Abstract:
A sterile intravenous flow valve includes in-line valve mechanism which is maintained sterile in all of its positions. The valve also includes an adjustment member and a locking mechanism for selectively locking the adjustment member in place to thereby assure accurate flow rate settings. Sterility is achieved by providing a sealed chamber formed by a snap-fit engagement between the adjustment member and the main body member of the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part application of our co-pending U.S. patent application Ser. No. 168,722, filed July 14, 1980, now U.S. Pat. No. 4,332,369 and entitled &#34;Adjustable In-Line Intravenous Valve With Locking Mechanism&#34;. That patent is expressly incorporated herein, in its entirety, by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to control valves in systems for parenteral fluid infusion. More specifically, the present invention relates to a valve which, although simple and inexpensive to manufacture, permits accurate and reliable adjustable settings of intravenous liquid flow rate. 
     BACKGROUND OF THE INVENTION 
     In administering intravenous fluids to a patient, control of flow rate is critical. If the amount of administered fluid delivered in a given period of time varies considerably from the prescribed dosage rate, the results can be of serious consequence and are often fatal. The most common types of adjustable flow control used today is a clamp device which pinches the IV (intravenous) tubing by an adjustable amount. It has been well documented in the medical literature (see &#34;Flow Rate Maintenance and Output Intravenous Fluid Test Sets&#34;, Demorouelle, et al., American Journal of Hospital Pharmacy, Vol. 32, pages 177-185, February 1975; and &#34;Regulatory Intravenous Fluid Flow: Controller versus Clamps&#34;, Ziser, et al., American Journal of Hospital Pharmacy, Vol. 36, pages 1090-1094, August 1979) that such clamps are unable to maintain constant flow rates for any reasonable period of time. The main cause of the problem in this regard is &#34;creep&#34;, a phenomeon wherein the plastic tubing diameter, when under stress, continues to change. In addition, the settings of these prior art IV clamps are accessible to curious patients and susceptible to variation upon movement by the patient. Thus, while adjustable IV clamps are very inexpensive, they represent a considerable sacrifice when it comes to maintaining accurate dosage rates. 
     On the other end of the cost spectrum, the prior art contains automatic systems for precisely maintaining selectable IV flow rates. These systems are generally made up of electrical pumps, sensors and controllers and, for most applications, are prohibitvely expensive. As a consequence, it is estimated that sales of such systems comprise less than ten percent (10%) of the available market, whereas the much less accurate but inexpensive adjustable clamps account for substantially all other sales. 
     Still another approach to adjustable IV flow control is in the in-line valve characterized by a valving mechanism which is adjustably inserted directly into the flow path of the IV fluid. Examples of in-line IV valves may be found in U.S. Pat. Nos. 3,880,401 (Waltse); 4,079,737 (Miller); 3,877,428 (Seagle, et al.) and 3,868,973 (Bierman, et al.). Such in-line valves tend to be more accurate than the adjustable clamp and far less expensive than the automatic control system. However, such in-line valves have not obtained a meaningful share of the relevant market for two (2) primary reasons. First, the in-line valves are sufficiently more complex and expensive to manufacture than the clamp valves as to make comparative cost an important factor to the user. Second, although not subject to the &#34;creep&#34; pehonomenon, the in-line valve is still subject to twiddling by a curious patient and to inadvertent setting variation during patient movement or inadvertent manipulation by health care personnel. 
     Valves for use in controlling administration of intravenous fluid must not introduce contamination of that fluid. In the case of in-line valves, this means that the valving mechanism must remain sterile in all of its adjustable positions. While sterility of a valving mechanism can be readily achieved for an in-line adjustable valve, the resulting valve is usually quite expensive and not readily suitable for a throw-away device. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an inexpensive device for controlling IV flow rate which provides an accurate and maintainable setting and which is not subject to inadvertent setting variation. It is a further object of the present invention to provide a device of the type described wherein setting changes by curious patients are considerably minimized. It is still another object of the present invention to provide an in-line valve wherein the valving mechanism remains sterile and does not contaminate the controlled fluid. 
     In accordance with the present invention, and inexpensively fabricated IV control valve includes an elongated body member having a longitudinal bore passage defined therethrough and adapted for connection in an IV line. A sluice gate type of valve is adjustably positioned in the bore passage by means of a bolt which threadably engages a bore in the handle and is controlled by an adjustment knob. The adjustment knob is positioned to be easily turned between the user&#39;s thumb and forefinger when the member is grasped in the user&#39;s palm. A brake lock, preferably formed as an integral part of the handle member, is arranged to snap into a locking position, wherein a brake surface is urged against the adjustment knob to prevent movement of the knob and maintain a constant valve setting. Other forms of valve locking may be used. 
