SYSTEMS AND METHODS FOR IMPLEMENTING RAPID RESPONSE MONITORING OF BLOOD CONCENTRATION OF A METABOLITE
First Claim
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1. A method for monitoring the concentration of a metabolite in vivo within a body fluid, the method comprising the steps of:
- (a) providing a monitoring device comprising;
(i) a microdialysis probe formed at least in part from a membrane permeable to the metabolite, the probe defining a probe volume containing dialysate,(ii) a measuring cell having a measuring volume, and(iii) a flow path connecting from the probe volume to the measuring volume;
(b) bringing the probe into contact with the body fluid;
(c) maintaining substantially zero flow conditions during a diffusion period to allow diffusion of the metabolite into the dialysate within the microdialysis probe; and
(d) generating a dialysate flow to carry a quantity of dialysate from the probe volume along the flow path to the measuring volume,wherein said generating a dialysate flow is performed such that said quantity of dialysate passes from the probe volume to the measuring volume in a given transport time, said transport time being no more than 25 percent of said diffusion period.
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Abstract
Systems and methods for monitoring the concentration of glucose or other metabolites by way of a low-volume microdialysis-probe (10) operative in accordance with a pulsed mode of flow through a flow path (12) defined by a layered structure. Also described are a system and a method for deployment of the microdialysis probe (10) within the body and a technique for deriving a metabolite concentration of the basis of a rate of change of an optical parameter.
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Citations
32 Claims
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1. A method for monitoring the concentration of a metabolite in vivo within a body fluid, the method comprising the steps of:
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(a) providing a monitoring device comprising; (i) a microdialysis probe formed at least in part from a membrane permeable to the metabolite, the probe defining a probe volume containing dialysate, (ii) a measuring cell having a measuring volume, and (iii) a flow path connecting from the probe volume to the measuring volume; (b) bringing the probe into contact with the body fluid; (c) maintaining substantially zero flow conditions during a diffusion period to allow diffusion of the metabolite into the dialysate within the microdialysis probe; and (d) generating a dialysate flow to carry a quantity of dialysate from the probe volume along the flow path to the measuring volume, wherein said generating a dialysate flow is performed such that said quantity of dialysate passes from the probe volume to the measuring volume in a given transport time, said transport time being no more than 25 percent of said diffusion period. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
wherein said elongated shaft and said actuator element are configured such that, in a first relative position of said elongated shaft and said actuator element, said inserter retains said probe for insertion through a biological barrier into tissue, and, when said actuator element is displaced relative to said elongated shaft, said probe is released, thereby allowing withdrawal of said inserter from the tissue while said probe remains inserted within the tissue.
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12. The method of claim 1, wherein the device further comprises:
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(a) an optical sensor deployed for sensing an optical parameter of fluid within said measuring volume; and (b) a concentration calculator operationally connected to the optical sensor, the concentration calculator comprising at least one processor, the concentration calculator being configured to derive a rate of change of the optical parameter of the fluid within said measuring volume under substantially zero flow conditions, and to calculate a concentration of the metabolite within the body fluid based at least in part on said rate of change.
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2. A device for monitoring the concentration of a metabolite in vivo within a body fluid, the device comprising:
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(a) a microdialysis probe for bringing into contact with the body fluid, said probe being formed at least in part from a membrane permeable to the metabolite, said probe defining a probe volume containing dialysate; (b) a measuring cell having a measuring volume; (c) a flow path connecting from the probe volume to the measuring volume; and (d) a fluid flow controller deployed to control flow of dialysate through said probe volume and said flow path to said measuring volume, said fluid flow controller being configured to generate a pulsed flow pattern including; (i) a diffusion period of substantially zero flow conditions to allow diffusion of the metabolite into the dialysate within said probe; and (ii) a dialysate flow to carry a quantity of dialysate from the probe volume along said flow path to the measuring volume, wherein said flow controller generates said dialysate flow such that said quantity of dialysate passes from the probe volume to the measuring volume in a given transport time, said transport time being no more than 25 percent of said diffusion period. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
wherein said elongated shaft and said actuator element are configured such that, in a first relative position of said elongated shaft and said actuator element, said inserter retains said probe for insertion through a biological barrier into tissue, and, when said actuator element is displaced relative to said elongated shaft, said probe is released, thereby allowing withdrawal of said inserter from the tissue while said probe remains inserted within the tissue.
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32. The device of claim 2, wherein the device further comprises:
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(a) an optical sensor deployed for sensing an optical parameter of fluid within said measuring volume; and (b) a concentration calculator operationally connected to the optical sensor, the concentration calculator comprising at least one processor, the concentration calculator being configured to derive a rate of change of the optical parameter of the fluid within said measuring volume under substantially zero flow conditions, and to calculate a concentration of the metabolite within the body fluid based at least in part on said rate of change.
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13. A device for monitoring the concentration of a metabolite in vivo within a body fluid, the device comprising:
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(a) a microdialysis probe for bringing into contact with the body fluid, said probe being formed at least in part from a membrane permeable to the metabolite, said probe defining a probe volume containing dialysate; (b) a measuring cell having a measuring volume; and (c) a flow path connecting from the probe volume to the measuring volume, wherein at least part of the flow path from the probe volume to the measuring volume is formed as a channel enclosed between at least two layers of a layered structure. - View Dependent Claims (14, 15, 16, 17, 18, 19)
wherein said elongated shaft and said actuator element are configured such that, in a first relative position of said elongated shaft and said actuator element, said inserter retains said probe for insertion through a biological barrier into tissue, and, when said actuator element is displaced relative to said elongated shaft, said probe is released, thereby allowing withdrawal of said inserter from the tissue while said probe remains inserted within the tissue.
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20-22. -22. (canceled)
Specification