Valve for use with a syringe and which prevents backflow

Abstract

A one-way valve assembly can be fitted to the end of a syringe to allow fluid to flow from the syringe and into a body cavity but to prevent backflow. The valve assembly is opened by insertion of the luer tip of the syringe into the assembly inlet. The valve has an internal elastic member that forms a variable volume internal chamber. This chamber expands upon insertion of the luer tip into the inlet and shrinks when the luer tip is removed from the assembly. The shrinking action creates a positive pressure in the valve assembly to prevent backflow.

1 . An intravenous valve assembly for providing a positive charge of intravenous fluid upon closure, the valve assembly comprising: 
 a valve body presenting an inlet and an outlet fixed relative to each other;    a flow pathway that extends through the valve body from the inlet to the outlet;    a plunger that is positioned in the valve body and which can move between a forward open position where fluid can flow from the inlet to the outlet, and a retracted closed position where fluid is prevented from flowing from the inlet to the outlet;    an at least partially elastic sock that has an outer end fixed to the valve body, and an inner portion which engages with the plunger such that reciprocation of the plunger from the retracted closed position to the forward open position causes at least part of the sock to stretch; and    a variable volume chamber having walls defined by the plunger and the sock, the chamber forming part of the flow pathway, said flow pathway having a smaller volume when the plunger is in the retracted closed position, and a larger volume when the plunger is in the forward open position, whereby upon retraction of the plunger, the variable volume chamber reduces in volume which results in a pumping action to pump fluid through the flow pathway out of the outlet, thereby reducing or preventing backflow.    
   
   
       2 . The assembly of  claim 1 , wherein the valve body is formed in two parts that are attached together.  
   
   
       3 . The assembly of  claim 2 , wherein one of the two parts comprises a top part having an outer passageway of smaller diameter or cross-section, and an inner passageway of larger diameter or cross-section, the inner passageway forming part of an internal chamber.  
   
   
       4 . The assembly of  claim 3 , wherein the outer passageway contains at least one longitudinal slot or recess that comprise fluid ports.  
   
   
       5 . The assembly of  claim 3 , wherein the other of the two parts comprises a base part which has an outer passageway of smaller diameter or cross-section, and an inner passageway of larger cross-section or diameter and which forms part of the internal chamber that is also defined by the top part.  
   
   
       6 . The assembly of  claim 5 , said flow pathway extending through the internal chamber.  
   
   
       7 . The assembly of  claim 1 , wherein the flow pathway extends at least partially through the plunger.  
   
   
       8 . The assembly of  claim 7 , wherein the plunger has an engagement means to engage with the at least partially elastic sock.  
   
   
       9 . The assembly of  claim 8 , wherein the engagement means comprises an annular step or shoulder portion on the plunger and which catches the at least partially elastic sock upon forward movement of the plunger.  
   
   
       10 . The assembly of  claim 1 , wherein the sock has a substantially circular base portion, and an extending tubular wall portion.  
   
   
       11 . The assembly of  claim 10 , said plunger including a forward portion wherein the extending tubular wall portion extends substantially about the forward portion of the plunger.  
   
   
       12 . The assembly of  claim 11 , wherein the base portion has a peripheral edge that is held against movement in the valve body.  
   
   
       13 . The assembly of  claim 12 , wherein the tubular wall portion includes an annular line of weakness and is thereby compressible and allowed to buckle in a controlled manner.  
   
   
       14 . The assembly of  claim 1 , wherein the sock has a substantial disklike configuration.  
   
   
       15 . The assembly of  claim 14 , 
 said plunger including a forward portion,    said sock having an outer peripheral edge that is attached to the valve body,    said sock presenting an internal opening through which the forward portion of the plunger extends.    
   
   
       16 . An intravenous injection site valve assembly for providing a charge of injection fluid to reduce backflow from the patient, the injection site valve assembly comprising: 
 a valve body presenting an inlet, an outlet in a relatively spaced apart and fixed relationship to the inlet, and a hollow interior; and    a plunger shiftable progressively into and out of the hollow interior of the valve body,    said plunger and valve body cooperatively presenting a chamber access port which is sealable to prevent injection fluid flow therethrough, with an expandable injection fluid chamber being defined between the chamber access port and the outlet,    said plunger being shiftable between an inner closed position and an outer closed position, with the access port being sealed when the plunger is at and between the closed positions to thereby prevent injection fluid flow therethrough,    said injection fluid chamber becoming volumetrically smaller as the plunger shifts from the inner position to the outer position, with the valve assembly being thereby operable to pump the charge of injection fluid from the injection fluid chamber and out of the outlet.    
   
   
       17 . The intravenous injection site valve assembly as claimed in  claim 16 , 
 said plunger being shiftable between an open position where the access port is unsealed and the outer closed position, with the inner closed position being intermediate to the open and outer closed positions.    
   
   
       18 . The intravenous injection site valve assembly as claimed in  claim 16;  and 
 an elastic member operable to urge the plunger from the inner closed position to the outer closed position.    
   
   
       19 . The intravenous injection site valve assembly as claimed in  claim 18 , 
 said elastic member interconnecting the plunger and valve body.    
   
   
       20 . The intravenous injection site valve assembly as claimed in  claim 19 , 
 said elastic member being located within the hollow interior of the valve body.    
   
   
       21 . The intravenous injection site valve assembly as claimed in  claim 19 , 
 said elastic member partly defining the injection fluid chamber.    
   
   
       22 . The intravenous injection site valve assembly as claimed in  claim 21 , 
 said elastic member comprising an elastic sock,    said elastic sock including an outermost margin sealingly fixed to the valve body and an inner margin sealingly attached to the plunger.    
   
   
       23 . The intravenous injection site valve assembly as claimed in  claim 22 , 
 said elastic sock being stretched to a greater extent in the inner closed position than in the outer closed position so as to urge the plunger into the outer closed position.    
   
   
       24 . The intravenous injection site valve assembly as claimed in  claim 22 , 
 said inner margin defining a single opening in the elastic sock for receiving the plunger.    
   
   
       25 . The intravenous injection site valve assembly as claimed in  claim 24 , 
 said plunger presenting an internal fluid flow path that provides the only path for injection fluid to flow between sides of the elastic sock.    
   
   
       26 . The intravenous injection site valve assembly as claimed in  claim 22 , 
 said plunger and sock cooperatively preventing fluid communication between the injection fluid chamber and a remainder of the hollow interior.    
   
   
       27 . The intravenous injection site valve assembly as claimed in  claim 26 , 
 said valve body presenting an opening that permits the remainder of the hollow interior to fluidly communicate with ambient.    
   
   
       28 . The intravenous injection site valve assembly as claimed in  claim 16 , 
 said access port being spaced inwardly from the inlet.    
   
   
       29 . The intravenous injection site valve assembly as claimed in  claim 16 , 
 said plunger presenting an outer terminal plunger end,    said valve body presenting a sleeve portion that slidably receives the terminal plunger end, with the sleeve portion presenting an outer terminal sleeve end,    said terminal plunger and sleeve ends being flush with one another when the plunger is in the outer closed position.    
   
   
       30 . An intravenous injection site valve assembly for providing a charge of injection fluid to reduce backflow from the patient, the injection site valve assembly comprising: 
 a valve body presenting an inlet, an outlet, and a hollow interior defined between the inlet and outlet; and    a plunger shiftable progressively into and out of the hollow interior of the valve body,    said plunger and valve body defining at least in part an injection fluid flow path extending between the inlet and outlet, with an expandable injection fluid chamber being defined along the fluid flow path and within the hollow interior,    said plunger and valve body defining at least in part an expandable compensating chamber within the hollow interior, with the compensating chamber being outside the fluid flow path and fluidly separated from the injection fluid chamber,    said injection fluid chamber becoming volumetrically larger and the compensating chamber becoming volumetrically smaller when the plunger shifts inwardly,    said injection fluid chamber becoming volumetrically smaller and the compensating chamber becoming volumetrically larger when the plunger shifts outwardly, with the valve assembly being thereby operable to pump the charge of injection fluid from the injection fluid chamber and out of the outlet.    
   
   
       31 . The intravenous injection site valve assembly as claimed in  claim 30 , 
 said injection fluid and compensating chambers changing volumetrically inversely proportionate to one another.    
   
   
       32 . The intravenous injection site valve assembly as claimed in  claim 30 , 
 said valve body including a vent communicating the compensating chamber to ambient.    
   
   
       33 . A backflow-reducing method of injecting intravenous fluid into a patient, 
 the method comprising the steps of:    (a) fluidly connecting an intravenous fluid infusion component to the patient via a valve that fluidly communicates the component with the patient when open;    (b) injecting intravenous fluid from the component, through the valve, and into the patient at a pressure greater than the patient venous pressure;    (c) after the valve closes to fluidly disconnect the component from the patient, pumping a volume of fluid in a downstream direction from the valve into the patient to reduce any backflow from the patient.    
   
   
       34 . A backflow-reducing method of injecting fluid as claimed in  claim 33 , 
 step (c) being performed by removing the component from the valve.    
   
   
       35 . The backflow-reducing method of injecting fluid as claimed in  claim 34 , 
 said valve presenting an expandable valve chamber,    step (a) including the step of expanding the chamber by connecting the component to the valve, with the valve being configured to contain a charge of intravenous fluid when opened,    step (b) including the step of filling the valve chamber with the charge of fluid.    
   
   
       36 . The backflow-reducing method of injecting fluid as claimed in  claim 35 , 
 step (c) including the step of purging the charge of intravenous fluid from the valve chamber.    
   
   
       37 . The backflow-reducing method of injecting fluid as claimed in  claim 36 , 
 said valve including a shiftable plunger, with the expanding step occurring by inserting part of the component into the valve and displacing the plunger.    
   
   
       38 . The backflow-reducing method of injecting fluid as claimed in  claim 37 , 
 step (c) including the steps of sealing the valve inlet and then shifting the plunger from a first position to a second position to decrease the volume of the valve chamber.