Apparatus for reducing fluid drawback through a medical valve

A medical valve for valving fluid includes a housing defining a chamber having an inlet, an outlet, and an interior wall, a compressible member within the chamber, and a fluid channel defined by the interior wall. The fluid channel directs fluid received from the inlet toward the outlet.

FIELD OF THE INVENTION

The invention generally relates to medical products and, more particularly, the invention relates to devices for reducing backflow through a medical valve.

BACKGROUND OF THE INVENTION

Medical valving devices commonly are utilized to valve fluids injected into and withdrawn from a patient. One exemplary type of medical valving device, known in the art as a “catheter introducer,” maintains a sealed port for accessing the patient's vasculature. Use of such a valve enables vascular access without requiring the patient's skin to be repeatedly pierced by a needle. Moreover, catheter introducers are constructed to withstand a range of back-pressures produced by a patient's blood pressure, thus minimizing blood loss resulting from fluid injections or withdrawals.

Fluid commonly is transferred to/from a patient by inserting a syringe (e.g., a needle) into a medical valve, thus communicating with the patient's vasculature. Problems arise, however, when the syringe is withdrawn from the valve. More particularly, a back pressure produced by withdrawing the syringe undesirably can cause blood to leak proximally into various parts of the valve. In addition to coagulating and impeding the mechanical operation of the valve, blood in the valve also compromises the sterility of the valve.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a medical valve for valving fluid includes a housing defining a chamber having an inlet, an outlet, and an interior wall, a compressible member within the chamber, and a fluid channel defined by the interior wall. The fluid channel directs fluid received from the inlet toward the outlet.

In preferred embodiments, the compressible member does not occlude fluid flow through the fluid channel. The compressible member may be any compressible object that is made from any compressible material known in the art. For example, the compressible member may be made from a sponge material. The compressible member also may be made from a material that merely expands and contracts in response to a mechanical force. For example, the compressible member may be a balloon device. The medical valve also may include a plunder, having a distal end within the interior, that controls the volume of the variable volume interior.

In some embodiments, the valve is movable between open and closed positions. In such case, the compressible member may cooperate with the interior to cause the interior to have a greater available volume (for containing fluid) when the valve is open than when the valve is closed. Accordingly, as the valve closes (and the available volume decreases), residual fluid within the valve should be forced from the chamber toward the outlet of the valve.

In accord with another aspect of the invention, a medical valve having an open mode for permitting fluid flow through the valve, and a closed mode for preventing fluid flow through the valve, includes an interior wall defining a variable volume fluid chamber, and a compressible member within the variable volume fluid chamber. The compressible member and interior wall together define both a closed chamber volume within the fluid chamber when the valve is in the closed mode, and an open chamber volume when the valve is in the open mode. The closed chamber volume preferably is no greater than the open chamber volume, thus reducing the potential for fluid drawback that may result when transitioning from the open mode to the closed mode.

In preferred embodiments, the interior wall defines a channel for channeling fluid flow through the valve. The compressible member preferably does not occlude fluid flow through the valve since it does not occlude the channel.

In accord with other aspects of the invention, a medical valve for valving fluid permits fluid flow when in an open mode and prevents fluid flow when in a closed mode. The valve includes an interior wall defining a chamber, and a compressible member within the chamber. The compressible member has a maximum volume and a minimum volume. The compressible member has a volume that is equal to the maximum volume when the valve is in the closed mode. In a similar manner, the compressible member has a volume that is equal to the minimum volume when in the open mode.

In preferred embodiments, the minimum volume is smaller than the maximum volume. In addition, the interior wall defines a channel for channeling fluid through the valve when in the open mode. In other embodiments, the compressible member and chamber cooperate to define a closed chamber volume when the valve is in the closed mode, and an open chamber volume when the valve is in the open mode. The closed chamber volume preferably is greater than the open chamber volume.

In accordance with yet another aspect of the invention, a medical valve includes a housing defining both a valve chamber and a fluid passageway for directing fluid through the valve, a compressible member within the chamber, and a vent defined by a wall of the chamber (chamber wall) extending through the housing to vent the member chamber. In addition, the valve chamber has an inlet for receiving fluid from the fluid passageway. The compressible member divides the valve chamber into a fluid chamber and a member chamber, where the fluid chamber receives fluid through the inlet and has an outlet for directing fluid to the fluid passageway. The member chamber is defined by the compressible member and the chamber wall and thus, includes the vent.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1schematically shows a medical valve5that preferably is configured to reduce fluid drawback (a/k/a “back-flow”) when a syringe or other type of nozzle is withdrawn from it. Accordingly, the valve5includes a proximal fluid port10for receiving the nozzle, a valve body11having a valving mechanism (FIGS.2and3A-3D) that controls fluid flow through the valve5, and a distally located fluid port50for directing fluid between the valve5and a patient. The fluid preferably is in liquid form, such as liquid medication. Although much of the discussion herein refers to the proximal port10as a fluid inlet, and the distal port50as a fluid outlet, the proximal and distal ports10and50also may be utilized respectively as outlet and inlet ports. In preferred embodiments, the valve5is similar to that disclosed in co-pending U.S. patent application Ser. No. 09/394,169, entitled, “SWABBABLE LUER-ACTIVATED VALVE,” filed Sep. 13, 1999 and naming Andrew Cote and Charles Ganem as inventors, the disclosure of which is incorporated herein, in its entirety, by reference. It should be noted that although preferred embodiments are discussed with reference to the above noted patent application, principles of the invention may be applied to other medical valve devices having dissimilar structures to those medical valves shown. As discussed below, the distal port50of the valve5may be at its location shown inFIG. 1, or at a location that is orthogonal to the longitudinal dimension of the valve5.

FIG. 2schematically shows a cross-sectional view of a first embodiment of the medical valve5shown inFIG. 1along line2—2. Among other things, the valve5includes an inlet housing portion34having the proximal port10, an outlet housing portion48having the distal port50, a stretchable and compressible gland12secured between the inlet housing34and outlet housing48, and a rigid, longitudinally movable cannula14secured within the valve5by the gland12. The cannula14forms a cannula flow channel36terminating at a transverse channel28that normally is occluded by the gland12. In addition, the outlet housing48forms a chamber65having a volume that changes as the cannula14is urged proximally and distally by a nozzle.

Insertion of a nozzle against a slit42at the proximal end of the gland12causes the cannula14to move distally, thereby moving the transverse channel28from its occluding contact with the gland12. Liquid then may be directed first through the cannula channel36and transverse channel28, then through the variable volume chamber65, and out of the valve5through the distal port50. Details of the cooperation of the various valving mechanisms within the valve5are more fully described in the aforementioned co-pending U.S. patent application.

In accord with preferred embodiments of the invention, the valve5also includes a compressible member41positioned within the chamber65, and one or more narrow flow channels formed in the interior wall forming the chamber65. One exemplary narrow flow channel is shown in phantom at reference number43. The compressible member41cooperates with the cannula14to reduce the available volume within the chamber65that may be utilized to contain fluid within the valve5. In preferred embodiments, the compressible member41occupies substantially the entire volume of the chamber65when the valve5is closed (i.e., in a “closed mode”).

The narrow flow channels43are not occluded by the compressible member41and thus, are utilized to direct fluid around the compressible member41and toward the distal port50. In preferred embodiments, the narrow flow channels43are in the form of relatively deep and narrow grooves formed in the interior walls of the distal housing48. It is anticipated that flow channels43having a depth of about 0.040-0.060 inches, and a width of about 0.020-0.040 inches would produce satisfactory results. These dimensions are not exact, however, and may be modified as necessary. Accordingly, practice of the invention should not be limited to these preferred dimensions. In preferred embodiments, the valve5includes three independent grooves longitudinally spaced about 120 degrees apart across the cylindrical inner surface of the variable volume chamber65.

The compressible member41may be any apparatus that performs the dual function of compressing and expanding within the chamber65, and limiting available chamber volume for containing liquid. Accordingly, such a member41directs liquid to the narrow channels43, thus bypassing the chamber65. In preferred embodiments, the compressible member41is a medical grade closed cell sponge rubber that is produced by conventional injection molding processes. Such member41may be made by injecting an elastomeric material with a nitrogen gas, and surrounding the injected elastomer with an outside skin, such as rubber. As shown in the figures, the compressible member41of this embodiment occupies most of the volume of the chamber65at all times (i.e., between the times when the valve5is opened, and when the valve5is closed).

In alternative embodiments, the compressible member41is a latex or polyester balloon having a hollow interior. The balloon changes shape based upon the position of the cannula14. Regardless of the type of apparatus is used as the compressible member41, however, its use necessarily adds a degree of mechanical resistance to the longitudinal movement of the cannula14.

FIGS. 3A-3Dschematically show the cross-sectional view of the valve5shown inFIG. 2as it is urged from a closed mode to an open mode. More particularly,FIG. 3Ashows the valve5as a nozzle is about to be inserted through the proximal port10.FIGS. 3B-3Dshow the nozzle at various stages of progression through the proximal port10and into the inlet housing34. More particularly, as shown inFIG. 3A, the compressible member41occupies substantially all of the chamber volume when the valve5is in the closed mode. As the nozzle is inserted, however, the compressible member41compresses between the (distally moving) distal end of the cannula14(that acts as a plunger) and the distal end of the interior wall of the chamber65. As the compressible member41compresses (i.e., thereby having a decreasing volume), a proximal region of the chamber65(hereinafter “proximal chamber66”) begins to form and increase in size until the valve5is in the fully open mode (FIG.3D). When the valve5is in the fully open position, the compressible member41is compressed to a minimum volume within a distal portion of the chamber65(hereinafter “distal chamber67”). In some embodiments, the proximal chamber66has a volume that is about equal to or less than that of the distal chamber67.

The total available volume for containing liquid in the chamber65preferably is greater when the valve5is open than when the valve5is closed. Accordingly, when in the open mode (FIG.3D), liquid can collect in the proximal chamber66. As the nozzle is withdrawn, the volume of the proximal chamber66reduces and the volume of the compressible member41increases. This forces liquid from the proximal chamber66into the narrow channels43, and then out the distal port50. When the valve5returns to the closed mode, the proximal chamber66has a minimum volume while the compressible member41has a maximum volume. As the valve5returns to closed mode, liquid formerly in the proximal region in excess of the minimum proximal chamber volume thus was forced from the proximal chamber66, into the narrow channels43, and toward the distal port50. As can be deduced by those skilled in the art, this creates a positive pressure from the distal port50, consequently preventing (or substantially reducing) fluid drawback that can cause blood or other contaminants to be drawn into the valve5.

Instead of the narrow channels43, liquid may be directed to the distal port50by some other means. Accordingly, principles of the invention should not be limited to those embodiments requiring narrow channels43.

FIG. 4shows a cross-sectional view of a second embodiment of the valve5shown in FIG.1. In this embodiment, the outlet housing portion48is reconfigured to have an orthogonal outlet100for directing fluid from the valve5, and an end cap102at its distal end. Further unlike the embodiment shown inFIG. 1, the compressible member41is in the form of a hollow cylinder having a closed top portion, and an open bottom portion (FIG.5A). In particular, the top portion comprises a top surface104having a depression106for receiving the bottom portion of the cannula14. The bottom portion includes an annular flange108for securing the compressible member41within the valve5(discussed below). The compressible member41may be manufactured from any material used in the art, such as silicone, latex, or plastic, that can compress and decompress without significantly affecting its overall structure.

As shown inFIG. 4, the compressible member41is free standing within the chamber65. Accordingly, when in the closed mode, the side of the compressible member41do not directly contact the side walls of the fluid chamber65. In illustrative embodiments, the side of the compressible member41is between about 0.002-0.010 inches from the side walls of the chamber65. This distance from the interior walls of the chamber65provides some additional clearance for compressing the compressible member41. In other embodiments, there is no such clearance and thus, the compressible member41compresses by collapsing upon its interior only.

The compressible member41in this embodiment (FIG. 4) includes a member interior112having a conventional spring114disposed therein. Although not necessary in many embodiments, the spring114may be provided to supply additional proximal biasing force for normally biasing the member41in a proximal direction. The spring114may be any spring known in the art, such as a coil spring, or an integral piece of material that provides the additional biasing force (FIG.6). In other embodiments, the member interior112is empty and thus, it has no internal spring114. In such other embodiments, the compressible member41preferably is manufactured from a material and/or with a geometry that normally biases the compressible member41proximally. In fact, such embodiments of the compressible member41themselves are springs. Additional details of such member geometry are discussed below with reference to FIG.7.

As noted above, the valve5shown inFIGS. 4 and 6also differ from that shown inFIG. 1in that it includes the outlet that extends from the side of the valve5. In particular, the chamber65includes an interior wall that defines an opening120to an outlet channel122that is formed through an outlet tube124. The outlet tube124may include an annular skirt126having threads128for coupling with a complimentary connector device. The outlet tube124thus is substantially orthogonal to the longitudinal dimension of the valve5. In some versions of this embodiment, the compressible member41may be positioned in the chamber65to normally occlude the outlet, thus preventing fluid flow from the chamber65.

Further unlike the embodiment shown inFIG. 1(as noted above), the second illustrative embodiment of the valve5also includes the end cap102, which is ultrasonically welded to its proximal end. As shown inFIGS. 5B-5D, the end cap102includes a top surface that forms a part of the member interior112. The top surface thus defines three venting grooves130, an annular protrusion132for securing the spring114(if any) within the member interior112, and an annular ridge134for mating with a complimentary part of the valve housing for securing the end cap102to the valve5.

The cap102preferably is connected to the distal end of the housing so that it defines a small annular space136(“cap space136,” or referred to by those skilled in the art as a “reveal”) between it and the housing. In preferred embodiments, the cap space136is between about 0.002 and 0.004 inches. The bottom portion of the compressible member41is secured over the three venting grooves130to the top surface of the cap102. Each groove is in fluid communication with the cap space136to form a vent140that vents the member interior112to the exterior of the valve5. Of course, vents may be interpreted herein to include any channel that extends from the member interior112to the exterior of the valve5. Accordingly, various embodiments of the invention are not to be limited to the specific disclosed vent configurations.

The member interior112preferably is fluidly isolated from the rest of the chamber65(i.e., the chamber area that is exterior to the compressible member41). To that end, the outlet housing portion48includes a distal rim144that, when coupled with the end cap102, compresses the annular flange108around the bottom portion of the compressible member41to form a liquid tight pinch-fit seal. This seal ensures that liquid does not leak into the member interior112. Accordingly, the rim144may be flat, or may converge to a pointed annular ring that pinches the member annular flange108.

When the compressible member41is compressed, air within the member chamber (i.e., the chamber formed by the interior of the member41) is forced out of the member interior112through the vents, thus facilitating compression of the compressible member41. Among other ways, the resistence to compressing the compressible member41may be adjusted by adjusting the size and geometry of the vents. Conversely, when the compressible member41is decompressed, air from the exterior of the valve5is drawn into the member interior112, thus facilitating decompression of the compressible member41.

