Valve device for a catheter

A valve device for a catheter with a catheter hub. A tubular housing has one end provided with an outer cone for fitting into an inner cone of the catheter hub and has a valve body within acting as a locking member of an axial channel for the passage of an elongate object. The housing is provided with an axially directed protrusion forming a radial space together with the outer surface of the outer cone and has a locking member cooperating with a complementary member at the catheter hub projecting into the space so as to act as a disconnection lock. Thus, a valve device is provided that is suitable for use with a catheter system destined for venous applications according to the Seldinger method, and which ensures a reliable sealing of the extracorporal end of the catheter.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a valve device for a catheter with a catheter hub. 
2. Description of Related Art 
A valve device of the type mentioned before and known from German Patent 30 
42 229 C2 serves to introduce elongate objects into a blood vessel through 
a cannula, and its outer cone is clampingly plugged into the inner cone of 
the hub. In this case, the valve body consists of a sequence of slotted 
seal elements, the sealing lips of which abut the elongate objects or each 
other and close the passages. This valve device can only be used as a 
sluice for guide wires or the like introduced into the blood vessel from 
outside. However, it is not suitable for a catheter system for venous 
applications according to the Seldinger method, wherein the catheter is 
threaded by its tip over a placed guide wire. This is due to the fact that 
the frictional forces occurring between the valve body and the guide wire 
strongly influence the feeling for the placement of the catheter so that 
the feeling for the placement is lost to a certain extent. Further, it is 
practically impossible in this valve device to hit the slot of the seal 
elements with the tip of the guide wire when threading the catheter 
thereon. Moreover, this known valve device is not suitable for an 
absolutely secure sealing closure of the passage of a catheter after the 
removal of the guide wire from its lumen, because the plug connection 
between the outer cone and the inner cone of the catheter hub is not 
reliably firm. There is a risk that, in the case of a longer use of a 
catheter, the plug conection will loosen with the movements of a patient, 
resulting in air possibly entering the catheter, which may be fatal to the 
patient if the catheter is placed in a hollow vein. In less dangerous 
applications, the loosening of the plug connection will cause a leak from 
which returning body fluid may emerge, leaking from the loosened 
connection and causing a contamination of the surroundings that might be 
hazardous to the patient and the personnel. 
In another known valve device according to U.S. Pat. No. 4,387,879, similar 
conditions are encountered that exclude the same from utilisation in a 
catheter system for venous implementation according to the Seldinger 
method. A body adapted for limited axial displacement is disposed in a 
flow channel of a tubular housing, the body cooperating with a disc of 
elastomeric material shutting off the passage and having an axial slot. 
The body is designed as a sleeve with a frustoconically tapered end. It is 
displaced when a connection cone is applied. In doing so, the 
frustoconical end penetrates the slot in the disc, spreads the same and 
keeps it open. Thereby, friction between the slots and an elongate element 
inserted from outside is reduced. To take advantage thereof when threading 
a venous catheter equipped with this valve device onto the end of a placed 
guide wire, the body would have to be displaced towards the opening of the 
slot by means of a connection cone, which cone would in turn impede the 
placement of the catheter. At one end, the housing of this valve device is 
provided with an inner cone for the connection cone used to operate the 
body, and the other end of the housing has a conically tapered stud with 
continuous ribs that serves to hold a hubless hose pushed thereon and 
leading to the vessel system. Such a connection between the hose and the 
valve device is not reliable. Were the valve device to be placed in a 
conduit system, the connection might become disengaged due to movements 
and media flowing from or into leaks could cause hazards to the patient 
and/or the personnel. 
It is an object of the invention to provide a valve device that is suitable 
for use with a catheter system destined for venous applications according 
to the Seldinger method, and which ensures a reliable sealing of the 
extracorporal end of the catheter. 
SUMMARY OF THE INVENTION 
According to the invention, this and other objectives are solved by 
providing the housing with an axially directed protrusion forming a radial 
space with the outer surface of the outer cone, and which has a locking 
element that cooperates with a complementary element at the catheter hub 
extending into the space, so as to form an axial disconnection lock. 
The invention profits from the fact that the feeling for the reliability of 
the placement of a catheter according to the Seldinger method is more 
important than the fact that a little blood flows when the catheter is 
placed by being set onto the guide wire, because, in this method of 
placement, a blood contact cannot be avoided, anyway. 
The valve device according to the present invention is only posteriorly 
connected to a catheter inserted into a vein by being pushed onto a placed 
guide wire so that, according to the Seldinger method, the catheter is 
placed without the valve device, but with the "feeling" being completely 
preserved. Only after the successfull placement of the catheter and the 
withdrawal of the guide wire from the catheter, will the valve device be 
mounted to the catheter hub in a manner not disconnectable so that the 
reflux of liquid and the intrusion of air are prevented. The valve device 
is provided separately in a catheter set with a guide wire and is set by 
the user after the placement of the catheter such that the device cannot 
be removed therefrom. The valve housing that may be permanently coupled to 
a catheter hub in a simple manner is locked with the catheter hub so that 
it cannot become detached from the catheter hub by movements of the 
patient. The extracorporal end of the catheter is always reliably 
connected with the valve device so that contaminations of the surroundings 
by outflowing body fluids and a hazard to the patient in the form of air 
entering the catheter are avoided. The safety of a catheterised mobile 
patient connected to a transfer system is increased by the valve device of 
the present invention. Further, in connection with a replacement of a 
catheter placed in a vessel, the valve device allows to put a guide wire 
through the valve device from outside over which the catheter to be 
removed is drawn from the vessel. The placement of the new catheter 
without valve may be done in the usual manner over the guide wire. When 
the catheter has reached the desired position, the non-disconnectable 
valve device of the present invention is again mounted. 
Advantageously, the second end of the housing is provided with a connection 
profile for a connector. Preferably, the connection profile is conform to 
a Luer lock and allows for the connection of a continuing conduit or an 
operating member for the valve body. A continuing conduit may be part of a 
transfer system, for example. The locking of the valve device housing to 
the catheter hub provides for a reliable tightness of the connection. The 
design of the valve body may be manifold--provided that it provides a 
passage for an elongate object, which closes sealingly again after the 
withdrawal of the object. 
In an advantageous embodiment of the invention, the protrusion is a 
circular cylindrical sleeve with an inwardly directed annular bead behind 
which radial outer projections of the catheter hub engage in the manner of 
a ring snap connection. The circular cylindrical sleeve acting as a 
cylindrical snap element is suitable for connection with conventional 
catheter hubs that have two diametrically opposed, outwardly directed 
radial locking cams. The deflection, also referred to as an undercut, 
occurring during the snapping in, must be dimensioned such that the 
allowable expansion of the materials employed is not exceeded and that a 
relaxed, positive engagement is obtained after the snapping in, which 
cannot be pulled apart in the axial direction. The ring snap connection 
serves to fix the interconnected elements in a certain relative position. 
It is an advantage of this connection that it can be mounted with a low 
joining force. The permanent ring snap connection fixedly retains the 
outer cone of the housing within the inner cone of the catheter hub, 
thereby ensuring the tightness of the connection. 
The shell of the circular cylindrical sleeve may be closed or may have 
longitudinal slots forming snap segments. In the first case, the joining 
force applied upon mounting is larger than in the second case, and 
increased requirements have to be met by the plastic materials of both 
components with respect to their elastic deformability. In both cases, it 
is important that after a short deformation during the joining process, 
the material restores quickly so that the engagement of locking element 
and complementary element becomes effective as the contrivance against 
axial disconnection. With a longitudinal slotting of the circular 
cylindrical sleeve a quartering or a halving of the circular cylindrical 
shell is favorable for a permanent snap connection. 
The annular bead may approximate a semicircular cross-sectional profile. 
Alternatively, it may also approximate a trapezoidal cross-sectional 
profile so that a sliding surface for facilitating the joining process is 
obtained on the one side, whereas a blocking surface is obtained on the 
other side. Both cross-sectional profiles are favorable for permanent snap 
connections. 
According to a further advantageous embodiment of the invention, it is 
provided that the protrusion is formed by at least one sector-shaped 
cylindrical fin with a groove extending from an opening at the edge to a 
circumferential portion with a closed end and into which a radial pin at 
the outer surface of the catheter hub is inserted for engagement in the 
manner of a bayonet connection. 
In this case the disconnection lock is formed by a pin provided at the 
catheter hub and engaging the groove. The groove that may be open or 
closed on the outer surface of the sector-shaped cylindrical fin, extends 
either in L-shape or circumferentially, approximating an S-shape, and in 
front of its inner end, an engaging projection is formed behind which the 
pin engages. In both cases, a relative movement of the catheter hub and 
the valve device housing moves the pin into abutment against the rear end 
of the groove, where it is engaged so that an axial disconnection lock is 
obtained. 
