# US 5,699,788 A · Anaesthetic system which is automatically switched to temporary operation as an open breathing system upon a change in an anesthetic, and method for operating same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,699,788 A - Document ID: US5699788A - Status: Granted - Kind: A - Application number: 08/645,501 - Filed: 1996-05-14 - Granted: 1997-12-23 - Earliest claimed: 1995-06-02 - Assignees: Siemens Elema AB - Inventors: Anders Lekholm; Leif W.ang.rd - Web page: https://patentgrep.com/patent/US5699788A ## CPC - A61M 16/104: {specially adapted for anaesthetics (A61M16/18 takes precedence)} - A61M 16/1015: {using a gas flush valve, e.g. oxygen flush valve} - A61M 16/202: {electrically actuated} - A61M 16/203: {Proportional} - A61M 16/20: Valves specially adapted to medical respiratory devices - A61M 16/209: {Relief valves} - A61M 16/22: Carbon dioxide-absorbing devices {; Other means for removing carbon dioxide}(cartridges with absorbing substances for respiratory apparatus A62B19/00) - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract An anaesthetic system, which can be switched between an open system and a rebreathing system, includes a breathing circuit, a setting unit and a switching unit. When the breathing circuit is connected as a rebreathing system and a change in anaesthetic concentration or a change of anaesthetic type is initiated via the setting unit, the switching unit automatically sets the breathing circuit as an open system for a predetermined period of time, at the end of which the breathing circuit is automatically reset as a rebreathing system. ## Claims ### Claim 1 In an anesthetic system comprising a breathing circuit, switching means for switching said breathing circuit between operation as an open system and operation as a rebreathing system, and setting means for setting a type of anesthetic and an anesthetic concentration, the improvement comprising: said setting means being connected said switching means and said setting means comprising means, when said breathing circuit is being operated as a rebreathing system, for automatically causing said switching means to switch said breathing circuit for operation as an open system for a predetermined period of time when a change in anesthetic is initiated via said setting means, and for automatically causing said switching unit to switch said breathing circuit back to operation as a rebreathing system after the expiration of said predetermined period of time. ### Claim 2 (depends on 1) The improvement of claim 1 wherein said setting means comprises means for causing said switching means to operate said breathing circuit as an open system for a predetermined period of time in a range between five seconds and three minutes. ### Claim 3 (depends on 1) The improvement of claim 1 further comprising: an anesthetic concentration meter, settable for respectively measuring different anesthetics, connected to said switching means, and wherein said switching means comprises means for automatically setting said concentration meter for measurement of a new anesthetic when a change in anesthetic is initiated via said setting means. ### Claim 4 (depends on 1) The improvement of claim 1 further comprising: an anesthetic concentration meter, settable for respectively measuring different anesthetics, connected to said setting means, and wherein said setting means comprises means for automatically setting said concentration meter for measurement of a new anesthetic when a change in anesthetic is initiated via said setting means. ### Claim 5 (depends on 1) The improvement of claim 1 wherein said setting means comprise a signal generator for generating a control signal upon said change in anesthetic, and wherein said switching means comprise a timer, supplied with said control signal, said timer generating an activation signal for said predetermined period of time following receipt of said control signal for operating said breathing circuit as an open system for said predetermined period of time. ### Claim 6 (depends on 5) The improvement of claim 5 wherein said signal generator comprises means for emitting said control signal with information identifying a duration of said predetermined period of time contained in said control signal. ### Claim 7 (depends on 5) The improvement of claim 5 wherein said switching means comprises a valve connected for interaction with said breathing circuit to control a flow path of a respiratory gas in said breathing circuit for causing said respiratory gas to selectively flow either in an open system or in a rebreathing system, said valve being connected to said timer and receiving said activation signal therefrom and causing said respiratory gas to flow in said breathing circuit as an open system as long as said activation signal is present. ### Claim 8 A method for operating an anesthetic system having a breathing circuit comprising the steps of: providing an anesthetic system comprising a breathing circuit and switching means; operating said breathing circuit as a closed system and administering anesthetic, via said breathing circuit, to a patient connected to said breathing circuit; initiating a change in anesthetic; upon said change in anesthetic, said switching means automatically switching said breathing circuit for operation as an open system for a predetermined period of time; and after expiration of said predetermined period of time, said switching means automatically resetting said breathing circuit for operation as a closed system. ### Claim 9 (depends on 8) A method as claimed in claim 8 wherein said anesthetic system includes an anesthetic concentration meter, settable for respective measurement of a plurality of different anesthetics, and comprising the additional step of: upon a change in anesthetic, automatically switching said anesthetic concentration meter for measurement of a new anesthetic.