1. Field of the Invention
The subject invention relates to a blood collection set with self-venting features.
2. Description of the Related Art
Phlebotomy procedures often are carried out using a blood collection set. A typical blood collection set includes an IV needle assembly with an IV cannula that has a proximal end, a sharply pointed distal end and a lumen extending between the ends. The needle assembly also includes a plastic IV hub with a proximal end, a distal end, and a passage extending between the ends. The proximal end of the IV cannula is mounted in the passage of the IV hub so that the lumen through the IV cannula communicates with the passage through the IV hub. The needle assembly may further include a shield for shielding the IV cannula after use and a packaging cover for safely covering the IV cannula prior to use. Packaging covers typically are rigid tubes with a proximal end that can be telescoped over the IV cannula and frictionally engaged with the distal end of the IV hub. Shields for blood collection sets have taken many forms. Some shields are telescoped over the IV hub and can be moved from a proximal position where the cannula is exposed to a distal position where the cannula is shielded. Other shields are hinged to the IV hub and can be rotated from an open position where the IV cannula is exposed to a closed position where the IV cannula is shielded. A needle assembly for a blood collection set also may include two flexible wings that project transversely from the IV hub or from the shield. The wings can be folded into face-to-face relationship with one another to effectively define a handle that facilitates manipulation of the needle assembly. The wings then can be rotated away from one another and held against the skin of the patient.
Blood collection sets also include a length of flexible plastic tubing. The tubing has a distal end that is connected to the proximal end of the IV hub. The tubing also has a proximal end that is connected to a plastic fitting. Thus, fluid communication is provided between the lumen of the IV cannula and the plastic fitting at the proximal end of the flexible tubing. The plastic fitting may be a female luer fitting that can be connected to a male luer fitting. The fitting then can be placed in communication with a reservoir or container for collecting a sample of blood.
Phlebotomy procedures often employ evacuated tubes, such as the VACUTAINER® brand of evacuated tubes sold by Becton Dickinson and Company. Evacuated tubes often are used with a tube holder that has a proximal end, a distal end, and a tubular side wall extending between the ends. The proximal end of the holder is widely open and is configured for slidably receiving the evacuated tube. The distal end of the holder typically includes an end wall with a mounting aperture. The mounting aperture includes internal threads or other mounting structures.
The tube holder may be used with a non-patient needle assembly that has a non-patient hub with external surface configurations for mounting in the mounting aperture of the holder. The non-patient needle assembly further includes a non-patient cannula extending proximally from the hub and a multiple sample sleeve telescoped over the non-patient cannula and mounted to the proximal end of the hub. The hub of the non-patient needle assembly can be threaded or otherwise engaged in the mounting aperture of the tube holder so that the non-patient needle and the multiple sample sleeve project into the tube receiving chamber of the holder.
The blood collection set may be used by mounting the fitting at the proximal end of the flexible plastic tubing to the distal end of the hub of the non-patient needle assembly. The packaging shield that covers the non-patient cannula then may be removed, and the hub of the non-patient needle assembly may be engaged with the tube holder. The medical practitioner then grips the IV needle assembly and removes the packaging cover from the IV cannula. The gripping of the IV needle assembly may include folding the flexible wings into face-to-face engagement and gripping the folded wings between a thumb and forefinger. The pointed distal end of the IV cannula then is urged into a targeted blood vessel. The wings then may be folded into engagement with the skin of the patient and may be taped in position. An evacuated tube then is urged into the open proximal end of the blood collection tube holder so that the non-patient needle pierces the stopper of the evacuated tube. As a result, the blood vessel of the patient is placed in communication with the interior of the evacuated tube, and the pressure differential between the blood vessel and the evacuated tube will generate a flow of blood through the IV cannula, through the passage of the IV hub, through the flexible tubing, through the non-patient hub and finally through the non-patient needle and into the evacuated tube.
