Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1999-05-13
2001-03-27
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S205270, C128S205280, C128S205290, C128S203130
Reexamination Certificate
active
06206002
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates a device and method for recovering anaesthetic during the use of inhaled anesthetics.
Such devices and methods are disclosed through SE-B 459 155 and SE-B-515 217, for instance. The purpose of such a device is to reduce the consumption of anaesthetic preparations when treating a patient, since preparations such as Fluothane-(2-bromine-2-chlorine-1,1,1-trifluorethane) are often relatively expensive. According to older, convertional technology the anaesthetic preparation is conducted away to the surroundings together with the air exhaled and is therefore lost, as well as contaminating the surroundings.
However, these devices are unable to compensate the loss of moisture upon exhalation. It would also be desirable to be able to improve the reflection efficiency, i.e. the proportion of exhaled anaesthetic which is absorbed and returned to the gas inhaled.
Against this background, the object of the present invention is to alleviate this deficiency in the known devices and methods, and to increase the reflection efficiency.
SUMMARY OF THE INVENTION
The present invention relates to a device comprising an anaesthetic reflector used for absorbing anaesthetic medium from the gas exhaled by the patient and desorbs anaesthetic medium to the gas inhaled by the patient. According to the invention a moisture-heat exchanger is arranged in the system, which in an equivalent manner recovers water vapor from the gas exhaled by the patient to the gas inhaled by the patient. The moisture-heat exchanger is preferably located between the anaesthetic reflector and the patient. The device and the method according to the invention enable the gas inhaled to be moistened to prevent dehydration, as well as increasing the efficiency of the reflector.
Thanks to the second unit with the ability to absorb and desorb water vapour, i.e. a moisture-heat exchanger, which is arranged in series with the first unit, i.e. the anaesthetic reflector, both anaesthetic and water vapour in the gas exhaled will be recovered since each component is absorbed in a separate unit. During inhaling, the anaesthetic preparation and water vapour recovered are released and desorbed out in the gases breathed, which will thus re-use a part of the anaesthetic preparation, as well as having part of its moisture content restored. The use of this device and this method thus enables a lower consumption of anaesthetic preparation than has been possible with known technology, as well as eliminating the need for any special supply of water vapour in order to avoid the risk of dehydration.
In a particularly preferred embodiment of the invention the second unit is situated between the patient and the first unit.
This has been found to have the surprising effect of greatly increasing the proportion of anaesthetic preparation recovered. It has been ascertained that the reflection efficiency is considerably increased with such an arrangement in comparison with other alternatives and even in comparison with a device without any moisture-heat exchanger at all. The optimal efficiency obtained with this preferred embodiment is probably a result of the reduced moisture content in the gas exhaled before it enters the anaesthetic reflector, increasing the ability of the after to absorb and desorb anaesthetic. A greater proportion of this will therefore be returned to the patient in the gas inhaled.
In another preferred embodiment, preferably a variation of that described above, both the units, i.e. the anaesthetic reflector and the moisture-heat exchanger, are located in a common housing. This simplifies the construction, making it more compact and easily managed. It also ensures that the two units are compatible from the point of view of size.
The supply means for the anaesthetic preparation is preferably arranged in the tube between the patient and the air-heat exchanger, which offers maximum utilization of the anaesthetic preparation as well as more reliable control of dosages. In this case the means suitably comprises an vaporizer arranged in the patient tube. The advantages of such an arrangement are further described in patent application SEB459 155 mentioned above.
The above and other advantageous embodiments of the device according to the invention are defined in the sub-claims to the main method claim.
Equivalent advantageous embodiments of the method according to the invention are defined in the sub-claims to the main method claim.
REFERENCES:
patent: 4905685 (1990-03-01), Olsson et al.
patent: 5471979 (1995-12-01), Psaros et al.
patent: 0496336 (1992-07-01), None
patent: 8807876 (1998-10-01), None
Hudson RCI AB
Knobbe Martens Olson & Bear LLP
Patel Mital
Weiss John G.
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