Patent US5368026A successfully refreshed from Google Patents.
US5368026A
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Oximeter with motion detection for alarm modification
Assignee: Nellcor Puritan Bennett LLC
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Filing: 1993-03-26
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Granted: 1994-11-29
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Expires: 2013-03-26
Abstract
Abstract A pulse oximeter which modifies the alarm condition when motion is detected. Basically, if the lack of a pulse is determined to be as a result of motion artifact, the generation of an alarm is postponed. In addition, the display indicates that motion is present and that the last reading is questionable due to the presence of motion. The invention also determines if motion artifact is present from the pulse oximeter detector signal itself. The ratio of the positive and negative peaks of the derivative of the pulse signal are compared to a motion/blood pulse threshold.
Inventors
- 👤 David B. Swedlow
- 👤 Robert S. Potratz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:30
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1455; A61B5/14551; A61B5/103; A61B5/11; A61B5/1104; A61B5/72; A61B5/7203; A61B5/7207; A61B5/721; A61B5/74; A61B5/746; A61B5/68; A61B5/6801; A61B5/6813; A61B5/6825; A61B5/6826; A61B5/7235; A61B5/7239
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
103 words
A pulse oximeter comprising: means for emitting light; sensor means for producing a detector signal corresponding to absorption of said light emitted by blood constituents; means for determining oxygen saturation based on the detector signal; control means, coupled to said sensor means, for qualifying pulses in the detector signal corresponding to arterial pulses; alarm generating means for generating an alarm when no qualified pulses are detected in a predetermined time-out period; motion artifact means for determining whether motion artifact is present during said time-out period; and means, responsive to said motion artifact means, for modifying the timing of the generation of said alarm.
Claim 2
Dependent Claim
103 words
A pulse oximeter comprising: means for emitting light; sensor means for producing a detector signal corresponding to absorption of said light emitted by blood constituents; means for determining oxygen saturation based on the detector signal; control means, coupled to said sensor means, for qualifying pulses in the detector signal corresponding to arterial pulses; alarm generating means for generating an alarm when no qualified pulses are detected in a predetermined time-out period; motion artifact means for determining whether motion artifact is present during said time-out period; and means, responsive to said motion artifact means, for modifying the timing of the generation of said alarm.
Claim 3
Dependent Claim
115 words
The pulse oximeter of claim 1 wherein said means for modifying includes a state machine having: means for operating in a qualified signal state for detecting and analyzing qualified pulses; means for operating in a probationary state for both determining whether non-qualified pulses are due to noise or motion artifact and searching for qualified pulses, said motion artifact means being activated during said probationary state; means for transitioning from said qualified signal state to said probationary state when no qualified pulses are detected for a first period of time; and means for transitioning from said probationary state to said qualified signal state when a predetermined number of qualified signals are detected in said probationary state.
Claim 4
Dependent Claim
14 words
The pulse oximeter of claim 2 wherein said state machine is a programmed microprocessor.
Claim 5
Dependent Claim
51 words
The pulse oximeter of claim 2 wherein said probationary state includes: means for operating in a motion artifact state wherein motion artifact is detected and said time-out period is extended; and means for operating in a noise state wherein no motion artifact is detected and said time-out period is not extended.
Claim 6
Dependent Claim
27 words
The pulse oximeter of claim 2 further comprising means for activating said alarm if said probationary state extends for more than a maximum probation period of time.
Claim 7
Dependent Claim
73 words
The pulse oximeter of claim 1 wherein said motion artifact means comprises: means for detecting a pulse waveform in said detected signal; means for determining the derivative of said pulse waveform; means for determining the ratio of a positive peak of said derivative to a negative peak of said derivative; means for comparing said ratio to a threshold value; and means for indicating motion artifact when said ratio is less than said threshold.
Claim 8
Dependent Claim
21 words
The pulse oximeter of claim 6 wherein said means for comparing is programmed with said threshold being between 1 and 1.4.
Claim 9
Dependent Claim
59 words
The pulse oximeter of claim 1 wherein said means for emitting includes means for producing an infrared (IR) signal and a red signal, said motion artifact means comprising: means for correlating an IR pulse to a corresponding red pulse; and means for indicating motion artifact when said pulse is not qualified and said IR and red pulses are correlated.
Claim 10
Dependent Claim
61 words
The apparatus of claim 1 further comprising: means, coupled to said control means, for calculating a numerical pulse rate from said pulses; a display, coupled to said means for calculating, for indicating said numerical pulse rate; means, responsive to said motion artifact means and coupled to said display, for alternating said numerical pulse rate with dashes when motion artifact is present.
