Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1996-08-19
1998-11-03
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604905, A61M 2500
Patent
active
058301950
DESCRIPTION:
BRIEF SUMMARY
This invention is concerned with medical equipment, and in particular relates to couplings for connecting cannulae or catheters to a connection tube through which liquid to be administered to a patient is delivered, or fluid to be taken from a patient is collected.
It is generally accepted practice for a catheter tube to be equipped, at the end thereof opposite the end which is introduced into the patient, with a moulded plastic connection hub defining a tapered socket of frustoconical configuration. This hub constitutes a female coupling member for cooperation with a complementary male member fitted to the end of the connection tube, e.g. of an administration set. The male member comprises a tapered frustoconical spigot which is dimensioned to engage with a friction fit in the tapered socket of the catheter hub. Thus, the coupling is made by pushing the male and female members together, and is disconnected simply by pulling the members apart. If a coupling should become separated unintentionally, there may be very serious consequences for the patient e.g. as a result of air being drawn in through the catheter and entering the blood stream. Various proposals have been put forward for applying safety devices to hold the members of the coupling against accidental separation, but none have gained practical acceptance, except that a small rotatable cap is sometimes provided, either held captive with the male member or loosely received on the connection tube attached to it, and this can has an internal thread which allows it to be screwed over the catheter hub by cooperation with a pair of small radial lips formed at its free end. However, this cap can become unscrewed and it is not always completely reliable, e.g. in a situation where a patient has a tendency to fiddle with equipment. Therefore, it is common practice for medical staff to wrap tape around the coupling. While tape helps to secure the coupling, it is inconvenient and has the disadvantage that the coupling is concealed from sight.
Another disadvantage of the conventional coupling is that the male and female members are quite small and need to be held in the fingers at or very closely to those surface portions which are contacted by fluid, when engaging and releasing the coupling. This carries with it a risk of infection as bacteria deposited on the plastic members have a tendency to colonise and the bacteria can be carried by the liquid flowing through the coupling into the patient's blood stream. Also, the patient may finger the coupling and cause bacterial contamination.
When the known coupling is released, for example for replacement of the administration set, there is a danger that air may enter the catheter through the open socket of the connection hub. While a device to pinch closed the catheter tube has been proposed, this does not provide a complete solution. When the male coupling member is withdrawn from the socket, there is left a space which naturally fills with air, and upon another male member being inserted into the socket it is possible for a bubble or air to become trapped within the coupling and subsequently pass through the catheter into the patient.
The present invention addresses the foregoing problems.
In accordance with one aspect the present invention resides broadly in a coupling for a medical cannula comprising two members secured against separation by a rotatably tightened part, charactered in that a locking arrangement is provided for locking said part against rotation in the loosening direction.
Stated more specifically the invention provides a coupling for a medical catheter, comprising separate male and female members which are connectable with a push fit, a cap for surrounding the members and rotatable for releasable engagement with one of the members to secure the members against being pulled apart, and means on said cap and said one member for locking the cap against reverse rotation.
In a particular embodiment, the said one member is the catheter hub and includes a peripheral surface portion provided with ratchet
REFERENCES:
patent: 5000739 (1991-03-01), Kulisz et al.
Kerr James W.
Peters Joseph L.
Clinical Product Development Limited
Yasko John D.
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