Injection Site For Flow Conduits Containing Biological Fluids

Abstract

An injection site for a flow conduit for biological fluids and the like, such as blood or parenteral solutions, is provided having improved resistance to leakage through needle punctures, even when the pressure within the flow conduit is substantially different from the pressure outside of the conduit. The conduit comprises tubing made of a biologically compatible material, in which a portion of the tubing is surrounded by an elastomeric sleeve injection site. A second elastic sleeve surrounds the first elastomeric sleeve, the second sleeve having an unstretched inner diameter which is less than the outer diameter of the elastomeric sleeve. As a result, the elastomeric sleeve is compressed by the second sleeve, whereby the sealing of the elastomeric sleeve after puncture by a needle is improved.

Description

BACKGROUND OF THE INVENTION

Parenteral solution administration equipment and blood flow conduits for solution infusion, blood transfusion, or the conveyance of blood between a patient and an artificial kidney or blood oxygenator generally require sites where an injection needle can be inserted into the conduit to withdraw samples, or to administer medication or the like. When the injection needle is withdrawn, it is important that there be no leakage of solution or blood through the needle puncture.

Problems can arise with the leakage of blood and solution, particularly when the interior of the conduit is under either a substantially elevated or substantially reduced pressure with respect to the exterior, as in the case of certain oxygenation and artificial kidney blood conduits, and in the case of the pressurized administration of parenteral solution or blood to a patient.

In the conventional arterial and veinous sets for coil dialyzers, which sets are used to transfer blood between a patient and the coil dialyzer, it is well known to provide an injection site which comprises a latex sleeve surrounding a portion of the blood tubing which is made of vinyl plastisol or the like. In this prior art structure, the latex sleeve is stretched over the blood tubing to attempt to provide a fluidtight seal between the latex sleeve and the blood tubing. Thus, when a needle penetrates the latex sleeve and the blood tubing, and is thereafter withdrawn after injecting a medicament or taking a sample, the latex sleeve is intended to provide a seal against fluid leaks which occur through the needle puncture in the blood tubing.

Unfortunately, it has been found that because the latex sleeve has to be stretched onto the blood tubing to provide a fluid-tight seal between the two members, the well-known excellent resealing characteristics of the latex are diminished because of the stretching of the latex. The needle puncture in the latex has been observed to sometimes fail to adequately reseal, particularly in the case where there is a pressure differential between the interior and exterior of the flow conduit. It is of course highly undesirable for fluid to leak through the puncture hole, forced out by an elevated fluid pressure in the flow conduit. Furthermore, it can be extremely dangerous for air bubbles to be sucked into the flow line through the needle puncture when the blood tubing interior is at a pressure of less than atmospheric, especially in the case where the blood tubing conveys blood between a dialyzer or an oxygenator and a living patient.

Furthermore, the prior art resealable injection site has also been observed to leak by the passage of fluid between the vinyl blood tubing and the latex sleeve, until fluid appears at the end of the latex sleeve as a continuous slow leak. However, if one uses a smaller diameter latex sleeve to increase the sealing pressure at the interface between the blood tubing and the latex sleeve, the stretching in the latex sleeve is increased, which results in less capability to seal needle punctures.

DESCRIPTION OF THE INVENTION

In accordance with this invention, the sealing capability of a fluid conduit of biologically compatable tubing surrounded by an elastomeric sleeve injection site is improved by a second elastic sleeve surrounding the first elastomeric sleeve, in which the second elastic sleeve has an unstretched inner diameter which is less than the outer diameter of the first elastomeric sleeve. The result of this is to compress the first elastomeric sleeve, whereby the sealing of the elastomeric sleeve after puncture by a needle is improved.

It is preferred for the second elastic sleeve to be longer than the first elastomeric sleeve, and to overlie the ends of the elastomeric sleeve. In this case, the unstretched inner diameter of the second elastic sleeve should be less than the outer diameter of the biologically compatible tubing, to seal the ends of the first elastomeric sleeve against fluid leakage between the elastomeric sleeve and the tubing. It is also desirable for the wall thickness of the second sleeve to be less than one-half of the wall thickness of the elastomeric sleeve, and for the inner diameter of the second sleeve to be less than the inner diameter of the elastomeric sleeve, so that the degree of stretching of the second sleeve is greater than that of the first elastomeric sleeve, and it tightly seals about the ends of the first sleeve. Typically, the outer diameter of the first elastomeric sleeve as mounted on the tubing is at least about twice the inner diameter of the second elastic sleeve for high compression of the first elastomeric sleeve, although lesser degrees of compression can be used by providing a second sleeve of larger inner diameter.

The first elastomeric sleeve is preferably made of natural latex or any other elastomeric material having excellent needle puncture resealing characteristics. The second elastic sleeve is also conveniently made of natural latex, although any elastic material having generally equivalent tensile strength can be used. However, it is generally desirable for the second sleeve to also have excellent needle puncture resealing characteristics equivalent to natural latex. Alternatively, the second elastic sleeve can be made of a material which shrinks upon drying of solvent in the material or upon heating, such as certain forms of polytetrafluoro-ethylene or polyvinylchloride plastisol. The use of such material simplifies the assembly procedure.

Referring to the drawings:

FIG. 1 is an elevational view of a portion of conduit tubing for blood, dialysis solution, parenteral solution, or the like, surrounded by the improved injection site of this invention.

FIG. 2 is a longitudinal sectional view taken along line 2--2 of FIG. 1, and enlarged in size.

FIG. 3 is a transverse sectional view taken along line 3--3 of FIG. 1 and enlarged in size.

