Liquid dispensing apparatus
First Claim
1. Apparatus for dispensing a predetermined quantity of liquid for infusion into a patient, which apparatus comprises a T-tube having a first arm, a second arm and a limb tube, of which the limb tube constitutes a reservoir for liquid and is closed at its free end to provide, in use, an air space above liquid in the reservoir;
- a first tube connected at one of its ends to said first arm of the T-tube and made of resiliently deformable material to enable the passage within said first tube to be closed at least partially, the other of the ends of said first tube being adapted for connection to a drip set containing the liquid which is to be infused into the patient;
a second tube made of a material having the same deformation property as said first tube and connected at one of its ends to said second arm of the T-tube and the other of its ends being adapted for connection to an infusion needle;
a first peristaltic pump operative to exert a pumping action on said first tube;
a first level detector external of and adjacent to said reservoir, and arranged to render said first peristaltic pump inoperative once liquid has been pumped into the reservoir to a predetermined datum level;
a second peristaltic pump operative to exert a pumping action on said second tube;
a second level detector external of and adjacent to said reservoir, and arranged to render said second peristaltic pump inoperative when liquid in the reservoir has fallen from said datum level to a predetermined lower level; and
control means arranged to control operation of said first and second peristaltic pumps cyclically such that, when said first tube is connected to said drip set and said second tube is connected to said infusion needle, operation of said first pump causes liquid from the drip set to be pumped through said first tube and into said reservoir until the level of liquid reaches said predetermined datum level whereupon said first level detector actuates the control means to render said first peristaltic pump inoperative and simultaneously to commence operation of said second peristaltic pump; and
operation of said second peristaltic pump causes liquid to be pumped out of the reservoir through said second tube and thence to the infusion needle until the level of liquid in the reservoir reaches said predetermined lower level, whereupon said second level detector actuates the control means to render said second peristaltic pump inoperative and to restart operation of said first peristaltic pump, whereby a predetermined quantity of liquid is dispensed from the infusion needle at regular intervals.
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Accused Products
Abstract
Liquid dispensing apparatus comprises a T-tube (9) of which the limb tube serves as a closed reservoir (8) for liquid, with an air space above. Liquid is pumped by a peristaltic pump (A) through a tube (6) and one arm of the T-tube into the reservoir until a level detector (D) responds to the liquid level in the reservoir reaching a datum level whereupon it renders the pump (A) inoperative. A further peristaltic pump (B) then starts to pump liquid from the reservoir out of the other arm of the T-tube and through tubes 13 and 15 to an infusion needle in a patient'"'"'s body. When the liquid level in the reservoir reaches a predeterined lower level detected by another detector (E), the second pump (B) is rendered inoperative and the cycle is then repeated starting with operation of the first pump (A).
The use of a peristaltic pump as the second pump (B) enables the liquid delivery pressure at the needle to be held just above the minimum necessary for infusion. Also, any air bubbles in the reservoir will generally migrate to the air space. Conveniently, the tube assembly comprising the parts 6, 9, and 13 constitutes a disposable assembly which is very cheap to manufacture.
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Citations
8 Claims
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1. Apparatus for dispensing a predetermined quantity of liquid for infusion into a patient, which apparatus comprises a T-tube having a first arm, a second arm and a limb tube, of which the limb tube constitutes a reservoir for liquid and is closed at its free end to provide, in use, an air space above liquid in the reservoir;
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a first tube connected at one of its ends to said first arm of the T-tube and made of resiliently deformable material to enable the passage within said first tube to be closed at least partially, the other of the ends of said first tube being adapted for connection to a drip set containing the liquid which is to be infused into the patient; a second tube made of a material having the same deformation property as said first tube and connected at one of its ends to said second arm of the T-tube and the other of its ends being adapted for connection to an infusion needle; a first peristaltic pump operative to exert a pumping action on said first tube; a first level detector external of and adjacent to said reservoir, and arranged to render said first peristaltic pump inoperative once liquid has been pumped into the reservoir to a predetermined datum level; a second peristaltic pump operative to exert a pumping action on said second tube; a second level detector external of and adjacent to said reservoir, and arranged to render said second peristaltic pump inoperative when liquid in the reservoir has fallen from said datum level to a predetermined lower level; and control means arranged to control operation of said first and second peristaltic pumps cyclically such that, when said first tube is connected to said drip set and said second tube is connected to said infusion needle, operation of said first pump causes liquid from the drip set to be pumped through said first tube and into said reservoir until the level of liquid reaches said predetermined datum level whereupon said first level detector actuates the control means to render said first peristaltic pump inoperative and simultaneously to commence operation of said second peristaltic pump; and
operation of said second peristaltic pump causes liquid to be pumped out of the reservoir through said second tube and thence to the infusion needle until the level of liquid in the reservoir reaches said predetermined lower level, whereupon said second level detector actuates the control means to render said second peristaltic pump inoperative and to restart operation of said first peristaltic pump, whereby a predetermined quantity of liquid is dispensed from the infusion needle at regular intervals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification