Valves and valve actuation – Tube compressors – Roller tube contacting element
Reexamination Certificate
2001-11-01
2003-03-25
Yuen, Henry C. (Department: 3754)
Valves and valve actuation
Tube compressors
Roller tube contacting element
C251S004000
Reexamination Certificate
active
06536739
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of flow control devices and more particularly to a rack and pinion clamping system to regulate flow of fluid or gases in flexible conduits, e.g., medical tubing in extracorporeal dialysis procedures.
BACKGROUND OF THE INVENTION
Flexible conduits or tubing carrying liquids or gases are used presently in the medical and pharmaceutical industries, as well as in laboratory settings, the chemical industry, the ink and print industries, and for photographic development. These uses are aided by the ability to fixedly open and reliably close the flexible conduit, and in some cases to establish stable partial flow as well.
For instance, many modem medical procedures require the use of flexible tubing to Withdraw fluid from a patient, or to administer fluid to a patient, or to do both. Such procedures include intravenous feeding blood transfusions and blood processing, and both peritoneal dialysis and hemodialysis. Typically, a catheter is temporarily or semi-permanently implanted in the patient, where it is connected in some manner to the appropriate tubing set necessary for the procedure that is to be performed.
In hemodialysis, the patient's blood is cleansed by drawing it out of the patient though a catheter and passing it through an artificial kidney. Patients in hemodialysis treatment typically require treatment several times a week for several hours each time. In peritoneal dialysis, a peritoneal dialysis solution is infused into the patient's peritoneal cavity and allowed to reside there for a “dwell time” during which blood impurities diffuse through the peritoneal membrane into the dialysis solution. The dialysis solution with the collected impurities is then removed from the peritoneal cavity and discarded.
Many of these procedures require tubing that can be readily opened and closed, either by the medical practitioner or by the patient in the more ambulatory treatment protocols. For example, a peritoneal dialysis patient will often have a semi-permanent implanted catheter in the peritoneal cavity which extends to outside the patient. The exterior end may then be attached to a tubing segment which in turn is usually attached to a connector, perhaps to a bag of fluid for intake, or to a collection device. A reliable system for opening and closing such tubing is essential; a system that also allows for the controlled constriction of the tubing at less-than-fully-open settings would be a bonus.
Pinching and clamping devices are well known, and historically involved a butterfly or alligator clip placed manually along a clampable portion of the tubing or conduit. Rarely was this more than an opened versus closed setting, though certain screw-type clamps were devised to provide adjustable flow and control. These adjustable methods of flow control generally required two hands to apply or adjust, however; most such closure mechanisms are also small and slippery in conditions common in a surgical unit.
An improvement in these devices involved a roller or rolling cam placed in near proximity to the flexible conduit. This was accomplished by pressuring an intermediate constriction device, as in U.S. Pat. No. 4,335,866 (Bujan 1982), or by rolling an externally ribbed wheel or gear in a track, either by direct roller-clamp restriction of the conduit, as in U.S. Pat. No. 3,135,259 (Evans 1964), and U.S. Pat. No. 3,099,429 (Roman 1963), or by rotating a cam that oblated the conduit along its longitudinal line with a V-shaped wedge, as in U.S. Pat. No. 4,911,399 (Green 1990). This latter approach of necessity requires a supporting channel or groove to keep the conduit centered under the impending wedge.
In the operation of existing devices, the user faces a number of problems. Wherever the rolling wheel or clamping means is exposed to facilitate manual control (usually a forward-or-back thumb action along the barrel or case), body fluids or congealing debris can clog the opening, impairing use. Similar material can find its way onto the ribbed wheel, or the operator's thumb, and cause slippage. When the moveable clamp is other than fixed rigidly in a track over the conduit, lack of traction can keep the clamp from being moved into its fully constricted position. The ability to fix and hold one or more middle positions is difficult, if available at all. Moreover, in some of the existing devices, the conduit must be trapped in a channel to ensure that the rotating clamp can restrict it fully, a channel which often complicates the threading of the conduit through the barrel or body of the flow control device, and adds design expense and detail to the interior of the barrel or case.
SUMMARY OF THE INVENTION
The present invention is a flow control device for regulating flow of fluids or gases in flexible conduits, with particular but by no means exclusive application in intravenous delivery systems using flexible tubing, as well as peritoneal dialysis and hemodialysis tubing sets. The flow-control device of the present invention comprises a case or barrel which houses a rack and pinion system which can slidably restrict one or more flexible conduits in the case, from a fully opened to a fully constricted flow. Intermediate restrictive settings may be achieved by a plurality of pre-set engagements comprising a means to “click in” or flexibly and reversibly ratchet along the rack. The case is preferably closed (it could be designed to be waterproof), with manual or machine control of the constrictive settings via a means to slide or rotate the pinion gear assembly, accomplished in one embodiment by an external and ergonomically pleasing slide assembly with ribs or flanges in one embodiment, connecting into the case with an upper rack engaging an adjustable clamping means, preferably a pinion gear assembly comprising rotatable gears, capping the ends of a bisected cylinder shaft.
The present device generally comprises the following: a case or barrel assembly, a rack and pinion assembly interior to the case assembly, and a slidable means that can engage the clamping means of the pinion gear assembly against the flexible conduit. The parts of the invention may all be made by injection molding. The invention may be advantageously pre-assembled, as where the flexible conduit is affixed inside the case to a receiving connector, or threaded by a user through the passage provided in the case. In one embodiment, the case is capped at each end with a port or opening as part of the tubing throughway, said cap preferably comprising a replaceable end piece. In a preferred embodiment, the assembly is sufficiently flexible that it can be snapped together but pried apart by ordinary hand strength.
The case assembly of the invention contains a lower surface for supporting a length of flexible tubing; this surface should be flat or otherwise capable of resisting compression where the pinion gear assembly constricts the conduit. As shown in one embodiment, no guides to seat the conduit are needed along this lower surface so long as the tubing throughway is maintained medially to the teeth of the pinion gear assembly. In a further embodiment, the lower surface has tracks or bilateral gear racks integral to the lower surface; other embodiments may have a single or bilateral rack assembly inserted above the lower surface or otherwise projecting from the side walls.
Whenever by design the clamping face of the pinion gear assembly is unable to achieve a position fully constricting the tubing at some point inside the case, a ramp or other inflexible means may be added along the opposing portion of the lower surface to ensure constriction of the flexible conduit.
The case or barrel is further comprised of opposing side walls extending generally in the vertical plane from and along the longitudinal axis of the lower surface, but possibly cylindrically or irregularly so long as the rack and pinion assembly can readily engage the pinion gear assembly to reliably constrict the conduit therein. Each sidewall may be grooved or shelved or designed to
Bastianelli John
Fresenius USA, Inc.
Gibson Dunn & Crutcher, LLP
Yuen Henry C.
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