Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2000-09-15
2003-06-10
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S322000, C250S339030, C250S339070, C250S341600
Reexamination Certificate
active
06577885
ABSTRACT:
FIELD OF INVENTION
This invention relates to methods of determining the presence and concentration of analytes in a test sample. More specifically, the present invention relates to methods for non-invasively determining the analyte concentrations in human or animal subjects. Most specifically, the present invention relates to a non-invasive methods for the determination of blood glucose concentration in a human patient.
BACKGROUND OF THE INVENTION
The analysis of samples and the determination of the presence or concentration of chemical species contained therein is a common and important process in chemistry and biology. Particularly important is the analysis of biological fluids, such as blood, urine, or saliva, to determine the concentration of various constituents. Also of great importance is the measurement of the concentration of various chemical constituents embedded within biological materials, such as tissue. Chemical analysis of blood, urine, and other biological fluids is crucial to the diagnosis, management, treatment, and care of a wide variety of diseases and medical conditions. In the case of diabetes, monitoring of blood glucose levels several times a day is necessary to the efficient management of this disease in many patients. Analysis of various blood components is of importance in both the diagnosis and treatment of diseases of the circulatory system. For example, the level of various types of cholesterol in the blood has a strong correlation with the onset of heart disease. Urine analysis provides valuable information relating to kidney function and kidney disease. The concentration of alcohol in the blood is known to be related to a subject's physical response time and coordination and can provide information related to, for example, the individual's fitness to drive a motor vehicle.
Additionally, there are many instances where it is desirable to measure the local concentration of chemical constituents in tissue, either in-vivo or in-vitro. For example, in stroke victims it is important to monitor the degree of brain edema or the concentration of various metabolic chemical constituents in the brain that serve as indicators of brain function. Such indicators include fatty acid compounds, water, blood, lactates, and certain proteins and lipids. Other specific examples may include the monitoring of tissue oxygenation or tissue blood perfusion as a means to of gauging the metabolic function of a human or animal subject.
Moreover, in many applications, a “real-time” measurement of chemical concentration in biological fluids is important. Current invasive methods require that a sample of fluid be removed from a subject and then analyzed in one or more chemical tests. The tests can be expensive and require skilled technicians to remove and analyze the samples. Furthermore, the analysis of samples may have an undesirably long turn-around time. Additionally, the tests are usually made in centralized clinical laboratories with a resulting complexity of sample tracking and quality control. These circumstances create additional problems related to the potential change in the chemical composition of the fluid between extraction and analysis and, even more detrimentally, the possibility of a sample being confused with the samples of other patients.
It is also advantageous to analyze the chemical nature of sample materials without physically extracting a sample from the subject. For example, it is advantageous to examine the chemical makeup of human blood without taking a blood sample. In addition to time and cost considerations such invasive testing causes skin trauma, pain, and generates blood waste.
For all of the foregoing reasons methods of “non-invasive” testing have long been considered an attractive alternative to invasive testing. However, prior non-invasive testing methods have suffered from a number of practical drawbacks. The present invention is a method of analytical and quantitative testing for the presence of chemical species in a test sample. The method is non-invasive and has wide utility, being easily applicable to the noninvasive measurement of humans, animals, plants, or even packaged materials. Being highly versatile the method is broadly applicable to both in-vivo and in-vitro samples.
1. Brief Description of Related Art
The concept of non-invasive testing is not unknown in the art. What has been elusive is the ability of quickly, easily, cheaply and accurately conducting measurements.
Certain infrared (IR) detection techniques are known and have been used to detect the presence of chemical constituents in the blood. Specific examples include the IR detection of oxygen saturation, nitrous oxide concentration, carbon dioxide concentration, or measurement of oxidative metabolism, and blood glucose levels. The goal of these inventions is the determination of human blood chemistry. A typical present technology projects light into the body while measuring the light after it passes through the body. Comparing the input beam with an exit beam allows a rough determination of blood chemistry. Unfortunately, these techniques suffer from a number of inadequacies, most especially, tissue interference, lack of specificity, and limited accuracy. A number of prior art patents describing such techniques are set forth below.
Kaiser describes, in Swiss Patent No. 612,271, a technique for using an IR laser as a radiation source to measure glucose concentrations in a measuring cell. This technique uses venous blood passed through extra-corporeal cuvettes at high blood flow rates. This has the undesirable effect of heating the blood and requiring that the blood be removed from the patient's body. Kaiser does not describe a non-invasive technique for measuring glucose concentration.
March, in U.S. Pat. No. 3,958,560, describes a “noninvasive” automatic glucose sensor system which projects polarized IR light into the cornea of the eye. A sensor detects the rotation of this polarized IR light as it passes between the eyelid and the cornea. The rotation of polarized light is correlated to glucose concentration. Although this technique does not require the withdrawal of blood, and is thus, “noninvasive”, the device may cause considerable discomfort to the patient due to the need to place it on the patient's eye. Furthermore, March does not use an induced temperature gradient or absorbance spectroscopy as does the present invention. As a result, the present invention involves no physical discomfort and is more accurate.
Hutchinson, in U.S. Pat. No. 5,009,230, describes a glucose monitor which uses polarized IR light to non-invasively detect glucose concentration in a person's blood stream. The method requires an external IR source, which is passed through a portion of the human body. However, the accuracy of measurement is limited by the wavelengths of the polarized light beam (940-1000 nm) being used. Unlike the present invention, Hutchinson relies on detected changes in the polarization of the incident light beam. Furthermore, Hutchinson does not use an induced temperature gradient as does the present invention.
Similar limitations are found in Dahne, et al., in U.S. Pat. No. 4,655,225, which describes a similar spectrophotometric technique. Dahne uses a directional external IR radiation source to emit a beam. Reflected and transmitted light from the beam is used to determine the glucose concentration. Dahne differs from other techniques in using radiation at wavelengths between 1000-2500 nm. Unlike Dahne, the present invention is not confirmed to using wavelengths between 1000-2500 nm. Dahne also does not use an induced temperature gradient as does the present invention.
Mendelson, et al., in U.S. Pat. No. 5,137,023, uses a different concept known as pulsatile photoplethysmography to detect blood analyte concentration. The instrument of Mendelson is based on the principles of light transmission and reflection photoplethysmography, whereby analyte measurements are made by analyzing either the differences or ratios between two different IR radiatio
Barnes Casper W.
Braig James R.
Goldberger Daniel S.
King Richard A.
Kramer Charles E.
Knobbe Martens Olson & Bear LLP
OptiScan Biomedical Corporation
Winakur Eric F.
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