Surgery – Respiratory method or device – Means for cooling respiratory gas or respiration device
Patent
1989-10-13
1991-09-03
Lewis, Aaron J.
Surgery
Respiratory method or device
Means for cooling respiratory gas or respiration device
12820312, A61M 1600
Patent
active
050443615
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an apparatus for reuse of anesthetics in inhalation anesthesia.
Inhalation anesthesia is a common form of narcosis, and the anesthetics usually consist of simple halogenated hydrocarbons, paraffins or ethers which are in a liquid state at room temperature and are gasified prior to inhalation. Common anesthetics are Halotan or Fluotan (2-bromo-2-chloro-1,1,1-trifluoroethane), Enfluran or Efran (1,1,2-trifluoro-2-chloroethyl difluoromethyl ether), or Isofluran or Foren (2,2,2-trifluoro-1-chloroethyl difluoromethyl ether). The effect obtained from such halogenated hydrocarbons is normally increased by an addition of laughing gas (N.sub.2 O) at concentrations of 50-70 vol %.
The trend of development is towards more and more refined anesthetics which, however, suffer from the disadvantage of being obtainable only at high costs.
Furthermore, anesthetics are harmful to the operating staff if they leak out into the operating room.
The exhalation air from a patient contains nonabsorbed oxygen, laughing gas, water vapor, nonabsorbed anesthetic gas and 4-6 vol % CO.sub.2.
Anesthetic gases can be administered to the patient by several different techniques and systems. The systems can be completely open, closed with re-breathing and CO.sub.2 adsorption, or combinations thereof.
In one type of inhalation anesthesia, use is made of a respirator to which is connected a gasifier for anesthetic, emitting anesthetic gas at a predetermined concentration, e.g. 0-5 vol %, in for example a mixture of oxygen and laughing gas. The same gas flow as is supplied to the patient passes through the anesthetic gasifier. The anesthetic not absorbed by the patient passes to a suction outlet when the patient exhales and is lost. New gas containing anesthetic is supplied all the time, resulting in a high loss of expensive anesthetic in addition to the harmful effect on the operating staff.
In another system, the anesthetic gasifier is connected to the conduit leading into and out of the patient, and a small flow of fresh gas having a high concentration of anesthetic and emanating from the anesthetic gasifier is added to a larger gas flow from the respirator. Also in this system, the exhalation air, including anesthetic that has not been absorbed, is sucked out into the surroundings, and is constantly replaced by new fresh gas.
It is also possible to employ an anesthetic circuit permitting gas to be recirculated to the patient. In this case, an absorber is generally used, which eliminates the carbon dioxide produced by the patient. This method makes considerable gas savings possible, but requires, besides the absorber, special valve systems. Alternative ways of saving anesthetic are therefore of interest.
The object of the invention is to provide a method and an apparatus for reuse of anesthetics by which it is possible, at reasonable costs, to utilise high-priced anesthetics.
According to the invention, there is provided a new method and a new apparatus for saving anesthetics, in which the anesthetic not absorbed by the patient is adsorbed in a filter on exhalation and then desorbed out of the filter and reintroduced into the inhalation flow, i.e. a selective reflection of the anesthetic.
FIG. 1 illustrates an embodiment of the apparatus according to the invention, wherein the apparatus is connected to a respirator.
FIGS. 2-4 illustrate different embodiments of the adsorption filter appropriate for use in the apparatus according to the invention.
The invention thus comprises a method for reuse of anesthetics in inhalation anesthesia, wherein fresh gas is mixed with highly concentrated anesthetic from an anesthetics evaporator 3 in a collector conduit 1 leading into and out of a patient 2. The method is characterised in that, when the patient exhales, the exhalation gas is passed through an adsorption filter 5 disposed in the ingoing and outgoing collector conduit 1 and arranged distally relative to the outlet 4 from the anesthetics evaporator 3, as seen from the patient 2, the anesthetic being ad
REFERENCES:
patent: 3592191 (1971-07-01), Jackson
patent: 3867936 (1975-02-01), Kelley
patent: 3941573 (1976-03-01), Chapel
patent: 4200094 (1980-04-01), Gedeon et al.
Luttropp Hans-Henrik
Psaros Georgios
Thomasson Ronnie
Werner Olof
Lewis Aaron J.
Siemens-Elema Aktiebolag
Zenova Aktiebolag
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