Externally powered syringe drivers and systems and methods for using them

A syringe driver for use with an external air source, comprising:

• a housing comprising a proximal end including a port communicating with a gas chamber within the housing and connectable to the external air source, and a distal end including a cavity sized to receive a syringe containing an agent;
• a drive piston comprising a first end slidably disposed within the gas chamber and a second end comprising a plunger connectable to the syringe received within the cavity, the drive piston movable from an initial proximal position to a distal position when gas is delivered from the air source into the gas chamber to generate pressure within the gas chamber that applies a distal force to advance the first end of the drive piston within the gas chamber, thereby advancing the second end of the drive piston and the plunger to deliver the agent from the syringe;
• and
• a damping fluid chamber including a damper piston disposed therein between a first region of the damping fluid chamber filled with damping fluid and a second region of the damping fluid chamber, and one or more passages or valves communicating between the first region and the second region such that movement of the drive piston between the proximal and distal positions causes the damping fluid to flow through the one or more passages or valves from the first region to the second region, thereby limiting movement of the drive piston,
• wherein the one or more passages or valves comprises one or more passages in the damper piston that communicate between the first and second regions.

An injector device for use with an external air source, comprising:

• a housing comprising a proximal end including a port communicating with a gas chamber within the housing and connectable to the external air source, and a distal end;
• an agent chamber within the distal end including an agent piston and an outlet port extending from the distal end;
• a drive piston comprising a first end slidably disposed within the gas chamber and a second end comprising a plunger connected to the agent piston, the drive piston movable from an initial proximal position to a distal position when gas is delivered from the air source into the gas chamber to generate pressure within the gas chamber that applies a distal force to advance the first end of the drive piston within the gas chamber, thereby advancing the second end of the drive piston, the plunger, and the agent piston to deliver the agent from the from the agent chamber through the outlet port;
• and
• a damping fluid chamber including a damper piston disposed therein between a first region of the damping fluid chamber filled with damping fluid and a second region of the damping fluid chamber, and one or more passages or valves communicating between the first region and the second region such that movement of the drive piston between the proximal and distal positions causes the damping fluid to flow through the one or more passages or valves from the first region to the second region, thereby limiting movement of the drive piston,
• wherein the damping fluid chamber is located within the drive piston such that the damping fluid chamber moves distally with the drive piston as the drive piston moves from the proximal position to the distal position to cause the damping fluid to flow between the first region and the second region.