System for pulse oximetry SPO.sub.2 determination
First Claim
1. Apparatus for measuring oxygen saturation of hemoglobin in arterial blood said apparatus connected to a probe which produces a series of sets of data values, each of said sets including first and second data values, each of said data values in a set being indicative of light absorption of arterial blood, said arterial blood having pulsatile and non-pulsatile components, each of said data values being measured at a respective one of two light wavelengths said apparatus comprising:
- means for storing a plurality of said sets of data values received from said probe;
means for computing a ratio of a first effective optical extinction coefficient of said pulsatile component of said arterial blood at a first one of said two light wavelengths to a second effective optical extinction coefficient of said pulsatile component of said arterial blood at a second one of said two light wavelengths, said ratio of effective optical extinction coefficients being determined by two variable least squares processing n of said sets of data values, where n is a positive integer greater than 2, to compensate for noise in said sets of data values at both of said first and second wavelengths; and
means for determining said oxygen saturation of said hemoglobin using said ratio.
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Accused Products
Abstract
The improved pulse oximeter preprocesses the sets of red and infrared signals received from the probe. The set of pairs of processed red and infrared data points are fitted to a linear equation to compute the slope of the best fit line through these data points and account for noise in both of these sets of data points. A measure of the linearity of the input data points, if less than a predetermined threshold, indicates that a distorted signal has been received from the probe. The computed slope of the best fit line is converted to a RRatio which is used in a empirical calibration formula to compute the average SpO2 value.
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Citations
18 Claims
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1. Apparatus for measuring oxygen saturation of hemoglobin in arterial blood said apparatus connected to a probe which produces a series of sets of data values, each of said sets including first and second data values, each of said data values in a set being indicative of light absorption of arterial blood, said arterial blood having pulsatile and non-pulsatile components, each of said data values being measured at a respective one of two light wavelengths said apparatus comprising:
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means for storing a plurality of said sets of data values received from said probe; means for computing a ratio of a first effective optical extinction coefficient of said pulsatile component of said arterial blood at a first one of said two light wavelengths to a second effective optical extinction coefficient of said pulsatile component of said arterial blood at a second one of said two light wavelengths, said ratio of effective optical extinction coefficients being determined by two variable least squares processing n of said sets of data values, where n is a positive integer greater than 2, to compensate for noise in said sets of data values at both of said first and second wavelengths; and means for determining said oxygen saturation of said hemoglobin using said ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for measuring oxygen saturation of hemoglobin in arterial blood from a series of sets of data values produced by a probe, each of said sets including first and second data values, each of said data values in a set being indicative of light absorption of arterial blood, said arterial blood having a pulsatile and non-pulsatile components at a respective one of two light wavelengths, comprising the steps of:
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storing a plurality of said sets of data values received from said probe; computing a ratio of first effective optical extinction coefficient of said pulsatile component of said arterial blood at a first one of said two light wavelength to second effective optical extinction coefficient of said pulsatile component of said arterial blood at a second one of said two light wavelengths said ratio of effective optical extinction coefficients being determined by two variable least squares processing n of said sets of data values, where n is a positive integer greater than 2, to compensate for noise in said sets of data values at both of said first and second wavelengths; and determining oxygen saturation of said hemoglobin using said ratio. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification