초록 ▼

The absence of a defined optical pathlength for in vivo measurements creates problems for the noninvasive measurement of analyte concentration. These problems can be reduced by combining measurements made at several wavelengths and using the fact that normal renal function causes the concentration o

The absence of a defined optical pathlength for in vivo measurements creates problems for the noninvasive measurement of analyte concentration. These problems can be reduced by combining measurements made at several wavelengths and using the fact that normal renal function causes the concentration of water in whole blood to be tightly controlled. Hence, the concentration of water in arterial blood can serve as a useful internal standard for such measurements. The measurements are then procured so as to remove the dependency of concentration on path length traversed by the illuminating radiation and on the scattering properties of the volume through which the illuminating radiation propagates. Using this method, one can create improved calibration for measurements of absorbing constituents in arterial blood and thereby provide absolute concentration measurements of constituents such as hemoglobin and glucose in arterial blood.

대표청구항 ▼

1. A method of improving accuracy in non-invasive, in vivo concentration measurements of a substance of interest in blood comprising the steps of:providing an illumination source which is adapted to generate illumination radiation to a measurement site, said illumination source providing illuminatio

1. A method of improving accuracy in non-invasive, in vivo concentration measurements of a substance of interest in blood comprising the steps of:providing an illumination source which is adapted to generate illumination radiation to a measurement site, said illumination source providing illumination radiation across a portion of the spectrum which contains absorbance bands of said substance of interest; illuminating said measurement site with said illumination radiation; detecting radiation transmitted, transflected, or reflected from said measurement site with a detector array, said detector array having a plurality of detectors each having broadband spectral response characteristics with broadband spectral response characteristics with distinct maximum spectral response characteristics within different regions of said portion of the spectrum used for illuminating; each of said detectors in said detector array being selected and located such that said detector collects radiation only from a limited solid angle, said detector array providing an output signal indicative of the amount of radiation it receives in a selected time period; determining a differential value of said output signals for periods of arterial pulsations of the blood in said measurement site, said differential values being a comparison of values obtained during a systolic portion of said pulsations and values obtained during a diastolic portion of said pulsations; and generating a response which comprises a comparison of said differential value of said output signals to a simultaneous water-specific measurement, said water specific measurement being related to the amount of water in said blood during the measurement cycle, said water specific measurement being generated using at least a portion of said detector array; whereby said response provides a means for improving the accuracy of said concentration measurements.