Abstract: Disclosed are methods of determining long-term deposition pattern of a compound in tissue. The following steps can be followed: placing tissue against a receptor; directing mid-infrared electromagnetic radiation onto the tissue; quantifying the electromagnetic radiation that is reflected from the tissue to obtain a reflected amount; using a calibration equation to calculate the concentration of a compound from the reflected amount; and using the concentration of the compound to evaluate presence of a clinical condition in the tissue.

Abstract: An analyte detection system is configured to measure concentrations of at least first and second analytes in a single material sample supported by a sample element. The measurement of a second analyte can be conditioned on a quantitative or qualitative result of the first measurement. In one embodiment, the first analyte is glucose and the second analyte is a ketone. According to such an embodiment the ketone is measured if the result of the glucose measurement exceeds a previously-specified value or falls outside of a previously-specified range.

Abstract: A method determines an analyte concentration in a sample. The sample includes the analyte and a substance. The method includes providing absorption data of the sample. The method further includes providing reference absorption data of the substance. The method further includes calculating a substance contribution of the absorption data. The method further includes subtracting the substance contribution from the absorption data, thereby providing corrected absorption data substantially free of a contribution from the substance.

Abstract: A method for determining a physiologic characteristic associated with cardiac function in a subject comprising the steps of providing at least one electromagnetic radiation absorption measurement, providing demographic information reflecting the subject's physical condition, determining a temporal plethysmographic value from the electromagnetic radiation absorption measurement, and determining at least one physiologic characteristic from the temporal plethysmographic value and demographic information by using a predetermined phenomenological model that is adapted to provide an estimate of a blood volume-time relationship proximate the heart and compute at least one physiologic characteristic associated with cardiac function based on the estimated blood volume-time relationship.

Abstract: A method and apparatus are described that permit an analyte concentration to be estimated from a measurement in the presence of compounds that interfere with the measurement. The method reduces the error in the analyte concentration in the presence of interferents. The method includes the use of a set of measurements obtained for a large population having a range of known analyte and interfering compound concentrations. From a sample measurement, which may or may not be one of the population, likely present interferents are identified, and a calibration vector is calculated.

Abstract: A method determines an analyte concentration in a sample. The sample includes the analyte and a substance. The method includes providing absorption data of the sample. The method further includes providing reference absorption data of the substance. The method further includes calculating a substance contribution of the absorption data. The method further includes subtracting the substance contribution from the absorption data, thereby providing corrected absorption data substantially free of a contribution from the substance.

Abstract: The invention comprises a method and apparatus for processing signals reflecting a physiological characteristic by detecting the intensity of light following tissue absorption at two wavelengths and subtracting the best estimate of the desired signal from the difference between the signals. Corrected first and second intensity signals are determined by applying a residual derived from a combination of the first and second intensity signals as multiplied by a residual factor and subtracted from a difference between the first and second intensity signals to the first and second intensity signals. In one embodiment, the method and apparatus are used to determine arterial oxygen saturation.

Abstract: The invention is method and apparatus for determining a physiological characteristic by detecting the intensity of light following tissue absorption at two wavelengths, estimating the pulse amplitude and indexing a calculated physiological characteristic to the estimated pulse amplitude. In one embodiment, the ratio of logarithms of absorbance signal amplitude is indexed to the pulse amplitude to improve the accuracy of arterial oxygen saturation as determined by a pulse oximeter.

Abstract: A method determines an analyte concentration in a sample including the analyte and a substance. The method includes providing an absorption spectrum of the sample. The absorption spectrum has an absorption baseline. The method further includes shifting the absorption spectrum so that the absorption baseline approximately equals a selected absorption value in a selected absorption wavelength range. The method further includes subtracting a substance contribution from the absorption spectrum. Thus, the method provides a corrected absorption spectrum substantially free of a contribution from the substance.

Abstract: A reagentless whole-blood analyte detection system that is capable of being deployed near a patient has a source capable of emitting a beam of radiation that includes a spectral band. The whole-blood system also has a detector in an optical path of the beam. The whole-blood system also has a housing that is configured to house the source and the detector. The whole-blood system also has a sample element that is situated in the optical path of the beam. The sample element has a sample cell and a sample cell wall that does not eliminate transmittance of the beam of radiation in the spectral band.

Abstract: A method uses spectroscopy to determine an analyte concentration in a sample. The method includes producing an absorbance spectrum of the sample. The method further includes shifting the absorbance spectrum to zero in a wavelength region. The method further includes subtracting a water or other substance contribution from the absorbance spectrum.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A reagentless whole-blood analyte detection system that is capable of being deployed near a patient has a source capable of emitting a beam of radiation that includes a spectral band. The whole-blood system also has a detector in an optical path of the beam. The whole-blood system also has a housing that is configured to house the source and the detector. The whole-blood system also has a sample element that is situated in the optical path of the beam. The sample element has a sample cell and a sample cell wall that does not eliminate transmittance of the beam of radiation in the spectral band.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: A method determines an analyte concentration in a sample including the analyte and a substance. The method includes providing an absorption spectrum of the sample. The absorption spectrum has an absorption baseline. The method further includes shifting the absorption spectrum so that the absorption baseline approximately equals a selected absorption value in a selected absorption wavelength range. The method further includes subtracting a substance contribution from the absorption spectrum. Thus, the method provides a corrected absorption spectrum substantially free of a contribution from the substance.

Abstract: A method calibrates a monitor that comprises a non-invasive blood constituent monitor and a traditional measurement system. The non-invasive blood constituent monitor includes a thermal gradient inducing element an analyzer window. A traditional monitor output representing a property of a blood constituent is generated by the traditional measurement system. A non-invasive monitor output representing the property of the whole blood constituent is generated by the non-invasive constituent monitor. The traditional monitor output and the non-invasive monitor output are compared to estimate an amount of error. The non-invasive monitor output is corrected by the amount of error.

Abstract: A solid-state device for the non-invasive generation and capture of thermal gradient spectra from sample tissue. The device includes an infrared transmissive layered window assembly, a means for inducing a thermal gradient in sample tissues. Also provided is an infrared radiation detector for detecting infrared emissions emanating from the tissue as the transient temperature gradient progresses into the sample tissues. The sensor provides output signals proportional to the detected infrared emissions. A data capture means is provided for the sampling of output signals received from the infrared radiation detector as the induced temperature gradient progresses into the sample tissue.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: This invention relates to a method and apparatus for in-vivo, real time measurement of pH, pCO2, base excess, hemoglobin, and hemoglobin oxygen saturation. Specifically, the invention relates to an apparatus placed in-line with an existing invasive patient access line to provide continuous, semi-continuous, or non-continuous monitoring of blood pH, pCO2, base excess, hemoglobin, and hemoglobin oxygen saturation in a manner which is relatively non-invasive. Further, the device and apparatus allows monitoring of the listed parameters in a non-destructive manner such that the blood sample under analysis can be returned to the patient.