Catheter assembly

The present invention provides a catheter assembly which comprises catheter tubing, a hollow needle and a guide member with a longitudinal bore there through for aiding insertion of the hollow needle into the catheter, which catheter assembly is characterized in that the longitudinal bore in the guide member has a narrower portion and a communicating broader portion, the narrower portion being adapted to receive in close fit the hollow needle and the broader portion being adapted to receive in close fit the catheter; whereby in use the catheter tubing may be positioned for insertion of the hollow needle.

This invention relates to improvements in a catheter assembly and 
especially to a reconnecting device for use in such an assembly. 
In conventional processes for catheter placement into body spaces, such as 
the lumen of a blood vessel or epidural space, admission is gained by 
breaching a wall defining the space with a needle having a hollow bore and 
an incising forward end, as for example a Tuohy needle. A catheter which 
by custom comprises a tube made from a flexible elastomeric material with 
thin walls may then be introduced into the space by either of two methods. 
Either the catheter tubing may be already in place surrounding the needle 
with the end just behind the needle point so the catheter tubing follows 
the needle into the space (the so-called `needle-inside` assembly) or the 
catheter tubing may be threaded through the needle after access to the 
space has been achieved (the so-called `through the needle` assembly). In 
either case if the catheter tubing is to remain in place for a long period 
of time, for example during drip feeding or epidural anaesthesia, it is 
desirable to remove the needle from the patient and from the catheter 
tubing. If the needle remains in place movements made by the patient may 
cause the needle point to damage the tissue of the patient or to the 
catheter tubing itself. Thus to avoid unnecessary and sometimes harmful 
restraint to the patient the needle is removed. 
In a `needle-inside` assembly removal of the needle from inside the 
catheter tubing may cause damage to the catheter walls resulting in the 
liberation of small particles of catheter material into the blood stream 
or may even cut through the wall of the catheter tubing thereby releasing 
administered liquids prematurely. The length of needle required for a 
conventional cathether is awkwardly long. It is known that attempts to 
overcome these disadvantages have been made by telescoping the catheter 
tubing behind the point of the needle or by attaching draw wires to short 
needles. Both approaches may lead to difficult manipulative processes from 
removing the needle from the patient in view of not dislodging the 
catheter tube from its placement and maintaining sterility. 
Conventionally, therefore, `through the needle` assemblies are preferred. 
However a problem may arise when removing the needle in that 
conventionally an adaptor such as a female luer site is fixedly carried at 
the other end of the catheter tubing to enable a connection to be made to 
a suitable hollow male fitting for communicating with a dispensing 
container such as a syringe or blood bag. Assemblies have been described 
to overcome this problem. British Pat. No. 1,123,624 describes a device in 
which the needle is withdrawn from the patient but not from around the 
catheter. The danger of damage to the patient or catheter tube by the 
incising point of the needle is avoided by securing the needle in a 
protective sheath. 
British Pat. No. 1.381.053 describes an assembly in which the needle has 
lines of weakness along its length which may be cracked open after the 
placement of the catheter to peel the needle from around the catheter. 
British Pat. Nos. 1,437,621 and 1,437,622 describe a hollow slotted needle 
carrying a catheter. After placement of the catheter the slotted needle is 
withdrawn from the patient and peeled away from the catheter. All these 
assemblies require manipulation of rigid and flexible components close to 
the site of injection where the danger is present of accidentally 
dislodging the emplaced catheter. 
Alternatively the catheter end may be left unencumbered and the connecting 
adapter fitted after catheter placement. British Pat. No. 1,099,496 
describes removable end connector in which the catheter is held in a 
rubber sleeve slightly compressed about the catheter to provide a seal, 
the connector being adapted to fit to a coaxial member on a syringe by 
means of for example a screw thread. 
British Pat. No. 1,255,086 and U.S. Pat. No. 3,554,580 describes an 
elastomeric bush used to grip the catheter. The catheter is placed in the 
bush by threading it through a tube in the bush. The cannula has an 
outside diameter greater that the internal bore of the bush, thus after 
removal of the tube from the bush, the bush and catheter form a tight 
seal. The bush is then formed into a unitary assembly with an adaptor for 
a dispensing container. This device is not capable of dissassembly and 
subsequent reassembly. 
One form of connector presently used is a blunt hollow needle, the distal 
end of which is able to be removably placed into the free end of a 
catheter and the proximal end of which is held in a synthetic polymeric 
female luer adaptor. In use it is customary to remove the luer adaptor 
with its associated hollow needle from the catheter, so as to enable 
removal of the Tuohy needle, and thereafter reconnect the hollow needle 
within the free end of the catheter tubing. 
This reconnection of a small diameter hollow needle inside the bore at the 
end of a flexible catheter tubing can be manipulatively difficult, 
especially with an epidural catheterization. The present invention sets 
out to overcome this manipulative difficulty and the difficulties which 
occur with the devices described hereinbefore by providing a guide member 
which facilitates and expedites the reconnection. The assembly has the 
further advantage that it allows for repetitive reconnection if, for 
example, a luer fitting needs changing to accommodate different dispensing 
containers. The device is readily manufactured, disposable and 
sterilizable. 
The present invention provides a catheter assembly which comprises catheter 
tubing, a hollow needle and a guide member with a longitudinal bore there 
through for aiding the insertion of the hollow needle into the catheter, 
which catheter assembly is characterised in that the longitudinal bore in 
the guide member has a narrower portion and a communicating broader 
portion, the narrower portion being adapted to receive in close fit the 
hollow needle and the broader portion being adapted to receive in close 
fit the catheter; whereby in use the catheter tubing may be positioned for 
insertion of the hollow needle. 
The hollow needle used in this invention will normally and preferably be 
mounted in a luer female adaptor for attachment to the source of liquid to 
be eventually passed through the catheter. 
In use the catheter tubing is inserted into the guide member as far as it 
will go, the guide member is gripped firmly and the hollow needle is 
inserted into the other end of the guide member and pushed in until it 
projects far enough through the guide member to enter the catheter tubing. 
The guide member is made of polymeric material which most aptly is a 
thermoplastic material such as polyethylene. 
Most aptly the broader and narrower portions of the longitudinal bore meet 
in a shoulder against which the catheter tubing can be held whilst the 
guide member is being used. 
In order to facilitate insertion of the catheter tubing and the hollow 
needle the one or both ends of the guide member may taper steeply inwards 
to meet the longitudinal bore, that is the entrance to the guide bore may 
be countersunk or shaped to provide an easy lead in. 
Desirably the guide member is adapted to grasp the catheter tubing when the 
guide member is compressed between finger and thumb. This may be effected 
by providing the walls of the guide member with longitudinal slots which 
extend from the end of the guide member (with the broader portion of the 
bore) to near the shoulder where the broader and narrower portions of the 
bore meet. The part of the guide member near the shoulder is preferably 
incompressible so that the end of the catheter tubing does not become 
compressed and thus the slots are preferably arranged as one or more 
opposing pairs. 
Most suitably all components of the catheter assembly are provided in 
sterile form. If desired the catheter assembly may be or form part of a 
sterile procedure pack. 
It will be realized that the longitudinal bore with broader and narrower 
portions could be considered as two interconnecting bores. From another 
view the invention accordingly provides an assembly of a length of 
catheter tubing with the distal end of a hollow needle removably held 
within the rearward end of the catheter tubing and the hollow needle 
itself having a connection hub at its proximal end; wherein a guide member 
has a first longitudinal bore communicating with the rearward end of the 
guide member, the first longitudinal bore being located around the hollow 
needle so that the guide member is slidable with respect thereto but 
leaves the distal end of the hollow needle extending beyond said first 
longitudinal bore in its assembled position, and said guide member further 
possessing a communicating second longitudinal bore for accepting the 
catheter tubing extending back from the forward end of the guide member, 
the interior end of said second longitudinal bore, where it meets the 
first longitudinal bore, being of the same dimension as the external 
diameter of the catheter tubing end; whereby gradual displacement of the 
guide member in a forward direction relatively to the hollow needle 
smoothly disconnects the catheter tubing as the hollow needle distal end 
disappears within the first longitudinal bore; while gradual displacement 
of the guide member and associated length of catheter tubing held immobile 
in relation thereto with its free rearward end located as far as possible 
within the second bore ensures that the hollow needle re-enters the bore 
of the catheter tubing for smooth reconnection. Of course, the catheter 
tubing may be located in the guide member before the hollow needle is 
inserted in its relevant bore, or with the hollow needle already inserted 
in the first longitudinal bore but not yet protruding into the second 
longitudinal bore. 
To facilitate introduction of the end of the catheter tubing into the guide 
member, the second longitudinal bore may be tapered inwardly towards the 
interior of the guide member, provided that a cylindrical bore portion 
remains within which the tubing can be gripped. Furthermore, a flared 
portion of steeper taper may be provided where the second longitudinal 
bore emerges from the forward end of the guide member. 
Generally the two bores will be coaxial and there will be a shoulder where 
the second longitudinal bore of larger diameter meets the first 
longitudinal bore. It is conceivable but unlikely that the shoulder may be 
dispensed with if a steeply tapering second longitudinal bore is employed 
for example to accommodate various sizes of catheter tubing. 
In that the hollow needle may be fully removed and replaced in the guide 
member a tapered portion can also be provided at the end of the first 
longitudinal bore. If identifiably different from the taper at the end of 
the second longitudinal bore, no confusion will arise; in any case colour 
or indicia can be used. 
It is preferred for the external shape of the guide member not to follow 
the internal configuration of the first and second longitudinal bores. The 
guide member could be cylindrical, but may itself slightly taper from the 
forward to the rearward end since this assists in one of its modes of use, 
namely, when the catheter tubing is to be gently disconnected by pushing 
the guide member. In this shape, moreover, there is a relatively high wall 
thickness around the first longitudinal bore so that it does not become 
distorted and prevent smooth movement along the needle. 
It will be appreciated that reconnection of the catheter tubing and the 
hollow needle is greatly facilitated. It is only necessary to push the 
catheter tubing into the wide end of the second longitudinal bore until it 
can no longer move, grip the guide firmly between finger and thumb and 
then slide the catheter tubing and guide member gently in relation to the 
hollow needle until this protrudes from the end of the first longitudinal 
bore down inside the catheter tubing. 
However, it is often difficult to manipulate in one hand the assembly of 
the catheter tubing positioned inside the guide member and at the same 
time introduce the hollow needle with the other hand whilst not 
simultaneously pushing the catheter tubing out of the guide member. To 
overcome this drawback it was preferred to develop a guide member which 
could be held in one hand so as to simultaneously grip and retain the 
catheter tubing therein. 
It is therefore preferred that the guide member be so arranged or 
constituted as to be capable of gripping the catheter tubing when the 
hollow needle is being inserted and releasing the catheter tubing at other 
times. 
Generally, this is acheived by distorting the walls of the second 
longitudinal bore by pressure for example from finger and thumb, so as to 
grip the catheter tubing. Thus the guide member may be of a resilient 
elastomeric material for example rubber. It may alternatively or 
additionally be provided with slots extending longitudinally of, and 
usually in communication with, the second longitudinal bore. So as to 
avoid distorting the open end of the catheter tubing when the catheter 
tube is gripped (and thereby hindering insertion of the hollow needle) the 
slots preferably extend only part-way back from the forward end of the 
guide member so as to leave undistorted the region where the second 
longitudinal bore communicates with the first longitudinal bore. When the 
finger pressure is removed the catheter tubing is released from the guide 
member allowing the guide member to slide along the hollow needle. 
While the invention as defined above relates to the whole catheter 
assembly, it will be appreciated that the guide member itself, possessing 
a first longitudinal bore in communication with second longitudinal bore 
as defined above, is another separate aspect of the invention.

FIG. 1 shows the free end of flexible catheter tubing 1, attached by a 
hollow needle 2 held in the free end of the catheter tubing and extending 
to a hollow metallic or synthetic polymeric hub 3 of characteristic 
stepped taper as shown for connection to a source of anaesthetic or other 
fluid. The assembly 1, 2 and 3 is conventional in the art, but according 
to the present invention there is provided around the hollow needle a 
guide member 4. This guide member possesses a first longitudinal bore 5 
with tapered opening 5a, in which the hollow needle is a snug sliding fit, 
and a longitudinal second bore 6 with tapered frusto-conical end 6a at the 
end nearer the catheter tubing 1. This second longitudinal bore 6 
terminates in small shoulders 7 at its bottom end. The outer surface of 
the guide member, as shown, is tapered as at 8 but this is optional and a 
cylindrical guide works equally as well. 
The same features are shown in FIG. 2 but in a slightly different relative 
position. 
The assembly is used as follows. When it is desired to disconnect the 
catheter tubing 1 from the hollow needle 2, so that the Tuohy needle can 
be removed from the catheter tubing, the guide member 4 is gripped in its 
relatively unyielding left-hand portion and moved gently to the right as 
shown in FIG. 2. The hollow needle can be completely removed from the 
guide member or can remain in place but retracted, as desired. In either 
case, this motion serves to gently disengage the free end of the catheter 
tubing from the free end of the hollow needle, so that the Tuohy needle 
can be removed as it is passed from the free end of the catheter tubing. 
To reconnect this assembly the catheter tubing free end is placed exactly 
as shown in FIG. 2 and the left-hand portion of the guide member is again 
firmly gripped while also preserving a grip on the free end of the 
catheter tubing 1 so that their relative positions are unaltered. The 
hollow needle, guided within the walls of the first longitudinal bore 5, 
enters the opening at the end of catheter tubing 1 whose extremity has 
been located within the frusto conical tapered recess and rests on the 
shoulder 7. 
It will be apparent that the assembly shown presents several advantages. 
Instead of threading a hollow needle of small bore into the opening in the 
end of free flexible catheter tubing, in which it must fit snugly by 
friction, the hollow needle is received and retained and guided within a 
corresponding bore in guide member 4. The catheter tubing only has to be 
guided into the wide opening of the frusto-conical recess, and it is 
located for engagement with the hollow needle by its end resting on the 
shoulder 7 of the guide member. 
FIGS. 3, 3A to 6, 6A and 7A show embodiments of this guide member which are 
adapted to enable the catheter tubing 1 to be gripped and so held in the 
guide member, whilst the hollow needle 2 is inserted into the end of the 
catheter tubing 1. 
When using the embodiment shown in FIGS. 1 and 2 it is necessary to hold 
both the free end of the catheter tubing 1 and the guide member 4 in one 
hand, whilst manipulating the hollow needle 2 in the other hand. It is a 
relatively difficult operation to hold both the free end of the catheter 
tubing and the guide member in one hand and to maintain their correct 
relative positioning--there is a possibility that one or other may be 
dropped accidentally. 
The second, third, fourth, fifth and seventh guide member embodiments are 
each adapted so that after the catheter tubing 1 has been inserted into 
the guide member, the catheter tubing is gripped and retained by holding 
the guide member for example between the thumb and forefinger and 
squeezing slightly. 
FIGS. 3, 3A show a guide member 4 formed of a resilient elastomeric 
material for example rubber. A longitudinal bore 5 is provided for 
accepting the hollow needle and a recess 9 for the catheter tubing 
connects thereto at shoulders 7. The recess 9 may be cylindrical, but is 
shown slightly tapered inwardly to accommodate variations in catheter 
tubing diameter. The end of the recess is flared at 10 to facilitate 
introduction of the catheter tubing. Operation is substantially as before, 
except that the reconnection is facilitated. Holding the guide member 4 in 
one hand, the catheter tubing held in the other hand is introduced into 
recess 9 up to shoulder 7. The guide member is then squeezed for example 
between thumb and forefinger to distort the resilient material around the 
recess 9 and so grip the catheter tubing. With the catheter tubing held 
inside the guide member in one hand, the free hand is used to insert the 
hollow needle into the open end of the catheter tubing. When the guide 
member 4 is released the resilient material adopts its original shape so 
allowing the guide member to be slid along the hollow needle 2. 
In the embodiment of FIGS. 4, 4A, the guide member 4 is made of a harder 
plastics material for example polyethylene. However the catheter tubing 1 
is gripped by squeezing together the material on either side of a slot 11. 
The slot 11 extends only part-way along recess 9 so that a portion 12 of 
the recess is undistorted on squeezing the guide member 4. This avoids 
distortion of the very end of the catheter tubing 1 when the guide member 
is squeezed, which might otherwise hinder insertion of the hollow needle 
2. 
The embodiment of FIGS. 5, 5A also has a slot 11 and undistorted portion 
12. However, resiliency is improved by thinning the material on either 
side of slot 11 to provide flaps 13. The flaps 13 are also provided with a 
raised surface pattern 14 to act as grips for the finger and thumb. 
The embodiment of FIGS. 6, 6A is similar in concept to the previous two 
embodiments, except that it has two intersecting slots 15 each provided 
with webs 16 at either end. Such a construction facilitates moulding of 
the guide member in plastics material. Any number of slots may be used to 
provide the required resiliency. 
Various modifications may be made within the scope of the invention defined 
above. In particular, while the invention has been described with 
reference to a catheter assembly, any form of manipulatively difficult 
introduction of one elongate member within the bore of another could be 
facilitated by a device of the general nature described above. 
In the embodiment of FIGS. 7 and 7A, the guide member 4 has a slot 11 
extending part-way along the recess 9 so that a portion 12 of the recess 
is undistorted when the catheter tube 1 is gripped by squeezing the guide 
member 4. At each end of the guide member 4 the recesses 5 and 9 each 
possess a tapered portion 17 and 10 respectively to aid the location of 
the hollow needle 2 and catheter tubing 1 in their recesses.