It will be appreciated that a significant volume of air must be displaced before blood enters the evacuated tube. This air will be displaced by the flowing blood and will be urged into the evacuated tube. The flow of air into the evacuated tube increases the air pressure in the tube and offsets the pressure differential that generates the flow of blood from the patient to the evacuated tube. Thus, blood flow is slowed. Blood flow into the blood collection tube may stop when the pressure in the tube equals the fluid pressure of the blood. In effect air from the blood collection set reduces the volume of blood collected into the tube. The reduced blood volume can be undesirable such as when it adversely affects the ratio of additive to blood within the tube. An example is when the tube contains the additive citrate for clotting time studies in which the ratio of blood to citrate is critical.
Medical practitioners have several approaches for addressing problems relating to air in a blood collection set at the start of a phlebotomy procedure. For example, the first tube of collected blood may be considered a discard tube. Thus, the evacuated tube will remain in communication with the non-patient needle until blood begins to flow into the tube. The tube then will be removed and discarded and a second tube will be inserted into the holder for collecting a sample that can be used reliably. This approach adds to the cost and time of the procedure and wastes blood. Some medical practitioners try to vent air from the system before the first blood collection tube is placed in communication with the non-patient needle. This approach also wastes blood and can lead to contamination or accidental sticks depending upon the method of venting.
The typical needle hub is formed from an opaque plastic material, and plastic tubing often is formed from a translucent plastic material. Neither the opaque plastic material nor the translucent flexible tubing provide a clear indication of venous or arterial access. Blood flow into an evacuated tube does provide an indication of venous or arterial access. However, the initial movement of air into the evacuated tube is delayed until the evacuated tube is added onto the non patient needle. Thus, a medical practitioner may have a delayed indication of venous or arterial access and may incorrectly assume that the blood vessel was not accessed properly. In these situations, the medical practitioner may try to access the blood vessel again even though the initial access was successful. Accordingly, the patient may be subjected to unnecessary trauma during a repeated attempt to access the targeted blood vessel. Thus, improved techniques for dealing with the issue of air trapped in tubing would be desirable.
The invention is a self-venting blood collection set with a self-venting mechanism that permits escape of air during use, and which, typically, also prevents an outflow of fluid, such as blood. As used herein, venting mechanism indicates one or more features or elements that provide venting of air, but which, typically, prevent fluid from passing through. Thus, air under venous pressure will be allowed to escape from the blood collection set through the mechanism until blood reaches the venting mechanism. The venting mechanism then will seal, or prevent blood flow through or around it, to prevent blood leakage and allow blood to be collected into evacuated collection tubes or into other appropriate blood collection receptacles. The invention thus provides good flash visualization, as well as the capability to provide a blood collection set that does not require a discard tube, without affecting accepted blood collection processes. A variety of venting mechanisms, venting media and venting locations are suitable, as set forth below. (As used herein, venting mechanism indicates the combination of elements, configurations, materials, etc. that provide the venting. As used herein, venting media indicates the actual element that vents the air, e.g., plug, coating, finish, etc.)
The blood collection set preferably includes an IV needle assembly, a length of flexible plastic tubing extending from the IV needle assembly and a non-patient needle assembly. The venting mechanism preferably is disposed on or near the non-patient needle assembly to permit venting of a maximum amount of the air that is in the blood collection set prior to the initiation evacuated tube use.
The IV needle assembly typically comprises an IV hub having a proximal end, a distal end and a passage extending between the ends. The IV needle assembly typically comprises an IV cannula having a proximal end mounted in the passage of the IV hub, a pointed distal end projecting distally from the IV hub and a lumen that communicates with the passage through the IV hub. The flexible tubing is connected to the proximal end of the IV hub. The IV needle assembly typically includes a packaging cover that protectively encloses the IV needle cannula prior to use. The packaging cover is removed immediately prior to use to permit access to the IV cannula. The IV needle assembly may further include a protective shield that is moveable relative to the IV cannula from an open position where the IV cannula is exposed to a closed position where the IV cannula is substantially shielded. The shield protects against accidental sticks with the used IV cannula. A pair of flexible wings may be mounted to the IV hub or to the shield to facilitate manipulation of the IV needle assembly.
