US4512349A
Expired / Lapsed
US
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Method of direct tissue gas tension measurement and apparatus therefor
Assignee: University of California
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Filing: 1983-05-13
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Granted: 1985-04-23
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Expires: 2003-05-13
Abstract
Abstract A new method of tissue oxygen tension measurement which is suitable for human use utilizes an implanted Silastic tube which is inserted through four to five cm of subcutaneous tissue leaving the ends exposed. With the tube filled, for example, with a saline solution, reference and oxygen electrodes are inserted at the exposed ends and by the use of a polarographic potential the amount of oxygen which permeates through the tube from the tissue into the saline solution may be measured on a continuous real-time basis.
Inventors
- 👤 Thomas K. Hunt
- 👤 William H. Goodson, III
- 👤 Ning Chang
- 👤 David R. Knighton
- 👤 Finn Gottrup
- 👤 Richard Firmin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:38
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/14542; A61B5/07; A61B5/076; A61B5/1468
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
100 words
A method of direct tissue gas tension measurement by use of a gas permeable tube implanted in such tissue and by gas polarography comprising the following steps: implanting a predetermined length of said tube through said tissue and leaving a pair of exposed ends of such tube; inserting reference and gas electrodes in respective ends of said tube; filling said tube with an electrolytic fluid; waiting for said gas to permeate from said tissue through said tube into said fluid; and applying a polarographic potential between said gas and reference electrodes and measuring the electrical signal from said gas electrode.
Claim 2
Independent Claim
100 words
A method of direct tissue gas tension measurement by use of a gas permeable tube implanted in such tissue and by gas polarography comprising the following steps: implanting a predetermined length of said tube through said tissue and leaving a pair of exposed ends of such tube; inserting reference and gas electrodes in respective ends of said tube; filling said tube with an electrolytic fluid; waiting for said gas to permeate from said tissue through said tube into said fluid; and applying a polarographic potential between said gas and reference electrodes and measuring the electrical signal from said gas electrode.
Claim 3
Dependent Claim
14 words
A method as in claim 1 including the step of calibrating said gas electrode.
Claim 4
Dependent Claim
18 words
A method as in claim 2 in which said calibration step is conducted before said tube is implanted.
Claim 5
Dependent Claim
130 words
A method as in claim 2 where said calibration step includes placing said tube or an equivalent tube in a water bath, maintaining the water bath at tissue temperature, inserting reference and gas electrodes in the tube ends, applying a polarographic potential across said electrodes, filling said tube with said electrolytic fluid, applying a polarographic potential between said gas and reference electrodes, bubbling in said water bath air allowing it to permeate into said electrolytic fluid within said tube; measuring the resultant electrical signal from the gas electrode, and utilizing this signal as a maximum level, bubbling nitrogen in said water bath allowing it to permeate into the electrolytic fluid within said tube, measuring the resultant electrical signal from the gas electrode, and utilizing this signal as a zero level.
Claim 6
Dependent Claim
34 words
A method as in claim 4 where said electrical signal is measured by an ammeter circuit including the step of regulating said ammeter by utilizing said zero and maximum levels of said calibration step.
Claim 7
Dependent Claim
101 words
A method as in claim 1 where said implanting step includes the steps of utilizing a spinal needle with a mandrel which fits within the spinal needle, allowing a portion of the mandrel to extend from the end of the needle opposite that of the sharpened end, and fitting on the extended mandrel and gluing thereon such tube whereby the outer diameter of the tube is matched to the outer diameter of the spinal needle so that insertion of the sharpened end of the needle through the tissue creates a hole in the tissue of the same diameter as said tube.
Claim 8
Dependent Claim
20 words
A method as in claim 6 in which said mandrel is maintained in said spinal needle by bending such needle.
Claim 9
Dependent Claim
27 words
A method as in claim 6 where after said implantation said spinal needle is cut off from said tube to allow insertion of one of said electrodes.
Claim 10
Dependent Claim
18 words
A method as in claim 1 in which said polarographic potential is of a magnitude for producing oxygen.
Claim 11
Dependent Claim
27 words
A method as in claim 1 where said electrical signal represents the average gas present in the electrolytic fluid throughout the implanted predetermined length of said tube.
Claim 12
Dependent Claim
31 words
A method as in claim 1 including the step of measuring said electric signal on successive days and applying a predetermined and different correction factor to such signal for each day.
Claim 13
Dependent Claim
14 words
A method as in claim 11 where said correction factor is progressively reduced day-by-day.
Claim 14
Dependent Claim
19 words
A method as in claim 12 where said correction factor is a constant after a predetermined number of days.
Claim 15
Dependent Claim
20 words
A method as in claim 11 where on successive days the transient response to said gas is different and definable.
Claim 16
Dependent Claim
106 words
Apparatus for the direct tension measurement by a gas polarography technique by use of a tube in such tissue comprising: a gas permeable tube of relatively small diameter suitable for implantation through said tissue leaving both ends exposed said tube being filled with an electrolytic fluid so that gas from the tissue may permeate through the tube into the fluid; a gas electrode and a reference electrode inserted into said tube and into said electrolytic fluid at respective ends of the tube; means for applying a polarographic potential between said gas and said reference electrodes; means for measuring the resultant electrical signal from said gas electrode.
Claim 17
Dependent Claim
106 words
Apparatus for the direct tension measurement by a gas polarography technique by use of a tube in such tissue comprising: a gas permeable tube of relatively small diameter suitable for implantation through said tissue leaving both ends exposed said tube being filled with an electrolytic fluid so that gas from the tissue may permeate through the tube into the fluid; a gas electrode and a reference electrode inserted into said tube and into said electrolytic fluid at respective ends of the tube; means for applying a polarographic potential between said gas and said reference electrodes; means for measuring the resultant electrical signal from said gas electrode.
Claim 18
Dependent Claim
12 words
Apparatus as in claim 15 including means for calibrating said gas electrode.
Claim 19
Dependent Claim
27 words
Apparatus as in claim 15 in which said electrical signal from said gas electrode is measured by an ammeter circuit which is entirely portable and battery powered.
Claim 20
Dependent Claim
17 words
Apparatus as in claim 15 in which said polarographic potential is produced by a portable battery source.
Claim 21
Dependent Claim
18 words
Apparatus as in claim 18 in which said battery source for the polarographic potential includes a memory cell.
Claim 22
Dependent Claim
29 words
Apparatus as in claim 15 in which said tube is of a material substantially impermeable to protein from said tissue to thus protect the gas electrode from protein poisoning.
Claim 23
Dependent Claim
20 words
Apparatus as in claim 15 in which said gas electrode is a platinum wire encased in a rigid tubular shield.
Claim 24
Dependent Claim
14 words
Apparatus as in claim 15 in which said electrolytic fluid is 0.9 percent saline.
Claim 25
Dependent Claim
15 words
Apparatus as in claim 15 in which said reference electrode is a silver/silver chloride electrode.
Claim 26
Dependent Claim
57 words
Apparatus as in claim 15 where one end of said tube is coupled to one port of a three port valve, where all ports interconnect, one of said electrodes being inserted through a second port into said electrolytic fluid and the third port being connected to a hypodermic syringe serving as a source of said electrolytic fluid.
Claim 27
Dependent Claim
122 words
Apparatus for directly measuring tissue gas tension in tissue subcutaneously comprising: (a) A catheter having an oxygen permeable membrane positionable in subcutaneous tissue for directly measuring tissue gas tension; (b) an electrolyte in said catheter in chemical contact with the oxygen permeable membrane; (c) an electrode sensitive to oxygen in the catheter in electrical contact with said electrolyte; and (d) a reference electrode in the catheter in electrical contact with said electrolyte, so that when said catheter is positioned in subcutaneous tissue the oxygen in said tissue permeates said membrane, and reaches chemical equilibrium with the electrolyte and an electrical signal is developed between said oxygen sensitive electrode and said reference electrode corresponding to the tissue gas tension in the subcutaneous tissue.
Claim 28
Dependent Claim
122 words
Apparatus for directly measuring tissue gas tension in tissue subcutaneously comprising: (a) A catheter having an oxygen permeable membrane positionable in subcutaneous tissue for directly measuring tissue gas tension; (b) an electrolyte in said catheter in chemical contact with the oxygen permeable membrane; (c) an electrode sensitive to oxygen in the catheter in electrical contact with said electrolyte; and (d) a reference electrode in the catheter in electrical contact with said electrolyte, so that when said catheter is positioned in subcutaneous tissue the oxygen in said tissue permeates said membrane, and reaches chemical equilibrium with the electrolyte and an electrical signal is developed between said oxygen sensitive electrode and said reference electrode corresponding to the tissue gas tension in the subcutaneous tissue.
Claim 29
Dependent Claim
25 words
Apparatus as in claim 25 further including means, connectable to said electrodes, for substantially instantaneously indicating the relative tissue gas tension in the subcutaneous tissue.
Claim 30
Dependent Claim
43 words
Apparatus as in claim 25 further including means, connectable to said oxygen electrode and said reference electrode, for applying a polarographic potential between said electrodes and for indicating the resultant electrical signal corresponding to the relative tissue gas tension in the subcutaneous tissue.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |