Blood pressure measurement with Korotkov sound artifact information detection and rejection
First Claim
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1. A machine implemented method for identifying and removing artifacts in Korotkov sound signals for use in a system for measuring systolic and diastolic blood pressure, obtaining a measure of the systolic slope of blood pressure waves, or the like, comprising the steps of:
- (1) recurrently obtaining cuff pressure measurements and arrival times of peak R-wave signals and Korotkov sound signals including artifacts through the active K-sound range of a cuff pressure deflation,(2) using arrival times of associated R-wave signals and Korotkov sound signals and artifacts, determining RK intervals from which a plurality of RK interval versus cuff pressure points are obtained, some of which are true points and others of which are artifact points,(3) processing said points to group the same such that one group includes substantially only true points, said processing comprising;
(a) from an existing point at high cuff pressure, estimating an RK interval value RK for a next lower cuff pressure which includes a point,(b) including the point at said lower cuff pressure in a group which includes also said existing point when the difference Δ
RK=RK-RK at a lower cuff pressure is within a predetermined range, and not including the point at said lower cuff pressure in the group when the difference Δ
RK is outside said predetermined range,(c) repeating steps 3a and 3b but using the last included point in the group for estimating an RK interval value for a next lower cuff pressure which includes a point,(d) repeating steps 3a, 3b and 3c using ungrouped points until all points are included in a group, and(4) selecting as the one group which includes substantially only true points that group which includes the greatest number of points.
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Abstract
Method and apparatus for recurrently obtaining systolic and diastolic blood pressure measurements, and measurements of the systolic slope of the blood pressure wave in a subject'"'"'s artery are disclosed. Artifact information in Korotkov sound signals employed in the apparatus are substantially eliminated to avoid errors which otherwise normally are present in such measurements.
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Citations
14 Claims
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1. A machine implemented method for identifying and removing artifacts in Korotkov sound signals for use in a system for measuring systolic and diastolic blood pressure, obtaining a measure of the systolic slope of blood pressure waves, or the like, comprising the steps of:
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(1) recurrently obtaining cuff pressure measurements and arrival times of peak R-wave signals and Korotkov sound signals including artifacts through the active K-sound range of a cuff pressure deflation, (2) using arrival times of associated R-wave signals and Korotkov sound signals and artifacts, determining RK intervals from which a plurality of RK interval versus cuff pressure points are obtained, some of which are true points and others of which are artifact points, (3) processing said points to group the same such that one group includes substantially only true points, said processing comprising; (a) from an existing point at high cuff pressure, estimating an RK interval value RK for a next lower cuff pressure which includes a point, (b) including the point at said lower cuff pressure in a group which includes also said existing point when the difference Δ
RK=RK-RK at a lower cuff pressure is within a predetermined range, and not including the point at said lower cuff pressure in the group when the difference Δ
RK is outside said predetermined range,(c) repeating steps 3a and 3b but using the last included point in the group for estimating an RK interval value for a next lower cuff pressure which includes a point, (d) repeating steps 3a, 3b and 3c using ungrouped points until all points are included in a group, and (4) selecting as the one group which includes substantially only true points that group which includes the greatest number of points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a blood pressure monitoring system for measuring blood pressure, obtaining a measure of the systolic slope of blood pressure waves, or the like, the combination comprising,
(1) an inflatable cuff adapted to encircle a subject'"'"'s arm, (2) means for inflating and deflating said cuff within a range of pressures within which Korotkov sounds are produced, (3) pressure transducer means responsive to cuff pressure and having an output signal related thereto, (4) electrode means for sensing electrocardiographic signals from the subject, (5) means for detecting the R-wave in the electrocardiographic signals, (6) transducer means for sensing Korotkov and artifact sounds during a cuff deflation, (7) means for detecting Korotkov and artifact sounds in the output from said sound transducer means, (8) means for accumulating a plurality of cuff pressure measurements and associated RK intervals comprising the time between the occurrence of an output from the R-wave detecting means and the associated signals from the Korotkov and artifact sound detecting means during a cuff deflation to establish a plurality of RK interval versus cuff pressure points, some of which are true points and others of which are artifact points, (9) machine implemented means for grouping true points to identify and distinguish the same from artifact points comprising (a) means responsive to one point at a high cuff pressure for estimating an RK interval, RK, for a true point at a next lower cuff pressure which includes a point, (b) means for including said point at said next lower cuff pressure in a group which includes said one point if the difference, Δ - RK, between the estimated RK interval value, RK, and the RK interval value at said next lower cuff pressure is within a predetermined range, and not including said point if the difference, Δ
RK, is outside said range,(c) means for repeating operations performed by elements 9a and 9b using the last-added point to the group for estimating RK until no ungrouped point at a lower cuff pressure remains, (d) means for repeating operations performed by elements 9a, 9b and 9c until all points are included in a group, points identified by element 9d being included in another group of points each repetition of element 9d operations, (10) means for identifying the group with the largest number of points as a group of substantially all true points. - View Dependent Claims (11, 12, 13, 14)
- RK, between the estimated RK interval value, RK, and the RK interval value at said next lower cuff pressure is within a predetermined range, and not including said point if the difference, Δ
Specification