EP0048591A2
Expired / Lapsed
EP
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An impedance plethysmographic apparatus and a method of removing cardiac artifact
Assignee: Datamedix Inc
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Filing: 1981-09-16
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Granted: —
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Expires: 2001-09-16
Abstract
Abstract An impedance plethysmographic apparatus for monitoring respiration of a patient by measuring an impedance signal generated by changes occurring in the patient's chest has filter elements (30, 36) for removing cardiac artifact from the impedance signal caused by cardiac activity in the chest. The filter elements (30, 36) produces an output signal dependent only upon respiration activity in the patient's chest by removing any signals from said output caused by cardiac activity which is substantially periodic in character. There is also disclosed a method of removing cardiac artifact during monitoring of a patient's respiration using impedance plethysmography.
Inventors
- 👤 Neil H. K. Judell
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 03:17
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/08; A61B5/085; A61B5/086; A61B5/24; A61B5/316; A61B5/318; A61B5/346; A61B5/349; A61B5/352
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
79 words
An impedance plethysmographic apparatus for monitoring respiration of a patient having means for measuring an impedance signal generated by changes occurring in the patient's chest, characterised by: means for removing cardiac artifact from the impedance signal caused by cardiac activity in the chest including filter means (30, 36) which produces an output signal dependent only upon respiration activity in the patient's chest by removing any signals from said output caused by cardiac activity which is substantially periodic in character.
Claim 2
Dependent Claim
79 words
An impedance plethysmographic apparatus for monitoring respiration of a patient having means for measuring an impedance signal generated by changes occurring in the patient's chest, characterised by: means for removing cardiac artifact from the impedance signal caused by cardiac activity in the chest including filter means (30, 36) which produces an output signal dependent only upon respiration activity in the patient's chest by removing any signals from said output caused by cardiac activity which is substantially periodic in character.
Claim 3
Dependent Claim
55 words
An apparatus as claimed in claim 1 characterised in that said filter means is connected to receive, as an input, an impedance signal which is a function of both cardiac and respiration activity, said filter means being adapted to filter said impedance signal so that its output signal is a function of only respiration activity.
Claim 4
Dependent Claim
62 words
An apparatus as claimed in claim 2 characterised in that said filter means includes a first analog filter (30) for receiving said impedance signal as an input, and a second analog filter (36) in cascaded, time-delay arrangement with said first filter, said output signal being a summation of outputs of said filters as a function of respiration activity with respect to time.
Claim 5
Dependent Claim
50 words
An apparatus as claimed in claim 3 characterised in that each of said filters (30, 36) is connected to receive an input signal as a function of heart rate information from said patient based on the time interval between peaks of successive heartbeats of a regularly beating, substantially periodic heartbeat.
Claim 6
Dependent Claim
71 words
' An apparatus as claimed in claim 4 characterised in that the frequency response of said first filter is represented by the following relationship: wherein n) is frequency and to is said time interval between peaks of successive heartbeats, and the frequency response of said second filter being represented by the following relationship; wherein p is a constant having a value greater than or equal to zero, but less than unity.
Claim 7
Independent Claim
73 words
A method of removing cardiac artifact during monitoring of a patient's respiration using impedance plethysmography when said patient has a regular, substantially periodic heartbeat by generating an impedance signal having cardiac and respiration activity components, characterised by filtering said impedance signal by removing the cardiac activity component due to its substantially periodic character, and producing an output signal from said filtered signal which is a function of substantially only the respiration activity component.
Claim 8
Independent Claim
73 words
A method of removing cardiac artifact during monitoring of a patient's respiration using impedance plethysmography when said patient has a regular, substantially periodic heartbeat by generating an impedance signal having cardiac and respiration activity components, characterised by filtering said impedance signal by removing the cardiac activity component due to its substantially periodic character, and producing an output signal from said filtered signal which is a function of substantially only the respiration activity component.
Claim 9
Dependent Claim
45 words
A method as claimed in claim 6 characterised in that said cardiac activity component is generated by monitoring the patient's heart rate and providing a signal which is based upon the time interval between peaks of successive heartbeats of a regularly beating, substantially periodic heartbeat.
Claim 10
Dependent Claim
63 words
A method as claimed in claim 7 characterised in that said filtering step includes passing said impedance signal to a first analog filter whose output is cascaded to a second analog filter, both of said filters receiving, as an input, a signal representative of the patient's heart rate, the output from said filters being a function of substantially only the patient's respiration activity.
References Cited (Backward Citations)
No citation records indexed.
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