The non-patient needle assembly includes a non-patient hub having a proximal end and a distal end. The non-patient needle assembly further includes a non-patient cannula having a distal end securely mounted in the hub, a proximal end projecting proximally from the non-patient hub and a lumen that communicates with the passage through the non-patient hub. A multiple sample sleeve is typically mounted over the non-patient cannula and secured to the proximal end of the non-patient hub. External portions of the non-patient hub near the proximal end thereof may be formed with an array of external threads or other mounting structure to enable the non-patient needle assembly to be mounted to a collection tube holder or other such medical device. Or, the holder may be pre-attached with the non-patient needle assembly. The blood collection set may further include a fitting mounted to the proximal end of the flexible plastic tubing and configured for mating with the distal end of the non-patient hub. For example, the fitting may be a female luer fitting that can be engaged with the male luer taper at the distal end of the non-patient hub.
In one embodiment, the venting mechanism is located at or near the non-patient hub, e.g., in the hub itself near the distal end of the non-patient needle or in the tubing itself at a proximal end thereof. The venting mechanism thereby provides communication between the passage and the surrounding environment either through the passage itself or through the non-patient hub. Alternatively, wherein the venting mechanism is located in the tubing, any location along the tubing is possible.
In a further embodiment, the venting mechanism location is in a space between a female and male luer interface or within a female luer and therefore will be at or near to the non-patient needle so that only a small amount of air will be collected with the first sample of blood.
In another embodiment, the venting mechanism is located beyond the non-patient cannula proximal end, which means that the air passes through the non-patient cannula proximal end from which blood is drawn, and then through the vent. Specifically, air is vented from the fluid passage and out of the non-patient cannula proximal end where it further flows through the space between needle exterior and multiple sample sleeve. The air then flows through the venting mechanism, which may be at the non-patient barb, the non-patient hub thread, the non-patient hub body, the multiple sample sleeve, or other location or combination of locations that are beyond the non-patient cannula proximal end. The collection tube, which is applied at the non-patient cannula proximal end, draws blood from only the fluid passage and not from the vent space. This embodiment thus enables blood to flow through the entire collection path for full tubing flash, eliminating the need for a discard tube and maintaining the desired blood to additive ratio. It also avoids the blood specimen coming in contact with the vent, which could potentially cause platelet activation, contamination or other undesirable result. It also avoids air being sucked back into the fluid passage when the evacuated tube is applied.
In a further embodiment, the venting mechanism is an opening in the side of the non-patient cannula, combined with a vent media, which vents air but not blood, e.g. a vent plug consisting of a hydrophobic material.
Another embodiment of this invention has a venting mechanism comprised of a unified non-patient hub that is at least partially constructed of porous material such as sintered plastic, ceramic or metal. The porous material can be arranged to provide venting of air either before that air enters the non-patient cannula, or after the air flows through the cannula, out the proximal end, and into the space between the cannula and a multiple sample sleeve. The porous material provides venting of the air but blocks leakage of the blood. In the typical embodiment, the porous material is hydrophobic. The porous material may further contain or be coated with materials that swell upon wetting to further contain the blood. Other venting methods are also possible. The internal passage wall's surface may be coated with a sealant to prevent contamination of the blood sample by the porous material. This embodiment enables blood to flow through the entire collection path for full tubing flash, and also enables elimination of the waste tube or variability in blood to additive ratio. Optionally, the hub can be permanently bonded to a tube holder obviating the need or inconvenience of threaded connections. Bonding to the holder may be accomplished by solvent, welding, heat, pressure or and other convenient means or combination thereof. Such an integrated device is highly efficient to manufacture, and promotes safe medical practice by having the holder be discarded with the needle.
