Patent EA-004154-B1 (EA)
Title: Infusion of liquids into the human or animal body
Inventor: MAKKINK ANDREW EUGENE
IPC: A61M5/168
Filed: 2001-05-25
Abstract: 1. A method of operating an infusion device infusing an infusing liquid into the human or animal body, the method including maintaining a constant level of said infusion liquid in a pressure control device which is in flow communication with a reservoir of said liquid, feeding said infusion liquid under a constant liquid head commensurate with said constant level of said infusion liquid via a first flow line section which is connected to a flow control device which is separate of and remote of the pressure control device, dispensing by means of the flow control device the infusion liquid at a predetermined flow rate, and conducting the infusion liquid at said predetermined flow rate, via a second flow line section to an infusion needle infusing said infusion liquid into the human or animal body. 2. A method as claimed in claim 1 which includes maintaining said first flow line section in constant orientation. 3. A method as claimed in claim 1 or claim 2 which includes sensing a level of said infusion liquid in the pressure control device by means of a sensor which is adapted to generate a signal for indicating a low level condition. 4. A method as claimed in claim 3 including, when a low level condition occurs, triggering an alarm by means of said signal. 5. A method as claimed in any one of the preceeding claims, which includes an earlier step of pre-calibrating the flow control device to dispense the infusion liquid at the predetermined flow rate. 6. A method as claimed in any one of the preceeding claims which includes the step of fine adjustment of the flow control device to dispense the infusion liquid exactly at the predetermined flow rate. 7. A method as claimed in any one of the preceding claims, including dispensing the infusion liquid at said predetermined flow rate in the form of droplets, counting the droplets by means of a sensor system connected to an electronic counter against time, and, when a droplet count moves outside of a predetermined range, actuating an alarm. 8. An infusion device for use in infusing an infusion liquid into the human or animal body, the infusion device including: a pressure control device including a chamber, an inlet and an outlet, a connector for connecting the inlet of the chamber in flow communication to a reservoir of infusion liquid, a level control mechanism for controlling a level of said infusion liquid in the chamber at a constant level, a flow control device including an orifice and an adjustable restrictor arranged, adjustably, to restrict flow through the orifice to a desired degree such as to dispense the infusion liquid at a selected flow rate, a first flow fine section connected at an upstream end thereof to said outlet of said chamber of the pressure control device by means of said connector, the first flow line section leading to the flow control device remote from, and at a relatively lower level to, the pressure control device, a downstream end of said first flow line section being connected to the flow control device a second flow line section connected at an upstream end thereof to the flow control device for receiving and conducting to an infusion needle the infusion liquid dispensed by the infusion device for infusion into the human or animal body. 9. An infusion device as claimed in claim 8 in which the flow control device includes: a drip chamber having an inlet by means of which the flow control device is connected to the downstream end of the first flow line section; a droplet inducer in said drip chamber arranged upstream of the orifice, the droplet indicator being arranged to drip infusion liquid to allow the droplets to be counted. 10. An infusion device as claimed in claim 8 or claim 9 in which said pressure control device includes a vent hole at a high level through a wall of the chamber to subject said level of infusion liquid in the chamber to atmospheric pressure, in which said outlet from the chamber of the pressure control device is surrounded by a seat, in which said level control mechanism includes a float in said chamber and which is buoyant in said infusion liquid, an inlet closure connected to the float at an upper end thereof and being aligned with said inlet into the chamber to close the inlet when the level of infusion liquid in the chamber rises above a predetermined limit, an outlet closure connected to the float at a lower end thereof and aligned with said seat such as to close onto said seat to close the outlet against communication with the atmosphere via said vent hole when the level of infusion liquid in the chamber drops below a predetermined lower limit, one of said seat in the outlet and said outlet closure being of a material which is a silicone based polymer material and which is more pliable than the other of said seat in the outlet and said outlet closure, to enhance the integrity of sealing. 11. An infusion device as claimed in claim 10 which further includes a sensor arranged to sense dropping of the float beyond a predetermined level, and an alarm responsive to said sensor to indicate an alarm condition. 12. An infusion device as claimed in any one of claim 9 to claim 11 which further includes a counter responsive to said sensor to count droplets against time. 13. An infusion device as claimed in claim 12 which further includes an alarm responsive to said counter to indicate an alarm condition when the droplet count falls outside of a predetermined range.