[A patient-controlled analgesia system using a disposable balloon catheter, a PCA polyethylene reservoir and a one-way umbrella check valve].

A disposable continuous infuser with differently sized balloon pressure sources (20 ml-3 hr, 40 ml-12 hr and 40 ml-24 hr) with a pressure of approximately 100 mmHg (DIB international Co., Ltd., Tokyo), is connected to a PCA polyethylene reservoir using a Y-connector. Capacity variations of the reservoir are 1 ml (assuming subcutaneous dose), 3 ml (intravenous dose) and 5 ml (epidural dose or peroral dose). The other opening of the Y-connector is equipped with a one-way umbrella check valve (opening pressure, 320-370 mmHg) to prevent the analgesic solution from flowing medially unless the PCA polyethylene reservoir is pressed. By this system, various target lock-out times can be obtained by varying the type of disposable infusor. The target amount of on-demand doses is obtained by varying the capacity of the PCA polyethylene reservoir.