Abstract:
An intravenous fluid administration apparatus may include a proximal conduit having a spiked first end for attaching to a reservoir of fluid and a second end, a distal conduit, an intermediate conduit network providing fluid communication from the proximal conduit&#39;s second end to the distal conduit and including first and second constituent conduits that provide parallel paths from the proximal conduit to the distal conduit, a flow regulator so engaged with the first constituent conduit as to enable control of fluid flow therethrough, and a pressure-responsive valve so interposed in the second constituent conduit as to permit flow from the proximal conduit to the distal conduit through the second constituent conduit when a fluid pressure difference across the valve exceeds a threshold and to prevent such flow when the difference does not exceed the threshold.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is the National Stage of International Application Ser. No. PCT/US2006/024864, filed Jun. 27, 2006, which claims the benefit of U.S. Provisional Application Ser. No. 60/694,401, filed Jun. 27, 2005, the entire contents of which are hereby incorporated herein by this reference. 
    
    
     BACKGROUND 
     Intravenous fluids are administered in almost all situations where invasive procedures are performed, where patients require repeated doses of injectable medications, where fluids or blood products are administered, and where a variety of tests are performed, as well as elsewhere. In order to regulate the volume of intravenous fluids that flow into a patient over a given period of time, thumb-wheel compression regulators are universally used. These thumb-wheel regulators (TWR) are manufactured in all intravenous fluid system tubing sold in the United States. Though the TWR is effective in controlling the rate of fluid infusion, it also acts as a restrictor when fluids need to be given rapidly. Though the TWR may be dialed “open” during this period, it may be cumbersome, especially when only an acute “bolus” of fluid is required, e.g., fluid used to flush an emergency drug into the patient. 
     Standard intravenous lines typically include: a) a proximal “spike and drip chamber” which is used to puncture a latex (or latex like) diaphragm on an intravenous fluid bag or bottle, or on a medication bottle, b) a length of PVC tubing, c) a TWR which is used to regulated the flow of fluid from the raised bag or bottle, and d) a distal connector which may be attached to a compatible intravenous catheter, or other components. 
     These systems allow the administration of fluids and drugs at a relative rate. The rate of fluid flow will depend on a) the height of the intravenous bag or bottle above the patient (e.g., gravity dependent), b) the set point of the TWR, c) the internal diameter of the intravenous catheter and d) resistance at the catheter-patient interface. Maximal flow will occur with the intravenous bag or bottle raised as high as the tubing and extension tubing will allow, a completely disengaged TWR, a large diameter intravenous catheter and a zero resistance catheter-patient interface. 
     Because of the limit of the length of tubing, the availability of large veins to accept large diameter catheters and non-zero resistance at the catheter-patient interface as flow through these systems may be slow. When flow is too rapid, the TWR is used to apply a restriction to flow. 
     When a drug must be delivered to the patient via the intravenous system, it is typically injected into an intravenous port or at the three-way stop cock. Once within the intravenous line, the rate of fluid flow of fluids from the intravenous bag or bottle will determine how rapidly the medication reaches the patient. This rate may not be rapid enough for the clinical situation. If the TWR is restricting flow, the caregiver may disengage the TWR, and then reengage it after he or she believes enough fluid flow has carried the medication into the patient. Often, and especially if flow in the system remains restricted after the disengagement of the TWR, a syringe is used at the injection port or three-way stop cock, to withdraw fluid (with negative pressure applied to the syringe) from the intravenous bag or bottle, which is then injected into the patient in order the “bolus” the medication to the patient (this is virtually impossible if the TWR is partially or fully engaged). Another way that flow may be increased is by squeezing the intravenous bag, creating a positive pressure force. If the TWR is not reengaged, the patient will continue to receive increased fluids, which, in some circumstances, may be detrimental. 
     In the neonate and infant population fluids are carefully regulated. Failure to reengage a TWR after a drug delivery can be devastating. Additionally, in this patient population, small boluses of fluid (e.g., 5 to 10 cc) may be used therapeutically (e.g., for hypotension). This requires constant disengage-reengagement of the TWR. Again, an error here may be devastating. 
     SUMMARY 
     The present disclosure describes a system for bypassing the TWR to allow rapid fluid (liquid) bolus injection. The system may allow an operator to withdraw (from an intravenous fluid bag) and inject a small amount of fluid through the intravenous line, without adjusting the TWR, to aid in medication delivery, improve patient care and save the caregivers time and energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a generic intravenous administration set. 
         FIG. 2  depicts a generic intravenous administration set with add on components. 
         FIG. 3  depicts an exemplary embodiment of a bypass valve having a ball bearing and spring mechanism. 
         FIG. 4  depicts an intravenous administration set that includes a bypass valve. 
         FIG. 5  depicts an exemplary embodiment of a bypass valve as an add on component to a generic intravenous administration set. 
         FIG. 6  depicts an exemplary embodiment of a bypass valve as an integral part of an intravenous administration set. 
         FIG. 7  depicts an exemplary embodiment of a one-way pressure-operated valve separate from a thumb-wheel regulator. 
         FIG. 8  depicts an alternative exemplary embodiment of a bypass valve with a plunger and spring mechanism. 
         FIG. 9  depicts an exemplary embodiment of a bypass valve with a clip applied to the proximal annular ring. 
         FIG. 10  shows a top view of the proximal annular PVC ring with the ball bearing in place. 
         FIG. 11  shows a top view of the proximal annular PVC ring with the ball bearing in place, with the clip distorting the shape of the annular ring. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides a system for acutely bypassing the flow restriction of the universally used thumb-wheel regulator (TWR) on intravenous fluid administration lines. This bypass may be required when an emergency medication is administered to the patient via an established intravenous infusion line, as well as when non-emergency medications are given, or in other circumstances in which the administration of a bolus is desired. 
     The Intravenous Fluid Bypass Valve (IVFBV) is an integral TWR-valved conduit. The IVFBV may function as a TWR in its neutral state. When a significant negative pressure is applied distal to the IVFBV (e.g., by a syringe attached to the intravenous port or three-way stopcock), the conduit valve opens and allows free flow of fluid past the TWR portion. When negative pressure ceases, the valve closes and the TWR once again functions to restrict flow. When positive pressure is applied to the valve (e.g., by the squeezing of the intravenous bag) the valve opens, allowing increased flow. The valve closes when positive pressure is released. Flow may then resume at the rate set by the TWR without having to re-set the TWR. 
     In one exemplary embodiment, a bypass valve may include: a) a Y-split in the intravenous tubing, b) an opaque or clear housing split by a septum into two longitudinal chambers, c) a TWR wheel on the lateral surface of one chamber, which progressively restricts flow in the intravenous tubing as its position is changed, d) a one-way, pressure operated valve in the second chamber (detailed below), and e) Y-rejoining of the intravenous tubing as it leaves the chamber. 
     The one-way valve may be selected, constructed, and/or arranged so that it will not open below a threshold pressure difference across the valve. The threshold pressure difference may be so selected as to exceed the normal pressure difference across the valve created by the fluid in the tubing and bag above the valve. In this way, the pressure of ordinary flow will not be sufficient to open the valve; instead, additional pressure must be applied to open the valve. The additional pressure may be supplied, for example, by squeezing the IV bag proximal to the valve or by suctioning using a syringe distal to the valve. 
     The one-way, pressure operated valve may reside completely within a length of intravenous like PVC tubing, within the second chamber of the housing. This tubing is of larger diameter than the remaining tubing of the intravenous system to allow for flow restriction caused by the valve mechanism. The proximal and distal ends of the valve are demarcated by annular rings of PVC (molded as part of the valve tubing). The centers of these annular rings are the lumens of fluid flow into and out of the valve. A ball bearing made of stainless steel, plastic, or other material sits beneath the proximal (intravenous bag/bottle side) ring, obstructing the lumen in the neutral state. Beneath the ball bearing is a spring, holding the ball bearing into the lumen of the proximal annular ring. The distal end of the spring is held in place on the distal annular ring. 
     Regardless of the position of the TWR, as negative pressure is applied to the distal system (via a syringe at the distal injection port or stopcock), or as positive pressure is applied to the proximal system (via pressure on the intravenous bag), the valve opens and flow is momentarily increased. Once negative or positive pressure is relieved, the valve closes, and the system is once again regulated by the position of the TWR. The rate of fluid flow is immediately returned to the rate which had been set by the TWR previously. 
     The IVFBV may be an integral part of an intravenous administration system, acting as the TWR for the system. The IVFBV may also be used as an “add-on” device between the intravenous administration system and the patient (then used as an add-on the TWR of the intravenous administration system would be disengaged at all times. 
     Additional components which may be added include a) a one way flow valve, b) an injection port for medication administration, c) a stop-cock, such as a three-way stop-cock, or d) extension tubing. 
     The tubing distal to the IVFBV may include a sideport for receiving a needle or needleless syringe for addition of fluid to the intravenous line. 
     In some embodiments, the bypass valve need not be enclosed by a housing. 
     In some embodiments, a bypass valve may include a one-way pressure-operated valve as described connected to proximal and distal lengths of tubing. The proximal tubing may connect to one branch of a proximal Y-split, with the stem of the proximal Y-split having a spike for introducing into a fluid bag. The other branch of the proximal Y-split may be configured to receive the tubing of a generic intravenous set that would normally be attached directly to the fluid bag. The distal tubing may incorporate or connect to a distal connector, such as a Y-split, a stopcock, or other connector, that engages a downstream device, such as a catheter, injection port, etc. The connector may be, for example, a luer lock or a needle, among other things. The distal connector may also receive the tubing of a generic intravenous set that would normally be attached to the downstream device. This arrangement may be well-suited for “retrofitting” existing generic intravenous sets with a bypass valve. 
     An alternative configuration of the IVFBV employs a plunger-shaped valve stop. The annular PVC rings and spring are similar to that described above. The plunger handle faces downwards within the spring. The plunger head sits on top of the spring and, in the neutral position, seals against the underside of the proximal annulus. Other valves may be used in place of the ball- and plunger-valves described, such as disc valves, check valves, and flapper valves, among others. 
     In some embodiments, the IVFBV may include a clip mechanism that pinches and distorts the proximal PVC annular ring from a circular to an oval opening. This clip would allow for the conduit chamber to fill with fluid when the IV fluid bag is spiked, in order to rid the entire system of air before connecting the system to the patient. The IVFBV may also include an air vent to facilitate purging the line of air when it is hooked to an IV bag. The vent may be a one-way valve that permits air to leave the system but not to enter it. The IVFBV may also include a bulb pump to facilitate drawing up and administering a bolus. 
     Other examples of one-way valves include a duck valve and a one-way flap valve. 
       FIG. 1  shows a standard intravenous administration system. Universally, these include a fluid bag  1  spike and drip chamber  2 , intravenous tubing  3 , TWR  4 , and an adaptor  5  for a compatible intravenous catheter. 
       FIG. 2  shows the additional components that are commonly added to the standard intravenous administration set, including a three-way stopcock  6 , injection port  7 , extension tubing  8 , and intravenous catheter  9 . 
       FIG. 3  shows the IVFBV with the Y-split in the IV tubing  11 , the housing  12 , including a septum  13  within the housing, the conduit bypass valve  10 , which includes the two PVC rings  14 , a ball bearing  15 , and spring  16 . The TWR  4  adjusts the flow of fluid in a parallel tubing. An air vent  22  provides a route for air to leave the system as the tubing fills with fluid. 
       FIG. 4  depicts an intravenous administration set that includes a bypass valve  10 . 
       FIG. 5  shows the IVFBV as it might be used as an add-on component to a standard intravenous administration set. 
       FIG. 6  shows the IVFBV manufactured as an integral part of an intravenous administration set, with a syringe  17  attached to the stopcock  6 . 
       FIG. 7  depicts a bypass valve in which the one-way pressure-operated valve  30  is separate from the TWR  4 . The pressure-operated valve is attached to proximal tubing  31  which is connected to one branch of proximal Y-split  32 . The stem of the proximal Y-split is inserted in an IV fluid bag. The pressure-operated value is also attached to distal tubing  33  which is connected to distal connector  34  (shown as a stopcock). A traditional IV set extends from the other branch of the proximal Y-split to the distal connector. 
       FIG. 8  demonstrates an alternative embodiment with annular PVC rings and the spring in a position similar to that described above. The plunger handle  18  faces downwards within the spring. The plunger head  19  sits on top of the spring and, in the neutral position, seals against the underside of the proximal annulus. 
       FIG. 9  demonstrates the IVFBV with a clip  20  applied that distorts the shape of the proximal annular PVC ring. 
       FIG. 10  shows a top view of the proximal annular ring, which is in the shape of a doughnut  14  and the ball bearing underneath the ring  15 , shown here in a dotted line. The housing  12  contains the septum  13  on the side of the annular ring. 
       FIG. 11  shows the annular ring  14  distorted with the clip  20  in place, which allows fluid to enter the valve without pressure applied (either positive or negative). The tab  21  coming off the clip holds the clip in place on the housing  12 , and the clip can be removed by detaching the tab from the housing.