US5372140A
Expired / Lapsed
US
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Depth of anaesthesia monitoring
Assignee: University of Manchester
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Filing: 1991-10-16
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Granted: 1994-12-13
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Expires: 2011-10-16
Abstract
Abstract A method and apparatus for providing a measure of the depth of anaesthesia. A series of R-waves are analyzed using circular statistics to derive a measurement vector length representing the R--R variation of the sample. The Rayleigh Test is applied to determine a reference vector length from a predetermined probability level and the number of R-waves in the analyzed series. The measurement vector length is compared to the reference vector length to derive a measure of the death of anaesthesia.
Inventors
- 👤 Christopher J. D. Pomfrett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:28
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/48; A61B5/4821; A61B5/02; A61B5/0205; A61B5/08; A61B5/0816; A61B5/103; A61B5/11; A61B5/1104; A61B5/1106; A61M; A61M16/00; A61M16/10; A61M16/104; A61B2505/00; A61B2505/05
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
107 words
A method for providing a measure of the depth of anaesthesia, said method comprising the steps of: analyzing a series of R-waves to determine the position in time of each R-wave relative to the respiratory cycle within which it occurs, deriving a measurement value representing the degree of clustering of the analyzed R-waves relative to the respiratory cycles, applying a test for randomness to the analyzed series of R-waves to derive a reference value representing a predetermined significance level for clustering of the R-waves relative to the respiratory cycles, and comparing the measurement value with the reference value to derive a measure of the depth of anaesthesia.
Claim 2
Independent Claim
107 words
A method for providing a measure of the depth of anaesthesia, said method comprising the steps of: analyzing a series of R-waves to determine the position in time of each R-wave relative to the respiratory cycle within which it occurs, deriving a measurement value representing the degree of clustering of the analyzed R-waves relative to the respiratory cycles, applying a test for randomness to the analyzed series of R-waves to derive a reference value representing a predetermined significance level for clustering of the R-waves relative to the respiratory cycles, and comparing the measurement value with the reference value to derive a measure of the depth of anaesthesia.
Claim 3
Dependent Claim
57 words
A method according to claim 1, including: determining the position in time of the R-waves on a normalised unit of respiratory waveform, resolving each R-wave as a vector with a unit amplitude and an angle representing the portion of the R-wave in the respiratory cycle, and calculating the resultant mean vector length to form said measurement value.
Claim 4
Dependent Claim
42 words
A method according to claim 2, including: applying the test for randomness to determine a reference vector length to form said reference value, the reference vector length corresponding to a predetermined probability level and the number of R-waves in the said series.
Claim 5
Dependent Claim
15 words
A method according to claim 3, wherein the test for randomness is the Rayleigh test.
Claim 6
Dependent Claim
43 words
A method according to claim 4, including obtaining the reference vector length by reference to a table correlating the number of R-waves in the sample to the length of the vector that will result given that number of R-waves for a given probability.
Claim 7
Dependent Claim
12 words
A method according to claim 5, wherein the given probability is 95%.
Claim 8
Dependent Claim
11 words
A method according to claim 1, including monitoring the respiratory rate.
Claim 9
Dependent Claim
31 words
A method according to claim 1, including displaying the measurement vector length and reference vector length simultaneously to provide the anaesthetist with a real time indication of the depth of anaesthesia.
Claim 10
Dependent Claim
30 words
A method according to claim 8, including displaying the measurement and vector lengths graphically using a bar-chart in which the two parameters are illustrated by adjacent bars of different colours.
Claim 11
Independent Claim
109 words
An apparatus for providing a measure of the depth of anaesthesia, comprising: means for analyzing a series of R-waves to determine the position in time of each R-wave relative to the respiratory cycle within which it occurs, means for achieving a measurement value representing the degree of clustering of the analyzed R-waves relative to the respiratory cycles, means for applying a test for randomness to the analyzed series of R-waves to derive a reference value representing a predetermined significance level for clustering of the R-waves relative to the respiratory cycle, and means for comparing the measurement value with the reference value to derive a measurement of depth of anaesthesia.
Claim 12
Independent Claim
109 words
An apparatus for providing a measure of the depth of anaesthesia, comprising: means for analyzing a series of R-waves to determine the position in time of each R-wave relative to the respiratory cycle within which it occurs, means for achieving a measurement value representing the degree of clustering of the analyzed R-waves relative to the respiratory cycles, means for applying a test for randomness to the analyzed series of R-waves to derive a reference value representing a predetermined significance level for clustering of the R-waves relative to the respiratory cycle, and means for comparing the measurement value with the reference value to derive a measurement of depth of anaesthesia.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-12-12 | 1998-06-13 | 1998-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-12 | 2002-06-13 | 2002-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-12 | 2006-06-13 | 2006-12-13 | $7700.00 | Window Closed / Lapsed |