Catheter set

In order to keep the opening for inserting a catheter into a blood vessel as small as possible, a catheter insertion tube is used which coaxially surrounds the puncturing canula and consists, at least in a circumferential area and/or at least along a portion of its length, of one or several dilatable or expandable areas permitting enlargement of its internal diameter. The diameter of the catheter insertion tube, at the front end where it is inserted into the blood vessel, is approximately equal or smaller than the outer diameter of the catheter. The catheter insertion tube is expandable at least over the front or forward portion of its length by the catheter. The catheter insertion tube i removable from the puncture over the catheter while the catheter is advanced into the puncture and is tighty sealed by the catheter because the catheter has an external diameter equal to or larger than the puncture previously occupied by the insertion tube.

This invention is concerned with a novel catheter set for inserting a 
catheter into a blood vessel. 
BACKGROUND OF THE INVENTION 
A number of catheter sets are already known. According to a construction 
disclosed in DE-GM 74 27 426, the catheter upon insertion, contacts and 
presses against the inner wall surface of a conically-shaped catheter 
insertion tube or sleeve. The tube is made of a polymeric synthetic 
material and is provided with a longitudinal tear line. The tube is split 
open along the tear line by the catheter pressure as it advances. Thus, 
the catheter insertion tube portion outside of the puncture site serves as 
a kind of guide channel to easily insert the catheter into the punctured 
blood vessel. However, this type of insertion presumes that the catheter 
insertion tube continues to remain in the punctured blood vessel until the 
following catheter also penetrates the puncture site, since the catheter 
insertion tube represents the sole insertion aid for the catheter. This 
means, however, that the puncture site must have a diameter larger by at 
least the wall thickness of the catheter insertion tube than is necessary 
for the insertion of the catheter. This enlarged size of puncture site, 
which is inherent in the previously known catheter set, can be even more 
enlarged inadvertently, due to the fact that the catheter insertion tube 
has to remain in the blood vessel during insertion of the catheter. 
Because of the splitting of the catheter insertion tube and its subsequent 
enlarged diameter, the puncture site is correspondingly enlarged so that 
one has to fear formation of blood vessel fissures at the puncture site. 
Consequently, as a rule it is not possible for the subsequently inserted 
catheter to effect an adequate seal at the blood vessel puncture site. 
This has lead, particularly in infants, to dangerous bleeding and side 
effects, in particular to infections. 
SUMMARY OF THE INVENTION 
The invention has, as one of its purposes, the provision of an improved 
catheter set and improved elements useful therein, broadly of the above 
mentioned type, which will not enlarge the dimensions of the puncture site 
beyond the outer diameter of the catheter which is to be subsequently 
inserted, so that a safe seal with the catheter to be inserted at the 
puncture site is guaranteed. 
Due to the improved catheter set and improved elements incorporated 
therein, provided according to the invention, which includes a catheter 
having an outer diameter at least approximately the same or slightly 
larger than the outer diameter of the catheter insertion tube, as well as 
the fact that the catheter insertion tube consists, at least in one or 
several circumferential areas and/or at least along a portion of its 
length, one or more dilatable areas which permit an enlargement or 
expansion of the diameter, it is possible for the catheter insertion tube, 
after the catheter or the mandrin, respectively, is inserted in the 
puncture, to be pulled back over the catheter and thus be removed from the 
puncture, whereby the puncture is efficiently sealed off by means of the 
catheter with an equally large or slightly larger outer diameter than the 
cross-sectional opening of the puncture site. In particular, 
over-expansion of the blood vessel, or fissure of the same at or in the 
area of the puncture, is avoided upon insertion of the catheter. Thus, 
with the catheter set according to the invention, not only a safe seal of 
the puncture is guaranteed, but also adverse side effects, such as the 
entrance of air, dirt particles or similar materials into the blood 
stream, are avoided to a greater extent than before. 
