Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2001-08-17
2004-01-06
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
active
06675030
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of near infrared spectrometry for predicting patient blood glucose levels.
BACKGROUND OF THE INVENTION
There are roughly four million people in the United States currently diagnosed with Diabetes Mellitus. This disease causes blindness, loss of extremities, heart failure, and other complications over time. There is no “cure” for the disease, which is caused by either the failure of the pancreas to produce insulin or the body's inability to use insulin, but rather only treatment, most commonly with insulin injections in order to change the blood-glucose level.
The majority of patients with Type I diabetes, as well as people with Type II diabetes or diagnosed as pre-diabetic, need to frequently monitor their blood glucose levels, establishing an individual blood glucose profile in order to adjust diet, medication, exercise, or to lower the blood glucose while avoiding hypoglycemia (low blood-sugar). In well-regulated patients, two or three blood samples are tested for glucose daily and are usually sufficient. In new or difficult patients, or when monitoring for hypoglycemia is required, blood samples may be required in rapid (every few minutes) succession.
Tests for blood glucose levels consist of obtaining blood by venipuncture or pricking an extremity (usually a finger) to draw a drop of blood. This blood sample is inserted into an analytical device (e.g., Accu-Check®, Hemo-Cue®, Diasensor 1000®, Coming Express 550®, Roche Cobas Mira®, or Ektachem (R)DT60II Analyzer®). The device may be an electrochemical detector that monitors reaction of glucose oxidase with glucose in the blood. The current or voltage is measured, and resulting data is displayed as a concentration, typically milligrams per deciliter (mg/dL). Another means of measuring glucose is by measuring the absorbance of the reaction at 540 nm. It is often difficult, particularly in elderly or infant patients, to perform the necessary measurement, particularly when needed several times a day.
As a result, a need has developed for non-invasive techniques useable in predicting the concentration of blood glucose in the bloodstream of a patient. In this regard, a significant number of researchers have attempted over the past few decades to develop non-invasive glucose monitors using near-infrared (NIR) spectrometers.
Infrared spectrometry is a technique that is based upon the vibrational changes of the atoms of a molecule. In accordance with infrared spectrometry, an infrared spectrum is generated by transmitting infrared radiation through a sample of an organic substance and determining the portions of the incident radiation that are absorbed by the sample. An infrared spectrum is a plot of absorbance (or transmittance) against wavenumber, wavelength or frequency. Infrared radiation is radiation having a wavelength between about 750 nm and about 1000 &mgr;m. Near-infrared radiation is radiation having a wavelength between about 750 nm and about 2500 nm.
A variety of different types of spectrometers are known in the art such as grating spectrometers, FT (Fourier transformation) spectrometers, Hadamard transformation spectrometers, AOTF (Acousto Optical Tunable Filter) spectrometers, diode array spectrometers, filter-type spectrometers, scanning dispersive spectrometers and nondispersive spectrometers.
Filter-type spectrometers, for example, utilize an inert solid heated to provide continuous radiation (e.g., tungsten filament lamp) to illuminate a rotating opaque disk, wherein the disk includes a number of narrow bandpass optical filters. The disk is then rotated so that each of the narrow bandpass filters passes between the light source and the sample. An encoder indicates which optical filter is presently under the light source. The filters filter light from the light source so that only a narrow selected wavelength range passes through the filter to the sample. Optical detectors are positioned so to as detect light that either is reflected by the sample (to obtain a reflectance spectra) or is transmitted through the sample (to generate a transmittance spectra). The amount of detected light is then measured and provides an indication of the amount of absorbance of the light by the substance under analysis.
Diode Array spectrometers use infrared emitting diodes (IREDs) as sources of near-infrared radiation. A plurality of (for example, eight) IREDs are arranged over a sample work surface to be illuminated for quantitative analysis. Near-infrared radiation emitted from each IRED impinges upon an accompanying optical filter. Each optical filter is a narrow bandpass filter that passes NIR radiation at a different wavelength. NIR radiation passing through the sample is detected by a detector (such as a silicon photodetector). The amount of detected light is then measured and provides an indication of the amount of absorbance of the light by the substance under analysis.
Acousto Optical Tunable Filter spectrometers utilize an RF signal to generate acoustic waves in a TeO
2
crystal. A light source transmits a beam of light through the crystal, and the interaction between the crystal and the RF signal splits the beam of light into three beams: a center beam of unaltered white light and two beams of monochromatic and orthogonally polarized light. A sample is placed in the path of one of the monochromatic beam detectors, which are positioned to detect light that either is reflected by the sample (to obtain a reflectance spectra) or is transmitted through the sample (to generate a transmittance spectra). The wavelength of the light source is incremented across a wavelength band of interest by varying the RF frequency. The amount of detected light is then measured and provides an indication of the amount of absorbance of the light by the substance under analysis.
In grating monochromator spectrometers, a light source transmits a beam of light through an entrance slit and onto a diffraction grating (the dispersive element) to disperse the light beam into a plurality of beams of different wavelengths (i.e., a dispersed spectrum). The dispersed light is then reflected back through an exit slit onto a detector. By selectively altering the path of the dispersed spectrum relative to the exit slit, the wavelength of the light directed to the detector can be varied. The amount of detected light is then measured and provides an indication of the amount of absorbance of the light by the substance under analysis. The width of the entrance and exit slits can be varied to compensate for any variation of the source energy with wavenumber.
A nondispersive infrared filter photometer is designed for quantitative analysis of various organic substances. The wavelength selector comprises: a filter as previously described to control wavelength selection; a source; and a detector. The instrument is programmed to determine the absorbance of a multicomponent sample at wavelengths and then to compute the concentration of each component.
As stated above, spectrometers have been used to measure the chemical composition of blood and, more particularly, blood glucose. The mean blood glucose level varies within a normal range of 70-120 mg/dL from person to person. For diabetics, these fluctuations can vary markedly, reaching values of 200-400 mg/dL within a very short time in accordance with their food intake, physical activity, a complication by another disease, or the like. The majority of patients with Type I diabetes, as well as people with Type II diabetes or diagnosed as pre-diabetic, need to frequently monitor their blood glucose levels, establishing an individual blood glucose profile in order to adjust diet, medication or exercise, or in order to lower the blood glucose while avoiding hypoglycemia (low blood-sugar). In well-regulated patients, two or three blood samples are tested for glucose daily and are usually sufficient. In new or difficult patients, or when monitoring for hypoglycemia is required, blood samples may be required in rapid (every few minutes) succession.
The majo
Bynum Kevin P.
Ciurczak Emil W.
Mark Howard
Davidson Davidson & Kappel LLC
Euro-Celtique S.A.
Hindenburg Max F.
McCrosky David J.
LandOfFree
Near infrared blood glucose monitoring system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Near infrared blood glucose monitoring system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Near infrared blood glucose monitoring system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3185600