Connecting Device For A Catheter

Abstract

A device for connecting a catheter with a container for contrast medium which is subjected to pressure is characterized by coupling means which are liquid-tightly connected with each other, at least one of these means being mounted so as to be rotated relatively to the other means about the flow axis. These means can be removably connected by connecting elements with the container for the contrast medium on the one hand and with the catheter on the other hand.

Description

This invention relates to a device for connecting a catheter with a container for contrast medium which is subjected to pressure.

It is known to introduce a catheter consisting of thin plastic or metal tubes, for example, into blood organs and then to connect it to a container for contrast medium subjected to pressure. When contrast medium begins to flow in, the catheter is subjected to high pressure by this medium, so that it can carry out uncontrolled movements and damage the blood vessels. Obviously it is of great importance to prevent these damaging catheter movements in a blood vessel.

It was determined, with surprise, that when the catheter is not fixed at its outer end directed toward the pressure medium container, but is capable of moving freely about its longitudinal axis, it is prevented from carrying out these detrimental movements.

Therefore, an object of the present invention is the provision of connecting means providing a complete seal and yet making possible a free rotation of the catheter relatively to the contrast medium container.

Other objects of the present invention will become apparent in the course of the following specification.

In the accomplishment of the objectives of the present invention it is found desirable to provide coupling means which are liquid-tightly connected with each other, at least one of these means being mounted so as to be rotated relatively to the other means about the flow axis, whereby the means can be removably connected by connecting elements with the contrast medium container on the one hand and with the catheter on the other hand.

According to an advantageous embodiment of the present invention the coupling means consist of a cylinder provided with a cover closing at least one of its front surfaces. A piston sealed against the cylinder walls is introduced into the cylinder and is mounted so as to be rotatable about the longitudinal axis of the cylinder. The piston is secured against sliding out. The cylinder has a flow channel for the flow of the contrast medium into its interior, the channel being closed by a connecting element. The piston has a flow channel closed by another connecting element for the flow of the contrast medium outwardly from the interior of the cylinder. This device which is similar in its structure to an injection syringe, solves the main object of the present invention in a surprisingly simple technically manufacturing manner.

According to a further development of the present invention the coupling means consist of two pistons introduced into the cylinder and secured against sliding out, the pistons being rotatable about the longitudinal axis of the cylinder. Each of the pistons has a flow channel provided with a separate connecting element for the flow of the contrast medium from one connecting element into the interior of the cylinder and then outwardly to the other connecting element. Practical experience has shown that this double rotating capacity provides better working conditions.

According to still another development of the present invention a particularly good seal against the outgoing contrast medium is produced when the cylinder can be closed at the front sides up to the flow channels and when the surfaces of the covers and pistons extending toward each other and at right angles to the axis of the cylinder are shaped as superior joints.

Furthermore, the present invention makes it possible for one of the pistons to run particularly softly, whereby only this piston must be provided with special bearing means, and to provide a good sealing for this piston. For that purpose a further piston is provided between that piston which is directed toward the catheter and the cover. This additional piston is introduced with liquid seal into the cylinder and it has a concentrical axial bore through which passes the shaft of the adjacent piston. This shaft is rotatable about the longitudinal axis of the cylinder and is also sealed against liquid. Frictionally poor bearing means are introduced between the surfaces of the two pistons which are directed toward each other and extend at right angles to the axis of the cylinder.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example only, a preferred embodiment of the inventive idea.

In the drawings:

FIG. 1 is a diagram illustrating the main features of a device for catheterizing a patient.

FIG. 2 is a side view, partly in section, of a connecting device in accordance with the present invention.

According to FIG. 1 an automatically operated high pressure injection syringe 1 supplies dosed amounts of contrast medium during predetermined time periods through a hose 2 to the catheter 3 which is introduced into an arm vein of a patient 5 lying upon the table 4 of an X-ray device (not shown). The high pressure injection syringe 1 has an operating section 6 with setting means 7 and 8 for the amount of the contrast medium and the duration of the injection, as well as a button 9 for releasing the flow of the contrast medium which can be also operated automatically, for example, depending upon the heart phase of the patient 5.

The contrast medium is located in the spray cylinder 10 which is connected with the operating section 6 by holding elements 11 and 12. The spray piston 13 is connected by a connecting rod 14 with a lever 15 which actuates the spray piston 13 depending upon values selected by the setting means 7 and 8.

In order to avoid the transmission of forces appearing in the hose 2 as the result of high pressure of the contrast medium to the catheter 3, the hose 2 carries a connecting device 16 which is shown in detail in FIG. 2.

This connecting device 16 has a cylinder 17 which may consist entirely of metal or of a glass tube having metallic end caps, as used in known injection syringes. One end of the cylinder is closed by a front wall 18. A piston 19 having a seal 20 is introduced into the upper part of the cylinder 17. The flow channel of the piston for the contrast medium is formed by a cylindrical shaft 21 extending through a concentric bore of the front surface 18 of the cylinder 17. The outer end of the shaft carries a connecting element 25 shaped as a box coupling for connecting the device with the pressure container (not shown) for the contrast medium. In order to provide a flow for the contrast medium the cylinder and the shaft have a channel 23 extending in the longitudinal direction.

The end surface of the piston 19 directed toward the front cover 18, as well as the surface of the cover 18 directed toward the piston extend at right angles to the central axis of the cylinder 17 and are so ground that the two surfaces tightly engage each other forming a so-called superior joint.