According to one embodiment, the invention provides an improvement in a 
catheter set including a catheter and a catheter insertion tube into which 
the catheter to be inserted into a blood vessel is insertable, with the 
improvement comprising a catheter having an elongated front end portion 
with an external diameter smaller than the external diameter of the main 
body of the catheter; a catheter insertion tube having a front end portion 
with an internal diameter smaller than the external diameter of the main 
body of the catheter; the elongated smaller front end portion of the 
catheter being axially slidable in the catheter insertion tube front end 
portion without expanding the same; and the front end portion of the 
catheter insertion tube being expandable by movement of the catheter main 
body axially therein. 
Desirably, the catheter main body external diameter is not less than the 
external diameter of the front end portion of the catheter insertion tube 
at a blood vessel puncture. 
According to another embodiment of the invention, there is provided an 
improved catheter set including a catheter and a catheter insertion tube 
into which the catheter to be inserted into a blood vessel is insertable, 
with the improvement comprising a catheter; a catheter insertion tube 
having a front end portion with an internal diameter smaller than the 
external diameter of the catheter; the front end portion of the catheter 
insertion tube being expandable by movement of the catheter axially 
therein; and a mandrin having an outer diameter not larger than the 
internal diameter of the catheter insertion tube front end portion 
internal diameter. 
Desirably, the catheter external diameter is not less than the external 
diameter of the front end portion of the catheter insertion tube at a 
blood vessel puncture. 
The invention will be described in detail in conjunction with the specific 
embodiments illustrated by the attached greatly enlarged drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
A catheter set according to the invention contains a conventional 
puncturing canula made of steel which is not illustrated in the drawing, 
said canula being coaxially surrounded by a catheter insertion tube 1 
(FIG. 1). The tube 1 is inserted, together with the above named puncturing 
canula, through the skin 2 into a blood vessel 3. The puncturing canula is 
then entirely withdrawn by pulling it back from the catheter insertion 
tube 1. Thereafter the catheter 4, with the coaxial mandrin (or mandrel) 5 
in place is inserted into the catheter insertion tube 1 as can be seen 
from FIG. 1. The catheter insertion tube 1 can be cylindrical or it can be 
slightly tapered conically with the smaller end to be inserted into the 
blood vessel 3. The inner diameter of the catheter insertion tube 1 in the 
vicinity of the puncture location 3a has the reference figure d.sub.1, 
while the outer diameter of the end inserted into the blood vessel 3 is 
referenced with d.sub.2. The outer diameter of the catheter insertion tube 
1 in the vicinity of the puncture location 3a is equal, or at least almost 
equal, to the diameter d.sub.2 at the container-side end of the catheter 
insertion tube 1. 
The catheter insertion tube 1 over its entire length L.sub.2 is provided 
with a dilatable area 6 running parallel to the longitudinal axis L. If 
necessary, several dilatable areas 6 can be distributed around the 
circumference of the catheter insertion tube 1. 
The cylindrical or tubular catheter 4 has an outer diameter d.sub.3 which 
is at least the same as, but preferably is a few tenths of a millimeter 
larger than, the outer diameter d.sub.2 of the catheter insertion tube 1, 
or of a conical ended catheter insertion tube 1. When the front end 7 of 
catheter 4 is inserted into the catheter insertion tube 1 an immediate 
spreading or enlarging effect is obtained because the catheter 4 outer 
diameter d.sub.3 is larger than the outer wall diameter d.sub.2 of the 
catheter insertion tube 1. As a result, the wall of the catheter insertion 
tube 1 is expanded in the dilatable area(s) 6. 
FIG. 1 shows the rounded forward end of catheter 4 after it has been pushed 
forward to approximately the middle of the catheter insertion tube 1 as 
illustrated by the expanded or enlarged area 6a. FIG. 1 shows that the 
catheter 4 with its slightly rounded front point 7 has reached 
approximately the center of the catheter insertion tube 1, as this is 
illustrated by the expanded dilatable area 6a. 
The mandrin 5 has an outer diameter d.sub.4 which is smaller, or 
approximately the same, as the inner diameter of the catheter 4. 
Therefore, the mandrin 5, together with the catheter 4, can be inserted 
into the catheter insertion tube 1 and it can be inserted into the blood 
vessel 3 through the catheter insertion tube 1 beyond the puncture site 
3a. This can be done without stressing, with respect to expanding, the 
dilatable area(s) 6 of the catheter insertion tube 1 by means of the 
mandrin 5. The mandrin 5 has a sufficient length to be securely placed in 
blood vessel 3 to function as a guide element for the subsequent insertion 
of the catheter 4 through puncture 3a. The mandrin or mandrel 5 can be 
designed as a solid body or as a hollow body like the coaxial catheter 4 
and preferably it is made from a sufficiently flexible synthetic polymeric 
material. 
After the mandrin 5 has been securely placed in the blood vessel 3, the 
catheter insertion tube 1 is continuously pulled back or withdrawn while 
simultaneously the catheter 4 can be moved towards the puncture location 
3a. Due to withdrawal of the catheter insertion tube 1 and, possibly, due 
to the simultaneous forward movement of catheter 4 which, as mentioned 
above, has an outer diameter d.sub.3 which is preferably equal to or 
larger than the outer diameter d.sub.2 of the catheter insertion tube 1, 
the dilatable area(s) 6 is or are expanded so that the catheter insertion 
tube 1 is withdrawn over catheter 4 and can be pulled out of the puncture 
site 3a. Thereafter the catheter 4, with the aid of the mandrin 5 as a 
guide member, is inserted completely through the skin 2 and the 
subcutaneous tissue into the blood vessel 3. Once the catheter 4 is 
positioned in the blood vessel 3, the mandrin 5 has served its purpose so 
that it can be removed from the blood vessel 3. Thus, only the catheter 4 
remains in the blood vessel 3. The puncture 3a is tightly sealed by means 
of catheter 4. To facilitate insertion of catheter 4 into the blood vessel 
3, the front end 7 of catheter 4 can be provided with a rounded nose or 
chamfering of a suitable length. 
The catheter insertion tube 1 can be made cylindrical, so that its outer 
diameter d.sub.2 approximately corresponds to the outer diameter d.sub.3 
of the catheter 4 and, furthermore, the catheter 4 can be provided with 
the chamfering mentioned above to facilitate its entry and advancement in 
the catheter insertion tube 1. 
It is also feasible for the catheter insertion tube 1 to be shaped like a 
truncated cone wherein its larger opening, for the insertion of the 
catheter 4, corresponds at least to the outer diameter d.sub.2 at the 
container-side end of the catheter insertion tube 1. 
For fast utilization of the catheter set according to the invention, it is 
desirable that the mandrin 5 and the catheter 4 be designed and assembled 
as a structural unit or combination so that they can be inserted together 
into the catheter insertion tube 1. 
The embodiment of the invention illustrated in FIG. 2 differs from that of 
FIG. 1 in that, instead of the mandrin, a catheter 4 with a bill-like 
projection 8 of smaller diameter is provided. The portion 8 of catheter 4 
having a smaller diameter than the remainder of the catheter 4, desirably 
has a length which is at least as long as, and advisably is a few 
centimeters longer than, the length L.sub.2 of the catheter insertion 
tube 1 so that it can be securely placed in blood vessel 3. The reduced 
portion 8 ends at 9 and by means of an enlarging step or transition area 
it merges into the main body of catheter 4. The step or transition area 
serves to expand or enlarge the dilatable area(s) 6 of the catheter 
insertion tube 1, preferably by simultaneously pulling back the catheter 
insertion tube 1 and pushing the catheter forward. In this way, the 
catheter insertion tube 1 is pulled back over the catheter 4. Since here 
too the outer diameter d.sub.3 of the catheter 4 is approximately equal to 
the outer diameter d.sub.2 of the point or front end of the catheter 
insertion tube 1, the catheter 4 can be securely placed in the blood 
vessel 3 without difficulty in the same manner as illustrated above, 
whereby simultaneously the desired sealing effect is obtained in puncture 
3a. 
In the embodiment shown in FIG. 2, the catheter insertion tube 1 front 
portion, by the puncture 3a, has one or more dilatable areas 6. These 
dilatable areas extend over about one-third to one-half the length L.sub.2 
of tube 1. The adjoining portion of the catheter insertion tube 1 is 
provided with a continuous area 10 which is separable in the longitudinal 
direction. In this type of construction, when the catheter insertion tube 
1 is pulled back over catheter 4 frictional resistance between them is 
reduced because the catheter insertion tube 1 separates or splits. The 
separated or split portion of the catheter insertion tube 1 actually can 
be retracted over the catheter 4 without friction. 
The bill-like or trunk-type projection 8 of the catheter 4 is not 
necessarily designed as one piece together with the main body of catheter 
4. The catheter portion 8 can be mounted on a corresponding connecting 
piece for the catheter 4. For example, it can be securely connected to 
catheter 4 by means of welding or a suitable fitting. It is also possible 
to insert the reduced portion 8 coaxially into the catheter 4. In this 
embodiment, different materials can be used for maximum benefit on the one 
hand for the guide member 8, and on the other hand for that part of 
catheter 4 which causes the catheter insertion tube 1 to expand as it is 
pulled back, and to seal with the puncture site 3a. 
In the embodiment of FIG. 2 the bill-like extension 8 of the catheter 4 
provides a particular advantage in that it has the same cross-sectional 
opening as the main body of catheter 4. Thus, the flow resistance is 
unchanged in the entire length of the catheter. 
The catheter 4 and the mandrin 8 preferably are made of a non-abrasive, 
sufficiently flexible synthetic polymeric material to avoid, on the one 
hand, the unintentional removal by abrasion of even the smallest particle 
from the catheter and, on the other hand, to be able to place these two 
elements securely and without danger in the blood vessel 3. 
As FIG. 2 shows, the catheter insertion tube 1 can be designed primarily 
cylindrically so that its outer diameter d.sub.2 approximately corresponds 
to the outer diameter d.sub.3 of the catheter 4. Furthermore, upon use of 
a mandrin 5 (see FIG. 1) the catheter 4 is desirably provided with 
chamfering of a suitable length for easy insertion into the catheter 
insertion tube 1. 
As briefly stated in connection with FIG. 1, the catheter insertion tube 1 
can be provided, along its circumference over its entire length L.sub.2, 
with one or several discreet, dilatable areas 6. These dilatable areas 6 
can consist preferably of rubber-elastic material, in particular, of 
elastomers or of equivalent resilient synthetic materials. 
As shown in FIGS. 3a and 3b, the discrete, dilatable areas may consist of 
zones 11a and 11b having reduced material thickness and strength. The 
thinner and weaker zones 11a, 11b preferably run parallel to the 
longitudinal axis L and represent enlargements of the cross-sectional 
opening of the catheter insertion tube 1. Since the wall thickness of the 
catheter insertion tube 1 is small by nature and, for example, lies 
between 0.1 to 0.3 mm, a sufficient dilation can be readily achieved by a 
slight reduction of the material thickness in the zones 11a, 11b. This 
especially holds good for sufficiently elastic materials used for the 
catheter insertion tube 1. 
In order to give the catheter insertion tube 1, despite the use of an 
adequately elastic material, sufficient rigidity, to guarantee its secure 
insertion into the puncture location 3a, the catheter insertion tube 1 can 
be provided along its circumference with at least one, preferably several, 
reinforcing or stiffening elements 13a to 13d corresponding to the number 
of weaker portions 12a to 12d. The reinforcing elements 13a to 13d 
preferably run parallel to the longitudinal axis L of the catheter 
insertion tube 1 and preferably consist of spring material, in particular 
spring steel. These reinforcing elements are embedded into the materially 
stronger or thicker portions of the catheter insertion tube 1 during its 
manufacture. 
As FIGS. 5a and 5b show, the catheter insertion tube 1 can have a 
continuously uniform cross-section except for the dilatable areas 14a and 
14b, which can be made from a material with highly elastic characteristics 
as, for example, silicone rubber or natural rubber. For improved guidance 
of the catheter insertion tube 1, the latter can be provided with a hand 
grip 15 at the end located away from the puncture location 3a. 
As shown in FIGS. 1 and 5a, the catheter insertion tube 1 can be provided 
with dilatable areas which extend over the entire length L.sub.2. 
