| 摘要 |
The gas supply appts. comprises a three-way valve having its common port connected to a displacer (21) by way of a conduit (22). One of the two option ports is connected by a line to a supply of respirating gas, typically oxygen (24). Gas delivered through the line is maintained at a relatively constant pressure, typically about 20 psig, by means of a pressure regulator (25). The other option port is connected to a cannula or other delivery system (26) which terminates in nares or a mask (27). In use, oxygen flows directly to the displacer effecting a preset displacement equal to a unit dose, for one breath, of oxygen measured at standard conditions. It thus performs two distinct functions. Premeters or measures a quantity or mass of gas equal to the prescribed unit dose for one breath, temporarily parks or stores that premetered quantity, or unit dose and then releases that stored unit dose in synchronization with the onset or start of the patient's inhalation. |
