Bubble free—self primed IV set

A bubble free, self-priming IV set for use in the administration of liquids that includes a drip chamber comprising a chamber inlet and a chamber outlet, a bubble isolation device disposed within the drip chamber that prevents air bubbles from exiting the chamber outlet, a tube having an inlet end coupled to the chamber outlet of the drip chamber and an outlet end, and an end plug that includes an air vent. The end plug may be coupled to the outlet end of the tube and is a flow restrictor so that when a liquid is moving through the tube, the velocity of the liquid flow is controlled such that the front of the liquid does not trap bubbles in the tube.

BACKGROUND OF THE INVENTION

This invention relates generally to tubing sets used in the administration of liquids to a patient that are commonly referred to as intravascular (“IV”) sets and more particularly concerns bubble free, self-priming IV sets. An IV set according to the invention is used broadly herein to describe tubing sets used in the arterial, intravenous, intravascular, peritoneal, and non-vascular administration of fluid. Of course, one of skill in the art may use IV set to administer fluids to other locations than those listed within a patient's body.

One common method of administering fluids into a patient's blood flow is through an IV set. An IV set is an apparatus that generally includes a connector for connection to a fluid reservoir, a drip chamber used to determine the flow rate of fluid from the fluid reservoir, tubing for providing a connection between the fluid reservoir and the patient, and a connector for attachment to a catheter that may be positioned intravenously in a patient. An IV set may also include a Y-connector that allows for the piggybacking of IV sets and for the administration of medicine from a syringe into the tubing of the IV set.

It is a generally good practice to remove air from IV sets which access a patient's blood flow. While this concern is critical when accessing arterial blood, it is also a concern when accessing the venous side. Specifically, if air bubbles are allowed to enter a patient's blood stream while receiving the intravenous administration of liquids, the air bubbles can form an air embolism and cause serious injury to a patient.

Normally, in a majority of adults, the right atrium and the left atrium are completely separated from each other so that the blood and air bubbles are moved from the right atrium, to the right ventricle, and then to the lungs where the air bubbles may be safely vented. The bubble free blood is then returned to the left atrium, where the blood is moved to the left ventricle and then sent throughout the body.

However, in infants and in a small portion of the adult population, the right atrium and left atrium are not completely separated. Consequently, air bubbles can move directly from the right atrium into the left atrium and then be dispersed throughout the body. As a result, these air bubbles may cause strokes, tissue damage, and/or death. Therefore, it is important to prevent air bubbles from entering a patient's blood stream.

In spite of the importance of removing air bubbles while priming an IV set for use in the intravenous administration of liquids, the complete removal of air bubbles can be a time consuming process. The process may also lead to contamination of the IV set by inadvertently touching a sterile end of the IV set. Typically, when an IV set is primed, a clamp is closed to prevent liquid from moving from a drip chamber through the tubing. The IV set is then attached to an IV bag or bottle. Once attached, the drip chamber, which is typically made of a clear flexible plastic, may be squeezed to draw the liquid out of the IV bag or bottle and into the drip chamber. The drip chamber is allowed to fill about ⅓ to ½ full when the clamp is opened to allow liquid to flow through the tube to an end of the IV set.

This initial process, however, typically traps air in tubing which must be removed. For example, the flow of the liquid through the tubing of the IV set may be turbulent and can entrap air within the tube as the boundary layer between the liquid and the tubing is sheared. The flow rate out of the drip chamber may be higher than the flow rate of liquid entering the drip chamber. This can cause a bubble ladder to form as air is sucked from the drip chamber into the tubing.

Additionally, air bubbles may be generated as drops of liquid strike the surface of the pool of liquid within the drip chamber. These air bubbles can be pulled into the tubing of the IV set from the drip chamber. This problem may be aggravated in pediatric applications where the drip orifice may be smaller which may result in increased turbulence.

To remove air bubbles from the IV set, liquid from the IV bag or bottle is allowed to flow through the tubing while an attendant taps the tubing to encourage the air bubbles out the end of the IV set. As the liquid is allowed to flow out of the IV set to clear air bubbles from the tubing, the liquid is generally allowed to flow into a waste basket or other receptacle. During this procedure the end of the tubing may contact the waste basket or be touched by the attendant and thus, become contaminated. An additional shortcoming of this debubbling process is that it requires attention and time that could have been used to perform other tasks that may be valuable to the patient.

Another debubbling method is to directly remove air bubbles from the IV set. More specifically, if the IV set includes a Y-connector, air bubbles may be removed at the Y-connector by a syringe.

In some cases, a small pore filter may be used in the drip chamber to prevent air from entering the IV tubing from the drip chamber. However, the bubbles formed from the dripping action may become trapped on the filter, thus, reducing the flow of liquid through the filter to the IV tubing. However, the filter is normally positioned so that air may be trapped between the bottom of the filter and the bottom of the drip chamber.

Accordingly, a need exists for an IV set that is self-priming and bubble free, and which does not require constant attention and supervision. Additionally, a need exists for an IV set that prevents bubbles from entering the tubing during use, while providing flow rates that satisfy the needs of the patient.

BRIEF SUMMARY OF THE INVENTION

The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not been fully solved by currently available IV sets. Thus, the present invention provides an IV set for use in intravenous administration of liquids that prevents air from being passed to a patient during the intravenous administration of liquids.

In accordance with the invention as embodied and broadly described herein in the preferred embodiment, an IV set is provided. According to one embodiment, the IV set may include a drip chamber having a chamber inlet and a chamber outlet and a bubble isolation device disposed within the drip chamber that prevents air bubbles from exiting the chamber outlet. Typically, IV sets are gravity fed so that the chamber inlet is disposed in a top surface and the chamber outlet is disposed in a bottom surface of the drip chamber. The IV set may also include a tube having an inlet end and an outlet end, with the inlet end of the tube coupled to the chamber outlet of the drip chamber.

Additionally, the IV set may include a means for venting air out of the tube, such as an end plug that has an air vent coupled to the outlet end of the tube. The air vent may include a hydrophobic material, which allows air to exit the IV set while preventing liquid from exiting. The air vent may also include several small holes which allow air to pass while limiting the passage of water through the end plug. The end plug and the air vent acts as a flow restrictor to the exiting air, so that when a liquid is moving through the tube, the velocity of the liquid flow is controlled such that the flow is generally laminar. The laminar flow of the liquid through the tube prevents air from becoming entrapped within the tube during priming and helps to completely eliminate the air from the tube during priming.

The bubble isolation device is a means for means for preventing bubbles from exiting the chamber outlet and may include an active portion that comprises a hydrophilic filter or an absorbent structure, such as a sponge. The bubble isolation device may also include an absorbent structure that includes a woven material and/or a mat of material. The mat may be sintered or adhered together by an adhesive. Additionally, the bubble isolation device may include a concave surface that is disposed within the drip chamber so that the liquid entering the drip chamber through the chamber inlet is directed toward the concave surface.

Where the active portion of the bubble isolation device includes a hydrophilic filter or an absorbent structure, the bubble isolation device may be shaped to match the profile and abuts the bottom surface of the drip chamber so that the active portion completely covers the chamber outlet. By disposing the bubble isolation device against the bottom surface of the drip chamber, air is prevented from being trapped between the bubble isolation device and the bottom surface of the drip chamber.

Where the bubble isolation device includes a concave surface, the bubble isolation device may be disposed to partition the chamber into a bubble isolation chamber and a calm fluid chamber. The bubble isolation chamber is above the concave surface and the calm fluid chamber is positioned below the concave surface but above the bottom surface of the drip chamber. The concave surface directs bubbles toward the surface of the liquid to be expelled as new bubbles are formed by the droplets of liquid striking the surface of the liquid.

The IV set may also include a particulate filter to prevent solid material from exiting the tube. Additionally, the IV set may include a zero dead space access port disposed between the inlet end and the outlet end of the tube. A zero dead space access port is designed to prevent the entrapment of air within the access port as liquid flows through the access port.

A method for priming the IV set described above may include the steps of coupling the chamber inlet to a source of the liquid, wetting the bubble isolation device with liquid, and using the bubble isolation device to prevent air bubbles from reaching the chamber outlet. Additionally, the method may include the steps of opening the clamp to permit liquid to flow through the tube, using the end plug to restrict the venting of air from the tube as liquid flows through the tube so that the fluid flow through the tube is laminar, and using the end plug to prevent liquid from exiting the outlet end of the tube.

As the configuration of the IV set varies, the method may also include additional steps. For example, where the bubble isolation device is an absorbent structure, the method may further include absorbing the liquid in the absorbent structure so that liquid does not pass the chamber outlet until the absorbent structure is saturated. Where the IV set includes a particulate filter, the method may include using the particulate filter to prevent material from the bubble isolation device from exiting the tube. Alternatively, where the tube includes a zero dead space access port, the method may include expelling all air from the zero dead space access port with the front of the liquid flowing through the tube.

Where the configuration of the IV set includes an end plug, the method may include the step of using the end plug to restrict the venting of air from the tube as liquid flows through the tube so that the volume of fluid flowing through the chamber inlet is greater than or about equal to the liquid flow through the chamber outlet. Alternatively, where the bubble isolation device includes a concave surface, the method may further include the steps of using the bubble isolation device to partition the chamber into a bubble isolation chamber and a calm fluid chamber and using the concave surface to retain the air bubbles in the bubble isolation chamber.

DETAILED DESCRIPTION OF THE INVENTION

For this application, the phrases “connected to,” “coupled to,” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, and thermal interaction. The phrase “attached to” refers to a form of mechanical coupling that restricts relative translation or rotation between the attached objects.

The phrase “attached directly to” refers to a form of attachment by which the attached items are either in direct contact, or are only separated by a single fastener, adhesive, or other attachment mechanism. The term “abutting” refers to items that are in direct physical contact with each other, although the items may not be attached together. The terms “integrally formed” refer to a body that is manufactured integrally, i.e., as a single piece, without requiring the assembly of multiple pieces. Multiple parts may be integrally formed with each other if they are formed from a single work piece.

FIG. 1is a perspective view illustrating a bubble free, self-priming IV set10according to the invention. As shown, the IV set10may be connected to an IV bag12, which provides a source of liquid14for priming the IV set10. The IV set10may include a connector16for connection to the source of liquid14, which may include a spike18or another type of connection known by those of skill in the art.

The IV set10may also include a drip chamber20that contains a bubble isolation device22. The drip chamber20is a metering device that permits the flow rate of liquid14entering the IV set10to be determined. As the liquid14enters the drip chamber, air may be trapped within the liquid14to form air bubbles. The bubble isolation device22within the drip chamber20helps to prevent air bubbles from exiting the drip chamber20with the liquid14.

The drip chamber20is connected to a tube24. The tube24is a conduit used to convey fluid14from the drip chamber20and the IV bag12to a patient.

A clamp26, a zero dead space access port28, and an end plug30may be attached to the tube24. The clamp26permits the flow of liquid14exiting the drip chamber20to be controlled and stopped. The zero dead space access port28permits another IV set (not shown) to be piggybacked onto the IV set10or to have medication directly added to the fluid14by a syringe (not shown). The zero dead space access port28is also designed not to trap air as the liquid14flows through it. The end plug30helps to protect an end32of the IV set from contamination and also helps to prevent air bubbles from moving through the tube24with the liquid14.

Before the IV set10is attached to a source of liquid14, the clamp26is typically closed to prevent the flow of fluid through the tube24. As shown, the clamp26is a roller clamp32. Once the IV set10is attached to a source of liquid14, a vacuum may be formed by squeezing the drip chamber20to draw the liquid14from the IV bag12into the drip chamber20.

The drip chamber20includes a chamber inlet40and a chamber outlet42. The chamber inlet40is coupled to the connector16and as shown, the chamber inlet40is a tube24shaped to encourage the liquid14entering the drip chamber20to form droplets46. As the liquid14initially enters the drop chamber20and forms droplets46, the first of the droplets46fall toward the bottom surface48of the drip chamber20and wet the bubble isolation device22.

The bubble isolation device22may have an active portion50, which in this configuration of the invention is a sponge52. The sponge52is an absorbent structure54that absorbs the liquid14and prevents the liquid14from passing through the chamber outlet24until the sponge52is saturated. The bubble isolation device22conforms to the profile of the bottom surface48and abuts the bottom surface48of the drip chamber20so that the active portion50of the bubble isolation device22fully covers the chamber outlet42. As the sponge52is saturated with liquid14, the liquid14displaces the air contained within the sponge52. Because the sponge52conforms to the profile of the bottom surface48and fully covers the chamber outlet42, air is not trapped between the bubble isolation device22and the chamber outlet42.

Once the sponge52is saturated, the liquid14begins to pass through the chamber outlet42into the tube24. Additionally, a pool56of the liquid14forms above the bubble isolation device22. The bubble isolation device22also acts to slow the flow rate of fluid14from the drip chamber20into the tube24.

The tube24includes an inlet end60coupled to the chamber outlet42and an outlet end62. The outlet end62may include a fitting64for attachment to the end plug30. The fitting64may be a luer type attachment that the end plug30protects from contamination.

Once the liquid14has filled the drip chamber20about ⅓ to about ½ full, the clamp26is opened to allow the liquid14to pass through the tube24. As the liquid14moves through the tube24, the air occupying the tube24is expelled through the end plug30. The end plug30includes a vent70that may include a hydrophobic material and/or small pores that permits the air to pass but prevents the liquid14from passing through the vent70. Thus, the end plug30prevents spillage of the fluid14. The vent70may have a pore size that effectively retards the flow of air out of the tube24.

The end plug30also includes an exit orifice72that may be sized to restrict the flow of air out of the exit orifice72. The vent70may also restrict the flow of air out of the exit orifice72.

Separately or in combination, the vent70and the exit orifice72allow the end plug30to act as a flow restrictor so that when the liquid14is moving through the tube24, the remaining air in the tube24develops a back pressure that reduces the flow rate of the liquid14such that the flow is generally laminar. By controlling the velocity of the liquid14so that the flow is generally laminar, the liquid14is prevented from entrapping air in the tube24as the liquid14moves through the tube24. If the liquid14is allowed to turbulently flow through the tube24, air may become entrapped as the liquid14shears at the boundary layer and the front of the flow moves past air in the tube24.

Because the end plug30is a flow restrictor, the end plug30also helps to maintain the flow rate of the liquid14exiting the drip chamber20to be less than or equal to the flow rate of liquid14entering the drip chamber20. Should the flow rate of the liquid14exiting the drip chamber20be greater than the flow rate of liquid14entering the drip chamber20, air may be pulled through the bubble isolation device22into the tube24.

As the liquid14flows toward the end plug30, the liquid14passes through the zero dead space access port28. The zero dead space access port28is shaped to prevent liquid14from slowing or stagnating as it flows through the zero dead space access port28and to prevent air from becoming entrapped as the liquid14passes through the zero dead space access port28. Thus, the zero dead space access port28may have a passage74that follows the internal shape of the tube24with a septum76shaping part of the passage74.

The zero dead space access port28may be used to piggyback a second IV set (not shown). Alternatively, the zero dead space access port28may be used to administer medication into the tube24by a needle and syringe (not shown). For example, a sedative may be given to a patient through the zero dead space access port28rather than being directly injected into a patient, which may result in tissue damage at the injection site.

Once the liquid14reaches the end plug30, the IV set10is bubble free, primed, and ready for use with a patient. For attachment to a patient, the end plug30is removed and the fitting64of outlet end62of the tube24may be attached to a needle (not shown), a catheter (not shown), another IV set (not shown), or another device known in the art.

Referring toFIG. 2, a cross sectional view along line2-2illustrates the bubble isolation device22and the drip chamber20ofFIG. 1. As shown, the bubble isolation device22conforms to the shape of the bottom surface48of the drip chamber20and completely covers the chamber outlet42with the active portion50of the bubble isolation device22. By positioning the active portion50to completely cover the chamber outlet42, air is prevented from being trapped under a frame (not shown) or between the bubble isolation device22and the bottom surface48as the fluid14moves through the bubble isolation device22. In an alternative embodiment, the bubble isolation device22may include a frame (not shown) which is not part of the active portion50that supports the sponge52. Additionally, the inlet end60of the tube24is shaped to prevent air from being entrapped between the coupling of the inlet end60and the chamber outlet42.

While in use, air bubbles80are generated as the droplets46strike the surface82of the pool56. The bubble isolation device22prevents the air bubbles80from reaching the chamber outlet42so that the air bubbles80are able to return to the surface82of the pool56and be discharged. Also, the sponge52may be made of a molded open-cell foam that has a general pore size of about 10 to 20 microns with the preferred pore size being about 12 to 15 microns.

Also shown, the connection90between the tube24and the drip chamber20is a zero dead space connection. In other words, the inlet end60is shaped to be attached flush to the chamber outlet42so that air may not be entrapped at the connection90as the fluid14passes the connection90and purges the air from the tube24.

FIG. 3is a perspective break-away view and illustrates an alternative bubble isolation device100located within the drip chamber20ofFIG. 1. As illustrated inFIG. 3, the bubble isolation device100comprises an absorbent structure102which includes a mat104of material covered by a woven material106. The material of both the mat104and the woven material106may be hydrophilic, such as cotton. For example, the mat104may be a cotton ball and the woven material106may be gauze.

The fibers of the mat104may be sintered or adhered together to prevent material from the mat104from becoming separated from the mat104and entering the tube24. The woven material106further helps to prevent material from entering the tube24.

Additionally, the bubble isolation device100may include a particulate filter108positioned to prevent solid material from exiting the tube24. The particulate filter108may be positioned in the drip chamber20or in the tube24. As shown, the particulate filter108includes a screen110that may be positioned over the chamber outlet42. The absorbent structure102is shaped to match the profile of the bottom surface48of the drip chamber20and is disposed to abut the bottom surface48around the particulate filter108. Thus, the absorbent structure102covers the screen110of the particulate filter108and the chamber outlet42.

The screen110and the absorbent structure102together form an active portion112of the bubble isolation device100. Therefore, the active portion112of the bubble isolation device100completely covers the chamber outlet42so that air bubbles are not trapped under the bubble isolation device100or in the tube24. In addition to the configuration described above and shown inFIG. 3, the particulate filter108may be used with any of the bubble isolation devices disclosed herein.

The bubble isolation device100functions similarly to the bubble isolation device22described above by absorbing the liquid14and then allowing the liquid14to enter the tube24once the bubble isolation device100has been saturated. The bubble isolation device100also acts to impede the flow rate of the liquid14from the drip chamber20into the tube24.

FIG. 4is a perspective break-away view illustrating another bubble isolation device200positioned within the drip chamber20ofFIG. 1. The bubble isolation device200prevents air bubbles80from exiting the chamber outlet42. As shown, the bubble isolation device200includes a concave surface202positioned under the chamber inlet40so that the droplets48are directed toward the concave surface202. In some configurations, the concave surface202may follow a parabolic curve or may have a set radius. Furthermore, the concave surface202may include a solid surface in the middle portion203of the concave surface202and edge ports204about the periphery205of the concave surface202.

The bubble isolation device200is located within the drip chamber20to partition the drip chamber20into a bubble isolation chamber206and a calm fluid chamber208. Once the surface82of the pool56extends above the concave surface202of the bubble isolation device200, the concave surface202isolates the bubbles in the bubble isolation chamber206. For example, as the droplet46strike the surface82of the pool56, air bubbles80are generated and move downward toward the concave surface202. The concave surface202redirects the force of the impacting droplets46and movement of the air bubbles80back towards the surface82and away from the point of impact by the droplets46. Thus, the concave surface202acts to prevent the air bubbles80from being kept in the liquid14by the later impact of the droplets46.

Proximate the periphery205of the concave surface202, the liquid14calms and is able to flow through the edge ports204into the calm fluid chamber208bubble free. The edge ports204may be holes210extending through the bubble isolation device200, cuts212positioned on the edges of the concave surface202, or the edge ports204may be a gap214between the edge of the bubble isolation device200and a wall216of the drip chamber20. The fluid14then moves from the calm fluid chamber208into the tube24through the chamber outlet42.

The bubble isolation device200is generally able to handle much higher flow rates of fluid14than the bubble isolation devices22and100described above, because the flow of the liquid14does not have to pass through an absorbent structure or a filter. To position the concave surface202the bubble isolation device200may be adhered to the drip chamber20, fastened in place using a mechanical fastener (not shown), or may be supported by support structure (not shown).

The bubble isolation device200may be made of metal, plastic, ceramic, or composite. For example, the bubble isolation device200may be made of an injection molded elastomer such as polypropylene. Additionally, the bubble isolation device200may be combined with any of the other bubble isolation devices disclosed herein. As shown, the bubble isolation device200may be a curved disc having concave surface202that is solid. The bubble isolation device200may be made by injection molding a plastic such as polyethylene. Alternatively, the concave surface202may be porous in configuration where the concave surface202is formed as part of an absorbent structure described above.

FIG. 5is perspective view of an additional bubble isolation device300disposed within the drip chamber20of the IV set10coupled to an IV bottle302. As shown, the bubble isolation device300includes a frame310supporting an active portion312that includes a filter314which may be made of hydrophilic material. The filter314is shaped to match the profile of the bottom surface48and is positioned within the drip chamber20so that the filter314abuts the bottom surface48and covers the chamber outlet42.

By disposing the active portion312to completely cover the chamber outlet42, air is prevented from being trapped between the bubble isolation device300and the bottom surface48of the drip chamber20. Additionally, the filter314may be sized so that the first droplet46of liquid14entirely wets the filter314, which when wet prevents air from passing through the filter314.

As liquid14collects in the pool56above the bubble isolation device300, the air bubbles80are allowed to rise to the surface82of the pool56. The air in the tube24is kept under the bubble isolation device300until the clamp26is released. Once the clamp26is opened, the liquid14is allowed to push the air in the tube24out of the end plug30. As noted above, the end plug30restricts the flow of air out of the tube24so that the flow rate of liquid14out of the drip chamber20is retarded in order to prevent the formation of a “bubble ladder.” A “bubble ladder” occurs when rate out of the drip chamber20is greater than the flow rate into the drip chamber20and the pool56is small enough that air is intermittently pulled through the bubble isolation device300and into the tube24so that air and liquid14form successive layers in the tube24.

The bubble isolation devices22,100,200,300disclosed above may be made of metal, plastic, ceramic, or a composite material. Additionally, some configurations of the bubble isolation devices22,100,200,300may be made by machining processes, molding processes, and other manufacturing processes known by those of skill in the art.

A method of using an IV set according to the invention, such as the IV set10ofFIG. 1, may include the steps of closing the clamp26and coupling the chamber inlet40of the drip chamber20to a source of the liquid14, such as an IV bag12, IV bottle302, or other source of liquid known in the art. The drip chamber20may be squeezed to draw the fluid14into the drip chamber20. Once the fluid14enters the drip chamber20, it wets the bubble isolation device, such as22,100,200,300, with the liquid14.

Once the drip chamber20is filled about ⅓ to about ½ full of liquid14, the clamp26is opened to permit the liquid14to flow through the tube24. The bubble isolation device22,100,200,300is used to prevent air bubbles80from reaching the chamber outlet42and the end plug30is used to restrict the venting of air from the tube24as liquid14flows through the tube24so that the fluid flow through the tube24is generally laminar. The end plug30may also be used to prevent liquid from exiting the outlet end62of the tube24and to restrict the venting of air from the tube24as liquid14flows through the tube24so that the volume of fluid14flowing through the chamber inlet40is greater than or about equal to the liquid flow through the chamber outlet42.

If the bubble isolation device22,100is an absorbent structure54,102, the method may include the step of absorbing the liquid14in the absorbent structure54,102so that liquid14does not pass the chamber outlet42until the absorbent structure54,102is saturated. Additionally, a particulate filter108may be used to prevent material from the bubble isolation device22,100from exiting the tube24.

In other embodiments of the invention, the method may include using the bubble isolation device200to partition the drip chamber20into a bubble isolation chamber206and a calm fluid chamber208and using the concave surface202of the bubble isolation device200to retain the air bubbles80in the bubble isolation chamber206. If the IV set10includes a zero dead space access port28, the method also include the step of expelling all air from the zero dead space access port with the front of the liquid flowing through the tube.