On the other hand, it is possible to design the catheter insertion tube 1 
in such a manner that it is provided over a portion of its length only 
with discreet dilatable areas 6, while the remaining portion is provided 
with a continuous longitudinal splittable separation area 10, as this has 
been explained in regard to FIG. 2. 
FIGS. 6 and 7 show variations of the above-described type of construction. 
According to FIG. 6, the end 16 of a conically tapered catheter insertion 
tube 1 consists of a different, particularly flexible, rubber-elastic 
material, while the adjoining area of the catheter insertion tube 1 is 
provided with a longitudinal splittable separation area 17. The material 
of the catheter insertion tube 1, in the area of the longitudinal 
separatable or dividable area 17, can be stiffer than the material of the 
elastically dilatable point or end 16 of the catheter insertion tube 1. In 
this embodiment too, the sliding resistance, upon retraction of the 
catheter insertion tube 1 over the catheter 4, is clearly reduced so that 
removal of the catheter insertion tube 1 from the puncture site 3a is 
entirely free of problems. 
In the embodiment according to FIG. 7, the catheter insertion tube 1 is 
made entirely of the same material. However, this material, in the area of 
the point or end 18 of the catheter insertion tube 1, is made thinner than 
in the remaining portion. Reference number 19 refers to a longitudinal 
separation or dividable area which makes possible effortless splitting of 
the catheter insertion tube 1 in its non-weakened or stronger portion. 
Reference number 15 in FIGS. 6 and 7 refers to a schematically shown hand 
grip which, of course, is so positioned that expansion of the catheter 
insertion tube 1 in the splittable area 17 or in the separation area 19 is 
not made more difficult. 
FIGS. 8a and 8b show an embodiment of the catheter insertion tube 1 with a 
continuous longitudinal separation area 20 parallel to the longitudinal 
axis L. FIG. 8a shows the catheter insertion tube 1 in its starting 
position without the insertable catheter 4, and FIG. 8b shows the catheter 
insertion tube 1 in the dilated position expanded by the inserted catheter 
4. The free longitudinal or axial edges 21, 22 of the catheter insertion 
tube 1 are provided in the area of the longitudinal separation area 20, so 
that even in the dilated condition a slight overlapping of the free edges 
21, 22 of the catheter insertion tube 1 is obtained. 
FIGS. 9a and 9b illustrate another variation of a continuous longitudinal 
separation area 23 running parallel to the longitudinal axis L. In this 
case the longitudinal or axial free edge sections 24, 25 of the catheter 
insertion tube 1 are provided, in the longitudinal separation area 23, 
with mating or cooperating overlapping step-like sections. In this 
embodiment too, some overlapping of the step-like sections 24, 25 
continues even in the dilated or expanded condition which results upon 
insertion of the catheter into insertion tube 1. 
The invention provides a catheter set which not only can be handled easily 
and securely, but which also guarantees an absolutely effective seal at 
the puncture site so that the numerous disadvantages which a leaking 
puncture causes are avoided. 
The catheter set according to the invention applies the insertion set 
Seldinger technology, but only consists of two portions or elements to be 
manipulated separately, namely, the catheter insertion tube 1 and the 
catheter 4, or the structural unit of catheter and mandrin respectively. 
Thus, the manipulation of this catheter set is substantially simplified 
and safer than the previous sets according to the Seldinger technology. In 
addition, this catheter set has the advantage that aseptic conditions can 
be much easier maintained. Also of advantage is the possibility of 
combining a catheter set according to the invention with an automatically 
closing and locking catheter connection head so that a complete one-piece 
set, according to the Seldinger technology, can be obtained. 
FIG. 10 shows a canula 30 consisting of a steel tube, the rear end of which 
has a tubular plastic extension 301 with a projecting handle 302. The 
front end 303 of the canula 30 is ground obliquely to puncture the skin. 
The catheter insertion tube 1 is slipped over the canula 30. The front end 
of said tube 1 has an expansible portion 6, the inner diameter of which 
corresponds to the outer diameter of the canula 30, and which is followed 
by and joined to a cylindrical portion 61 having a greater diameter. A 
tubular extension 101 of plastic is secured to the rear end of portion 61. 
