Patient-controlled medication delivery system with overmedication prevention

A medication delivery system comprising:

• an infusion pump including,
• a flexible fluid reservoir for storing a treatment fluid, said fluid reservoir having a treatment fluid inlet port and an inlet valve with an open position and a closed position,
• a rigid dosage chamber having a fluid outlet for the treatment fluid,
• a displacement piston slidably displacable within said dosage chamber,
• a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a flow restrictor;
• and
• an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with said treatment fluid from said fluid reservoir at a charge flow rate controlled by said flow restrictor while said inlet valve remains in said closed position blocking said treatment fluid inlet port and transitionable from said less stressed position to said more stressed position to discharge said treatment fluid from said dosage chamber via said fluid outlet, wherein said elastic member displaces said displacement piston in a first direction away from said fluid outlet to expand said dosage chamber when said elastic member transitions from said more stressed position to said less stressed position, and wherein said displacement piston is displaced in a second direction toward said fluid outlet to contract said dosage chamber when said elastic member transitions from said less stressed position to said more stressed position;
• and
• a medicine catheter having first and second ends, wherein said medicine catheter is in fluid communication with said fluid outlet of said dosage chamber, and wherein said first end of said medicine catheter is positionable in a treatment site of a patient to deliver the treatment fluid to the treatment site.

An infusion pump for delivering a medical treatment fluid to a patient comprising:

• a fluid reservoir;
• a dosage chamber;
• a displacement piston displacable within said dosage chamber;
• a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a passive flow restrictor;
• and
• an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with the medical treatment fluid from said fluid reservoir at a charge flow rate controlled by said passive flow restrictor and transitionable from said less stressed position to said more stressed position to discharge the medical treatment fluid from said dosage chamber, wherein said elastic member displaces said displacement piston in a first direction to expand said dosage chamber when said elastic member transitions from said more stressed position to said less stressed position, and wherein said displacement piston is displaced in a second direction to contract said dosage chamber when said elastic member transitions from said less stressed position to said more stressed position.

An infusion pump for delivering a medical treatment fluid to a patient comprising:

• a fluid reservoir;
• a dosage chamber;
• a displacement piston displacable within said dosage chamber;
• a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a passive flow restrictor having a fixed length and a fixed cross-section;
• and
• an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with the medical treatment fluid from said fluid reservoir at a charge flow rate controlled by said passive flow restrictor, wherein said fixed length and said fixed cross-section are selected to produce the controlled charge flow rate.

A method for charging a dosage chamber of an infusion pump with a liquid medical treatment fluid comprising:

• providing a fluid reservoir containing a liquid medical treatment fluid and a dosage chamber containing a displacement piston;
• providing fluid communication between said fluid reservoir and said dosage chamber via a charge flowpath, said charge flowpath including a passive flow restrictor having a fixed length and a fixed cross-section;
• displacing said displacement piston in said displacement chamber to create a positive pressure differential between said fluid reservoir and said dosage chamber;
• and
• driving said medical treatment fluid from said fluid reservoir through said charge flowpath into said dosage chamber by said positive pressure differential at a charge flow rate controlled by said passive flow restrictor, wherein said fixed length and said fixed cross-section are selected to produce said controlled charge flow rate.