Method and apparatus for determining the concentration of a component
First Claim
1. A method of determining at least the concentration of a blood component from the intensity of electromagnetic waves with at least two selected wavelengths which are reflected by a patient'"'"'s tissue or transmitted through the patient'"'"'s tissue, said method comprising the following steps:
- (a) converting the intensities of received electromagnetic signals into at least one first and one second time-dependent electric signal;
(b) time-discretely transforming the first and the second time-dependent electric signal into the frequency domain for determining first and second spectral values of the first and of the second signals;
(c) selecting physiologically relevant first and second spectral values by evaluating said first and second spectral values according to criteria selected in accordance with the patient'"'"'s physiological parameters; and
(d) calculating the concentration of the blood component making use of the selected first and second spectral values.
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Abstract
A method of determining at least the concentration of a component from the intensity of electromagnetic waves with at least two selected wavelengths which are reflected by human tissue or transmitted through human tissue comprises firstly the step of converting the intensities of the received electromagnetic signals into at least one first and one second time-dependent electric signal. Then a time-discrete transformation of the first and of the second electric signal into the frequency domain is performed to determine first and second spectral values of the first and of the second signal. Complex combinatorial values are formed from said first and second spectral values and physiologically relevant combinatorial values are selected by evaluating the complex combinatorial values according to given criteria for the physiological relevance thereof. Finally, the concentration of the component is calculated by using the selected combinatorial values or by using the frequencywise-associated spectral values.
222 Citations
14 Claims
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1. A method of determining at least the concentration of a blood component from the intensity of electromagnetic waves with at least two selected wavelengths which are reflected by a patient'"'"'s tissue or transmitted through the patient'"'"'s tissue, said method comprising the following steps:
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(a) converting the intensities of received electromagnetic signals into at least one first and one second time-dependent electric signal; (b) time-discretely transforming the first and the second time-dependent electric signal into the frequency domain for determining first and second spectral values of the first and of the second signals; (c) selecting physiologically relevant first and second spectral values by evaluating said first and second spectral values according to criteria selected in accordance with the patient'"'"'s physiological parameters; and (d) calculating the concentration of the blood component making use of the selected first and second spectral values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for determination of at least the concentration of a blood component from the intensity of electromagnetic waves with at least two selected wavelengths which are reflected by a patient'"'"'s tissue or transmitted through the patient'"'"'s tissue, comprising:
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means for converting the intensities of the received electromagnetic signals into at least one first and one second time-dependent electric signal; means for time-discretely transforming the first and of the second electric signal into the frequency domain for determining first and second spectral values of the first and of the second time-dependent signals; means for selecting physiologically relevant first and second spectral values by evaluating said first and second spectral values according to criteria that are selected to be physiologically relevant to the patient; and means for calculating the concentration of the component making use of the selected first and second spectral values. - View Dependent Claims (14)
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Specification