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US 5,190,038 AGranted
Pulse oximeter with improved accuracy and response time
AssigneeNovametrix Medical Systems, Inc.
InventorsMichael J. R. Polson, Gregory L. Morris
Life of this patent
Estimating the term…
Abstract
An improved pulse oximeter for the measurement of oxygen saturation in the blood, which is faster and more accurate than conventional pulse oximeter. Improved speed and accuracy is attained by elimination of normalization and feedback circuitry and the use of analog to digital converting devices having a wide dynamic range along with a sophisticated computer analysis. The instant invention eliminates inaccurcies resulting from channel matching errors, and detects and eliminates aberrant input data.
Claims14
A pulse oximeter for measuring oxygen saturation in the blood of a living person, comprising:
- reference signal generation means for generating a reference signal having a fixed level;
- light generation means for generating light having a first wavelength and light having a second wavelength, said light of said first and second wavelengths each having a fixed output level proportional to said fixed level of said reference signal, and said light generation means being capable of directing said light towards a blood carrying tissue sample;
- light detection means for detecting the light of said first and second wavelengths, after passage through said tissue sample, and for generating, in response to said light detection, a first electrical signal related to said first wavelength, and a second electrical signal related to said second wavelength, said first and second electrical signals each having a signal magnitude related to the degree of oxygen saturation in said blood, and being less than an expected maximum signal magnitude and more than an expected minimum signal magnitude;
- signal conversion means having a dynamic range extending from at least said expected minimum signal magnitude to at least said expected maximum signal magnitude so that said signal conversion means can accommodate said first and second electrical signals and convert said first electrical signal into a first digital signal and said second electrical signal into a second digital signal;
- and
- computer processing means for processing said first and second digital signals so as to compute the oxygen saturation level of said blood.
3 more elements
A pulse oximeter for measuring oxygen saturation in the blood of a living person, comprising:
- reference signal generation means for generating a reference signal having a fixed level;
- light generation means for generating light having a first wavelength and light having a second wavelength, said light of said first and second wavelengths each having a fixed output level proportional to said fixed level of said reference signal, and said light generation means being capable of directing said light towards a blood carrying tissue sample;
- light detection means for detecting the light of said first and second wavelengths, after passage through said tissue sample, and for generating, in response to said light detection, a first electrical signal related to said first wavelength and a second electrical signal related to said second wavelength, said first and second electrical signals each having a signal magnitude related to the degree of oxygen saturation in said blood, and being less than an expected maximum signal magnitude and more than an expected minimum signal magnitude;
- signal conversion means having a dynamic range extending from at least said expected minimum signal magnitude to at least said expected maximum signal magnitude so that said signal conversion means can accommodate said first and second electrical signals and convert said first electrical signal into a first digital signal, said first digital signal having a first digital AC portion and first digital DC portion, and said second digital signals having a second digital AC portion and a second digital DC portion;
- and
- computer processing means for performing first and second digital signal processing operations upon said first and second, digital signals, said first digital signal processing operation including separation of said first digital AC portion from said first digital DC portion and separation of said second digital AC portion from said second digital DC portion, and said second digital signal processing operation including the computation of the oxygen saturation level of said blood utilizing said first and second AC digital portions separated from said first and second DC digital portions, respectively.
3 more elements
Apparatus for measuring and displaying oxygen saturation present in pulsating blood flow in a living person, comprising:
- data generating means for generating incoming data structures produced by directing light having a first wavelength and light having a second wavelength, towards said pulsating blood flow, and detecting said light after passage through said pulsating blood flow;
- data processing means for processing said incoming data structures so as to produce output data structures, each including data representative of the oxygen saturation level present in a pulsation of said pulsating blood flow;
- data storage means for storing at any instant, a plurality of output data structures produced from said data processing means;
- data scanning means for scanning data in said stored output data structures, and generating a set of parameters relating to the confidence level of a first number of stored output data structures;
- data invalidation means for invalidating a second number of said output data structures on the basis of one or more of said set of parameters, each said invalidated output data structure being precluded from use in the computation of oxygen saturation levels;
- computing means for computing the oxygen saturation level of said pulsating blood flow, on the basis of data contained in a third number of stored output data structures;
- and
- display means for displaying said computed oxygen saturation level of said pulsating blood flow.
5 more elements
Dependencies are inferred from the claim text.