The cylinder 17 also contains a second piston 27 similar in shape to the first piston 19 and arranged also with fine fitting in the lower part of the cylinder. A flow channel 31 extends longitudinally through the piston 27 and its shaft 29. At the end of the shaft 29 there is a further coupling member 33 having the shape of a plug coupling for providing a liquid-tight connection between the channel 31 and a catheter.

The front surfaces of the two pistons 19 and 27 extend at right angles to the longitudinal axis of the cylinder and are separated from each other by a small intermediate space 22.

A third piston 37 is located between the surface of the piston 27 directed toward the catheter and the cover 39 of the cylinder 17. The cylindrical shaft 29 which is concentrical to central axis of the cylinder, is freely rotatable in the piston 37 and extends through it with liquid-tight seal. The piston 37 is also introduced into the cylinder 17 with a sealing slide, The front surface of the piston 37 extending toward the catheter also engages the inner surface 40 of the cover 39 with a so-called superior joint. The inner surface 40 of the cover 39, just as the front surface of the cover 18, is also preferably surface ground and extends at a right angle to the axis of the cylinder.

The cover 39 has a concentric bore, similar to that of the piston 37, and the shaft 29 is rotatably mounted in that bore with fine fitting. The cover 39 can be screwed upon the outer surface of the cylinder 17 by screw threads 41. The surfaces of the pistons 27 and 37 which face each other also extend at a right angle to the axis of the cylinder. Axial ball bearings 35 are located between these surfaces.

The operation of the described device is as follows:

Liquid contrast medium is introduced under pressure into the connecting element 25 and flows through the channel 23 in the direction of the arrow 26. The fine sealing of the engaging surfaces between the piston 19 and the cylinder 17 results in that the contrast medium cannot penetrate to the bore of the front cover 18. This seal is also strengthened by the fine joint engagement of the front surface of the piston 19 with the inner ground surface 24 of the cover 18.

The contrast medium penetrates through the channel 23 into the space 22 between the pistons 19 and 27 and then flows through the channel 31 and the coupling member 33 to the catheter in the direction of the arrow 34.

The device composed of the piston 27 with the shaft 29 and the connecting element 33 must easily rotate in the cylinder 17 while remaining sealed and must be able to move slightly axially. For that purpose a frictionally poor bearing consisting of ball bearings 35 is provided between the piston 27 and the piston 37. The space 22 between the two pistons 19 and 27 has the purpose to prevent any difficulty in the rotation of the piston 27 which could occur if the two opposed front surfaces of the pistons 19 and 27 would be in engagement. The piston 37 does not serve essentially as a seal but to guide the shaft 29 of the piston 27; its front surface directed toward the interior of the cylinder serves as a support for the ball bearings 35.

The construction of the piston 37 in such manner that it can be shifted with slide seal into the cylinder 17, has essentially the manufacturing reason that the device can be composed of pistons of the same diameter and of at least approximately equal lengths. Furthermore, the manufacture is simplied in that the two pistons 19 and 27 with their shafts 21 and 29 and extending channels 23 and 31 have essentially the same structure. In addition, the described construction with three pistons results in a higher safety as far as seal is concerned.

It is basically possible to eliminate the piston 37 and to provide the friction-poor bearing consisting of balls 35 between the inner surface 40 of the cover 39 and the opposed front surface of the piston 27.

However, by keeping the piston 37 and providing a fine adjustment between the shaft 29 and the channel 31 in the piston 37 and a fine adjustment between the outer surface 38 of the piston 37 and the inner surface of the cylinder 17, a greater security is provided for the contrast medium which could penetrate between the outer surface 38 of the piston 37 and the inner surface of the cylinder 17. The contrast medium will penetrate outwardly, since the pressure in the range of the ball bearings 35 is small as long as this intermediate space is not completely filled with the contrast medium.

In order to further improve the sealing, the outer surface of the piston 27 is provided with an annular groove 43. As long as this groove is not completely filled with liquid, the pressure between the hollow of the groove 43 and the intermediate space at the ball bearings 35 is small, and thus prevents to a substantial extent the passage of the medium along the outer wall of the piston 27.

It is also basically possible to eliminate the piston 19 by firmly connecting the shaft 21 with the cover 18 or making the two of one piece.

However, there is an advantage of having the piston 19 which in the illustrated construction is provided with an annular groove 42 in a manner similar to that of piston 27. This advantage consists in being able to provide a relative rotary movement between the cylinder 17 on the one hand and the device consisting of the piston 19, the shaft 21 and the connecting element 25 on the other hand. This provides the possibility of a double rotary movement between the two connecting elements 25 and 33.

Claims

I claim:

1. A device for connecting a catheter with a container for a contrast medium, said container being subjected to pressure, said device comprising coupling means having a cylinder, a connecting element removably connecting said cylinder with said container and having a channel for the flow of the contrast medium, another connecting element removably connecting said cylinder with said catheter and having a channel for the flow of the contrast medium, covers closing both ends of the cylinder and having openings for said channels, a first piston liquid tightly mounted in said cylinder and directed to the first-mentioned connecting element, said piston having a transverse axial passage coaxial with said cylinder and communicating with the first-mentioned channel, a second piston liquid tightly mounted in said cylinder and directed to the second-mentioned connecting element, said second piston having a transverse axial bore, a third piston located between the first and second pistons and liquid tightly mounted in said cylinder, said third piston being spaced from said first piston, a shaft firmly connected with said third piston and extending through the bore of said second piston and to the second-mentioned connecting element, said third piston and said shaft having a continuous transverse axial passage constituting a continuation of the first-mentioned axial passage, and ball bearings between the second and third pistons, whereby the third piston and its shaft are rotatable relatively to the first piston.