Calibration technique for non-invasive medical devices
First Claim
1. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue, comprising:
- (a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters;
(b) acting on the tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters;
wherein non-invasively measuring the first values of the first physiologic parameter includes exciting the tissue with excitation light and detecting a resulting fluorescent signal.
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Accused Products
Abstract
There is a need for a non-invasive method of calibrating medical devices at the point of care, where the calibration is performed without the removal of blood or bodily fluids. The invention is directed to an approach for calibrating a first non-invasive sensor in which the tissue being measured is modulated in some way so as to after the value of the parameter being measured by the first optical sensor. A second sensor detects another parameter that also changes with the modulation. The second sensor is absolutely calibrated. Where there is a known relationship between the first and second parameters, a calibration may be derived for the first sensor. Such a technique is applicable to calibrating non-invasive sensors for monitoring a wide variety of physiologic parameters including, inter alia, glucose, blood gases, blood electrolytes and blood pH.
341 Citations
54 Claims
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1. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters;
(b) acting on the tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters;
wherein non-invasively measuring the first values of the first physiologic parameter includes exciting the tissue with excitation light and detecting a resulting fluorescent signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue of a patient, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters;
(b) administering a drug to the patient to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters. - View Dependent Claims (13)
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14. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters, wherein the first physiologic parameter is pH;
(b) acting on the tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters that includes a third physiologic parameter substantially unaffected by the acting on the body;
(b) acting on the tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters. - View Dependent Claims (21, 22)
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23. A method of calibrating a non-invasive sensor for a first physiologic parameter in tissue, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters;
(b) acting on the tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters;
wherein the tissue is epithelial tissue. - View Dependent Claims (24, 25, 26)
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27. An apparatus for determining a value of a first physiologic parameter within tissue, comprising:
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an uncalibrated, first non-invasive pH sensor for measuring the first physiologic parameter of the tissue;
a calibrated, second non-invasive sensor for measuring a second physiologic parameter of the tissue; and
a processor coupled to receive first and second signals from each of the first and second non-invasive sensors, and to calculate calibrated values for the first physiologic parameter from the first and second signals from each of the first and second non-invasive sensors when a characteristic of the tissue is modulated between the first and second signals. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. An apparatus for determining a value of a first physiologic parameter within tissue, comprising:
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an uncalibrated, first non-invasive sensor for measuring the first physiologic parameter of the tissue;
a calibrated, second non-invasive sensor for measuring a second physiologic parameter of the tissue; and
a processor coupled to receive first and second signals from each of the first and second non-invasive sensors, and to calculate calibrated values for the first physiologic parameter from the first and second signals from each of the first and second non-invasive sensors when a characteristic of the tissue is modulated between the first and second signals;
wherein the processor calculates calibration constants for the first physiologic parameter from the first and second signals from each of the first and second non-invasive sensors;
wherein the processor produces calibrated values for the first physiologic parameter from measurement signals received from the first non-invasive sensor and the calibration constants; and
,wherein the processor performs a check on the calibration constants by measuring the first and second physiologic parameters before and after application of a stimulus to the tissue.
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43. A method of calibrating a non-invasive sensor for a first physiologic parameter in muscle tissue, comprising:
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(a) non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the muscle tissue, a known relationship existing between the first and second physiologic parameters;
(b) acting on the muscle tissue so as to change the first and second physiologic parameters;
(c) non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the muscle tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) determining a calibrated value for at least one of the first arid second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters.
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44. An apparatus for determining a value of a first physiologic parameter within tissue, comprising:
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(a) means for non-invasively measuring first values of the first physiologic parameter and of a second physiologic parameter in the tissue, a known relationship existing between the first and second physiologic parameters;
(b) means for acting on the tissue so as to change the first and second physiologic parameters;
(c) means for non-invasively measuring second values of the first physiologic parameter and of the second physiologic parameter in the tissue, the measurements of the first and second values of the second physiologic parameter being absolutely calibrated; and
(d) moans for determining a calibrated value for at least one of the first and second values of the first physiologic parameter from the first and second values of both the first and second physiologic parameters;
wherein the means for non-invasively measuring the first values of the first physiologic parameter includes a means for exciting the tissue with excitation light and a means for detecting a resulting fluorescent signal. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification