Abstract: A syringe for injecting medicinal fluids into a patient or aspirating fluids or tissue from a patient, wherein the syringe incorporates a self-locking mechanism on the plunger thus preventing the plunger from being withdrawn back into the barrel by the action of a vacuum in the syringe barrel. The self-locking mechanism is independent of the relative rotational relationship of the plunger with respect to the barrel. Unlocking may be effected by simply squeezing the self-locking mechanism on the plunger, no rotational force being necessary.

Abstract: A locking syringe selectively operable in either of a freely reciprocating or a restricted, threaded mode. A trigger attached to the plunger includes internal threads on the interior of the barrel of the syringe and external threads located on the plunger on a spine slidable in a longitudinal slot in the plunger. A handle is affixed to the plunger, and a retraction bar is rigidly secured to the spine. The threads on the plunger may be retracted from engagement with the threads on the barrel, thereby placing the syringe in its freely reciprocating mode. The trigger, which is spring biased to engage the external and internal threads, employs a plurality of ramps and channels disposed at approximately the same angle to the longitudinal axes of the plunger and barrel as are the threads. A pawl is pivotally securable on the retraction bar at a position receivable into a pawl receiving aperture on the handle when the receiving bar is in its first position permitting reciprocating movement of the plunger.

Abstract: An electronically controlled syringe system for connection to a balloon catheter or other balloon-type member and for automatically monitoring, displaying and recording inflation data when the syringe system is used to inflate the balloon of the catheter or other balloon-type member. A syringe having a barrel and a syringe plunger is selectively operable to increase fluid pressure applied to the balloon catheter or other balloon member by sliding the plunger further into the barrel. Positive pressure applied to the balloon catheter or member is released by withdrawing the syringe plunger toward the rear of the barrel. A piezoresistive semiconductor transducer housed on the barrel of the syringe senses fluid pressure applied by the syringe.

Abstract: A syringe apparatus is described which has a novel adaptor assembly used for mounting a strain gauge to the syringe barrel. The adaptor assembly includes a housing in the form of a well formed on the distal end of the syringe barrel, and a housing insert which fits into the well and which caps the well when fully inserted. The housing insert in turn receives the mounting post of a strain gauge without having to thread the mounting post of the strain gauge into the housing insert. The housing insert properly aligns the mounting post of the strain gauge with an opening in the syringe barrel that provides fluid communication for purposes of reading pressures in the syringe barrel, and also properly rotationally orients the strain gauge so that the dial of the strain gauge is readable from the proximal end of the syringe apparatus.

Abstract: An electronically controlled syringe system for connection to a balloon catheter or other balloon-type member and for automatically monitoring, displaying and recording inflation data when the syringe system is used to inflate the balloon catheter or other balloon-type member. A syringe having a barrel and a syringe plunger is selectively operable to increase fluid pressure applied to the balloon catheter or other balloon member by sliding the plunger further into the barrel. Positive pressure applied to the balloon catheter or member can be released by withdrawing the syringe plunger toward the rear of the barrel. A piezoresistive semiconductor transducer housed on the barrel of the syringe senses positive fluid pressure applied by the syringe.

Abstract: A syringe and method for use which may be selectively operated between a freely reciprocating position and a restricted position. A triggering means configured with a trigger attached to the plunger of the syringe is employed. The triggering means includes threads located external of the plunger and corresponding threads internal of the barrel of the syringe. Upon actuation of the trigger, the threads on the plunger are retracted from their position of engagement with the threads on the barrel, thereby placing the syringe in position for free sliding movement of the plunger with respect to the barrel. The trigger is biased to the engaged position so that if the trigger is released, the threads on the plunger return to their position of engagement with the threads on the barrel. In the restricted position, the plunger may be screwed into or out of the barrel by rotating the plunger, enabling the operator of the syringe to maintain strict control over the amount of pressure in the syringe.