A dosing device for adding an additive gas or liquid to breathing gas in an anaesthesia machine or ventilator

摘要

A dosing device for adding small amounts of an additive gas or liquid, such as NO or liquid anaesthetic, to a breathing gas in an inspiratory line in an anaesthetic machine or ventilator, comprises a constant-volume dosing chamber (6). The dosing chamber has an inlet (2), equipped with a first valve (4), for connection to a source of gas or liquid supplying the additive gas or liquid at a predetermined, constant, positive pressure, and an outlet (10), equipped with a second valve (8), for injecting gas or liquid from the dosing chamber into breathing gas. Control means (20, 22) are arranged to open and close the valves (4, 8) in a controlled fashion. A control unit is also arranged to cause the operating means (20, 22) to open the second valve (8) for one or a plurality of predetermined intervals during the inspiratory phase.