| 摘要 |
A syringe actuation device comprises an internally-threaded hollow outer sleeve with an open proximal end, and an externally-threaded hollow cylinder with a tapered internal diameter, that encloses a spring-biased piston, and that threads into the open distal end of the sleeve. The outer sleeve has a longitudinal opening parallel to its axis for receiving the fully-extended plunger of a pre-filled syringe, and a distal wall portion through which the barrel of the syringe extends. The cylinder contains a coil spring extending axially within its hollow interior, the spring having a proximal end seated against a proximal end wall of the cylinder, and a distal end attached to the proximal side of the piston. The piston is attached to the distal end of the spring so as to be pivotable from a canted orientation with respect to the cylinder's axis when the spring is compressed, to a substantially coaxial orientation with respect to the cylinder's axis when the spring is extended to a less compressed state. This pivoting function is facilitated by the tapered internal diameter of the cylinder, which decreases toward the distal end of the cylinder. This pivoting of the piston tends to equalize the axially-directed force component applied by the spring to the plunger as the spring decompresses, thereby substantially reducing the difference in flow rate from the syringe between the beginning and the end of the infusion process. |
