"Intravascular multi-lumen catheter, capable of being implanted by ""tunnelling"""

This intravascular catheter comprises a multi-aperture pipe design for the perfusion of medicines which are mutually incompatible in their pure state or for carrying out several different functions. In order to permit the implantation of this catheter by the "tunnelling" method, this multi-aperture pipe (1) forms only the distal part of this catheter. The catheter also comprises separate tubes (2a, 2b) equal in number to the apertures of the first pipe and which extend back from this pipe to form the middle part (2) of the catheter; and a single-aperture pipe (3) forming the proximal end of the assembly which terminates in a rigid needle (4) suitable for carrying out the tunnelling. Two connectors (5 and 6) serve respectively to join each aperture (1a, 1b) of the multi-aperture pipe (1) to one of the separate tubes (2a or 2b) of the middle part (2), and to connect the opposite ends of these tubes (2a, 2b) to the corresponding end of the single-aperture pipe (3). Each of these connectors is made of plastic and is molded onto the ends of the parts to be joined.

The present invention concerns a medical instrument of the catheter type 
the pipe of which comprises at least two apertures. 
The term "medical" is used here in the broadest sense and concerns 
veterinary applications as well as those relating to human medicine, while 
the designation "intravascular catheter" applies to a device which must be 
placed in the patient's vascular system, by puncturing the selected 
vessel. 
When a catheter is intended for prolonged use on a patient, the catheter is 
placed in position by means of the SELDINGER technique, which consists of 
puncturing a vessel with a fine needle, the aperture of which allows the 
passage of a fine spiral guide, withdrawing the needle when the guide has 
been inserted sufficiently far into the vessel, then advancing the 
catheter pipe along the guide and finally withdrawing the guide, leaving 
the catheter in place in the vessel. However in general the catheter pipe 
is also "tunnelled" over a certain length. This process consists of 
causing the catheter pipe to follow a course of several centimeters 
between the point at which the vessel is punctured and the external 
surface of the patient's body, more or less parallel to the skin and some 
millimeters from the surface. Thus all external germs liable to pass along 
the catheter pipe to the punctured vessel, or to one of the patient's 
organs, come up against the natural obstacle formed by the tissues crossed 
when the "tunnelling" is carried out. 
A catheter specially designed for the application of this technique is 
described in U.S. Pat. No. 2,522,504. However this relates to a 
single-aperture catheter. 
The development of diagnostic and therapeutic techniques has shown the need 
for catheters composed of a multi-aperture pipe, so that several separate 
apertures can be used, either for identical but nevertheless necessarily 
independent functions, for example, in the case of the simultaneous 
perfusion of two medicines which are mutually incompatible in their pure 
state, or for different functions, for example, monitoring intravascular 
pressure or the concentration of CO.sub.2 perfusion, taking blood samples 
etc. 
With existing equipment, it is very difficult for a practitioner to apply 
the practice of "tunnelling" to a catheter with several apertures which 
inevitably has a larger cross-section than a catheter with a single 
aperture. Furthermore, it is then necessary to open up in the patient's 
flesh a passage with a diameter considerably greater than the external 
diameter of the catheter, which has the effect of cancelling out, or at 
the very least reducing, the role of the barrier to external attack, which 
is precisely what the practice of tunnelling seeks to achieve. 
For this reason the aim of the present invention is to produce a catheter 
device with several apertures which can nevertheless be inserted by 
tunnelling without encountering the disadvantages explained above. 
To this end the multi-aperture pipe of this catheter constitutes only the 
distal part of the catheter which also comprises: 
separate tubes equal in number to the apertures of the first pipe, which 
extend back from the latter to form the middle part of the catheter, 
a pipe with a single aperture forming the proximal end of the assembly, 
which terminates in a rigid needle suitable for use in tunnelling, 
two connectors which respectively join each aperture of the multi-aperture 
pipe to one of the separate tubes of the middle part and connect the 
opposite ends of these tubes to the corresponding end of the 
single-aperture pipe, each of these connectors being made up of a body in 
the shape of a tapered olive, made of plastic and moulded onto the ends of 
the parts to be joined. 
Thanks to the subdivision of this catheter into several parts which are 
distinct in character and the joining of these latter by means of 
moulded-on tapered connectors, the technique of tunnelling can be 
practised without difficulty. After the application of this technique, 
only the distal multi-aperture pipe remains implanted in the patient's 
body, so that the catheter only has to be cut in the middle part to make 
available two or more independent tubes to which detachable connectors can 
simply be connected as required.

As has already been indicated, the catheter illustrated in FIGS. 1 to 12 
comprises three successive parts with different structures, namely: 
a distal part designated by the general reference 1 which is made up of a 
multi-aperture pipe, in this case, in the example illustrated, a pipe 
comprising two apertures 1a and 1b, 
a middle part designated by the general reference 2 which is made up of 
separate tubes 2a and 2b, equal in number to the apertures 1a and 1b of 
the distal part, 
a proximal part designated by the general reference 3 which is made up of a 
single-aperture pipe terminating in a rigid needle 4 suitable for 
tunnelling. 
As for the free end of the distal part 1, a special feature of this is that 
only one of the apertures of pipe 1 opens out at this point, so that it 
can be used for sliding the assembly along the spiral guide used to 
position the catheter. The other aperture of the distal part 1 opens 
through a small orifice 7 provided on the side, close to the end. 
These three successive parts 1, 2 and 3 are joined by means of two 
connectors 5 and 6 which are each made up of a plastic body in the shape 
of a tapered olive, moulded onto the ends of the parts to be joined. 
FIG. 2 and FIGS. 4 to 7 illustrate the first connector 3 which joins the 
distal part 1 to the middle part 2. 
Apart from the distinctive external shape of this connector, another of its 
essential characteristics resides in the fact that there is a space E 
between the ends of the pipes connected by this connector. The 
corresponding part of the body of the connector comprises two channels 5a 
and 5b formed on the inside of the moulded material with a space between 
them in the transverse direction (see FIG. 6). Also there is to some 
extent a connecting bridge 8 between the moulded-on parts on either side 
of the plane passing through the axes of channels 5a and 5b. This ensures 
that the body of the connector 5 and the corresponding pipes are firmly 
joined to make a whole, by preventing in particular any possibility of 
sliding in the longitudinal direction. 
FIG. 12 shows the mould used to make this connector. Before the ends of the 
pipes 1 and 2 are positioned inside the moulding cavity 10 of this mould, 
two mandrels 11a and 11b are inserted into these pipes. In this instance 
the first mandrel 11a is inserted into both the aperture 1a of pipe 1 and 
one of the tubes 2a of the middle part 2 of the catheter. The other 
mandrel is, of course, inserted into both the aperture 1b of pipe 1 and 
tube 2b of the middle part 2. But the space E is then preserved between 
the corresponding ends of the pipes to be joined. Thus the two mandrels 
11a and 11b ensure the formation of the connecting channels 5a and 5b 
inside the corresponding part of the body of the connector 5. 
It should be noted that in this embodiment the connector forms a sleeve 
round both the corresponding end of the pipe 1 with two apertures and the 
neighbouring ends of the two tubes 2a and 2b of the middle part of the 
catheter. However the thickness of the walls of this sleeve is reduced to 
the minimum technically possible, so that the transverse section of the 
connector 5 is itself reduced to facilitate the subsequent tunnelling of 
the catheter. 
To ensure that the assembly is secure after moulding on, the corresponding 
part of the catheter is then placed between two welding electrodes of 
which the active part has the same shape as the mould used for 
moulding-on. A high-frequency current is then applied which melts, or at 
least sufficiently softens, the assembly so that it forms one piece. To 
this end it is advisable to choose plastics from the same family to form 
the different pieces. For example, if aliphatic polyurethane is chosen to 
make the pipes, the material used for the moulded-on connectors should 
also be an aliphatic polyurethane, and the degrees of hardness of these 
polyurethanes should, if possible, be very close, which also means that 
their melting points will be similar. 
The connector 6 which connects the middle part 2 to the proximal part 4 is 
made in the same way as connector 5 and with a similar mould. Here too 
there is a space E between the ends of the pipes to be joined, for the 
same purpose as before. At this point the body of connector 6 therefore 
has two channels 6a and 6b which are separated from each other and which 
each ensure the connection of a tube 2a or 2b with the single aperture of 
pipe 3. 
The diagrams in FIGS. 14 to 20 illustrate the different successive stages 
of the operation of putting the catheter in place using the tunnelling 
method: 
A--After the usual disinfection procedure, the practitioner punctures the 
tissue that he has chosen to catheterise using a puncture needle 12 
approximately 8 cm long, which enables the selected vessel 13, for example 
the subclavian vein or the femoral vein, to be reached easily, even on an 
obese patient. In general, the practitioner does not manipulate this 
needle directly, but starts by attaching it to a syringe fitted with an 
ISO standardised tip of the "luer"-type or a "luer" lock. Once a good 
reflux of blood has been obtained, the practitioner withdraws the syringe 
and inserts, in the needle 12, a spiral metal guide 14 for a distance of 
about fifteen centimeters (see FIG. 14). 
B--Holding the end of the guide by pressure on the vein beyond the tip of 
the puncture needle 12, the practitioner withdraws this puncture needle 
and discards it. With one hand the practitioner then takes hold of the end 
of the spiral guide 14 remaining outside the patient and fits to it the 
distal end of the catheter 1-2-3 according to the invention. He then 
advances the whole of this catheter along the guide 14 until it is able to 
penetrate the selected vessel 13, still following the course of the guide 
14 previously put in place (see FIG. 15). 
C--When the catheter has advanced sufficiently far, the spiral guide 14 
goes beyond the end of the needle 4. The practitioner can then take hold 
of this guide and withdraw it gently without changing the position of the 
end of the catheter which is situated in the vessel 13 (see FIG. 16). 
D--The practitioner then takes the tunnelling needle 4 and pricks exactly 
at the point of the initial puncture whilst slanting the catheter sideways 
(FIG. 17). To facilitate the remainder of the operation he can then make a 
slight cut with the lancet in order to enlarge the point where the 
catheter pipe and the tunnelling needle 4 cross. 
E--The practitioner then advances the tunnelling needle 4 under the skin to 
the chosen point of emergence. 
F--Next the practitioner continues to withdraw the tunnelling needle 4 
slowly out of the skin. This needle then pulls out the pipe 3, followed by 
the connector 6 and the tubes 2a and 2b of the middle part 2, and finally 
the connector 5, the latter until the loop 15, formed when the tunnelling 
needle 4 was inserted, has completely disappeared (see FIG. 19). 
G--At this stage of the operation, the practitioner can check that the 
catheter is positioned correctly by attaching, at the pointed end of the 
tunnelling needle 4, a special standardised female connector, preferably 
of polyurethane, by means of which he can check the reflux of blood or 
inject heparinated serum into the various conduits, those which are not 
used for the test being closed off by attaching a clamp provided for this 
purpose. Once this check has taken place and the last pipe 3 has in its 
turn been fitted with a closing clamp, the practitioner can cut the two 
tubes 2a and 2b in the desired order and fit them one at a time with a 
female connector 16, the end 17 of which is inserted into the 
corresponding tube. 
The practitioner then checks the closure of the point of initial puncture 
and the closure of the point of emergence of the catheter with the usual 
dressings and can now proceed to make the required connections. 
In this way, due to the distinctive design of the present catheter, it can 
be positioned by means of the tunnelling method, even if the catheter in 
question has several apertures. In the example described above, two 
apertures are provided in the distal part 1 of the catheter. However, this 
could comprise three apertures, or perhaps even more, in which case the 
middle part 2 would, for its part, comprise the same number of separate 
tubes, each connected to one of the apertures provided in the pipe of the 
distal part. 
FIGS. 22 to 25 illustrate another embodiment of the catheter connectors 
according to the invention. This is designed in such a way that the 
catheter produces as little trauma as possible during tunnelling. To this 
end the external diameter of the body of each of the two connectors is 
equal to the total of the external diameters of the two tubes 2a and 2b of 
the middle part 2 of the catheter. Only the first connector 25, which 
joins the distal part 1 of the catheter to the middle part 2, is 
illustrated in the figures in question. However, the structure of the 
second connector is exactly the same. 
To prevent any prior infiltration of liquid between the two tubes 2a and 2b 
of the middle part 2, and above all to avoid any difficulty when moulding 
on the body of the connector 25, the ends of these two tubes to be 
incorporated into the connector are first stuck together for a length of 
about 5 mm. In this embodiment the section of the connector is therefore 
reduced to the minimum since the walls of the two tubes 2a and 2b are 
flush with the sides, as can be seen from FIG. 24. In this case, the body 
of the connector 25 forms a sleeve only around the corresponding end of 
pipe 1. 
It is, of course, advantageous to follow this with intimate welding of the 
pieces, as already described in the case of connector 5 in FIG. 2. To this 
end electrodes powered by a high-frequency current are used, and the same 
precautions as before are taken as regards the nature of the plastics used 
for the pieces to be joined. 
FIG. 26 is a transverse section made at the same level as FIG. 24 (but on a 
different scale), in a variant 25c of the connector 25 from FIG. 22, this 
variant corresponding to the case in which the pipe 1 of the distal part 
of the catheter comprises three apertures. The middle part 2 of the 
catheter then comprises for its part three separate tubes 2a, 2b and 2c. 
In this case, the external wall of the connector 25a corresponds to a 
circle drawn around these three tubes after these tubes have been placed 
side by side so that the diameter of this circle is as small as possible. 
Consequently, even though in such a case the middle part 2 of the catheter 
comprises three separate tubes, the section of the connectors is still 
very small, which permits tunnelling of the catheter, as already described 
previously. 
Finally it should be noted that the section of the connectors of the 
devices according to the invention may have a contour of a different shape 
from the circular form illustrated in the attached drawings, for example 
an elliptical or oval shape as close as possible to the external surface 
of the pipes, so as to reduce the total surface area of the section of 
these connectors.