Claim 11
Independent Claim
94 words
An apparatus for detecting motion artifact in a pulse oximeter signal comprising: means for emitting light at a body; means for receiving light from said body to generate said pulse oximeter signal; means for detecting a pulse waveform in said pulse oximeter signal; means for determining the derivative of said pulse waveform; means for determining the ratio of a positive peak of said derivative to a negative peak of said derivative; means for comparing said ratio to a threshold value; and means for indicating motion artifact when said ratio is less than said threshold.
Claim 12
Independent Claim
94 words
An apparatus for detecting motion artifact in a pulse oximeter signal comprising: means for emitting light at a body; means for receiving light from said body to generate said pulse oximeter signal; means for detecting a pulse waveform in said pulse oximeter signal; means for determining the derivative of said pulse waveform; means for determining the ratio of a positive peak of said derivative to a negative peak of said derivative; means for comparing said ratio to a threshold value; and means for indicating motion artifact when said ratio is less than said threshold.
Claim 13
Independent Claim
86 words
A method of operating a pulse oximeter comprising the steps of: emitting light; producing a detector signal corresponding to absorption of said emitted light by blood constituents; determining oxygen saturation based on the detector signal; qualifying pulses in the detector signal corresponding to arterial pulses; generating an alarm when no qualified pulses are detected in a predetermined time-out period; determining whether motion artifact is present during said time-out period; and modifying the timing of the generation of said alarm based on whether motion artifact is present.
Claim 14
Independent Claim
86 words
A method of operating a pulse oximeter comprising the steps of: emitting light; producing a detector signal corresponding to absorption of said emitted light by blood constituents; determining oxygen saturation based on the detector signal; qualifying pulses in the detector signal corresponding to arterial pulses; generating an alarm when no qualified pulses are detected in a predetermined time-out period; determining whether motion artifact is present during said time-out period; and modifying the timing of the generation of said alarm based on whether motion artifact is present.
Claim 15
Dependent Claim
113 words
The method of claim 11 wherein said modifying step includes operating in a qualified signal state for detecting and analyzing qualified pulses, and operating in a probationary state for both determining whether non-qualified pulses are due to noise or motion artifact and searching for qualified pulses, said step of determining whether motion artifact is present being performed during said probationary state; and further comprising the steps of: transitioning from said qualified signal state to said probationary state when no qualified pulses are detected for a first period of time; and transitioning from said probationary state to said qualified signal state when a predetermined number of qualified signals are detected in said probationary state.
Claim 16
Dependent Claim
21 words
The method of claim 12 further comprising the step of performing said steps of operating and transitioning in a software program.
Claim 17
Dependent Claim
42 words
The method of claim 12 wherein said probationary state includes: a motion artifact state wherein motion artifact is detected and said time-out period is extended; and a noise state wherein no motion artifact is detected and said time-out period is not extended.
Claim 18
Dependent Claim
27 words
The method of claim 12 further comprising the step of activating said alarm if said probationary state extends for more that a maximum probation period of time.
Claim 19
Dependent Claim
64 words
The method of claim 10 wherein said determining step comprises the steps of: detecting a pulse waveform in said detected signal; determining the derivative of said pulse waveform; determining the ratio of a positive peak of said derivative to a negative peak of said derivative; comparing said ratio to a threshold value; and indicating motion artifact when said ratio is less than said threshold.
Claim 20
Dependent Claim
13 words
The method of claim 16 wherein said threshold is between 1 and 1.4.
Claim 21
Dependent Claim
54 words
The method of claim 10 wherein said step of emitting includes producing an infrared (IR) signal and a red signal, said determining step comprising the steps of: correlating an IR pulse to a corresponding red pulse; and indicating motion artifact when said pulse is not qualified and said IR and red pulses are correlated.
Claim 22
Independent Claim
83 words
A method for detecting motion artifact in a pulse oximeter signal comprising the steps of: emitting light at a body; receiving light from said body to generate said pulse oximeter signal; detecting a pulse waveform in said pulse oximeter signal; determining the derivative of said pulse waveform; determining the ratio of a positive peak of said derivative to a negative peak of said derivative; comparing said ratio to a threshold value; and indicating motion artifact when said ratio is less than said threshold.
Claim 23
Independent Claim
83 words
A method for detecting motion artifact in a pulse oximeter signal comprising the steps of: emitting light at a body; receiving light from said body to generate said pulse oximeter signal; detecting a pulse waveform in said pulse oximeter signal; determining the derivative of said pulse waveform; determining the ratio of a positive peak of said derivative to a negative peak of said derivative; comparing said ratio to a threshold value; and indicating motion artifact when said ratio is less than said threshold.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-11-28 | 1998-05-30 | 1998-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-28 | 2002-05-30 | 2002-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-28 | 2006-05-30 | 2006-11-29 | $7700.00 | Window Closed / Lapsed |