Surgery – Truss – Pad
Patent
1982-03-26
1985-08-13
Cohen, Lee S.
Surgery
Truss
Pad
204403, 204415, 204431, A61B 500
Patent
active
045343551
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is concerned with certain medical devices which employ hydrophilic polyurethanes and is also concerned with certain hydrophilic polyurethanes suitable for such a purpose. More specifically this invention is concerned with medical devices for determining blood gas which devices employ a membrane of hydrophilic polyurethanes and is also concerned with certain hydrophilic polyurethanes suitable for use in such devices.
DESCRIPTION OF THE PRIOR ART
Medical devices used to determine blood gas levels normally employ a membrane which allows the passage of a specie involved in the determination while preventing the passage of materials such as proteins that could disadvantageously effect the operation of the device. Such medical devices are generally those which are employed in contact with the body although some devices are used in conjunction with extracorporeal circulation of blood or blood samples otherwise removed from the body. Whereas this invention is concerned with medical devices which can be used in either or both these modes it is especially concerned with medical devices suitable for use in contact with the body (even if the devices are also suitable for use away from the body). The body contact medical device will normally be one adapted to operate in contact with a body fluid such as blood, perspiration or a fluid exuded from a lesion. Whereas the devices of this invention offer considerable advantages when adapted to contact a body fluid such as perspiration or exudate on the exterior surface of the body, the advantages are most profound in medical devices used in direct contact with blood present in the circulation of the patient.
Devices for determining blood gases or electrolytes are normally either electrochemical sensors or collection devices. Electrochemical sensors are devices which in the presence of the relevant specie produce an electrical change as a result of a chemical change (which includes change of the concentration of a species). Collection devices serve to transport the gas to another place for determination. The medical devices with which this invention is particularly concerned are electrochemical sensors.
Electrochemical sensors which may be used for the determination of blood gases are described in, for example, British Patent Specifications Nos. 1265505, 1325873, 1503908, 2005418 and 2055476, U.S. Pat. Nos. 3,088,905 and 3,912,614, European Patent Specifications Nos. 0015075 and 0027385 and Med. and Biol. Eng. Comput., 1978, 16, 599-600. The publications describe blood gas detectors requiring the presence of membranes and a number of useful or potentially useful membrane materials are described. Some of the publications disclose the advantages of using hydrophilic materials such as polyHEMA but none suggest that hydrophilic polyurethanes may be employed in blood gas detectors.
Hydrophilic polyurethanes have been previously described in, for example, U.K. Patent Specification No. 1551620, U.S. Pat. Nos. 3,975,350, 3,822,238, 4,156,067 and C. T. Chen. et. al., J. Appl. Polymer Science Vol. 16, p. 2105-2114 (1972). However none of these documents suggest the use of hydrophilic polyurethanes in devices for determining the concentrations of blood gases.
SUMMARY OF THE INVENTION
It has now been found that hydrophilic polyurethanes membranes can be employed in devices for determining blood gas and that advantages can be found to accrue from use of hydrophilic polyurethane in various medical devices of this invention selected from good binding of the membrane to the mounting, rapid response time, rapid equilibration time, reduction in dependency upon certain electrolytes used within certain types of device and simplification of manufacture.
The present invention provides a medical device for use in determining blood gas which employs a membrane of material permeable to the blood gas to be determined characterised in that the membrane is hydrophilic polyurethane.
The medical device of this invention either may be adapted for use remo
REFERENCES:
patent: 4041933 (1977-08-01), Reichenberger
patent: 4061618 (1977-12-01), Stanley et al.
patent: 4273636 (1981-06-01), Shimeda et al.
Cohen Lee S.
Smith and Nephew Associated Companies Inc.
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