EP0029349A2
Expired / Lapsed
EP
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Apparatus for automatically measuring blood pressure
Assignee: Ethicon Inc
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Filing: 1980-11-13
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Granted: —
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Expires: 2000-11-13
Abstract
Abstract An inflatable blood pressure cuff is volumetrically contiguous with a reservoir, and has a microphone mounted on the inside cuff surface. Electrocardiograph signals are obtained, and the cuff is first inflated, then incrementally deflated. At each pressure increment, and for a number of heart beats dependent on the subject's heart rate, data acquisition is gated based on cardiac R-waves. In particular, a first plurality of microphone signal samples are taken, approximately about the R-wave occurrence, and a second, larger and subsequent plurality is also taken. Sample combination techniques yield indices respectively representing noise and signal plus noise, and at least at the first instance when signal exceeds noise by a specified amount, a Korotkoff sound is deemed to have occurred, and systolic pressure is identified. Subsequent deflation and similar processing is utilized to detect diastolic pressure, which occurs when the Korotkoff sounds decrease rapidly or substantially cease.
Inventors
- 👤 Ramsey Maynard Iii
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 00:29
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B5/022; A61B5/02208; A61B5/24; A61B5/316; A61B5/318; A61B5/346; A61B5/349; A61B5/352; A61B5/72; A61B5/7271; A61B5/7285
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
309 words
A method of automatically measuring the blood pressure of a subject comprising the steps of: a) providing an inflatable pressure cuff on a suitable limb of the subject, said cuff including a microphone means on an inner surface for rendering a signal representative of noises generated within said limb; b) inflating said cuff to a predetermined pressure in excess of systolic pressure; c) providing electrocardiograph electrodes for generating ECG signals representative of the cardiac function of the subject; d) incrementally decreasing the pressure of said, cuff, and at each pressure level, performing the steps of i) sampling the signal from said microphone; ii) sensing said ECG signals for cardiac R-waves; iii) for each such R-wave sensed, storing a first plurality of microphone signal samples having a first temporal correspondence to each said R-wave; iv) for each such R-wave sensed, storing a second plurality of microphone signal samples occurring a predetermined interval after said first plurality; v) repeating said storing steps (iii) and (iv) for a predetermined time period dependent on the heart rate of the subject; (vi) combining all of said first pluralities of signal samples into a first index, representative of spurious signal plus noise; (vii) combining all of said second pluralities of signal samples into a second index, representative of true signal plus noise; viii) comparing said first index with said second index; and ix) identifying said second index as a Korotkoff sound if it exceeds said first index by at least a predetermined factor; e) displaying the pressure level at which said Korotkoff sound is first identified as systolic blood pressure; f) repeating said step d) of incrementally decreasing, until there is identified at least a predetermined relationship between said first and second indices; g) displaying the pressure level at which said second index, has said predetermined relationship with said first index, as diastolic blood pressure.
Claim 2
Independent Claim
309 words
A method of automatically measuring the blood pressure of a subject comprising the steps of: a) providing an inflatable pressure cuff on a suitable limb of the subject, said cuff including a microphone means on an inner surface for rendering a signal representative of noises generated within said limb; b) inflating said cuff to a predetermined pressure in excess of systolic pressure; c) providing electrocardiograph electrodes for generating ECG signals representative of the cardiac function of the subject; d) incrementally decreasing the pressure of said, cuff, and at each pressure level, performing the steps of i) sampling the signal from said microphone; ii) sensing said ECG signals for cardiac R-waves; iii) for each such R-wave sensed, storing a first plurality of microphone signal samples having a first temporal correspondence to each said R-wave; iv) for each such R-wave sensed, storing a second plurality of microphone signal samples occurring a predetermined interval after said first plurality; v) repeating said storing steps (iii) and (iv) for a predetermined time period dependent on the heart rate of the subject; (vi) combining all of said first pluralities of signal samples into a first index, representative of spurious signal plus noise; (vii) combining all of said second pluralities of signal samples into a second index, representative of true signal plus noise; viii) comparing said first index with said second index; and ix) identifying said second index as a Korotkoff sound if it exceeds said first index by at least a predetermined factor; e) displaying the pressure level at which said Korotkoff sound is first identified as systolic blood pressure; f) repeating said step d) of incrementally decreasing, until there is identified at least a predetermined relationship between said first and second indices; g) displaying the pressure level at which said second index, has said predetermined relationship with said first index, as diastolic blood pressure.
Claim 3
Dependent Claim
48 words
A method as described in claim 1 wherein said step e) of representing systolic pressure comprises repeating said step d) of incrementally decreasing, until a Korotkoff sound is identified for at least two successive cuff pressure increments, the former of said successive levels being represented as systolic pressure.
Claim 4
Dependent Claim
48 words
A method as described in claim 1 wherein said step-a) of providing a cuff comprises providing a reservoir, having a volume substantially larger than the volume of said cuff, and being substantially volumetrically integral with said cuff, for reducing the significance of spurious volumetric variations in cuff pressure.
Claim 5
Dependent Claim
45 words
A method as described in claim 1 and further including the step, after said step e) of representation of systolic pressure, of accelerating decrease of cuff pressure, in accordance with select criteria, to a lower pressure level which is still in excess of diastolic pressure.
Claim 6
Dependent Claim
30 words
A method as described in claim 4, wherein said lower pressure level is the smaller of 135 mmHg pressure, or 30 mmHg pressure less than the representation of systolic pressure.
Claim 7
Dependent Claim
31 words
A method as described in claim 5, repeatedly performed in extenso, wherein said lower pressure level is in any event at least 25 mmHg above the most recently evaluated diastolic pressure.
Claim 8
Dependent Claim
40 words
A method as described in claim 1 wherein said step d) of incrementally decreasing includes varying the decremen size by an amount which is dependent upon the amplitude of said second index calculated at at least the previous pressure level.
Claim 9
Dependent Claim
39 words
A method as described in claim 1 wherein said step d) (v) of repeating said storing steps includes repeating said storing steps at least four and at most ten times, in proportion to the heart rate of the subject.
Claim 10
Dependent Claim
46 words
A method as described in claim 1 wherein said step f) of repeating said step d) includes identifying a given cuff pressure as diastolic pressure if and only if said second index is identified as being less than said predetermined factor greater than said first index.
Claim 11
Dependent Claim
30 words
A method as described in claim 1 and further including the step, after identification and representation of diastolic pressure, of automatically, rapidly, an substantially completely relieving pressure within said cuff.
Claim 12
Dependent Claim
270 words
Apparatus for automatically measuring the blood pressure of a subject comprising; a signal processing circuit connectable to, a microphone means on an inner surface of an inflatable pressure cuff producing a microphone signal representative of noises generated within a limb of the subject to which the cuff is secured, electrocardiograph electrodes producing ECG signals representative of the cardiac function of the subject, a pressure sensor producing a pressure signal representative of the pressure within the inflatable pressure cuff, and a pressure release valve on the inflatable pressure cuff, the signal processing circuit comprising sensing means for sensing the occurrence of an R-wave in the ECG signals, first and second storage means connected to receive successive microphone signal samples and being controllable in synchronism with the sensing of R-waves by the sensing means, so as to store a different set of microphone signal samples in each respective storage means, processing means connected to the first and second storage means and capable of generating first and second index signals from the microphone signal samples stored in the respective storage means, a comparator circuit connected to receive the first and second index signals and produce at its output a control signal determined by the difference between the index signals, display control means connected to the output of the comparator circuit and arranged to receive the pressure signal from the pressure sensor and display the value of the pressure within the cuff in dependence on the control signal, and deflection control means connected to the output of the comparator circuit and arranged to control the pressure release valve in dependence on the control signal.
Claim 13
Dependent Claim
270 words
Apparatus for automatically measuring the blood pressure of a subject comprising; a signal processing circuit connectable to, a microphone means on an inner surface of an inflatable pressure cuff producing a microphone signal representative of noises generated within a limb of the subject to which the cuff is secured, electrocardiograph electrodes producing ECG signals representative of the cardiac function of the subject, a pressure sensor producing a pressure signal representative of the pressure within the inflatable pressure cuff, and a pressure release valve on the inflatable pressure cuff, the signal processing circuit comprising sensing means for sensing the occurrence of an R-wave in the ECG signals, first and second storage means connected to receive successive microphone signal samples and being controllable in synchronism with the sensing of R-waves by the sensing means, so as to store a different set of microphone signal samples in each respective storage means, processing means connected to the first and second storage means and capable of generating first and second index signals from the microphone signal samples stored in the respective storage means, a comparator circuit connected to receive the first and second index signals and produce at its output a control signal determined by the difference between the index signals, display control means connected to the output of the comparator circuit and arranged to receive the pressure signal from the pressure sensor and display the value of the pressure within the cuff in dependence on the control signal, and deflection control means connected to the output of the comparator circuit and arranged to control the pressure release valve in dependence on the control signal.
Claim 14
Dependent Claim
35 words
Apparatus according to claim 11, wherein the signal processing circuit is connected to a recording apparatus so that the microphone signal samples, ECG signals and pressure signal are recorded during measurement of the blood pressure.
References Cited (Backward Citations)
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