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US4240438A
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Method for monitoring blood glucose levels and elements
Assignee: Wisconsin Alumni Research Foundation
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Filing: 1978-10-02
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Granted: 1980-12-23
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Expires: 1998-10-02
Abstract
Abstract A method for monitoring blood glucose levels at frequent intervals, which includes a method for equalizing the temperature and oxygen level in the blood and sensing the rate of oxygen consumption by the glucose contained in the blood in the presence of glucose oxidase enzyme immobilized on a hydrophobic membrane covering a measurement electrode and elements employed therein including the equalizing method and the electrode and method for preparing same.
Inventors
- 👤 Stuart J. Updike
- 👤 Mark C. Shults
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:40
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1468; A61B5/1486; A61B5/14865; C; C12; C12Q; C12Q1/00; C12Q1/001; C12Q1/005; C12Q1/006; G; G01; G01N; G01N27/00; G01N27/26; G01N27/28; G01N27/30; G01N27/327; G01N27/3271
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
138 words
A method for monitoring blood glucose levels consisting essentially of the steps of withdrawing patient's whole blood, uniformly oxygenating increments of the patient's withdrawn blood by contacting the increment of withdrawn patient's blood with air for a sufficient length of time to effect oxygen equilibration, transferring the increment of blood after air-oxygen equilibration to a sensor having an electrode covered with a hydrophobic membrane having an etched hydrophilic surface on which glucose oxidase is immobilized whereby oxygen is consumed by reaction with glucose in the blood in the presence of the glucose oxidase, measuring rate of change in oxygen tension resulting from the reaction of glucose in the blood, said rate of change being proportional to the glucose concentration in the blood, and diluting the increment of patient's blood before measuring for rate of change in oxygen tension.
Claim 2
Independent Claim
138 words
A method for monitoring blood glucose levels consisting essentially of the steps of withdrawing patient's whole blood, uniformly oxygenating increments of the patient's withdrawn blood by contacting the increment of withdrawn patient's blood with air for a sufficient length of time to effect oxygen equilibration, transferring the increment of blood after air-oxygen equilibration to a sensor having an electrode covered with a hydrophobic membrane having an etched hydrophilic surface on which glucose oxidase is immobilized whereby oxygen is consumed by reaction with glucose in the blood in the presence of the glucose oxidase, measuring rate of change in oxygen tension resulting from the reaction of glucose in the blood, said rate of change being proportional to the glucose concentration in the blood, and diluting the increment of patient's blood before measuring for rate of change in oxygen tension.
Claim 3
Dependent Claim
29 words
The method as claimed in claim 1 in which determinations are made on an intermittent basis at frequent intervals continuously to monitor the blood glucose level of the patient.
Claim 4
Dependent Claim
43 words
The method as claimed in claim 1 in which a catheter for the withdrawal of the patient's blood remains inserted in the blood vessel of the patient for withdrawal of blood at frequent intervals for continuous monitoring of the patient's blood glucose level.
Claim 5
Dependent Claim
27 words
The method as claimed in claim 3 which includes the step of flowing an IV solution to the catheter during the period of time between blood withdrawal.
Claim 6
Dependent Claim
45 words
The method as claimed in claim 4 in which the IV solution contains an anti-coagulant in an amount sufficient to insure the absence of clotting in the blood sampling system but insufficient to cause a significant effect on the coagulating ability of the patient's blood.
Claim 7
Dependent Claim
13 words
The method as claimed in claim 5 in which the anti-coagulant is heparin.
Claim 8
Dependent Claim
42 words
The method as claimed in claim 1 which includes the step of removing the increment of blood from the sensor and flushing the sensor with buffer solution in preparation for the introduction of a next increment of equilibrated patient's blood for testing.
Claim 9
Dependent Claim
33 words
The method as claimed in claim 1 which includes the step of equilibrating the increment of the patient's blood as to temperature as well as to oxygen levels before measurement of oxygen consumption.
Claim 10
Dependent Claim
22 words
The method as claimed in claim 8 in which the increment of blood is equilibrated to a temperature of about 37° C.
Claim 11
Dependent Claim
30 words
The method as claimed in claim 1 in which the increment of blood is equilibrated for oxygen level by bubbling the air through the increment for a period of time.
Claim 12
Dependent Claim
42 words
The method as claimed in claim 1 in which the increment of blood is equilibrated for oxygen level by holding the blood in an oxygen equilibration coil exposed to atmospheric air for diffusion of oxygen therethrough from the atmosphere to the blood.
Claim 13
Dependent Claim
34 words
The method as claimed in claim 1 in which the sensor operates in a rate determination mode based upon the rate of oxygen consumption by the glucose present in the blood at the electrode.
Claim 14
Dependent Claim
25 words
The method as claimed in claim 1 which includes the step of mixing the increment of blood with a buffer solution before the equilibration step.
Claim 15
Dependent Claim
21 words
The method as claimed in claim 13 in which the increment of blood is flushed to the sensor with the buffer.
Claim 16
Dependent Claim
96 words
The method as claimed in claim 1 in which the steps are automated for operation in sequence to withdraw the blood and flush the sensor with the buffer, to drain an IV solution to the catheter during the period of time that blood is not being withdrawn and flushing the increment of blood with buffer for equilibration, equilibrating the oxygen level and temperature of the flushed increment of blood, flowing the equilibrated blood into the sensor for a rate determination of the glucose level in the blood, and flushing the blood from the sensor to waste.
Claim 17
Dependent Claim
27 words
The method as claimed in claim 1 in which the hydrophobic membrane is polytetrafluoroethylene (Teflon) having an etched hydrophilic surface on which the glucose oxidase is immobilized.
References Cited (Backward Citations)
US3857771A
Cited
US3838682A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-23 | 1984-06-23 | 1984-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-23 | 1988-06-23 | 1988-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-23 | 1992-06-23 | 1992-12-23 | $7700.00 | Window Closed / Lapsed |