Preferably, the connection profile at the second end of the housing 
consists of an inner cone within a pipe socket surrounded on the outside 
by a thread member. This design is in conformity with a Luer lock, i.e. 
the connection profile may be connected to a lockable connector having an 
outer cone so that a conduit may be connected, for example, and a secure 
connection within a conduit system is provided also at this end of the 
valve device. Preferably, the valve body is a rubber elastic cup-shaped 
hollow cylinder that is operated by the outer cone of the connector or a 
helical spring surrounding the same, as defined in claim 8. As soon as the 
connector is detached and its outer cone is pulled from the valve device 
housing, the valve body closes sealingly by the action of the spring and 
no air can flow into the catheter, neither can body fluid flow therefrom. 
The valve body passage may be opened again when a guide wire is to be 
inserted over which the placed catheter may be withdrawn from the vessel 
and a new catheter without a valve device may be inserted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The valve device 10 of FIGS. 1 to 3 consists of a tubular housing 11 of 
plastics material formed as an injection moulded part. Moulded to the 
first end of the housing 11, there is a coaxial circular cylindrical 
sleeve 12 that surrounds a slightly longer outer cone 13 at a uniform 
radial distance so that a space 14 is formed between the outer surface of 
the outer cone 13 and the inner surface of the circular cylindrical sleeve 
12. The sleeve 12 and the outer cone 13 are arranged coaxially and lie on 
the longitudinal axis of the tubular housing 11. In the outer end portion 
of the sleeve 12, a radially inward directed annular bead 17 is provided 
that has a semi-circular cross-sectional profile and consists of four 
equal sectors 17a. The sectors 17a of the annular bead 17 are formed by 
dividing the circular cylindrical sleeve 12 into four snap segments 16 by 
four symmetrical longitudinal slots 15. The snap segments 16 form an axial 
disconnection lock for the catheter hub 30 of a preferably long venous 
catheter (not illustrated). The catheter hub 30 is also made of plastics 
material. It has an inner cone 31 into which the outer cone 13 may be set 
fittingly and sealingly. At the outer edge of the catheter hub 30, two 
diametrically directed radial outer projections 32 are provided that are 
designed conventionally as locking cams with an inclined undersurface 33. 
Arranged coaxially in the circular cylindrical cavity 20 of the tubular 
housing 11, there is a rubber elastic cup-shaped hollow cylinder 21 acting 
as a valve body. The hollow cylinder 21 has a circular cylindrical shaft 
22 with a profiled rim 23 at the one end and an axially thick bottom 
portion 24 at the other end, having a diverging outer annular cone 25 at 
its free end. Its outer bottom surface 26 is circular and plane. A locking 
ring 27 having a bevel adapted to the conical form 25 of the bottom 
portion 24 surrounds the bottom portion 24 in the closed position of the 
hollow cylinder 21. The thick bottom portion 24 is divided into two legs 
40, 41 by a longitudinal slot 28 bisecting the same diametrically and 
extending far into the shaft 22, the legs being spreadable up to the inner 
end of the longitudinal slot 28 when released by the locking ring 27. The 
wall of the hollow cylinder 21 encloses a circular cylindrical 
longitudinal channel 42 which, on the one hand, ends at the inner base 
surface of the bottom portion 24, and which, on the other hand, is openly 
connected with an inner cone 44 of a pipe socket 45 through an opening 43, 
the pipe socket being surrounded on its outer surface by a thread member 
46. A screw-on cap of a connector 47 may be screwed onto the thread 
portion 46, the outer cone 48 of the connector sealingly projecting into 
the inner cone 44. 
The hollow cylinder 21 is surrounded by a helical spring 35, the one end of 
which is supported at a shoulder of the outer profile rim 23 of the hollow 
cylinder 21, while the other end presses against an annular surface of the 
locking ring 27. The helical spring 35 is biased and retains the hollow 
cylinder 21 in the closed position in which its bottom portion 24 is drawn 
into the conical recess of the locking ring 27 and the radial outer 
portion of the edge of its opening 43 abuts a shoulder at the inner end of 
the inner cone 44. When the connector is applied at the pipe socket 45, 
the hollow cylinder 21 is pressed axially into the cavity 20 by the front 
end face of the outer cone 48, and the two legs 40, 41 are spread apart by 
the pressure of the inflowing liquid. 
When a catheter without a valve has been placed with the help of a guide 
wire, according to the Seldinger method, and this wire has been withdrawn, 
the catheter hub 30 and the valve device 10 are assembled. This is done by 
pushing the sleeve 12 axially onto the catheter hub 30. In doing so, the 
snap segments 16 are radially deflected by the two radial outer 
projections 32 and the outer cone 13 penetrates into the inner cone 31. As 
soon as the outer projections 32 have passed the annular bead 17, the snap 
segments 16 restore themselves due to the elasticity of the material and 
the outer projections 32 engage behind the annular bead 17. This ring snap 
connection forms a disconnection lock that prevents a separation of outer 
cone 13 and inner cone 31 by axial pulling so that a tight permanent 
connection between the catheter hub 30 and the valve means 10 is ensured. 
If the catheter disposed in the vessel is to be replaced, the connector 47 
is removed from the pipe socket 45 of the valve means 10 and an operating 
member is inserted into the inner cone 44 that displaces the hollow 
cylinder 21 towards the opening direction. A guide wire is put through the 
hollow cylinder 21 over which the catheter is pulled from the vessel with 
the valve device 10. A new catheter without a valve is then threaded onto 
the placed guide wire in the usual way, following the Seldinger method. 
When the new catheter is in the desired position, a new valve device 10 is 
connected with its catheter hub 30 in a manner not disconnectable. 
The valve device 110 of FIG. 4 corresponds to the embodiment of FIGS. 1 to 
3 as far as the valve body and the connection profile at the second end of 
the housing 111 are concerned. Only the disconnection lock is of a 
somewhat different design. In this embodiment, the ring snap connection is 
formed by a circular cylindrical sleeve 112 with an entirely closed shell. 
At the outer edge portion of the sleeve 112, an annular bead 117 is 
provided on the inside at a short distance from the outer edge, the 
annular bead extending continuously over the entire periphery of the 
sleeve 112 and having an almost trapezoidal cross-sectional profile. 
During the joining process, the sleeve 112 is radially expanded and 
restores itself to the circular cylindrical initial shape as soon as the 
outer projections 32 of the catheter hub 30 engage behind the annular bead 
117 and the snap-in process is ended. Thus, a permanent snap connection is 
achieved in which the undercut is dimensioned such that the allowable 
expansion of the plastics material is not exceeded. The bevels of the 
annular bead 117 are favorable in the joining process. Moreover, they 
offer the advantage of being well removable from the mould when produced. 
The snap connection provides for an interconnection without play, if the 
engagement of the annular bead 117 and the outer projections 32 is 
effected at such an axial distance from the front end edge of the outer 
cone 13 that the penetration depth of the outer cone 13 into the inner 
cone 31 is sufficient to sealingly close the catheter lumen. 
In FIGS. 5 and 6, a phantom housing 211 of a valve device is provided with 
an outer cone 213 projecting coaxially from the front end of the housing 
211. A sector-shaped cylindrical fin 50 that is provided on the housing 
211 with a radial distance from the outer cone 213, serves as a 
disconnection lock. A groove 51 is formed in the fin 50, which perforates 
the fin 50 in the manner of a slot. The groove 51 is open at 52 at one 
longitudinal edge of the fin and extends with a circumferential pitch in a 
slight S-shaped curve up to its closed end 53 that forms an upward 
directed pocket. In the groove 51, an engaging projection 55 is arranged 
at the beginning of the pocket, by which the passage of the groove is 
narrowed. The fin 50 is shorter in the axial direction than the outer cone 
213. Upon assembling the inner cone 31 and the outer cone 213, a radial 
pin 54 is moved into the groove 54 by turning, the pin radially projecting 
from the outer surface of the catheter hub 30. The pin 54 penetrating into 
the groove 51 and the fin 50 together form a kind of bayonet connection, 
wherein, in the locked position, the pin 54 engages behind the engaging 
projection 55 so that it is trapped in the pocket at the closed end 53 of 
the groove 51. In this state, locked against disconnection, the outer cone 
213 is firmly drawn into the inner cone 31 so that the connection is 
tight. Movements of the conduit line into which the valve device is 
installed cannot loosen the connection and its firmness upon the action of 
axial forces is ensured. Movements of the conduit line between a transfer 
system and a patient occur in particular during the increasingly practiced 
early mobilisation of patients that carry the transfer system along when 
moving about freely.