Drug infusion with pressure sensing and non-continuous flow for identification of and injection into fluid-filled anatomic spaces

An apparatus for administering fluid into a fluid-filled anatomic space capable of receiving fluid at a lower pressure than tissues surrounding the anatomic space, the apparatus comprising:

• a disposables assembly comprising:
• a syringe having a body for containing a fluid to be injected into the anatomic space, the syringe having a plunger movable in one end of the body for dispensing fluid from an opposite end of the body,
• tubing permanently connected to the opposite end of the body,
• a needle connected to the tubing and having a point insertable into a subject and movable through tissues surrounding the anatomic space, for seeking the anatomic space, and
• an in-line pressure transducer for generating a signal corresponding to an instantaneous pressure at the point of the needle;
• a drive unit mechanically connected to the syringe and electrically connected to the pressure transducer, the drive unit including
• a controller with a computer, a memory for storing a first selected pressure (P1) that is selected to be compatible with injecting fluid into the fluid-filled anatomic space and a second selected pressure (P2) that is below the first selected pressure (P1) by a first selected amount,
• a motor connected to and controlled by the computer, and
• a syringe armature connected to the motor and mechanically connected to the syringe for moving the plunger into and out of the body for respectively injecting and aspirating fluid at the point of the needle for injecting and aspirating fluid into and out of the subject;
• and
• the computer being programmed to control the motor to move the plunger to provide fluid flow into the subject until the first selected pressure (P1) is detected by the pressure transducer at which time the motor is stopped to stop the flow of fluid to the subject until the instantaneous pressure at the point of the needle drops below the second selected pressure (P2), at which time the program resumes operation of the motor to resume fluid flow to the subject, so that as the needle is moved in tissues of the subject surrounding the fluid-filled anatomic space, fluid flow to the tissues stops at instantaneous pressures above the first selected pressure (P1) and resumes when the instantaneous pressure falls below the second selected pressure to then resume injecting fluid into the anatomic space.