Method and apparatus for metering an anaesthetic to a patient
First Claim
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1. Apparatus for metering the amount of anaesthetic supplied to a patient comprising:
- first conduit means (7,8,20,21) having one end for receiving breathable gas from a vessel means and having an other end serving as a gas connection to the patient;
a container (18) for receiving a vaporizable liquid anaesthetic, said container having a gas space into which the liquid anaesthetic vaporizes;
second conduit means (19) coupled to said first conduit means at a connection point upstream of the other end of said first conduit means for connecting said gas space of said container to said first conduit means, said second conduit means conducting anaesthetic vapor from said gas space to said first conduit means for mixing with breathable gas for supply to the patient;
sensor means operatively associated with said first conduit means downstream of said connection point for ascertaining the amount of anaesthetic being supplied to the patient;
control means (44) coupled to said sensor means for comparing the amount of anaesthetic being supplied to the patient with a desired amount of anaesthetic to be supplied to the patient; and
a flow constricting valve (42) interposed in said second conduit means and coupled to said control means for altering the amount of anaesthetic vapor flowing in said second conduit means to bring the amount of anaesthetic being supplied to the patient into conformity with a desired concentration of anaesthetic to be supplied to the patient.
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Abstract
The invention relates to a method and apparatus for metering to a patient an anaesthetic vaporized from anaesthetic liquid held in a liquid space (27) of a liquid container (18) into a gas space (28). The anaesthetic dose contained in a gas flow supplied to a patient is determined and the dose is adjusted in a manner that the dosage of anaesthetic in a gas intended to be respired by a patient matches a desired dosage and the dosage adjustment of anaesthetic contained in a gas supplied to a patient is effected automatically whenever the current dosage differs from a desired value.
72 Citations
35 Claims
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1. Apparatus for metering the amount of anaesthetic supplied to a patient comprising:
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first conduit means (7,8,20,21) having one end for receiving breathable gas from a vessel means and having an other end serving as a gas connection to the patient; a container (18) for receiving a vaporizable liquid anaesthetic, said container having a gas space into which the liquid anaesthetic vaporizes; second conduit means (19) coupled to said first conduit means at a connection point upstream of the other end of said first conduit means for connecting said gas space of said container to said first conduit means, said second conduit means conducting anaesthetic vapor from said gas space to said first conduit means for mixing with breathable gas for supply to the patient; sensor means operatively associated with said first conduit means downstream of said connection point for ascertaining the amount of anaesthetic being supplied to the patient; control means (44) coupled to said sensor means for comparing the amount of anaesthetic being supplied to the patient with a desired amount of anaesthetic to be supplied to the patient; and a flow constricting valve (42) interposed in said second conduit means and coupled to said control means for altering the amount of anaesthetic vapor flowing in said second conduit means to bring the amount of anaesthetic being supplied to the patient into conformity with a desired concentration of anaesthetic to be supplied to the patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for metering the amount of anaesthetic supplied to a patient, said method comprising the steps of:
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flowing a breathable gas through a first conduit means to the patient; vaporizing a liquid anaesthetic in a container to provide an anaesthetic vapor; conducting the anaesthetic vapor from the container to said first conduit means via a second conduit means for mixing with the breathable gas flowing through the first conduit means for supply to the patient; sensing the amount of anaesthetic conducted within said first conduit means downstream of a point of connection of said first and second conduit means for ascertaining the amount of anaesthetic being supplied to the patient; establishing a desired concentration of anaesthetic to be supplied to the patient; comparing the amount of anaesthetic being supplied to the patient with a desired concentration of anaesthetic to be supplied to the patient; and operating a flow constricting valve in said second conduit to alter the amount of anaesthetic vapor conducted in said second conduit means to bring the amount of anaesthetic being supplied to the patient into conformity with the desired concentration of anaesthetic to be supplied to the patient. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification