WO1991014398A1

WO1991014398A1 - A cannula and a holder coacting therewith

Info

Publication number: WO1991014398A1
Application number: PCT/SE1991/000215
Authority: WO
Inventors: Hans Axel Hedlund
Original assignee: Hans Axel Hedlund
Priority date: 1990-03-20
Filing date: 1991-03-20
Publication date: 1991-10-03
Also published as: SE9001004D0; AU7567991A; SE9001004A; SE465703B

Abstract

A cannula of the kind which includes a front part having a pointed-part for insertion into a patient, and a rear part having a pointed-part for insertion into a blood collecting container. The cannula is provided on a part located between the pointed-parts with a screw thread intended for coaction with a corresponding screw thread in a container guide sleeve. The invention is characterized in that the cannula (1) is provided with a further screw thread (9) adjacent the first mentioned screw thread (6), but closer to the rear pointed-part (4). The diameter of the further screw thread (9) is smaller than the diameter of the first mentioned screw thread (6) and in that the further screw thread (9) is threaded in a direction opposite to the first mentioned screw thread (6). The further screw thread (9) is intended for coaction with a protective sleeve (10) provided with a corresponding internal screw thread (11).

Description

A Cannula and a Holder Coactincr Therewith

The present invention relates to a cannula and to a holder coacting therewith.

More and more attention is being paid in public health and medical services to the aspect of safety when handling hypodermic needles, cannulas and blood taken from patients, with respect to preventing the transmission of infectious diseases from patient to nursing personnel.

Nursing personnel are constantly at risk when handling hypodermic needles car cannulas. For instance, when taking a blood sample with the aid of a vacuum container, a so-called vacutainer, a protective sleeve is first removed frαn the rear part of the cannula, whereafter this rear part is screwed onto a vacuum-container guide sleeve. A protective sleeve is then removed from the front part of the cannula. The needle or cannula is then inserted into a vein of the patient concerned. A vacuum container is introduced into the guide sleeve, wherein the rear part of the cannula penetrates the seal on the vacuum container, so as to enable blood to flow into the container. Subsequent to filling the container with blood, the cannula is reraoved and a protective sleeve is fitted to the front part of the cannula. This procedure involves the risk of being pricked by the cannula trocar or needle point.

U.S. Patent Specification No. 4,778,453 describes a cannula in which this latter risk is eliminated by the provision of a protective sleeve which embraces the front part of the cannula and which is axially mσveable relative thereto. When removing a cannula from a patient, the protective sleeve is gripped and held stationary at the same time as the cannula is withdrawn, causing the protective sleeve to move to a position in which it surrounds the front part of the cannula.

When this step is completed, the nursing attendant unscrews the back part of the cannula from the container and fits a protective sleeve to the rear end of the cannula. Consequently, there is again a risk that the attendant will be pricked, namely by the pointed rear part of the cannula.

This last mentioned risk is eliminated by means of the present inven- tiαn. The present invention also enables the aforesaid guide sleeve and protective sleeve for the rear part of the cannula to be handled more simply.

The present invention thus relates to a cannula of the kind which comprises a front part provided with a sharp point, or trocar, for insertion of the cannula into a patient, and a rear part provided with a sharp point for introduction into a blood collecting container, said cannula having a screw-threaded part located between said two pointed parts for coaction with a cαrrespαnding screw thread in a container guide sleeve. In accordance with the invention, a cannula of this kind is characterized in that the cannula is provided with a further screw thread which is located adjacent the first mentioned screw thread but closer to the rear pointed part, this further screw thread having a smaller diameter than the first mentioned screw thread; and in that the further screw thread is threaded in a direction opposite to the thread of the first mentioned screw thread, said further screw thread functioning to coact with a corresponding internal screw thread on a protective sleeve.

The invention also relates to a cannula holder of the kind defined in Claim 4 and having the characteristic features set forth therein.

