Oximeter with motion detection for alarm modification
First Claim
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1. 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.
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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.
319 Citations
19 Claims
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1. A pulse oximeter comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for detecting motion artifact in a pulse oximeter signal comprising:
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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. - View Dependent Claims (16, 17, 18)
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11. A method of operating a pulse oximeter comprising the steps of:
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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. - View Dependent Claims (12, 13, 14, 15)
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19. A method for detecting motion artifact in a pulse oximeter signal comprising the steps of:
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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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Specification