Portable automated blood pressure monitoring apparatus and method
First Claim
1. A method for automatically measuring at least one cardiovascular parameter of a subject, comprising the steps of:
- (1) producing a random value;
(2) converting the random value produced in said producing step to a time duration;
(3) timing said time duration;
(4) when said time duration timed by said timing step (3) has elapsed, measuring and storing at least one cardiovascular parameter of the subject; and
(5) repeating said producing step (1), converting step (2), timing step (3), and measuring and storing step (4) to obtain a series of measurements of said at least one parameter.
1 Assignment
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Accused Products
Abstract
A portable auscultatory blood pressure and heart rate measurement system is wearable by an ambulatory patient and measures systolic and diastolic pressure upon request or at random time intervals within a user-programmed range. Cuff inflation pressure and deflation rate are also user programmable. During cuff deflation, pressure and korotkoff sound signal amplitudes are obtained and stored in timed relation to the user'"'"'s ECG, a threshold level is derived from pressure signal amplitudes and system noise level, and systolic and diastolic pressure determined and validated by trend analysis in relation to this threshold level. Analysis results are stored along with a sample number and time of measurement under on-board digital signal processor control, in both a solid state memory and an analog serial data storage medium such as magnetic tape. Data may be retrieved by local display, for example, in a biofeedback setting, or display on an external video display or printer, or can be downloaded in digital form to a local or remote digital computer.
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Citations
24 Claims
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1. A method for automatically measuring at least one cardiovascular parameter of a subject, comprising the steps of:
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(1) producing a random value; (2) converting the random value produced in said producing step to a time duration; (3) timing said time duration; (4) when said time duration timed by said timing step (3) has elapsed, measuring and storing at least one cardiovascular parameter of the subject; and (5) repeating said producing step (1), converting step (2), timing step (3), and measuring and storing step (4) to obtain a series of measurements of said at least one parameter. - View Dependent Claims (2, 3, 4)
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5. A method of automatically measuring the blood pressure of a subject comprising the steps of:
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(1) inflating an occluding cuff disposed on said subject to a first predetermined pressure; (2) deflating said cuff at a controlled rate until the pressure within said cuff falls to a second predetermined pressure less than said first pressure; (3) during said deflating step (2), sensing the pressure within said cuff; (4) during said deflating step (2), sensing the amplitude level of sounds generated by said subject as a result of said cuff deflation; (5) during said deflating step (2), periodically storing levels representing said sensed pressures and sensed sound amplitude levels; and (6) after said deflating step (2), selecting, in response to said stored sensed sound amplitude levels, the stored pressure levels indicating the systolic and diastolic blood pressures of said subject, said selecting step including the steps of; (a) determining the time of occurrence of a predetermined number of stored sound amplitude levels measured consecutively in time which have the highest mean level, said time of occurrence being the time of the center of maximum Korotkoff sound activity; (b) determining the stored sound amplitude level measured latest in time before said time of the center of maximum Korotkoff sound activity which is less than a predetermined threshold level; (c) selecting as the systolic blood pressure of said subject the stored pressure level measured simultaneously with said stored sound amplitude level determined by said determining step (b); (d) determining the stored sound amplitude level measured earliest in time after said time of the center of maximum Korotkoff sound activity which is less than said predetermined threshold level; and (e) selecting as the diastolic blood pressure of the subject the stored pressure level measured simultaneously with said stored sound amplitude level determined by said determining step (d). - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method of automatically measuring the systolic and diastolic blood pressures of a subject, comprising the steps of:
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(1) disposing an occluding cuff, a sound transducer and ECG electrodes on a subject; (2) inflating the cuff to a pressure greater than the systolic blood pressure of said subject; (3) linearly deflating said cuff at a controlled rate until the pressure within said cuff falls to less than the diastolic blood pressure of said subject; (4) during said deflating step (3), continuously producing a first signal indicating the amplitude of sound detected by said sound transducer; (5) during said deflating step (3), continuously producing a second signal indicating the pressure within said cuff; (6) detecting the onset of each cardiac cycle of said subject in response to signals generated by said ECG electrodes; (7) for each cardiac cycle detected by said detecting step (6) during deflation of said cuff, detecting the peak level PKS of said first signal; (8) for each cardiac cycle detected by said detecting step (6) during deflation of said cuff, detecting the level PRE of said second signal at the time said peak level PKS is detected by said detecting step (7); (9) for each cardiac cycle detected by said detecting step (6) during deflation of said cuff, storing said peak level PKS detected by said detecting step (7) and said level PRE detected by said detecting step (8); (10) determining, in response to said stored peak levels PKS, a predetermined number of consecutive cardiac cycles generating the highest average peak level of said first signal; (11) calculating the mean value AKSN of all of said peak levels PKS stored by said storing step (9); (12) calculating the mean value ANOISE of all of said peak levels PKS stored by said storing step (9) which are less than said mean value AKSN calculated by said calculating step (11); (13) calculating a threshold level ##EQU3## (14) determining the stored peak level PKS measured for last cardiac cycle occurring before the center one of said predetermined number of consecutive cardiac cycles determined by said determining step (10) which is less than K-THRESHOLD; (15) selecting said level PRE stored by said storing step (9) for said last cardiac cycle determined by said determining step (14) as the systolic blood pressure of said subject; (16) determining the stored peak level PKS measured for the first cardiac cycle occurring after the center one of said predetermined number of consecutive cardiac cycles determined by said determining step (10) which is less than K-THRESHOLD; and (17) selecting said level PRE stored by said storing step (9) for said first cardiac cycle determined by said determining step (16) as the diastolic blood pressure of said subject.
