An anesthetic vaporizer having a means of mixing the anesthetic agent with a relatively low flow of carrier gas or a larger amount of carrier gas. A valve is operable by the user to select between the high flow anesthesia where the carrier gas and anesthetic agent are mixed in a mixing chamber and the low flow anesthesia where the carrier gas and anesthetic agent are diverted directly into the patient circuit. Accordingly, the anesthetic vaporizer is usable for high flow anesthesia, however, when used for low flow, the diverted flow allows more rapid response by eliminating the large volume of the mixing chamber.
RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 08/137,209, filed as PCT/GB92/00751 Apr. 24, 1992, now abandoned.
The invention relates to a vaporizing having a vaporizing chamber which includes a gas inlet and a gas outlet. The vaporizing chamber accommodates a porous liquid delivery device which communicates with an external liquid source via liquid supplier. Liquid to be vaporized is exposed to the by-passing gas through the medium of the liquid delivery device. According to the invention, the liquid is exposed to the gas exclusively via the pores in the liquid delivery device and the liquid supplier are controllable. The vaporizer is intended for use in the treatment of patients, preferably for administering an anaesthetic. The present invention also relates to a vaporizing method applied with the aid of the inventive vaporizer.
A vaporizer for vaporizing a liquid anaesthetic has an inlet for a carrier gas, an outlet for the carrier gas and vaporized anaesthetic, a flow channel connecting the inlet to the outlet, a chamber for liquid anaesthetic, a first connection between the flow channel and the chamber, a second connection between the flow channel and the chamber downstream from the first connection and a throttle in the flow channel between the first connection and the second connection. The second connection has a conduit, one end of which is immersed in the liquid anaesthetic, and a valve connected to the other end of the conduit so as to increase safety, prevent leakage and erroneous dispensing and allow the use of liquid anaesthetics with a low boiling point. The valve is devised to open when there is a predetermined drop in pressure across the throttle, allowing liquid anaesthetic to be dispensed into the flow channel.
A portable anesthetic machine comprises a chassis having a cradle which removably receives a vaporizer, a control panel and a support member. The control panel and support member are pivotal relative to each other to selectively change the machine between carrying and use configurations. The control panel includes a gas flow path having gas inputs connectable to sources of carrier gases, a manifold which combines the gases, a carrier gas outlet and inlet connectable to the vaporizer input and outlet, respectively, a common gas port, and flow control devices to control the carrier gas flow rate and to control the anesthetic and carrier gas mixture. A controller is also provided which controls the flow of gas into and around the vaporizer to maintain a substantially constant concentration of anesthetic agent in the gas stream delivered to the patient without the need to adjust the flow of gases from the gas supply sources.
