Abstract: A vaporizer for delivery of a volatile medium to a gas flow, the vaporizer comprising: a gas delivery unit (3) which receives a flow of gas and provides a flow of gas containing a metered amount of a vaporized medium; a reservoir unit (5) which contains a volatile medium and maintains a supply of the vaporized medium, wherein the reservoir unit is selectively fluidly connected to the gas delivery unit; a gas sensing unit (7) for sensing a flow rate and/or composition of the gas flow; a vaporized medium sensing unit (9) for sensing a flow rate of the vaporized medium; a manifold (10) which includes flow paths for the vaporized medium and fluidly connects the reservoir unit and the vaporized medium sensing unit; and a control unit (11) for controlling a flow rate of the gas flow and an amount of the vaporized medium which is metered into the gas flow.

Abstract: Anaesthesia equipemnt comprising an anaesthesia unit such as a vaporizer detachably mounted on a mounting rack by connecting means comprising guide means to provide substantial leak-proof engagement of the connecting means.The guide means may comprise an elongated pin or tongue mounted on the unit or rack to cooperatively engage an aperture groove or slot on the rack or unit respectively to substantially prevent movement of the unit towards or away from the rack when mounted thereon.

Abstract: An apparatus for controlling the flow of gas to and from a patient in an anaesthesia system has first and second flow passages arranged in parallel between the patient and a reservoir bag. Selector valves allow multiple anaesthesia configurations involving no rebreathing or considerable rebreathing. A selector valve can be operated to connect the reservoir bag to either or both flow passages. A one way valve in the first passage, which communicates with a gas supply inlet, can be operated to prevent the back flow of gas from the patient into the passage. A one way valve in the second passage can selectively prevent the flow of gas in the second passage to the patient. The second passage has a selectively bypassable carbon dioxide absorbing fitter and a spill valve. The apparatus allows reconfiguration without disconnecting and reconnecting hoses.

Abstract: An apparatus and method for analysing a gas of the kind adapted to produce an interference pattern displacements of which are indicative of changes of the constitution of the gas involves exposing an array 8 of photosensitive elements to the interference pattern. Respective digital indications of the intensity of the interference pattern falling of the elements are produced by means of a timing circuit 16 adapted to clock data out of the array 8 as a series of analogue pulses which are held by a fast peak detector 17 and converted by an analogue-to-digital converter 18 into digital indications. The position of a principal peak of the interference pattern is then determined by means of a microprocessor (not shown) adapted to determine the best fit of the digital indications with appropriate pre-stored values.

Abstract: Gas mixing and flow smoothing apparatus for use in for example an anaesthesia system comprises a mixing chamber (8) which receives the flow of two or more gases via control valves (6,7). The mixing chamber (8) is adapted to absorb fluctuations in the pressure of the gases therein through the provision of for example a spring-loaded piston (not shown) which forms one wall of the chamber, and the pressure at the outlet (30) from the chamber (8) is maintained at a substantially constant pressure by means of a valve (9). If desired, further attenuation of the gas flow may be achieved through the provision of a second series arrangement of surge damper (11) and back pressure valve (10) located downstream from the valve (9).

Abstract: An apparatus and method for humidifying gases, suitable for use in conjunction with a high frequency positive pressure ventilation (HFPPV) respiratory system, includes a nebulizing chamber 11 arranged to receive a pulsed gas flow from an oscillating valve 5 and a liquid reservoir 15 communicating with the chamber 11 such that in use liquid from the reservoir 15 passes into the chamber and is entrained in droplet form by the gas flow. A pump 20 is intermittently operable to introduce a predetermined quantity of liquid into the reservoir 15, and control means 6 of the apparatus are adapted to maintain the valve 5 in its closed condition during operation of the pump 20.