Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1996-03-26
1998-03-17
Buiz, Michael Powell
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604260, A61M 500
Patent
active
057280770
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to intravenous delivery systems.
BACKGROUND OF THE INVENTION AND SUMMARY OF PRIOR ART
The infusion of large volumes such as 500 to 1000 ml of intravenous solutions is typically carried out by hanging a container above the level of the patient in order to achieve flow by gravity. Infusion can also be achieved by pumps and pressure means and many such devices are known in the art for example, EP 0,321,996 and U.S. Pat. Nos. 4,722,732, 5,735,497 and 5,163,909 all disclose devices of varying complexity that pressurise a solution container to control delivery of intravenous solutions.
The infusion of solution by gravity presents significant problems for staff setting and controlling the infusion rate. With collapsible intravenous solution containers, a further problem encountered is the difficulty in determining the amount of solution infused. The bags are usually transparent with calibrated scales printed on the exterior. The amount of solution delivered is determined by checking where the meniscus of the solution is on the calibrated scale.
Flow rate of solution is typically controlled by adjusting a roller clamp on the plastics tubing which connects the intravenous solution container to the patient. Plastic creep in the tubing at the point of impingement of the roller causes a change in internal dimensions of the tubing and a result change in flow rate. Thus, it is necessary to reset the roller clamp from time to time.
Normal production variations in the wall thickness of the tubing also causes difficulty in setting repeatable flow rates. These problems are further compounded by changes in the head pressure as the intravenous solution container empties. For a one litre bag, the variation in head pressure is in the order of 12%.
A further problem with gravity feed of intravenous solution is that of shutting down flow before the container empties. Because of the changes that occur in flow rates as set forth above, medical staff can expend excessive time in checking the container for runout as it is not possible to assess accurately the time at which a container should empty.
Pressure driven infusion devices exist which correct for all the above difficulties but these devices are expensive and the solution administration sets used with these devices are also expensive. Furthermore, specialist staff is usually required to operate and maintain such pressure driven devices. It is therefore foreseen that there is a need for a cost effective gravity feed intravenous system that is easy to use and reliable. Previous attempts to control pressure variation through change of head pressure in gravity systems have been complicated and expensive and fail to provide a simple and effective means of determining the volume of solution that has been delivered at a particular time. U.S. Pat. Nos. 2,578,374, 2,771,878, 4,137,915 and 4,455,139 disclose examples of such systems.
It is, therefore, an object of the invention to provide an intravenous delivery system that maintains a constant head of pressure.
SUMMARY OF THE INVENTION
According to the present invention there is provided an intravenous delivery system for delivering a volume of solution to a patient intravenously from a solution container positioned above the patient and coupled to the patient via a length of narrow flexible tube, said system comprising frame means to support the solution container above the solution delivery outlet, means to raise the container as it empties to ensure a constant head of pressure, and a pointer displaceable about a calibrated scale on the frame means, the pointer being adapted to move with the container to provide visual indication of the volume of solution delivered to the patient.
Preferably, the solution container is suspended from an arm that extends laterally from the frame means, the pointer being constrained by the frame to move up and down the calibrated scale as the container moves.
In a preferred embodiment, the solution container is a flexible bag that is hung from a rolle
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Taylor Rodney John
Williams Robert Paul
Buiz Michael Powell
Gring N. Kent
Health Care Technology Australia PTY. Ltd.
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