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US4781201A
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Cardiovascular artifact filter
Assignee: Corometrics Medical Systems Inc
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Filing: 1986-07-22
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Granted: 1988-11-01
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Expires: 2006-07-22
Abstract
Abstract For suppressing cardiovascular artifact from a respiration signal derived from a patient's transthoracic impedance, an adaptive filtering device determines the patient's heart rate, converts the respiration signal from an analog to digital representation at a rate proportional to the heart rate, and then filters the digital respiration signal such that that portion of the respiration signal having a frequency content at or above the heart rate is most greatly attenuated.
Inventors
- 👤 John C. Wright
- 👤 Harry M. Triebel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:06
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/0205
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
107 words
For suppressing cardiovascular artifact from a respiration signal derived from a patient, a filtering device comprising: heat beat detecting means for detecting heart beats of the patient; processing means for determining the heart rate of the patient in response to the detected heart beats; and filtering means operable for sampling the respiration signal in proportion to the heart rate and producing a filtered respiration signal as follows: Filtered Respiration Signal=S.sub.(t) +(K.sub.1 +K.sub.2)Z.sup.-1.sub.(t-1) +(K.sub.3 +K.sub.4)Z.sup.-2.sub.(t-1) where: S.sub.(t) is the respiration signal currently being sampled; Z.sup.-1.sub.(t) =S.sub.(t) +K.sub.1 Z.sup.-1.sub.(t-1) +K.sub.3 Z.sup.-2.sub.(t-1) Z.sup.-2.sub.(t) =Z.sup.1.sub.(t-1) ; and K 1 , K 2 , K 3 , and K 4 are constants.
Claim 2
Dependent Claim
107 words
For suppressing cardiovascular artifact from a respiration signal derived from a patient, a filtering device comprising: heat beat detecting means for detecting heart beats of the patient; processing means for determining the heart rate of the patient in response to the detected heart beats; and filtering means operable for sampling the respiration signal in proportion to the heart rate and producing a filtered respiration signal as follows: Filtered Respiration Signal=S.sub.(t) +(K.sub.1 +K.sub.2)Z.sup.-1.sub.(t-1) +(K.sub.3 +K.sub.4)Z.sup.-2.sub.(t-1) where: S.sub.(t) is the respiration signal currently being sampled; Z.sup.-1.sub.(t) =S.sub.(t) +K.sub.1 Z.sup.-1.sub.(t-1) +K.sub.3 Z.sup.-2.sub.(t-1) Z.sup.-2.sub.(t) =Z.sup.1.sub.(t-1) ; and K 1 , K 2 , K 3 , and K 4 are constants.
Claim 3
Dependent Claim
32 words
A filtering device as in claim 1; wherein the heart beat detecting means comprises a QRS detecting means for detecting the QRS complex of each heart beat waveform produced by the patient.
Claim 4
Dependent Claim
36 words
A filtering device as in claim 1, wherein the processing means comprises timing means for producing pulses at a predetermined rate and first counting means for counting the number of pulses occurring between detected heart beats.
Claim 5
Dependent Claim
49 words
A filtering device as in claim 1; wherein the device further comprises conversion means for converting from an analog to a digital representation of the respiration signal at a converting rate proportional to the heart rate and wherein the filtering means samples the digital representation of the respiration signal.
Claim 6
Dependent Claim
17 words
A filtering device as in claim 4; wherein the conversion means is a successive approximating analog-to-digital converter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-01 | 1992-05-02 | 1992-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-01 | 1996-05-02 | 1996-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-01 | 2000-05-02 | 2000-11-01 | $7700.00 | Window Closed / Lapsed |