Catheter Placement Unit

Abstract

A catheter placement unit primarily useful with equipment for monitoring central venous pressure comprises a length of flexible hollow tubing having a female fitting at one end for attachment to the equipment and a male fitting adjacent the other end for attachment to the hub of a flexible intravenous plastic catheter that has been introduced into the vein of a patient. The male fitting has an axial opening through which the tubing passes and across the opening is positioned an elastomeric diaphragm having a slit which tightly engages the outer periphery of the tubing to form a seal between the male fitting and the tubing and to yieldingly resist the movement of the tubing relative to the male fitting. A stylet is preferably provided within the lumen of the tubing and a flexible plastic sheath preferably covers the tubing to provide a sterile procedure for feeding the tubing through the male fitting and plastic catheter.

Description

This invention relates to catheters and, more particularly, to a unique catheter placement unit which minimizes the trauma to the veins and other body tissue and also minimizes the leakage of blood from the patient during the period the catheter is in use.

Many prior devices and procedures have heretofore been used to introduce relatively long flexible catheters, such as, catheters useful in combination with equipment for measuring and monitoring central venous pressure, into the venous system of a patient.

These prior systems have usually required the use of a metal introducer needle which was inserted into a vein and provided a passage for the catheter into the venous system. Because the needle was substantially larger in outside diameter than the catheter, it was impossible to remove the needle without causing a leakage of blood between the skin and the outer surface of the catheter. Therefore, the needle has usually been permitted to remain in the vein during the period of use of the catheter, thus, creating a twofold hazard in that the extremely sharp point on the needle could cause tissue damage and also sever the catheter and render it useless.

The present invention provides a unique structure and procedure which eliminates the disadvantages heretofore experienced with prior catheter placement systems. This structure includes the use of a conventional over-the-needle plastic catheter in combination with uniquely constructed catheter tubing having a female fitting at its proximal end for connection to the fitting of an administration set or pressure monitoring equipment. A second fitting is slidably mounted on the distal end of the catheter tubing and provides structure for at least the following three functions: (1) an attachment between the catheter tubing and the hub of the conventional plastic catheter; (2) a seal to prevent the leakage of blood between the catheter tubing and the plastic catheter; and (3) a component for yieldingly resisting the movement of the catheter tubing relative to the plastic catheter so that the catheter tubing cannot be easily withdrawn from the venous system of the patient by an inadvertant action.

The invention also provides a sterile procedure for introducing the catheter tubing into the venous system and an optional method for connecting the catheter tubing to pressure monitoring equipment, or the like, prior to the introduction of the catheter.

The invention will be particularly described with reference to the following detailed description of the preferred embodiment of the invention when considered together with the attached drawing, in which:

FIG. 1 is a view showing a patient's arm and vein in section with a conventional plastic catheter introduced into the vein and with the catheter placement unit of the subject invention in position for connection to the hub of the plastic catheter;

FIG. 2 is a view similar to FIG. 1 but showing the catheter placement unit connected to the hub of the plastic catheter and the catheter tubing of the catheter placement unit being fed through the plastic catheter into the vein of a patient;

FIG. 3 is a fragmentary cross sectional view showing the connection between the hub of the plastic catheter and the slidable fitting mounted adjacent the distal end of the catheter tubing of the catheter placement unit of the present invention;

FIG. 4 is a fragmentary cross sectional view taken along line 4--4 in FIG. 3 but showing the catheter tubing and stylet illustrated in FIG. 3 removed from the sealing component within the fitting; and

FIG. 5 is a fragmentary view illustrating the end of the plastic bag shown in FIGS. 1 and 2 before it is assembled to the fitting which is slidably mounted on the distal end of the catheter tubing of the catheter placement unit of the present invention.

Referring to FIG. 1, the catheter placement unit of the present invention is shown generally at 10 and comprises as its main components an elongated flexible length of plastic tubing 11, having an open lumen extending from one end to the other and having a female fitting 12 secured to the proximal end thereof and a male fitting 13 slidably mounted adjacent the distal end thereof. Catheter placement unit 10 further comprises a transparent flexible plastic sheath 14 which has a frangible connection 15 with fitting 13. Preferably, a stylet 16 (see FIG. 3) is positioned within the entire length of the lumen of tubing 11 and has a plug 17 secured to its proximal end and firmly seated within female fitting 12.

Catheter placement unit 10 is intended to be utilized in combination with a conventional flexible plastic catheter shown generally in FIG. 1 at 20. Catheter 20 is preferably of the over-the-needle type and may be constructed in a manner illustrated in U.S. Pat. No. 3,094,122. In this patent the manner of manufacturing such a catheter and of introducing such a catheter into the vein of a patient is very thoroughly described. In FIG. 1, the arm A and vein V of a patient is illustrated in cross section with flexible tubing portion 21 of catheter 20 introduced therein. Tubing 11 and catheter 21 are preferably made from a bio-compatible material, such as, polytetrafluroethylene and are preferably very flexible so that the trauma to the vein and other body tissue of the patient is greatly minimized. A standard plastic or metal hub 22 is secured to the proximal end of catheter 21 and is adapted to be connected to the male tapered fitting 24 secured to the end of fitting 13.

Referring to FIG. 3, the internal construction of fitting 13 and the manner in which it is connected to fitting 22 are clearly illustrated. However, in order to best understand the complete operation of catheter placement unit 10 and its cooperation with catheter 20, fitting 13 will first be described in detail.

Referring to FIG. 3, fitting 13 comprises an essentially cylindrical housing 30 which has an axial opening 31 extending therethrough. In the initial assembly of fitting 13 and catheter tubing 11, the tubing is passed through the axial opening 31 to a location adjacent the tip 32 of male fitting 24. Within housing 30 is mounted an elastomeric diaphragm 33 which is securely held within the proximal end of housing 30 by a metal ferrule 34.

Referring to FIG. 4, the location of diaphragm 33 relative to catheter tubing 11 and stylet 16 is shown in cross section. It will be appreciated that elastomeric diaphragm 33 extends completely across axial opening 31 extending through housing 30 and, except for the slit 35 formed in the center of diaphragm 33, the diaphragm completely seals the axial opening. Slit 35 may be opened sufficiently to permit the passage of catheter tubing 11 therethrough but retains a close contact with the outer priphery of the tubing so that any passage of blood or other fluid is prohibited. Also, the tight fit between slit 35 and the outer periphery of tubing 11 provides a means for yieldingly resisting the movement of tubing 11 relative to fitting 13 and catheter 21. This aspect of the invention will be more thoroughly discussed herein below.

As stated above, the distal end of fitting 13 is provided with a tapered connector or fitting 24 which is adapted to be received in the open end of hub 22 connected to plastic catheter 21. As shown in FIG. 3, fitting 13 is also provided with a threaded locking element 36 which is adapted to engage the outwardly extending flange 23 on the extreme end of hub 22. This engagement securely locks hub 22 within fitting 13 and prevents accidental separation of the two parts.

Referring to FIG. 5, a portion of plastic bag 14 is illustrated prior to its attachment to the proximal end of fitting 13. Bag 14 is formed from a flexible plastic material that may be conveniently attached to fitting 13 as illustrated in FIG. 3. The open end 40 of the bag is placed over the proximal end of housing 30 and secured thereto by a substantially cylindrical elastomeric band 41 which completely encircles housing 30. The bag is so positioned that the frangible section 15 is positioned adjacent the extreme end of housing 30.

The introduction and use of catheter placement unit 10 will now be described in detail. After catheter 20 has been appropriately introduced into vein V in a manner similar to that illustrated in FIGS. 7-9 of U.S. Pat. No. 3,094,122, fitting 13 is connected to hub 22 by positioning connector 24 within the tapered open end of hub 22 and turning fitting 13 to securely lock the two components together as shown in FIG. 3. With the components thus assembled, the operator may then grasp the plastic bag, as illustrated in FIG. 2, and move catheter tubing 11 forward through axial opening 31 within housing 30 and, thus, through catheter 21 into the venous system of the patient.

After catheter tubing 11 is appropriately positioned within the venous system of the patient, plastic bag 14 may be removed from fitting 13 by merely pulling or "snapping" the bag in a direction away from the fitting.

In order to connect the appropriate tubing from an administration set or a pressure monitoring device, it is only necessary to remove plug 17 and its associated stylet 16 and connect the tubing to hub 12. The catheter placement unit is thus placed in an operable condition.

If it is desirable to attach the pressure monitoring tubing prior to the placement of catheter tubing 11 into the venous system of a patient, the operator may expose fitting 12 by pulling the open end 45 of bag 14 over the fitting and removing plug 17 and stylet 16. The tubing may then be connected to fitting 12 prior to the connection of fitting 13 to hub 22 and prior to the feeding of catheter tubing 11 into the vein. Both of the above described procedures are effective to provide means for feeding the catheter tubing into the venous system with a sterile procedure.

It will be apparent from the foregoing description that the present invention provides a unique catheter placement unit that accomplishes the desired results of minimizing trauma to the vein and surrounding tissue of a patient and also minimizes the leakage of blood and other body fluids during the procedure. This is accomplished by utilizing a flexible plastic introducer catheter and a uniquely designed fitting for attaching the catheter tubing to the hub of the plastic catheter. As stated before, this fitting serves the functions of preventing the leakage of blood between the catheters and providing an element for yieldingly resisting the movement of the catheter tubing relative to the plastic introducer catheter. This latter advantage greatly minimizes the opportunity for inadvertent removal of the catheter tubing.

Claims

We claim:

1. A catheter placement unit for use with an intravenous catheter having a hub with an internal tapered surface and a terminal flange, an elongated flexible length of hollow tubing; a first fitting secured to the proximal end of said tubing; and a second fitting slidably mounted adjacent the distal end of said tubing, said second fitting having an axial opening therethrough and an elastomeric diaphragm secured across said opening and having an aperture for the passage of said tubing, defining a means to cause said diaphragm to tightly engage the outer periphery of said tubing, said second fitting further having a tapered male connector extending axially from its distal end for mating with the internal tapered surface of the intravenous catheter hub and a threaded locking element encompassing said tapered connector defining a means for coacting with said terminal flange on said catheter hub to securely lock said second fitting to said catheter hub.

2. The catheter assembly of claim 1 wherein said aperture is a slit formed in said diaphragm.

3. The catheter assembly of claim 1 further comprising a flexible plastic sheath secured to said second fitting and being of sufficient length to enclose the entire length of said tubing and said first fitting.

4. The catheter assembly of claim 3 wherein said sheath has a frangible connection to said second fitting.

5. The catheter assembly of claim 4 further comprising a stylet completely filling the lumen of said tubing.