Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-12-08
2001-02-27
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06193689
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to an apparatus and process for regulating the rate that liquid flows through an intravenous (I.V.) set used to infuse liquids and drugs into humans and animals. More particularly, the present invention is directed to an I.V. liquid flow regulator that uses a wick and a vertical tube clamp to regulate the rate of flow.
2. Description of Related Art Including Information Disclosed Under 37 C.F.R. Sections 1.97-1.99.
Regulating the rate of flow through an I.V. set into a patient to achieve a desired or necessary rate of infusion of liquid or dissolved drugs is sometimes critical to successful patient treatment. Conventional I.V. sets alone do not regulate the rate of flow of liquid through them and into the patient. In these, after an initial air purge and set up, the operator adjusts the tube clamp to give the desire liquid flow setting. The conventional tube clamp is in effect a simple variable orifice device that roughly regulates the flow of liquid by squeezing the tube more or less tightly. Therefore, changes in either the upstream or downstream hydraulic conditions (as gauged from the tube clamp) will cause changes in the flow rate across the orifice. The upstream fluid head will gradually change as the fluid height in the I.V. bag or container slowly decreases. Because of the size of the container, however, and the relatively low flow rate, the change of flow rate due to the change of column height in the I.V. bag or container is slow and predictable. The change in flow rate below the tube clamp, however, has the largest unpredictable effect on the flow rate. Patient movement, such as rolling over, lifting an arm, standing, walking, sitting up and the like can cause significant changes in the patient's blood pressure, which substantially changes the rate at which the liquid will be infused into him. Further, by moving, the patient can clamp, or unclasp the vein that the catheter enters, changing the back pressure on the liquid in the I.V. set. Any movement, or even change in certain patient physiology, effectively alters the back pressure into which the catheter discharges. Additional, movement of the patient can cause the tube running to the catheter to be pinched or unpinched, changing the local flow restriction of the transport tube and the local pressure of liquid upstream of the catheter.
Changing any of these downstream conditions ultimately changes the pressure drop across the tube clamp of a common I.V. set, thus changing the flow rate from the desired settings.
Currently a number of different infusion pumps designed to provide a certain defined rate of flow and therefore infusion through an I.V. set are in use. The majority of these pumps use a roller pump designed to work against the plastic tubing of the I.V. set. Although these devices work well, they are quite expensive and can serve only one patient at a time.
Therefore, a demand exists for an I.V. liquid flow regulator that is simple, reliable, easy to manufacture and relatively inexpensive to the ultimate consumer.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide an I.V. liquid flow regulator that is simple in use and manufacture.
It is another object of the present invention to provide an I.V. liquid flow regulator that is reliable.
It is another object of the present invention to provide an I.V. liquid flow regulator that is inexpensive to the ultimate consumer.
These and other objects of the present invention are achieved by providing a vent directly below the conventional tube clamp. The vent is open to the air, but includes a means for preventing contamination of the I.V. liquid through the vent. By venting the regulating tube, the pressure drop of the I.V. system above the vent is isolated from the regulating tube. This arrangement allows the pressure head in the regulating tube to control the rate of flow of liquid through the I.V. liquid flow regulator. A wick of predetermined size and absorption characteristics inside the tube downstream of the tube clamp prevents the formation of bubbles in the transport tube under all normal conditions and a bubble separator further downstream removes any bubbles that may have been entrained in the system.
A bubble separator separates any bubbles from the flow of liquid through the I.V. set and, in two embodiments, is designed to positively separate any entrained bubbles from the I.V. liquid regardless of the orientation of the bubble separator in space.
Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, the preferred embodiments of the present invention and the best mode currently known to the inventor for carrying out his invention.
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patent: 4177808 (1979-12-01), Malbec
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patent: 4775482 (1988-10-01), Thurman
patent: 4861617 (1989-08-01), Pall et al.
patent: 4898581 (1990-02-01), Iwatschenko
patent: 4994022 (1991-02-01), Steffler et al.
patent: 5562638 (1996-10-01), Severs
patent: 5674200 (1997-10-01), Ruschke et al.
Iles Kenneth W.
Mendez Manuel
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