     Sterility is achieved in one embodiment by providing a sealed chamber for the gate member and threaded bolt by a snap-fit engagement between the adjustment member and the main body of the valve. In this embodiment, the threaded bolt remains longitudinally stationary but threadedly engages the gate member which is movably positioned in the bore passage as the threaded bolt is rotated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The embodiments of the present invention will become more clear when taken in conjunction with the drawings, wherein: 
     FIG. 1 is a view in perspective of the valve and locking mechanism of the present invention; 
     FIG. 2 is a plan view in section of the valve and locking mechanism of FIG. 1; 
     FIG. 3 is a view in section taken along lines 3--3 of FIG. 2; 
     FIG. 4 is a view in section taken along lines 4--4 of FIG. 2; 
     FIG. 5 is a view similar to FIG. 4 of a different locking mechanism suitable for use in the present invention; 
     FIG. 6 is an exploded view of another valve embodiment of the present invention; 
     FIG. 7 is a view in longitudinal section of the valve of FIG. 6; and 
     FIG. 8 is a view in section along lines 8--8 of FIG. 7. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more specifically to the drawings, the valve of the present invention includes an elongated body member generally designated by the reference numberal 10. Body member 10 and other valve parts described below can be made from plastic polymers, nylon, teflon, stainless steel, rubber, etc. Body member 10 should be somewhat longer than the width of an average adult palm and, in one embodiment, is approximately four and one-half (41/2) inches in length. The thickness of the thickest part of that embodiment is approximately one and one-quarter (11/4) inches. It should be noted that these dimensions are by way of example only and that neither the dimensions nor the exact contours of the device as illustrated, are limiting features of the present invention. Body member 10 is sub-divided lengthwise into two (2) sections, a handle section 11 and a control section 12. Handle section 11 may be longitudinally ribbed, as shown, to facilitate grasping of that section without rotation in the palm of a user. Control section 12 is described in greater detail below. 
     A bore passage 13 extends longitudinally through body member 10 and terminates in respective nipples of projections 14, 15 at opposite ends of the body member. These nipples or projections are adapted to receive ends of IV tubing 40, 41 so that the valve may be inserted directly into an IV line. Of course, other convention means of engaging IV tubing may be employed, the important feature being that bore passage 13 is disposed in series in the IV line. 
     The control section 12 of body member 10 includes a slot 16 extending longitudinally through most of the control section length from the end of the body member in which the control section is located. Slot 16 extends entirely through the thickness of the control section 12 so that the slot is open at both sides and at one end. A transverse threaded cylindrical bore 17 extends radially from bore passage 13 into communication with slot 16. Across slot 16 from the termination of bore 17, there is defined a cylindrical recess 18 which is coaxially aligned with bore 17 but smaller in diameter. 
     A control member 20 includes adjustment knob 21 in the form of a flat circular disc. From one side of the center of knob 21 there extends a retainer pin 22 adapted to be received in recess 18. An adjustment pin 23, threaded to engage bore 17, extends perpendicularly from the center of the opposite side of knob 21. Pins 22 and 23 are coaxially aligned but, as is the case with bore 17 and recess 18, adjustment pin 23 has a larger diameter than retainer pin 22. A gate member 24 is journaled in the end of adjustment pin 23 remote from knob 21. Gate member 24 is adapted to move transversely across bore passage 13, in adjustable degrees of flow blocking relationship, as the adjustment pin rotates in bore 17 due to rotation of adjustment knob 21. A slot 19 is defined in part of the periphery of bore passage 13 opposite bore 17 and contoured to receive the peripheral portion of gate member 24. The control member is readily inserted into position, with pin 22 in recess 18 and pin 23 in bore 17, by flexibly spreading the opposite walls of slot 16. The diameter of knob 21 is sufficiently great to permit the knob to project somewhat out of the slot 16 to permit access by a user. 
     The primary feature of the present invention involves a locking member 26 which is arranged to maintain adjustment knob 21 in the position to which it has been set. In the preferred embodiment illustrated, locking mechanism 26 is formed integrally with body member 10 and is located at the end of the body member which contains the control section 12. The locking member is in the form of a flap 28, secured to the body member at one side of slot 16 and arranged to pivot about a region or line at which it is secured. The other or remote end of the flap includes a projection 27, adapted to mate with and be retained in a suitably provided notch 29 located in the body member on the opposite side of slot 16 from the pivot region. A brake surface 30 is positioned to project into slot 16 and bear firmly against the rim of knob 21 when locking member 26 is closed (i.e., when projection 27 is engaged in notch 29). To further secure the locking function, the brake surface 30 and the rim of knob 21 may be ribbed or knurled, as illustrated in FIG. 4, to provide a gear-like mating arrangement. 
     In use, with locking arrangement 26 open, a nurse or other health care personnel grasps handle section 11 across the palm, leaving the control section 12 and, in particular knob 21, accessable between the thumb and forefinger. Knob 21 is adjusted until the desired IV flow is achieved through IV tubes 40, 41 by viewing the drip rate in a conventional manner. When the desired flow rate is achieved, locking mechanism 25 is closed by snapping projection 27 into notch 29. This forces brake surface 30 against knob 21 and precludes inadvertent movement of the knob. Moreover, the locking arrangement serves as a psychological barrier to conscious or sub-conscious twiddling of the valve by a curious patient. Since there is no clamping of a plastic tube, there is no &#34;creep&#34; phenomeon and the IV flow rate remains constant. 
     The locking mechanism need not be a brake type lock of the type described above. For example, as illustrated in FIG. 5, a detect lock arrangement may be employed whereby the rim of knob 21 is provided with a plurality of special recesses 33 and the brake surface 30 is replaced by a projection 34 adapted to be received by whichever recess 33 radially faces the projection. 
     It should also be noted that the in-line valve itself need not be a sluice gate type valve but may be a globe valve, butterfly valve, ball valve, etc., the important point being that the valve adjustment device can be selectively locked in place. 
     The particular valve described herein is advantageous in that it is very inexpensive to manufacture. The valve includes three (3) parts, namely the body member 10, control member 20, and gate member 25. If locking member 26 is made as a separate piece (whereby it may be pivoted by a pin or the like), additional but simple parts are required. However, it is quite simple to make a pivotal locking member integral with the body member by using, for example, thin-walled polypropylene at the joint between the locking and body members. In either case, the valve is sufficiently inexpensive to justify single use disposability without sacrificing setting accuracy. 
     The valve assembly is inserted into an IV line between two tubes 40, 41 such as standard polyvinylchloride, flexible Tygon, or like medical grade tubing at a convenient level to permit the IV drip chamber to be easily viewed. The unit may be placed in line by the supplier of the tubing 40, 41 or by a technician under sterile conditions. Tubing clamps may be provided if the connection is to be made in situ. 
     Depending upon the specific design of the valve of FIGS. 1-5, it is possible that the valve will not maintain its sterility. Specifically, gate member 24 which comes into direct contact with the sterile intravenous fluid, may be subjected to a non-sterile environment when raised into and partially above the threaded bore 17. The intravenous fluid can therefore become contaminated. The valve embodiment illustrated in FIGS. 6 and 7 overcomes this problem by providing a sterile chamber in which the threaded pin and gate member reciprocate. This valve embodiment is described below with specific reference to FIGS. 6, 7 and 8, wherein the various elements bear the same reference numerals employed for similar elements in FIGS. 1-5. 
     The body or handle section 11, having fluid bore passage 13 defined longitudinally therethrough, has a slot 51 extending transversely through the body member entirely across passage 13. Slot 51 is larger in length and width than the diameter of bore passage 13. The transverse cross-section of slot 51 (i.e., parallel to the longitudinal dimension of bore 13) is substantially rectangular with rounded ends so that the slot approximates an ellipsoid. The flat sides of the ellipsoid slot correspond to walls through which the interrupted segments of bore passage 13 are defined. In other words, the segments of bore 13 terminate in flat walls of slot 51. In addition, the depth of slot 51 extends below bore 13. 
     An annular rim 53 formed as an integral part of body member 11, extends upwardly into slot 16 above slot 51. An annular recess 55 is defined in the inner walls of rim 53 just below the upper lip of the rim. The diameter of rim 53 is greater than the length of slot 51 between its rounded ends. 
     Control member 20 is provided with an integral annular rim member 57 which is concentrically disposed about a short length of threaded pin 23. The outer surface of rim 57 is provided with an annular protuberance 58 sized to engage recess 55 in a snap-fit engagement which permits rim 57 to be rotated within rim 53. The outer diameter of rim 57 is substantially equal to the inner diameter of rim 53 so that the rims form a sterile seal when engaged by the snap-fit. 
     Gate member 59 has a transverse cross-section configuration which exactly matches that of slot 51. A threaded bore 61 is defined longitudinally into gate member 59 throughout most of the length of the gate member. The threads of bore 61 mate with the threads of pin 23 which is threadedly insertable into bore 61 at variable depths. Gate member 59 is preferably made of a low friction plastic material so that it can be moved in slot 51, when snuggly fitted therein, by turning knob 21 to vary the length of pin 23 disposed in bore 61. In operation, a sterile region is formed by rims 53, 57 so that the threaded pin 23 and gate member 59 are not exposed to contaminates in the ambient environment. Gate member 59 is raised or lowered in slot 51 by rotating knob 21 relative to rim 53. The knob 21 and threaded pin 23 remain longitudinally or axially fixed due to the snap-fit engagement of protuberance 58 in recess 55. On the other hand, gate member 59 is precluded from rotating within slot 51 by the similar substantially rectangular or ellipsoid contours of the slot and gate member. Thus, as pin 23 is rotated, its depth in bore 61 changes to force the gate member to be raised or lowered in slot 51. The gate member is therefore capable of blocking flow between the two segments of bore 13 for providing controlled communication between those segments as it is moved in the slot. This control is continuous and depends upon the depth of insertion of the threaded pin 23 within bore 61. 
     The knob locking mechanism for the embodiment of FIGS. 6 and 7 is substantially the same as described in relation to FIGS. 1-5 and is therefore not described in detail herein. 
     The present invention is not to be limited to the embodiments as herein described and illustrated, for numerous modifications can be made by a person skilled in the art without detracting from the true spirit and scope of the invention as defined in the appended claims.