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13. A system for automatically measuring at least one cardiovascular parameter of a subject comprising:
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means for producing a random value and for converting said random value to a time duration; means for timing said at least one time duration; means for measuring at least one cardiovascular parameter of a subject hen said duration timed by said timing means has elapsed; means for storing said parameter measured by said measuring means; and automatic sequencing means operatively connected to said random value producing and converting means, timing means, measuring means and storing means, for repeatedly causing, in sequence, (1) said random value producing and converting means to produce a random value and convert said random value to a time duration, (2) said timing means to time said time duration, (3) said measuring means to measure said cardiovascular at least one parameter after said time duration timed by said timing means has elapsed, and (4) said storing means to store said parameter produced by said producing means, to obtain a series of measurements of said at least one parameter. - View Dependent Claims (14, 15, 16)
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17. A system for automatically measuring the blood pressure of a subject comprising:
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means for inflating an occluding cuff disposed on said subject to a first predetermined pressure; means for deflating said cuff at a controlled rate until the pressure within said cuff falls to a second predetermined pressure less than said first pressure; means for sensing the pressure within said cuff; means for sensing the amplitude level of sounds generated by said subject as a result of said cuff deflation; means for periodically storing levels representing pressures sensed by said pressure sensing means and sound amplitude levels sensed by said sound amplitude level sensing means during deflation of said cuff; and means for selecting, in response to said sensed sound amplitude levels stored in said storing means, the stored pressure levels indicating the systolic and diastolic blood pressures of said subject, said selecting means comprising a digital signal processing means for; (a) determining the time of occurrence of a predetermined number of stored sound amplitude levels measured consecutively in time which have the highest mean level, said time of occurrence being the time of the center of maximum Korotkoff sound activity; (b) determining the stored sound amplitude level measured latest in time before said determined time of the center of maximum Korotkoff sound activity which is less than a predetermined threshold level; (c) selecting as the systolic blood pressure of said subjecting the stored pressure level measured simultaneously with said determined sound amplitude level measured latest in time; (d) determining the stored sound amplitude level measured earliest in time after said determined time of the center of maximum Korotkoff sound activity which is less than said predetermined threshold level; and (e) selecting as the diastolic blood pressure of the subject the stored pressure level measured simultaneously with said determined earliest in time sound amplitude level. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A system for automatically measuring the systolic and diastolic blood pressures of a subject, said system of the type including an occluding cuff, a Korotkoff sound transducer and ECG electrodes, said system comprising:
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means for inflating said cuff to a pressure greater than the systolic blood pressure of said subject; means for linearly deflating said cuff at a controlled rate until the pressure within said cuff falls to less than the diastolic blood pressure of said subject; means for continuously producing a first signal indicating the amplitude of sound detected by said Korotkoff sound transducer; means for continuously producing a second signal indicating the pressure within said cuff; means for detecting the onset of each cardiac cycle of said subject in response to signals generated by said ECG electrodes; storing means for storing digital signals; and digital signal processing means for; (a) determining the peak level PKS of said first signal for each cardiac cycle detected by said cardiac cycle detecting means, (b) determining the level PRE of said second signal at the time said peak level PKS is determined for each cardiac cycle detected by said cardiac cycle detecting means, (c) storing, in said storing means, said peak level PKS and said determined level PRE for each cardiac cycle detected by said cardiac cycle detecting means, (d) determining, in response to said peak levels PKS stored by said storing means, a predetermined number of consecutive cardiac cycles having the highest average peak level, (e) calculating the mean value AKSN of all of said peak levels PKS stored by said storing means, (f) calculating the mean value ANOISE of all of said peak levels PKS stored by said storing means which are less than said mean value AKSN, (g) calculating a threshold level ##EQU4## (h) determining the stored peak level PKS measured for the last cardiac cycle occurring before the center cardiac cycle of said predetermined number of consecutive cardiac cycles determined to have the highest average peak level which is less than K-THRESHOLD, (i) selecting said level PRE stored by said storing means for said last cardiac cycle as the systolic blood pressure of said subject, (j) determining the stored peak level PKS measured for the first cardiac cycle occurring after the center cardiac cycle of said predetermined number of consecutive cardiac cycles determined to have the highest average peak level which is less than K-THRESHOLD, and (k) selecting said level PRE stored by said storing means for said first cardiac cycle as the diastolic blood pressure of said subject.
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Specification