Method and apparatus for continuously monitoring the concentration of a metabolyte
First Claim
1. A method for continuously monitoring the concentration of a metabolite in biological tissue comprising the steps of:
- implanting a microdialysis probe in subcutaneous tissue so that it contacts with lymph contained in the subcutaneous tissue;
feeding a perfusion liquid to the microdialysis probe whereby the perfusion liquid is enriched with the metabolite contained in the lymph;
removing the enriched perfusion liquid as a dialysate from the microdialysis probe;
adding an enzyme in the form of an enzyme solution continuously to the dialysate in an amount based on the flow rate of the dialysate to form a dialysate measurement solution;
determining the concentration of the metabolite in the dialysate by measuring the dialysate measurement solution ex vivo with an electrochemical sensor; and
determining the concentration of the metabolite in the biological tissue based on the concentration of the metabolite in the dialysate.
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Accused Products
Abstract
The present invention is directed to a method and an apparatus for continuously monitoring the concentration of a metabolite, such as glucose or lactic acid, in biological tissue, in which a perfusion fluid is fed to a microdialysis probe implanted in the subcutaneous tissue and removed therefrom as dialysate after enrichment with the metabolites contained in the lymph. An enzyme is added to the dialysate and/or perfusion fluid, and the concentration of the metabolite in the dialysate is determined under the selective effect of the enzyme at a measuring point which is positioned ex vivo, using an electrochemical sensor. The enzyme is added to the dialysate in the form of a continuous enzyme solution flow upstream of the measuring point and in dependence of the throughput of the microdialysis probe.
689 Citations
28 Claims
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1. A method for continuously monitoring the concentration of a metabolite in biological tissue comprising the steps of:
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implanting a microdialysis probe in subcutaneous tissue so that it contacts with lymph contained in the subcutaneous tissue; feeding a perfusion liquid to the microdialysis probe whereby the perfusion liquid is enriched with the metabolite contained in the lymph; removing the enriched perfusion liquid as a dialysate from the microdialysis probe; adding an enzyme in the form of an enzyme solution continuously to the dialysate in an amount based on the flow rate of the dialysate to form a dialysate measurement solution; determining the concentration of the metabolite in the dialysate by measuring the dialysate measurement solution ex vivo with an electrochemical sensor; and determining the concentration of the metabolite in the biological tissue based on the concentration of the metabolite in the dialysate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for continuously monitoring the concentration of a metabolite in biological tissue comprising a microdialysis probe for implantation in subcutaneous tissue;
- means for feeding a perfusion liquid to the microdialysis probe comprising a perfusion liquid reservoir, a first transport means for providing a flow of the perfusion liquid from the perfusion liquid reservoir to the microdialysis probe and a perfusion liquid tube for carrying the perfusion liquid from the first transport means to the microdialysis probe;
a dialysate tube for removing a perfusion liquid enriched with the metabolite from the microdialysis probe;
an enzyme solution reservoir containing an enzyme solution;
a feed channel for carrying the enzyme solution to a junction formed by said feed channel and said dialysate tube where the enriched perfusion liquid and the enzyme solution are intermixed with each other to form a dialysate measurement solution;
an ex vivo measuring device comprising a sensor for determining the concentration of the metabolite in the dialysate measurement solution, a second transport means for providing a constant flow of the dialysate measurement solution to the ex vivo measuring device and a dialysate measurement solution tube for carrying the dialysate measurement solution from the junction to the ex vivo measuring device. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
- means for feeding a perfusion liquid to the microdialysis probe comprising a perfusion liquid reservoir, a first transport means for providing a flow of the perfusion liquid from the perfusion liquid reservoir to the microdialysis probe and a perfusion liquid tube for carrying the perfusion liquid from the first transport means to the microdialysis probe;
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28. In a method for continuously monitoring the concentration of glucose in the tissue of a patient and compensating for diabetical defects in the patient by automatic insulin infusion means wherein insulin infusion is controlled according to the glucose level measured in the tissue of the patient, the improvement comprising the concentration of the glucose in the tissue of the patient being continuously monitored by a method comprising the steps of:
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implanting a microdialysis probe in subcutaneous tissue of the patient so that it contacts with lymph contained in the subcutaneous tissue; feeding a perfusion liquid to the microdialysis probe whereby the perfusion liquid is enriched with glucose contained in the lymph; removing the enriched perfusion liquid as a dialysate from the microdialysis probe; adding an enzyme in the form of an enzyme solution continuously to the dialysate in an amount based on the flow rate of the dialysate to form a dialysate measurement solution; determining the concentration of the glucose in the dialysate by measuring the dialysate measurement solution ex vivo with an electrochemical sensor; and determining the concentration of the glucose in the tissue of the patient based on the concentration of the glucose in the dialysate.
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Specification