Patent GB-1297794-A (GB)
IPC: A61M39/00
Filed: 1969-12-18
Abstract: 1297794 Apparatus for administering medicines PALL CORP 18 Dec 1969 [27 Dec 1968] 61663/69 Heading A5R [Also in Divisions B1 and F1] A disposable liquid medicament administration assembly comprises a syringe 20, Fig. 1, acting as a reciprocating pump and being connected to one arm 14 of a twin valve having non-return inlet and outlet valves 12, 73 and three arm connector 10, the other two arms of connector 10 being connected to tubing 5 for communication with a supply reservoir and to tubing 16 connected to an air eliminator 30 which removes gas from the liquid being administered, the downstream side of the air eliminator being connected to means for delivering the liquid to a patient, such as a hypodermic needle 41. Tubing 5 is connected to a visual flow indicator 1 communicating with the reservoir from which, on the suction stroke of the syringe pump, fluid flows via non-return valve 12 into a chamber 54 in connector 10 and into syringe 20. On the pressure stroke of the syringe pump, fluid flows therefrom via non-return valve 73 into the air eliminator and thereto the patient. The volume of the chamber 54 is less than 1c.c. and preferably less than 0.1 c.c. The valves 12, 73 are preferably duckbill valves, a resilient foamed material spring (13), Fig. 3 (not shown) assisting in closing valve 73. Part of the fluid entering the air eliminator flows into a deadend-tube air cushion 34 compressing the air therein, the fluid flowing out of air cushion 34 on the suction stroke of the syringe pump into the air eliminator 30 thereby reducing fluid pressure peakes due to the reciprocating action of the pump. The degree of fluid penetration into air cushion 34 depends on the fluid pressure which may be measured by means of calibrated graduations 35. The syringe pump comprises the syringe 20 which is attached by spring clips to the base of a pump drive system (21), Fig. 5 (not shown) having a pivoted lever (25) with one end connected to the syringe plunger 22 and with a slot (26) formed in its other end. An electric motor driven eccentric pin (23) engages in slot (26) to oscillate lever (25) about its pivot to thereby reciprocate plunger 22. The air eliminator 30, Fig. 6, comprises a disc-like housing 50 having a central annular part 56 within which is a chamber 80 having two opposed walls formed by a liquid-wetted filter 76 and a liquid-repellant filter 64. An air-liquid mixture enters chamber 80 and is separated into air which passes through filter 64 only and via a perforated sheet 69 to a venting port 32, and liquid which passes through filter 76 only and via a perforated sheet 75 to an outlet 36. Alternatively sheets 69, 75 may be eliminated, channels being formed in the housing itself adjacent the filters for permitting flow of air and liquid to the outlets, the housing either being a flat disc-like structure, Figs. 13-15 (not shown) or curved for positioning against a patient's limb, Figs. 10-12 (not shown). A further type of air eliminator, Figs. 8, 9 (not shown) comprises a cylindrical housing (90), the filters being concentric cylindrical tubes supported by stainless steel mesh tubes. Suitable materials for the filters and methods of preparation thereof are described.