Surgery – Truss – Pad
Patent
1995-04-10
1996-07-09
Sykes, Angela D.
Surgery
Truss
Pad
128665, 356 41, A61B 500
Patent
active
055335098
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for non-invasively measuring a blood sugar level on an in vivo and in situ basis using spectroscopic techniques. More specifically, the invention relates to a method and apparatus for non-invasively measuring the concentration of glucose in the blood stream or tissue of a patient suspected of suffering from diabetes based on a combination of wavelength modulation and intensity modulation of light.
2. Description of the Related Art
Various methods and apparatus for measuring the concentration of glucose in vitro and in vivo using spectroscopic techniques have been proposed.
For example, International application No. WO 81/00,622 discloses a method and apparatus for measuring the absorption of infrared light by glucose in body fluid using CO.sub.2 laser light as an irradiation light source. The method and apparatus measure the absorption spectra of serum and urine by transmittance and reflectance, i.e.--back scattering effects, at different wavelengths .lambda..sub.1 and .lambda..sub.2. Here, .lambda..sub.2 is a characteristic absorption wavelength of the substance to be measured, e.g. glucose, and .lambda..sub.1 is a wavelength at which absorption is independent of the concentration of the substance to be measured. The measurements are obtained by calculating the ratio of the absorbance at .lambda..sub.1 to the absorbance at .lambda..sub.2. The absorption band of the substance to be measured is between 940 cm.sup.-1 : and 950 cm.sup.-1 ; ie. between 10.64 and 10.54 .mu.m for wavelength .lambda..sub.1, and the absorption band is between 1090 cm.sup.-1 ; and 1095 cm.sup.-1 ; i.e.--between 9.17 .mu.m and 9.13 .mu.m for wavelength .lambda..sub.2.
U.S. Pat. No. 4,169,676 discloses an non-invasive examining method for detecting biological substances through skin using an attenuated-total-reflectance (ATR) prism. The method attaches the wave guide (ATR prism) directly to the surface of a sample under examination (e.g. a lip or tongue) and guides in infrared light. The refractive index of the wave guide is greater than that of the sample medium, ie. an optically thin layer of the surface, and the infrared light is made to pass through the prism along the total-reflection path. The infrared light interacts with the thin layer of the surface, and the interaction is related to the frustrated attenuation component of the light at the reflecting part (see Hormone & Metabolic Res. Suppl. Ser. (1979) pp. 30- 35). If infrared light of a wavelength related to the absorption of glucose is used, then the light passing through the prism is attenuated depending on the concentration of glucose in the optically thin layer of the surface. Therefore, the attenuated quantity is detected and processed into data on the glucose concentration.
U.S. Pat. No. 3,958,560 discloses a non-invasive detection apparatus that detects glucose in a patient's eye. Specifically, the apparatus of this U.S. patent is a sensor apparatus in shape of a contact lens comprising a light source that applies infrared light to one side of cornea and a detector that detects the transmitted light on the opposite side. When infrared light is applied to a measured location, the infrared light passes through the cornea and the aqueous humor and reaches the detector. The detector converts the quantity of transmitted light into an electric signal and provides it to a remote receiver. Then the reader of the receiver outputs the concentration of glucose in the patient's eye as a function of the individual change of quantity in the applied infrared light passing through the eye.
British Pat. application No. 2,035,557 discloses a detecting apparatus for assessing substances near the blood stream of a patient such as CO.sub.2, oxygen, or glucose. The detecting apparatus comprises an optical source and an optical receiving means that detects attenuated light back-scattered or reflected from inside a patient's body, i.e.--from the hypoderma, and uses ultraviolet or
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Koashi Katsue
Minami Shigeo
Kurashiki Boseki Kabushiki Kaisha
Nasser Jr. Robert L.
Sykes Angela D.
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