In a further embodiment, the venting mechanism involves venting air through a side opening located somewhere along the fluid passage to the exterior, where the opening is covered by a venting material having a shape which mechanically holds the venting material in or on the opening. Preferably, the vent material is hydrophobic such that the surface tension also prevents leakage. The vent media material in this embodiment typically has an elastic property and shape such that spring energy holds the vent material onto the device. For example, it is possible to use a C-shaped vent in which distortion of the shape is required for the vent to stretch over the receiving structure on the hub. Once the vent is placed over the receiving structure, it is released and fully maintained in place using it's own resiliency and in absence of bonding materials such as epoxies, which could be disadvantageously absorbed into the vent. The vent mechanism of this embodiment could alternatively involve first compressing a vent material, placing the material into the opening, and releasing the vent material to expand into the opening. This embodiment enables efficient mass production.
In a further embodiment, the venting mechanism utilizes a branch in the fluid passage, e.g., a “Y” or “T”. The branching may be at any location or locations along the fluid passage, but is preferably at the proximal end such as at the non-patient hub. The branching may be in the form of a separate component added into the fluid passage such as in between the female and male luer fittings or it may be integral within the hub. The branching includes some type of vent media, as discussed herein.
The invention is a self-venting blood collection set with a self-venting mechanism that permits escape of air during use which, typically, also prevents an outflow of fluid, such as blood. As used herein, venting mechanism indicates one or more features or elements that provide venting of air, but which, typically, prevent fluid from passing through.
It should be noted that the vent media could be, for example, a distinct physical element such as a plug or insert, a integral portion of a device that has been treated such as by laser drilling or has been formed in whole or in part from a porous material, or a coating, layer, etc. formed by disposing a material onto the device, e.g., by dipping, coating, spraying or the like.
A prior art blood collection set in accordance with the subject invention is identified generally by the numeral 10 in
Blood collection set 10 includes an IV needle assembly 24 that comprises an IV hub 26. IV hub 26 includes a proximal end 28, a distal end 30 and a passage (not shown) extending between the ends. IV needle assembly 24 further includes an IV cannula 32 with a proximal end 34, a pointed distal end 36 and a lumen 38 extending between the ends. Proximal end 34 of IV cannula 32 is mounted securely in the passage of IV hub 26. Thus, lumen 38 through IV cannula 32 communicates with the passage through IV hub 26. Flexible wings 40 are mounted to IV hub 26 at a location near distal end 30. Wings 40 can be folded into face-to-face relationship with one another for convenient gripping between a thumb and forefinger to enable manipulation of IV needle assembly 24. Wings 40, however, also can be rotated into a substantially coplanar disposition for taping to the skin of a patient.
IV needle assembly 24 further includes a tubular shield 42 that is telescoped over IV hub 26. Shield 42 is formed with transverse slots 44 that slidably receive wings 40. Thus, shield 42 can be slid from a proximal position, as shown in
Blood collection set 10 further includes a length of flexible plastic tubing 46. Tubing 46 includes opposite proximal and distal ends 48 and 50 and a passage extending between the ends. Distal end 50 of tubing 46 is securely mounted to proximal end 28 of IV hub 26 so that the passage through IV hub 26 communicates with the passage through tubing 46. A female luer fitting 52 is securely mounted to proximal end 48 of tubing 46.
Blood collection set 10 further includes a non-patient needle assembly 54, as shown in
Blood collection set 10 is employed by folding wings 40 into face-to-face engagement with one another and gripping wings 40 between a thumb and forefinger. Any packaging cover that may be mounted over IV cannula 32 then is removed and discarded. Pointed distal end 36 of IV cannula 32 then is urged into a targeted blood vessel. The healthcare practitioner then may release the grip on wings 40, and if long term access to the blood vessel is required, wings 40 may be taped into face-to-face engagement with the skin of the patient. Blood collection set 10 includes a plurality of internal spaces that will initially be at ambient air pressure. These internal spaces include lumen 38 through IV cannula 32, the passage through IV hub 26, the passage through flexible tubing 46, passage 62 through non-patient hub 56 and lumen 74 through non-patient cannula 68. The venous or arterial access achieved with IV cannula 32 places these interior spaces of blood collection set 10 in communication with the pressure of the blood in the patient. Blood pressure exceeds the ambient air pressure. Accordingly, the pressure of air in the above-referenced internal spaces will increase, and blood will begin to flow into these internal spaces. As discussed above, prior art systems may reach equilibrium as the air pressure within the blood collection set increases in response to a reduction of volume caused by the inflow of blood. Hence, a portion of the internal spaces in the prior art system may remain filled with air at a pressure substantially equal to the venous or arterial pressure. Stated differently, a prior art system will include its original volume of air in the space between the proximal end of the non-patient needle and the blood that enters the blood collection set. This high-pressure air will escape into the first evacuated collection tube that is placed in communication with the non-patient needle. Hence, the first collection tube employed with prior art systems normally is a discard tube. With the subject invention, however, the communication of blood at venous or arterial pressure with the interior spaces of blood collection set 10 will urge air through a venting mechanism. Various embodiments of such venting mechanisms are described in detail below.
