Pulse oximeter
First Claim
1. A method for detecting the validity of measurement circumstances in connection with a monitoring device intended for determining the amount of at least one light absorbing substance in a subject, the monitoring device comprising emitters for emitting radiation at a minimum of two wavelengths, driving means for activating said emitters, and a detector for receiving said radiation at said wavelengths and for producing an electrical signal in response to the radiation, the method comprising the steps of driving an emitter by a drive signal having predetermined characteristics, analyzing the electrical signal traveling from the direction of said detector in order to detect whether a crosstalk component caused by electric power coupled directly from said drive signal is present, and taking predetermined measures when a crosstalk component is detected.
1 Assignment
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Accused Products
Abstract
The invention relates to pulse oximeters used to measure blood oxygenation. The current trend towards lower power consumption has brought a problem of erroneous readings caused by intrachannel crosstalk, i.e. errors due to the coupling of undesired capacitive, inductive, or conductive (resistive) pulse power from the emitting side of the pulse oximeter directly to the detecting side of the oximeter. The pulse oximeter of the invention is therefore provided with means for detecting whether intrachannel crosstalk is present and whether it will cause erroneous results in the oxygenation measurements. The pulse oximeter is preferably further provided with means for eliminating intrachannel crosstalk which are adapted to control the measurement so that measurement signals can be obtained which are substantially void of crosstalk components.
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Citations
30 Claims
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1. A method for detecting the validity of measurement circumstances in connection with a monitoring device intended for determining the amount of at least one light absorbing substance in a subject, the monitoring device comprising
emitters for emitting radiation at a minimum of two wavelengths, driving means for activating said emitters, and a detector for receiving said radiation at said wavelengths and for producing an electrical signal in response to the radiation, the method comprising the steps of driving an emitter by a drive signal having predetermined characteristics, analyzing the electrical signal traveling from the direction of said detector in order to detect whether a crosstalk component caused by electric power coupled directly from said drive signal is present, and taking predetermined measures when a crosstalk component is detected.
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23. An apparatus for non-invasively determining the amount of at least one light absorbing substance in a subject, the apparatus comprising
emitters for emitting radiation at a minimum of two different wavelengths, driving means for activating said emitters, a detector for receiving said radiation at said wavelengths and producing an electrical signal in response to the radiation, sampling means for sampling the electrical signal, whereby a sampled signal is obtained, signal processing means for determining said amount by processing the sampled signal, and crosstalk detection means for analyzing whether a direct electric crosstalk component is present in the electrical signal, the direct electric crosstalk component being caused by electric power coupled directly from said driving means to said electrical signal.
Specification