Referring to the drawings, tubing 10 is shown as a conduit for blood in a medical device such as a conventional arterial or veinous set for an artificial kidney. Such sets are commercially available at the present time from Travenol Laboratories, Inc. of Morton Grove, Ill. Tubing 10 might also be part of a blood line in a blood oxygenation system. Tubing 10 can be made of any needle-puncturable, biologically compatible material, for example, plastic materials including vinyl plastisol or polyurethane, and silicone rubber.

The improved injection site 12 of this invention comprises an elastomeric sleeve 14 surrounding a portion of tubing 10. The unstretched inner diameter of elastomeric sleeve 14 is smaller than the outer diameter of tubing 10 to provide a compressive seal at the interface 22 between sleeve 14 and tubing 10.

Second elastic sleeve 16 overlies the first elastomeric sleeve 14, and is longer than elastomeric sleeve 14, so that overlying portions 18, 20 cover the ends of sleeve 14 and provide sealing against any fluid leakage that takes place along the interface 22 between tubing 10 and elastomeric sleeve 14 after puncture by a needle 24, shown in phantom in FIG. 2. Sleeve 16 has less than half the wall thickness of sleeve 14, to permit it to closely conform about the ends of sleeve 14 for improved sealing.

Second sleeve 16 is proportioned to compress elastomeric sleeve 14, which compression provides improved sealing of needle puncture holes through sleeve 14 after the puncturing needle 24 has been withdrawn. The inner diameter of second sleeve 16 is less than the unstretched outer diameter of sleeve 14, so that sleeve 14 is substantially compressed.

In one suitable form, tubing 10 has an inner diameter of about 0.18 to 0.2 inch and a wall thickness of about 0.06 to 0.07 inch, to give a total outer diameter of about 0.3 to 0.34 inch.

Correspondingly, elastomeric sleeve 14 can have an unstretched inner diameter of about 0.2 to 0.3 inch and a wall thickness of about 0.09 to 0.1 inch. In one specific embodiment, the inner diameter is 0.312 inch and the wall thickness 0.094 inch, to give a total outer diameter of 0.5 inch. In the same specific embodiment, the outer diameter of tubing 10 is 0.34 inch. Thus, sleeve 14 exerts a substantial compression upon the outer wall of tubing 10 and is correspondingly stretched in the process.

In the above situation, second elastic sleeve 16 may have an inner diameter of about 0.25 inch and a wall thickness of about 0.03 inch. It can thus be seen in the above specific embodiment that the outer diameter of elastomeric sleeve 14 is about twice the inner diameter of second sleeve 16 in the above specific embodiment. Accordingly, sleeve 14 is placed under quite substantial compression by second sleeve 16, which results in an improvement in the sealing characteristics of sleeve 14. Similarly, since the unstretched inner diameter of second sleeve 16 is less than the outer diameter of tubing 10, an additional pressure seal is applied to tubing 10 by end portions 18, 20, resulting in additional sealing about the ends of elastomeric sleeve 14.

In another suitable configuration, tubing 10 has an inner diameter of 0.187 inch and a wall thickness of 0.063 inch, while elastomeric sleeve 14 has an inner diameter of 0.25 inch and a wall thickness of 0.094 inch. The remaining dimensions are similar to the previous embodiment.

Elastomeric sleeve 14 is generally about 2 to 6 inches long, while second sleeve 16 is about 1 to 3 inches longer than sleeve 14, to provide suitable sealing about the ends of sleeve 14.

Sleeves 14 and 16 can be placed upon tubing 10 simply by expanding them with a suitable expansion fork made of a plurality of rods, and lever means for spreading the rods apart, to stretch the sleeves while threading them onto tubing 10 to the desired position. Then the expansion fork is allowed to collapse, and is withdrawn from the inside of each sleeve. Likewise, sleeves 14, 16 can be threaded upon a suitably sized rigid collet, and threaded on the tubing 10, the collet being then withdrawn.

The above has been offered for illustrative purposes only, and is not intended to limit the invention which is defined in the following claims.

Claims

That which is claimed is:

1. In a conduit for blood and the like which comprises needle puncturable, biologically compatible tubing, a portion of said tubing being surrounded by an elastomeric sleeve injection site, the improvement comprising a second, elastic sleeve surrounding said elastomeric sleeve, said second sleeve having an unstretched inner diameter which is less than the outer diameter of said puncturable tubing, to compress said elastomeric sleeve, whereby the sealing of said elastomeric sleeve after puncture by a needle is improved, and in which said second, elastic sleeve is longer than said elastomeric sleeve and overlies the ends of said elastomeric sleeve, to seal the ends of said elastomeric sleeve against fluid leakage between the elastomeric sleeve and the tubing.

2. The blood conduit of claim 1 in which the wall thickness of said second sleeve is less than one half the wall thickness of said elastomeric sleeve.

3. The blood conduit of claim 2 in which said elastomeric sleeve is made of natural latex.

4. The blood conduit of claim 3 in which said second sleeve is made of natural latex.

5. The blood conduit of claim 4 in which said tubing is made of a material selected from the group consisting of vinyl plastisol, polyurethane, and silicone.

6. The blood conduit of claim 2 in which said tubing has an inner diameter of about 0.18 to 0.2 inch and a wall thickness of about 0.06 to 0.07 inch; said elastomeric sleeve has an unstretched inner diameter of about 0.2 to 0.3 inch and a wall thickness of about 0.09 to 0.1 inch, and said second, elastic sleeve has an unstretched inner diameter of about 0.25 inch and a wall thickness of about 0.03 inch.

7. The blood conduit of claim 1 in which the unstretched outer diameter of said elastomeric sleeve is at least two times the inner diameter of said second elastic sleeve.

8. The blood conduit of claim 1 in which the inner diameter of said second sleeve is less than the inner diameter of said elastomeric sleeve.