Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2002-06-03
2004-05-25
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S322000, C356S328000, C250S339050, C250S339070, C250S341800
Reexamination Certificate
active
06741875
ABSTRACT:
FIELD OF INVENTION
This invention relates to a device and method for determining and monitoring concentration levels of one or more constituents within a varying in time, complex multi component structure, (for example blood constituents in blood sample, tissue or body parts) or, in particular, blood and tissue constituents in living subjects such as humans or animals.
BACKGROUND OF INVENTION
The application of spectroscopy for chemical analysis is well known. For many years, however, it was mainly used for atomic analysis because sufficiently sensitive detectors did not exist for infrared, where information on vibration states of the molecules (especially those of organic origin) is located. Advances in technology of IR detectors have dramatically changed the situation and presently a large number of detectors, instruments and methods exist for such applications. This has also opened the way for new applications, but has imposed new requirements on the technology. One of the most important applications is a noninvasive analysis of chemical compositions of living subjects.
It is generally appreciated that light in spectral range 500 nm to 770 nm belongs to the visible part of the spectrum but, since it does not cover whole visible range and it is directly adjacent to the infrared part of the spectrum, herein it is referred to as adjacent visible (AV). It is widely accepted that of the infrared part of the electromagnetic spectrum (IR) is divided into the near infrared (NIR), which expands beyond the visible to about 2700 nm, the middle infrared radiation (MIR), which expands beyond the NIR range and a further expanding far infrared range (FIR). There are some photodetectors (mainly silicon) whose sensitivity covers the visible part of spectrum and initial part of NIR. Therefore, part of visible range adjacent to NIR and part of NIR adjacent to visible will be referred here as AV/NIR, while the remaining part of NIR range will be referred to as the “longer wavelength NIR region” or “LWNIR”.
Non-Invasive Techniques
Previous devices for non-invasively monitoring concentration of blood constituents of a patient are known. Usually, a sensor is used to externally measure either the concentration of the constituents in gases emitted by the body or contained in the perspiration, or the concentration of the constituents contained in body fluids such as tears, saliva, or urine. Alternatively, the blood constituents are identified by measurement of attenuation of some radiation passed through a part of a patient's body such as an earlobe, a finger or skin. In majority cases, radiation is measured at one, two or limited number of relatively narrow spectral bands obtained from separate, narrow band light sources (see for example U.S. Pat. No. 4,655,225; U.S. Pat. No. 4,883,953; and U.S. Pat. No. 4,882,492). Some of these devices perform measurements at limited number relatively narrow spectral bands consecutively selected from spectrally broad light by a set of exchangeable narrow-band spectral filters. Analysis of absolute and relative changes in light intensity at these bands under certain conditions may provide important information on body constituents. Exchange of the filters and time required for their stabilization to obtain precise measurement, very often significantly increase duration of the measurement process and as a result, the measurement in different bands are taken with significant time delays. Because of physiological variability of physical state of the alive person, this leads to situation when measurements at different wavelengths are taken under changed physical conditions of the body, making impossible to measure the constituents of the body. Another source of the error in the systems with limited number of discrete spectral bands is wavelength shift of the selected bands from measurement to the measurement and from instrument to the instrument. There are some medical and other applications when these two sources of the error make measurement of constituents impossible. In such a case it becomes important to make the measurement in whole spectrum virtually simultaneously and to preserve as complete as possible information on whole spectrum. This is achieved applying other techniques, which measure either a full spectrum of light interacting with sample, with a large number (for example, 128 or 256) of wavelengths in a specific range and those that measure a limited number of wavelengths. Those that measure full spectra typically use the wavelengths in the AV/NIR range (see for examples U.S. Pat. No. 5,361,758 and U.S. Pat. No. 4,975,581), where arrays of the photodetectors, produced with application of well established silicon technology, have been available for long time for simultaneous registration of the spectra in large number of discrete points. There are several advantages in measurement of whole spectrum. One of them consists in that the spectra provide information about the desired analyte as well as information about interfering substances (e.g., other analytes) and effects (e.g., light scattering). The second advantage is capability to register a complete information on spectrum even if it is shifted due to temperature changes of sample. Finally, the third advantage is that even if the instrument loses wavelength calibration, whole information is still preserved in the spectrum and can be easily extracted once new wavelength calibration data is available. In some cases, however, there is not enough information available in the above range or available information is insufficient for precise measurement of body constituents and additional information outside the above mentioned spectral range (usually at longer wavelengths) is required.
In some cases, the methods that take measurements at limited number of wavelengths only within the 1100 to 1700 nm region can be sufficient, because of the sharper analyte spectra that exist in this region. In majority cases, however, while they provide information relating to the analyte of interest, there is not enough independent information on other analytes whose absorption spectra interferes with that of the desired analyte. In some cases additional information obtained in earlier mentioned spectral range 580 nm to 1100 nm helps to eliminate ambiguity introduced by interfering analytes. It is clear that if the sample demonstrates a temporal variability, a simultaneous measurement in whole spectral range of the interest is preferred, to eliminate possible errors caused by changes in the sample.
Furthermore, as in earlier discussed cases for shorter spectral range, spectral measurement in limited number of points within 1100 nm to 1700 nm spectral range in some cases may not be sufficient for recognition of desired analyte. In addition, the measurements usually are very sensitive to both: variations of spectral position of the selected points and width and shape of spectral bands measured at those points. Thus, the methods when measurement in different parts of spectrum are taken at different time, or from different part of samples or within limited number of points may not be sufficient for precise analysis of constituents of the samples and more advanced instruments are required. The way to eliminate these limitations and provide instrument suitable for such measurements is given it this invention. Overall, previous non-invasive devices and techniques have not been sufficiently accurate to be used in place of invasive techniques in the measurement of blood constituent concentration in patients. Some of them have been designed to measure one component only and physical changes to the instrument have to be applied to adapt them to measurement of different components. For some devices it takes unreasonably long time to produce a results; or, some other cannot produce results in an easy-to-use form; or, they cannot measure concentration of two or more constituents simultaneously. Obviously, if the device gives an inaccurate reading, disastrous results could occur for the patient using the device to calculate, for exa
Cadell Theodore E.
Pawluczyk Romauld
Scecina Thomas
CME Telemetrix Inc.
Hovey & Williams, LLP
Winakur Eric F.
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