| 摘要 |
A PCA device includes a fluid conduit having an upstream portion and a downstream portion, a first flow-restricting orifice in the upstream portion, a second flow-restricting orifice in the downstream portion, a pressure-responsive check valve in the downstream portion in parallel with t he second flow-restricting orifice, and a bolus dose delivery mechanism includi ng a chamber in fluid communication between the upstream portion and the down- stream portion. Continuous flow is provided through the first flow-restricting orifice, the chamber, and the second flow-restrictive orifice, the continuou s flow serving to fill the chamber at a controlled rate through the first flow- restrictive orifice. The bolus dose delivery mechanism is manually actuable to express t he contents of the chamber through the check valve to supplement the continuous flow through the downstream portion. The bolus dose delivery mechanism includes a resilient diaphragm that forms a sealed closure for the chamber. The diaphragm is movable from a decompressed position to a compressed position by a plunger that directly engages the diaphragm, and it is restored to the de-compressed position by the flow of fluid into the chamber. |
