Patent ID: 7335186

Claim:
A delivery device for patient-controlled infusion of a medicament, the delivery device comprising: (i) a reservoir for the medicament, which reduces in volume as medicament is withdrawn from the reservoir; and (ii) a pump which has a predetermined delivery dose, wherein the pump comprises at least a first conduit which connects the reservoir to a pump chamber, a one-way valve in fluid communication with the first conduit and the pump chamber which permits medicament flow into the chamber but prevents reverse flow there from, a second conduit extending from the pump chamber and having a distal end through which the medicament may be released, and a controlling means in fluid communication with said pump chamber and said second conduit, wherein: (a) the first conduit is a fine calibre tube, which is capable of restricting the filling time of the pump chamber to greater than 1 minute, and is suitably adapted to restrict the flow of medicament into the chamber to a predetermined maximum delivery rate; (b) the controlling means: (i) opens when pressure within the pump chamber exceeds a pre-selected minimum opening pressure, said opening pressure being greater than 760 mmHg; (ii) is adapted to prevent the reverse flow of medicament and air into the pump chamber; and (c) the second conduit is adapted to release the medicament in the form of a spray; wherein after expulsion of medicament from the pump chamber a working interrelationship is formed between the fine calibre tubing and the controlling means to generate a lockout phase during which a patient is unable to effectively access a dose of medicament being drawn into the pump chamber until said chamber contains sufficient medicament to aid in treating said patient.