Method and apparatus for control of skin perfusion for indirect glucose measurement

Abstract

A method and apparatus for noninvasive glucose measurement measures glucose indirectly from the natural response of tissue to variations in analyte concentration. The indirect measurement method utilizes factors affected by or correlated with the concentration of glucose, such as refractive index, electrolyte distribution or tissue scattering. Measurement reliability is greatly improved by stabilizing optical properties of the tissue at the measurement site, thus blood perfusion rates at the sample site are regulated. Perfusion is monitored and stabilized by spectroscopically measuring a control parameter, such as skin temperature, that directly affects perfusion. The control parameter is maintained in a range about a set point, thus stabilizing perfusion. Skin temperature is controlled using a variety of means, including the use of active heating and cooling elements, passive devices, such as thermal wraps, and through the use of a heated coupling medium having favorable heat transfer properties.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 363,345, filed Mar. 8, 2002; and is a Continuation-in-part of U.S. patent application Ser. No. 09 / 955,531, filed Sep. 17, 2001, which claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 235,369, filed Sep. 26, 2000.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates generally to the field of noninvasive glucose measurement. More particularly, the invention relates to control of optical properties of the sampling site to improve reliability of a noninvasive glucose measurement. [0004] 2. Background Information [0005] Diabetes is a chronic disease involving the improper production and utilization of insulin, a hormone that facilitates glucose uptake into cells. While a precise cause of diabetes is unknown, both genetic and environmental factors such as obesity and lack of exercise appear to play roles. Pe...

AI Technical Summary

Benefits of technology

[0034] The invention provides methods and a system for non-invasively measuring key constituents and properties of tissue. A target analyte is measured indirectly based on the natural response of tissue to variations in analyte concentration. The indirect method of measuring utilizes factors that are effected by or correlated with the concentration of glucose, such as the index of refraction, electrolyte distribution or reduced scattering coefficient of the bulk tissue. An indirect measurement means that an ancillary effect due to changes in glucose concentration is being measured.

[0035] The reliability of the measurement is greatly improved by stabilizing the optical properties of the tissue at the measurement site, thus means are provided for regulating blood perfusion rates at the sample site. In one embodiment, perfusion is monitored and stabilized by spectroscopically measuring a control parameter, such as skin temperature, that directly affects perfusion. The control parameter is maintained in a range about a set point, thus stabilizing perfusion. Skin temperature is controlled using a variety of means, including the use of active heating and cooling elements, passive devices, such as thermal wraps, and through the use of a heated coupling medium having favorable heat transfer properties.

Problems solved by technology

There are a number of issues related to obtaining representative samples in analytical technologies.

Furthermore, temperature effects the localized perfusion of the tissue.

First, vasodilatation of the surface capillaries affects the amount of blood present near the skin surface.

While tissue perfusion can be increased to maximal levels though application of thermal energy, it has the additional undesirable effect of destabilizing optical properties of the tissue sample.

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