Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
2001-12-21
2003-10-07
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
Reexamination Certificate
active
06630673
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to devices and methods for measuring optical parameters of a sample, e.g., a sample of tissue in a human body. More specifically, this invention relates to devices and methods for the non-invasive determination of one or more optical parameters in vivo in tissues comprising a plurality of layers.
2. Discussion of the Art
Non-invasive monitoring of metabolites by optical devices and methods is an important tool for clinical diagnostics. 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 result in increased frequency of testing when necessary, accurate monitoring and control, 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 (Toke 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 techniques include determination of tissue oxygenation (WO 92/20273), determination of hemoglobin (U.S. Pat. No. 5,720,284) and of hematocrit (U.S. Pat. Nos. 5,553,615; 5,372,136; 5,499,627; WO 93/13706).
Measurements in the near-infrared region of the electromagnetic spectrum have been proposed, or used, in prior art technologies. 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 deep enough 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, thereby increasing the number of donations by offering an alternative to the invasive procedure, which is inaccurate and could 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. Non-invasive determination of hematocrit values can yield important diagnostic information on patients with kidney failure before and during dialysis. There are more than 50 million dialysis procedures performed in the United States and close to 80 million dialysis procedures performed worldwide per year.
The most important potential advantage for non-invasive diagnostics possibly will be for non-invasive diagnosis and monitoring of diabetes. 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 (S. L. 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 principal treatment for Type I diabetes involves periodic injection of insulin. Appropriate insulin administration can prevent, and even reverse, some of the adverse clinical manifestations of Type I diabetes. Frequent adjustments of the level of glucose in blood can be achieved either by discrete injections of insulin or, in severe cases, by an implanted insulin pump or artificial pancreas. The amount and frequency of insulin administration is determined by frequent or, preferably, continuous testing of the level of glucose in blood (i. e., blood glucose level).
Precise control of blood glucose level in the “normal range”, 60 mg/dL to 120 mg/dL, is necessary for Type I and Type II diabetics to avoid or reduce complications resulting from hypoglycemia and hyperglycemia. To achieve this level of control, the American Diabetes Association recommends that diabetics test their blood glucose level five times per day when the control of blood glucose level is necessary. Thus, there is a need for accurate and frequent or, preferably, frequent glucose monitoring to combat the effects of diabetes.
Conventional measurements of blood glucose level in a hospital or a physician's office rely on the withdrawal of a 5 mL to 10 mL blood sample from the patient for analysis. This method is slow and painful and cannot be used for frequent glucose monitoring. An additional problem for hospitals and physicians' offices is the disposal of testing media that are contaminated by blood.
Portable personal glucose meters are the most popular devices for monitoring blood glucose levels. Typically, a drop of blood is obtained by sticking a patient's finger with a sharp object, and the blood obtained is analyzed by means of chemical reactions on a strip. These reactions provide an optical or electrochemical signal. This type of device provides a convenient way to monitor blood glucose level. However, the pain associated with collecting samples of blood, the potential contamination at the puncturing site, the disposal of biohazardous testing materials, the cumbersome procedures, and the chance of making mistakes often prevent patients from using the meters as frequently as recommended by physicians.
Implantable biosensors have also been proposed for glucose measurement. (G. S. Wilson, et al., “Progress toward the development of an implantable sensor for glucose”, Clin. Chem., Vol. 38 (1992), pages 1613-1617). These biosensors are electrochemical devices having enzymes immobilized at the surface of an electrochemical transducer. They are usually implanted into a patient's tissue by means of a surgical procedure.
All of the foregoing categories of glucose monitoring techniques have one feature in common: they all involve a procedure whereby the skin of a human body part is disrupted by means of a mechanical device. These techniques are referred to as invasive techniques.
“Non-invasive” (alternatively referred to herein as “NI”) glucose-monitoring techniques measure in vivo glucose concentrations without collecting a blood sample. 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 tissues. The concept upon which most such technologies are based involves irradiating a vascular region of the body with electromagnetic radiation and measuring the spectral information that results from at least one of four primary processes: reflection, absorption, scattering, and emission. The extent to which each of these processes occurs is dependent upon a variety of factors, including th
Bolt Rene' Alexander
de Mul Frits Frans Maria
Hanna Charles F.
Kanger Johannes Sake
Khalil Omar S.
Abbott Laboratories
Hannaher Constantine
Weinstein David L.
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