Several embodiments involve a venting mechanism location beyond the proximal end 70 of the non-patient cannula. In the embodiment of
In the embodiment of
In a further embodiment, the venting mechanism utilizes a one way valve located somewhere along the fluid passage. The valve allows air to escape but shuts closed when vacuum is applied thus, when an evacuated collection tube is applied at the needle tip, the tube draws blood from the fluid passage but not air.
As will be apparent to one skilled in the art, it is possible to combine one or more vent mechanisms in a single device, or put identical vent mechanisms at more than one location in a device. Moreover, it is possible to use any of a variety of vent plugs in the vent mechanisms of the invention. In addition, vent mechanisms herein may be applicable in a variety of devices other than blood collection sets.
For example,
Vent media, as used herein, can include, for example, either or a combination of:
Typically, a porous plug is formed from a hydrophobic material, such as high-density polyethylene (HDPE), which is coated with, impregnated with, or otherwise contains a hydrophilic material such as carboxymethylcellulose (CMC) or a polyacrylate. Alternative hydrophobic materials include but are not limited to polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE), Nylon 6, polypropylene (PP), polyvinylidine fluoride (PVDF) or polyethersulfone (PES).
An embodiment of the vent media consists of micro-sized holes formed in an exterior wall. The holes are large enough to permit airflow but small enough to prevent blood leakage. The vent holes may be any number including a single hole although multiple holes are typical for a more reliable function. The holes may be laser-drilled, meaning that they may be burned through the wall or substrate using one or more laser beams. The substrate may be any convenient material although thin plastic or plastic film is typical. The vent mechanism may include a one-way valve as previously described. The vent mechanism may be located at any convenient space along the fluid passage in the flexible tubing, luer or non-patient hub or in an added component although location at the proximal end is typical to provide flash along the full length of the tubing.
A porous plug that becomes sealed upon contact with blood using biological phenomena may use, for example, a porous material such as a sintered plastic, ceramic or metal, or a breathable cord, or by locating the biological agent in small holes or spaces between parts. The vent may be of any convenient shape. The venting may be at any location or locations along the fluid passage, but is preferably at the proximal end such as at the hub near the collection device. The vent is typically made from, contains, is adjacent to, or works in collaboration with, a stimulant that interacts with blood to promote clotting and/or cell agglutination such that the clot and/or clumped cells block ongoing flow of blood through the vent. An example a clotting stimulant is silica or crushed glass, or fiberglass. An example of an agglutinizing agent is lectin. An example of a platelet activator is collagen or thrombin. A neutralizer for anti-coagulant such as protomine sulfate may be included. The biological stimulant may be applied using any convenient process including as a powder, a solution, a suspension, a slurry, or any other form. It may be dried or lyophilized.
The present application is a continuation of U.S. patent application Ser. No. 11/971,697, filed Jan. 9, 2008, which is a continuation of U.S. patent application Ser. No. 11/141,446, filed May 31, 2005, which claims priority to U.S. Provisional Patent Application Ser. No. 60/576,140, which was filed on Jun. 2, 2004.
Number | Date | Country | |
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60576140 | Jun 2004 | US |
Number | Date | Country | |
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Parent | 11971697 | Jan 2008 | US |
Child | 12470916 | US | |
Parent | 11141446 | May 2005 | US |
Child | 11971697 | US |