Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2000-05-08
2003-06-24
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S325000
Reexamination Certificate
active
06584335
ABSTRACT:
The invention concerns an analysis device for determining an analytic substance in the body of a patient (human or possibly animal) having a measuring probe comprising a hollow needle which can pierce through the skin.
The concentration of components of body fluids (analytes) is almost exclusively determined, in medical applications, by means of reagents. Towards this end, a sample of the body fluid (in particular blood) is taken and analyzed in the laboratory in vitro. The methods are being continuously improved and small hand-held analysis systems have meanwhile become available for important analytes, in particular blood glucose. The methods nevertheless have the disadvantage that each individual investigation requires the removal of blood and continuous measurements are not possible.
Fiber optic chemical sensors (FOCS) are known in the art for continuous measurement via immersion in a sample liquid. The absorption or luminescence of an indicator molecule is thereby observed via an optical fiber, the indicator molecule being localized on the tip of the optical fiber or in a jacket surrounding same. FOCS have also been used for continuous measurements of analytes in the blood of a patient, e.g. using a catheter introduced into the vein. Devices of this type are described in the following publications:
a) U.S. Pat. No. 5,127,077
b) EP 0 589 862 A2
c) U.S. Pat. No. 4,846,548
Efforts have been made for a long period of time to develop primarily based on spectroscopic principles reagent free analysis procedures. Conventional absorption spectroscopy using a transmission measurement is, however, in the major part of the spectrum not possible in blood, since blood contains strongly absorbing substances (in particular hemoglobin) which cover the characteristic spectral bands of the analytes being sought. Even if one removes the hemoglobin using a centrifuge, a strong interfering optical absorption remains in the particularly interesting regions of the infrared spectrum.
For this reason the possibility of using ATR (Attenuated Total Reflection) spectroscopy for investigation of aqueous biological liquids, in particular blood, has been studied. Reference is made to the following publications:
1) Y. Mendelson: “Blood Glucose Measurement by Multiple Attenuated Total Reflection and Infrared Absorption Spectroscopy”, IEEE Transactions on Biomedical Engineering, 1990, 458-465.
2) H. M. Heise et al.: “Multi component Assay for Blood Substrates in Human Plasma by Mid-infrared Spectroscopy and its Evaluation for Clinical Analysis”, Applied Spectroscopy 1994, 85 to 95.
3) R. Simhi et al.: “Multi-component Analysis of Human Blood Using Fiber Optic Evanescent Wave Spectroscopy”, SPIE Proc. Vol. 2331: Medical Sensors II and Fiber Optic Sensors Sep. 6-Sep. 10, 1994, Lille, France, A. V. Scheggi et al. (Eds.), ISBN 0-8194-1664-9, published 1995, pages 166 to 172.
These references show that it is, in principle, possible to use ATR spectroscopy to detect important analytes, in particular glucose, in blood reagent free by spectroscopic means. In ATR spectroscopy, light is transported through a light guide whose outer surface is in contact with the sample. The index of refraction within the light guide (relative to the index of refraction of the sample) and the angles of reflection of the light at the boundary must be selected such that the light is totally internally reflected. Total internal reflection comprises penetration of an evanescent wave into the neighboring medium (the sample). The absorption which thereby occurs leads to an attenuation of the intensity of the light transported in the light guide. This attenuation in intensity can be evaluated as a function of wavelength in order to extract information from the spectrum concerning the presence of the analyte in the sample. Further details can be taken from the relevant literature, in particular, 1) to 3) cited above.
ATR measurements generally utilize special ATR measuring cells with a light guide having a prismatic shape. Alternatively, fiber optic light guides have been frequently proposed. An example, with regard to medical analysis of blood components, is reference 3).
The publication
4) U.S. Pat. No. 5,436,454,
describes a device which allegedly enables ATR spectroscopy of blood of a patient in vivo. Towards this end, a thin hollow needle, similar to an injection needle, can be introduced through the skin of the patient into a blood vessel for in vivo measurements. A thin optical fiber passes through the hollow needle up to the tip thereof and is bent at this location back in the opposite direction in a narrow loop to travel back through the hollow needle. A light guide leg passing through the hollow needle transports measuring light to the loop. A second leg passes the light back to a detector. The hollow needle has a diameter of approximately 3 mm and an inner bore of approximately 2 mm for acceptance of the optical fibers having a diameter of 0.7 mm to 1 mm. The publication discloses that many more reflections of the light transported in the light guide occur in the region of the loop than in the straight sections. As a result thereof, a substantially higher sensitivity is present in the loop region. In the measurement state, the loop protrudes somewhat past the tip of the hollow needle and a seal prevents the sample from penetrating into the hollow needle. The measurement is thereby confined solely to the region of the loop. The measurement is intended to be carried out in a spectral region having wave numbers between 7,000 and 700 (corresponding to 1.5 to 15 &mgr;m). Chalcogenic glass is proposed as a material for the optical fibers.
Another example of a publication concerned with ATR spectroscopy for in vivo analysis of body components, in particular glucose, is
5) WO 91/18548.
A further measurement concept, namely the measurement of the index of the refraction, is recommended for measuring glucose in blood in
6) WO 90/101697.
On the basis of this prior art, it is an object of the invention to provide an improved analysis device for determination of an analyte in vivo in the body of the patient.
This purpose is achieved using an analysis device for the determination of an analyte in vivo in the body of a patient, including a measuring probe comprising a hollow needle for puncturing into the skin and with an optical fiber travelling through the hollow needle by means of which light emanating from a light source and coupled into the optical fiber can be guided through the hollow needle to the measuring probe which is pierced into the skin and thus into the body, wherein the light in the measuring probe transported through the optical fiber undergoes, through direct reagent free interaction with interstitial liquid surrounding the optical fiber within in the body, a change characterizing the presence of the analyte and having a measurement and evaluation unit for measuring the change and for deriving, from this change, information concerning the presence of the analyte in the body, characterized in that the hollow needle is permeable through at least a partial section of its length which penetrates into the skin and which serves as a measuring section, so that the interstitial liquid passes through the hollow needle wall and gains access to a measuring section of the optical fiber extending in the hollow needle, and the change in the light characterizing the presence of the analyte results from interaction with the interstitial liquid in the measuring section.
It has been discovered within the context of the invention that in contrast to the recommendation of publication 4) the measurement is advantageously not concentrated at a loop at the tip of the hollow needle. Rather it is carried out along a longer measuring section of preferentially at least 2 mm and particularly preferentially between 3 mm and 10 mm of length within a hollow needle which can be penetrated along the length of this measuring section. The measuring medium is not blood in a vein but rather the interstitial liquid in skin tissue, preferentially in subcutaneous s
Boecker Dirk
Haar Hans-Peter
Kastner Joachim
Lambrecht Armin
Werner Gerhard
Kremer Matthew
Roche Diagnostics GmbH
Winakur Eric F.
Woodburn Jill L.
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