Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
1999-08-03
2003-09-02
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S316000, C600S331000
Reexamination Certificate
active
06615061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to devices and methods for the determination of the concentration of an analyte in a human tissue. More specifically, this invention relates to devices and methods for the non-invasive determination of the concentration of one or more analytes in vivo in a human tissue, wherein an optical property at a given depth in the tissue is significantly affected by a given analyte.
2. Discussion of the Art
Non-invasive monitoring of analytes in the human body by optical devices and methods is an important tool for clinical diagnosis. “Non-invasive” (alternatively referred to herein as “NI”) monitoring techniques measure in vivo concentrations of analytes in the blood without taking out a blood sample from the human body. As defined herein, a “non-invasive” technique is one that can be used without removing a sample from, or without inserting any instrumentation into, the human body. The ability to determine an analyte, or a disease state, in a human subject without performing an invasive procedure, such as removing a sample of blood or a biopsy specimen, has several advantages. These advantages include ease in performing the test, reduced pain and discomfort to the patient, and decreased exposure to potential biohazards. These advantages will promote increased frequency of testing, accurate monitoring and control of a disease condition, and improved patient care. Representative examples of non-invasive monitoring techniques include pulse oximetry for oxygen saturation (U.S. Pat. Nos. 3,638,640; 4,223,680; 5,007,423; 5,277,181; 5,297,548). Another example is the use of laser Doppler flowmetry for diagnosis of circulation disorders (Tooke et al, “Skin microvascular blood flow control in long duration diabetics with and without complication”, Diabetes Research, Vol. 5, 1987, pages 189-192). Other examples of NI techniques include determination of tissue oxygenation (WO 92/20273), determination of hemoglobin (U.S. Pat. No. 5,720,284), and hematocrit (U.S. Pat. Nos. 5,553,615; 5,372,136; 5,499,627; WO 93/13706). Determination of bilirubin was also described in the art (R. E. Schumacher, “Noninvasive measurement of bilirubin in the newborn”, Clinics in Perinatology, Volume 17, 1990, pages 417-435, and U.S. Pat. No. 5,353,790).
Measurements in the near-infrared region of the electromagnetic spectrum have been proposed, or used, in the prior art. The 600 nm to 1300 nm region of the electromagnetic spectrum represents a window between the visible hemoglobin and melanin absorption bands and the strong infrared water absorption bands. Light having a wavelength of 600 nm to 1300 nm can penetrate sufficiently deep into the skin to allow use thereof in a spectral measurement or a therapeutic procedure.
Oximetry measurement is very important for critical patient care, especially after the use of anesthesia. Oxygenation measurements of tissue are also important diagnostic tools for measuring oxygen content of the brain of the newborn during and after delivery, for monitoring tissue healing, and in sports medicine.
Non-invasive determination of hemoglobin and hematocrit values in blood would offer a simple, non-biohazardous, painless procedure for use in blood donation centers. Such techniques could increase the number of donations by offering an alternative to an invasive procedure, which is inaccurate and may possibly lead to the rejection of a number of qualified donors. Non-invasive determination of hemoglobin and hematocrit values would be useful for the diagnosis of anemia in infants and mothers, without the pain associated with blood sampling. Non-invasive determination of hemoglobin has been considered as a method for localizing tumors and diagnosis of hematoma and internal bleeding (S. Gopinath, et al., “Near-infrared spectroscopic localization of intracamerial hematomas”, J. Neurosurgery, Vol. 79, 1993, pages 43-47). Non-invasive determination of hematocrit values can yield important diagnostic information on patients with kidney failure before and during dialysis (R. R. Steuer, et al., “A new optical technique for monitoring hematocrit and circulating blood volume; Its application in renal dialysis”, Dialysis and Transplantation, Volume 22, 1993, pages 260-265). There are more than 50 million dialysis procedures performed in the United States and close to 80 million dialysis procedures performed world-wide annually.
Non-invasive diagnosis and monitoring of diabetes may be the most important potential advantage for non-invasive diagnostics. Diabetes mellitus is a chronic disorder of carbohydrate, fat, and protein metabolism characterized by an absolute or relative insulin deficiency, hyperglycemia, and glycosuria. At least two major variants of the disease have been identified. “Type I” accounts for about 10% of diabetics and is characterized by a severe insulin deficiency resulting from a loss of insulin-secreting beta cells in the pancreas. The remainder of diabetic patients suffer from “Type II”, which is characterized by an impaired insulin response in the peripheral tissues (Robbins, S. L. et al.,
Pathologic Basis of Disease,
3rd Edition, W. B. Saunders Company, Philadelphia, 1984, p. 972). If uncontrolled, diabetes can result in a variety of adverse clinical manifestations, including retinopathy, atherosclerosis, microangiopathy, nephropathy, and neuropathy. In its advanced stages, diabetes can cause blindness, coma, and ultimately death.
The concept upon which most NI detection procedures are based involves irradiating a tissue or a vascular region of the body with electromagnetic radiation and measuring the spectral information that results from at least one of three primary processes: absorption, scattering, and emission. The extent to which each of these processes occurs is dependent upon a variety of factors, including the wavelength of the incident radiation and the concentration of analytes in the body part. Signals are measured as a change in reflectance or transmittance of the body part. Concentration of an analyte, e.g., glucose, hemoglobin or bilirubin is determined from the spectral information by comparing the measured spectra to a calibration data set. Alternatively the concentration of an analyte is determined by comparing the magnitude of the change in signal to the results of calculations based on a physical model describing the optical properties of the tissue under examination. Various categories of non-invasive measurement techniques will now be described.
NI techniques that utilize the interaction of a sample with infrared radiation can be categorized according to three distinct wavelength regions of the electromagnetic spectrum: near-infrared (NIR), mid-infrared (MIR) and far-infrared (FIR). As defined herein, NIR involves the wavelength range from about 600 nm to about 1300 nm, MIR involves the wavelength range from about 1300 nm to about 3000 nm, and FIR involves the wavelength range from about 3000 nm to about 25000 nm. As defined herein, “infrared” (or IR) is taken to mean a range of wavelengths from about 600 nm to about 25000 nm.
Due to the highly scattering and absorption nature of the human skin and tissue, light in the 600 nm to 1300 nm spectral range penetrates the skin and underlying tissues to different depths. The tissue depth at which most of the reflectance signal is generated (sampling depth) depends on the wavelength of light and positioning of the source and detector. Analyzing the reflected or transmitted signal without accounting for the effect of different layers of skin can lead to erroneous estimates of the optical properties of the tissue and hence, the concentration of metabolites determined from these measured properties. The stratum corneum, epidermis, dermis, adipose tissue, and muscle layers can interact with light differently and contribute separately to the measured signals. Controlling the sampling depth of the light and understanding the effect of the different layers of the skin on the generated signal are important for the accurate non-invasive determi
Hanna Charles F.
Jeng Tzyy-Wen
Kantor Stanislaw
Khalil Omar S.
Wu Xiaomao
Abbott Laboratories
Weinstein David L.
Winakur Eric F.
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