| 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 the second flow-restricting orifice, and a bolus dose delivery mechanism including a chamber in fluid communication between the upstream portion and the downstream portion. Continuous flow is provided through the first flow-restricting orifice, the chamber, and the second flow-restrictive orifice, the continuous 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 the 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 decompressed position by the flow of fluid into the chamber. |
