Locking syringe with integrated bias member

Abstract

A locking syringe with an integrated bias member, for delivering medical fluids at high pressure, can include a housing, a shaft, a piston, a cap assembly, a bias member, and a locking member. A distal end of the housing can interface with a patient delivery apparatus. The housing includes an internal cavity into which a distal end of the shaft can be inserted. The piston can be connected to the distal end of the shaft and can include a peripheral sealing surface that can slidably engage the inside surface of the housing to form a movable seal. The cap assembly at the proximal end of the housing can engage the shaft. A base cap can secure the piston within the housing. The bias member can have a distal end coupled to the piston and a proximal end restrained, such as to help pressurize the internal cavity. The user-actuatable locking member can user-selectively engage and inhibit unwanted movement of the shaft.

What is claimed is: 
     
         1 . An apparatus comprising:
 a housing including a hollow interior cavity, a distal end, and a proximal end, the distal end configured to interface with a medical device and including an opening into the hollow interior cavity;   a plunger including a shaft and a piston at a distal end of the shaft, the piston including a peripheral sealing surface configured to slidably engage an inside surface of the hollow interior cavity of the housing to form a movable seal, the shaft extending beyond the proximal end of the housing;   a bias member with a distal end coupled to the plunger and a proximal end restrained proximate to the proximal end of the housing, the bias member configured to assist the plunger in pressurizing the hollow interior cavity of the housing; and   a user-actuatable locking member configured to user-selectively inhibit unwanted movement of the plunger when engaged.