Patent ID: 7022107

Claim:
An infusion device for continuous delivery of a quantity of fluid into a living body at a substantially constant flow-rate over an extended period of time, comprising: a variable volume storage chamber for holding the fluid, said storage chamber including means for allowing fluid to be added to the storage chamber, a pressurizing means for the storage chamber, said pressurizing means maintaining the pressure within the storage chamber above a preselected outflow pressure, an outflow chamber for receiving fluid from the storage chamber, said outflow chamber including means for attachment thereto of a flow restrictor means and catheter through which fluid in the outflow chamber is delivered to a patient, and a pressure responsive valve means located between the storage chamber and the outflow chamber, said pressure responsive valve means functioning to maintain the fluid in the outflow chamber at the preselected outflow pressure, said pressure responsive valve means providing for fluid transfer from the storage chamber to the outflow chamber at a flow rate substantially equal to or greater than the flow rate out of the outflow chamber so that there is a continuous, uninterrupted and controlled volume of flow from the outflow chamber through the flow restrictor means and catheter to the patient over said extended period of time, wherein said pressure responsive valve means comprises: a valve attached to a flexible diaphragm such that the pressure of the fluid in the outflow chamber acts on the diaphragm to close the valve to prevent flow of fluid from the storage chamber to the outflow chamber when the pressure in the outflow chamber is elevated to the preselected outflow pressure, and a force applying means attached to the flexible diaphragm such that the force applied acts to open the valve when the pressure in the outflow chamber is less than the preselected outflow pressure, thereby allowing fluid in the storage chamber to enter the outflow chamber and the pressure in the outflow chamber to be held at a substantially constant preselected outflow pressure.