| 摘要 |
A lung ventilator which changes over automatically to provide either ventilation or to allow for natural breathing has an oxygen inlet (1) connected through a pressure regulator (2) and a flow regulator (4) to a reservoir (7). A secondary supply to the reservoir (7) takes place through a NOT unit (10). Oxygen from the reservoir (7) is supplied to a face mask connection (29) either through a demand valve (34) or through a second flow regulator (18) and a spool valve (26). The spool valve (26) is controlled by a pneumatic timing system (20-25) and the oxygen from the reservoir either flows intermittently through the spool valve (26) which is opened and closed by the timing system to provide ventilation or, it is supplied through the demand valve (34). Changeover from one supply to the other and back again is controlled in dependence upon the pressure in the reservoir (7). When there is a demand supply through the valve (34), this is greater than the gas supply through the regulator (4) and in consequence when the pressure in the reservoir (7) falls to a predetermined minimum value, the NOT unit (10) opens to provide an increased oxygen flow to the reservoir. |