Portion 61 includes a laterally projecting handle 102. 
Canula 30 is introduced through the longitudinal bore of the plastic 
extension 101 and through the catheter insertion tube 1, and its front end 
protrudes from the catheter insertion tube. To avoid injuries, a tubular 
plastic cap 62 is provided which covers the front region of the canula 30 
and the catheter insertion tube 1 and which is slipped clampingly over the 
front end of the catheter extension 101. 
Catheter 4 with the inserted mandrin 5 is illustrated in FIG. 11. Catheter 
4 consists of a tubular hose, the front end 8 of which has a smaller 
diameter. The bore or channel extending through the catheter 4 continues 
to the front end 8 by having a smaller diameter. In other words, the front 
end 8 of the catheter 4 is also hollow. The front end of the mandrin 5 
introduced into the catheter 4 extends to point 9 where the tapered 
catheter section 8 begins. 
At the rear end of the catheter 4, there is a plastic tubular connecting 
piece 42 on which a tubular coupling member 41 is axially rotated or 
pivoted. At the rear end of the mandrin 5, a connecting piece 51 is 
mounted which can be locked with the connecting piece 42 of the catheter 4 
so that the rear ends of catheter 4 and mandrin 5 can be fixed relative to 
each other. 
Catheter 4 is enclosed by a protective hose 63 of a transparent thin 
plastic film to ensure the sterility of the catheter. At the front end of 
the protective hose 63, there is attached a tubular connecting piece 64, 
which is slipped over the rear end of an insertion piece 65. The insertion 
piece 65 consists of two halves hinge-connected at one longitudinal side 
and capable of being opened up. The catheter 4 is pushed through the 
insertion piece 65, while the protective hose 63 is flexibly folded 
together. According to FIG. 11, a plastic protective hood 66 is slipped 
over the front end of the insertion piece 65 to protect the front end of 
the catheter against contamination. 
FIG. 12 shows the canula 30 with an insertion tube 1 slipped over it, while 
a blood vessel 3 is punctured. The insertion tube 1 consists of a 
thin-walled rigid plastic material. Region 6 of insertion tube 1 contains 
a longitudinal slot 67 thus permitting its subsequent expansion. After 
having punctured the blood vessel 3 by the canula with the insertion tube 
1 in position thereon as shown in FIG. 12, the canula 30 is removed by 
withdrawing the handle 302 in the direction of arrow 68, while the 
insertion tube 1 maintains its position. 
As shown in FIGS. 13 and 14, catheter 4 containing mandrin 5 is then moved 
forward through the insertion piece 65 through the bore of the extension 
101 into the insertion tube 1 until the soft front end 8 of the catheter 
penetrates the blood vessel, according to FIG. 14, and is guided by it. 
Then, the front end of the insertion piece 65 is introduced into the 
extension 101 of the insertion tube 1, as shown in FIG. 14, thus allowing 
the catheter 4 to slide forward in the insertion piece 65 and in the 
insertion tube 1 without being touched manually. The catheter 4 is 
advanced in that it is moved by seizing the insertion piece 65. 
When point 9 of the catheter 4 moves into the tapered portion 6 of the 
insertion tube 1, the slot 67 is pressed apart. At the same time, the 
insertion tube 1 is removed according to FIG. 15, while the catheter is 
advanced further. 
After the catheter 4 has been positioned in the blood vessel 3, the mandrin 
5 is removed from the catheter 4 by pulling on the connecting piece 51. At 
the same time, the hose 63 with the ring 64 is withdrawn to the rear. 
Then, according to FIG. 17, the rear end of the catheter 4 is joined with 
the rear end of the insertion tube 1 by rotating or screwing the coupling 
member 41 on the extension 101. Then, by inserting the front end of a 
syringe 68 into the extension 42, liquid can be injected into the catheter 
4. 
The foregoing detailed description has been given for clearness of 
understanding only, and no unnecessary limitations should be understood 
therefrom, as modifications will be obvious to those skilled in the art.