| 摘要 |
A breathing apparatus is described for supplying pulses of a breathable gas to a patient; the apparatus comprises a gas inlet (10) connectable to a source of breathable gas, an outlet (37) connectable to provide gas to the patient, a gas flow passage (14, 15, 34, 36) extending between the inlet and the outlet, a main valve (16) located in the gas flow passage for interrupting the flow of gas to the outlet, a throttle (38) in the flow passage downstream of the main valve, a gas reservoir (42) and a valved duct (40, 44) connected to supply gas to the reservoir from the part of the flow passage between the main valve and the throttle; the main valve includes a piston (24) that is slidable within a cylinder (22) to open and close the gas flow passage, which piston is biassed in one direction by a resilient member (28) and biassed in the other direction by the gas pressure within the reservoir. When the main valve is open and gas flows from the source to the patient, gas leaks into the reservoir along valved duct (40, 44), thereby increasing the pressure in the reservoir (42); this continues until the pressure in the reservoir is sufficient to overcome the spring (28) when the piston moves to close off the gas flow passage. Gas can leak via the valved duct (40, 44) into the flow passage until the pressure in the reservoir falls to a level that allows the spring to move the piston to re-open the flow passage. |
