjacent to the inside of the first rim;

a second indentation that runs parallel and adjacent to the inside of the first indentation;

a bore, that is approximately centrally located within the second indentation;

a second rim having an inside and an outside, that is located on the periphery of the back of the housing;

a third indentation having an inside and an outside, that runs parallel and adjacent to the inside of the second rim; and

a fourth indentation, that runs parallel and adjacent to the inside of the third indentation.

24. The sensor assembly as claimed in claim 23, wherein the electronic module nests within the bore.

25. The sensor assembly as claimed in claim 23, wherein the first shock dampener is an "O" ring and the second shock dampener is an "O" ring.

26. The sensor assembly as claimed in claim 23, wherein the first mounting means is a plastic mounting ring and the second mounting means is a plastic mounting ring.

27. The sensor assembly as claimed in claim 23, wherein the first transducer is a piezoelement and the second transducer is a piezoelement.