Precise dosing syringe assembly

A syringe assembly for pre-setting a precise fluid dose comprising:

• a barrel formed by a cylindrical body having an interior chamber configured to contain a total volume of fluid, a distal end for dispensing the fluid contained in the interior chamber, and a proximal entrance having an outer rim;
• a plunger comprising a plunger rod having a proximal thumb press;
• and
• a repositionable locking clip mounted on the plunger rod between the thumb press and the proximal entrance of the barrel, the locking clip comprising:
• a gripping portion configured to be manually actuated by a user to transition the locking clip between a locked configuration and a released configuration;
• one or more engagement features configured to engage the plunger rod in the locked configuration to prevent sliding movement of the locking clip along the plunger rod, and to disengage from the plunger rod in the released configuration to permit sliding movement of the locking clip along the plunger rod;
• and
• a stop surface sized such that an outer extent thereof exceeds the inner diameter of the proximal entrance of the barrel,
• wherein the locking clip is repeatedly repositionable to different selected positions along the plunger rod at any time after the barrel contains fluid and without requiring rotation of the locking clip relative to the plunger rod, such that each selected position determines a selected maximum dispensable volume when the plunger is subsequently advanced distally until the stop surface contacts the outer rim of the proximal entrance during fluid dispensing,
• wherein, when the plunger is advanced distally during fluid dispensing and the stop surface contacts the outer rim of the proximal entrance, the one or more engagement features engage the plunger rod to prevent further longitudinal movement of the locking clip relative to the plunger rod, thereby limiting the dispensed volume to the selected maximum dispensable volume of fluid, and
• wherein the barrel is configured to receive fluid either by aspiration through the distal end or as a prefilled syringe.

A method of preparing and administering a precise fluid dose using a syringe assembly, the method comprising:

• (a) providing a syringe assembly comprising:
• a barrel having a proximal entrance with an outer rim and filled with fluid;
• a plunger with a plunger rod extending proximally from the barrel, the plunger rod comprising a plurality of indentations spaced longitudinally along the plunger rod;
• and
• a locking clip mounted on the plunger rod proximal to the barrel;
• (b) selecting a maximum dispensable volume of fluid based on patient parameters;
• (c) positioning the locking clip on the plunger rod at a selected position corresponding to the maximum dispensable volume of fluid by sliding the locking clip longitudinally along the plunger rod without rotating the locking clip, such that a portion of the locking clip will contact the outer rim of the proximal entrance of the barrel when the plunger is advanced to a position corresponding to dispensing the maximum dispensable volume of fluid;
• and
• (d) advancing the plunger distally to dispense the fluid, wherein a dispensed volume does not exceed the maximum dispensable volume of fluid.