Accordingly, when in the closed mode, the compressible member41is fully decompressed, thus causing the proximal chamber66to have a minimum volume. When in the open mode, the compressible member41is compressed to enlarge the proximal chamber66to its maximum volume. Liquid or other fluid injected through the cannula14and transverse gland1228thus flows into the proximal chamber66, and out of the valve5through the outlet. To direct fluid to the outlet, this embodiment of the valve5may have one or more narrow flow channels (similar to those in the valve5of FIG.1), or the clearance between the compressible member41and the interior wall of the chamber65may form a channel. In yet other versions of this embodiment, the compressible member41normally occludes the outlet. Accordingly, to open the valve5, the compressible member41of this version must be forced distally until the top of the compressible member41is more distal than the top of the outlet channel122, thus fluidly1≡communicating the proximal chamber66with the outlet.

FIG. 7shows a cross-section of a third illustrative embodiment of the valve5shown in FIG.1. In a manner similar to that shown inFIG. 4, this embodiment includes the orthogonal outlet100, the compressible member41with an open distal end, and the vented end cap102. Unlike the embodiment shown inFIG. 4, however, the top portion of the compressible member41is contoured to a complimentary shape to that of the bottom portion of the cannula14. For example, as shown inFIG. 7, both the bottom portion of the cannula14and the top portion of the cannula14are flat. Each of the embodiments described herein may have a similar complimentary geometry.

In addition, the compressible member41also is shaped in a distally bowed configuration to further enhance its proximal biasing force. In particular, the compressible member41of this embodiment includes an upper portion148having a substantially uniform outer diameter, a diverging middle portion150having a distally expanding outer diameter, and a lower portion152having a substantially uniform inner diameter. In a manner similar to other embodiments, the lower portion152includes the annular flange108for securing the compressible member41within the complimentary recess of the valve5. The upper portion148includes an inner surface154(i.e., defining a portion of the member interior112) having a substantially uniform radius for providing support for the cannula14upon its top portion.

As shown in the figure, this embodiment of the valve5does not include a spring with the member interior112. Although not necessary, one may be provided to further proximally bias the compressible member41. Some versions of this embodiment may utilize an inverted cone type of compressible member41(not shown), where the compressible member41has an hourglass shape. Similar to the distally bowed compressible member41, a compressible member41in an inverted cone configuration generally readily returns to its normal uncompressed state when distally applied force is not applied to its top portion.

FIG. 8schematically shows a fourth illustrative embodiment of the valve5shown in FIG.1. In a manner similar to the embodiment shown inFIG. 1, the distal port is located at the proximal end of the valve5and not orthogonal to the flow channel through the cannula14. Also like the embodiment shown inFIGS. 4,6, and7, the compressible member41is hollow and open distal ended similar to the embodiment shown in FIG.5A. It should be noted that although the compressible member41with a substantially uniform outer diameter is shown, various other compressible members may be utilized, such as the compressible member41shown in FIG.7. Although not shown, some versions of this embodiment include a spring114within the member interior112.

The chamber65in the fourth illustrative embodiment forms a vent155that extends through the housing, thus venting the member interior112to the atmosphere. In addition, this embodiment also includes two distal flow channels156that fluidly connect the chamber65(i.e., the part of the chamber65that is external to the member interior112) with the distal port50. Accordingly, when in the open mode, fluid is directed from the proximal chamber66, through the narrow flow channel(s)43in the side of the interior walls to the distal flow channels156, to the distal port50. Moreover, when the compressible member41is compressed, air is expelled from the member interior112via the vent155. In a similar manner, when the compressible member41decompresses, air is drawn into the member interior112to facilitate its decompression.

It should be noted that although a swab valve is shown in the disclosed embodiments, other valves may be utilized in accord with the various embodiments disclosed herein. Moreover, in some embodiments implementing a swab valve, the slit top surface of the gland12may be substantially flush with the proximal opening to the valve5(e.g., see FIG.8), while in other embodiments, such surface extends above the proximal opening (e.g., see FIG.4).