The invention will now be described in more detail with reference to exemplifying embodiments thereof illustrated in the accompanying drawing, in which

Figure 1 illustrates a cannula constructed in accordance with the invention;

Figure 2 is an axial section view of a protective sleeve; - Figure 3 illustrates the protective sleeve of Figure 2 from above; Figure 4 illustrates a cannula with a protective sleeve screwed thereon; - Figure 5 illustrates an inventive cannula; Figure 6 is an axial section view of a holder constructed in accordance with the invention;

Figure 7 illustrates the holder of Figure 6 from above; Figure 8 illustrates a guide sleeve; and - Figure 9 is a cross-sectional view taken on the line A-A in Figure 8.

Figures 1 and 5 illustrates the function of a cannula in accordance with the aforesaid U.S. patent specification. This cannula eliminates the risk of personnel being pricked by the front pointed part 2, of the cannula 1. The cannula includes a protective sleeve 3 which surrounds the front part of said cannula and which can be moved axially in relation to the cannula, between the position shown in Figure 1 and the position shewn in Figure 5. The protective sleeve is located in the position shown in Figure 5 when the cannula is to be removed from a patient. When the cannula is removed, the protective sleeve 3 is gripped and held stationary while drawing-out the cannula 1 at the same time, wherewith the protective sleeve 3 is moved to a position in which it surrounds the front part of the cannula, this position being shown in Figure 1.

The present invention relates to a cannula 1 of the kind which includes a front part provided with a pointed part or trocar 2 for insertion into a patient, and a rear pointed part 4 which is intended for insertion into a blood collecting container. The cannula 1 has located between said pointed parts 2, 4 a part 5 which is provided with a screw thread 6 intended for coaction with a corresponding screw thread 7 in a guide sleeve 8 which coacts with the aforesaid holder.

In accordance with the invention, the cannula 1 is provided with a further, second screw thread 9 which is located adjacent the first mentioned, first screw thread 6. The second screw thread is located nearer the rear pointed-part 4 and has a .smaller diameter than the first screw thread 6. The diameter of the second screw thread is suitably about half the diameter of the first screw thread. The second screw thread 9 is also threaded in a direction opposite to the first screw thread 6. The second screw thread 9 is intended for coaction with a protective sleeve 10 provided with a cxjrresponding internal screw thread 11, see Figures 2 and 4. When screwed into position, the protective sleeve 10 covers the rear pointed part 4 of the cannula 1, as shown in Figure 4.

Aαxsrding to one preferred embodiment, both the first thread 6 and the second thread 9 have the same or essentially the same pitch.

As before mentioned, the first screw thread 6 is intended for coaction with a cxjrresponding screw thread 7 provided in a guide sleeve 8 for the aforesaid container. This known container may have the form of a glass test tube closed at one end by means of a rubber stepper. A partial vacuum corresponding to the amount of blood to be tapped or drained into the container is established in the container interior.

The container is filled in a conventional manner, by removing a protective sleeve, corresponding to the protective sleeve 10, where¬ after the cannula 1 is screwed onto the protective sleeve 8, through mutual coaction of the screw threads 6 and 7. In the case of known cannulas, the protective sleeve exacting with the rear pointed-part 4 is not provided with screw threads. The protective sleeve 3 is then moved to the position shown in Figure 4, whereafter the pointed-part 2 is inserted into a vein of the patient. The pointed-part 4 extends slightly belcw the wall 12 of the guide sleeve 8 in this stage of the procedure. The container is then pushed into the guide sleeve 8 in a direction downwards and upwards in Figure 8, with the rubber stopper upwards. The rear pointed-part 4 of the cannula will therewith pene¬ trate the rubber stopper and blood is drawn into the container.

When the requisite amount of blood has been taken from the patient, the cannula is removed and the protective sleeve 3 will move to the position shewn in Figure 1 at the same time. The cannula 1 is then unscrewed from the guide sleeve 8, whereafter the protective sleeve for the rear pointed-part is fitted. It is this fitting of the pro¬ tective sleeve on the rear pointed-part which involves the risk of being pricked unintentionally by said pointed-part 4. A∞ordingly, the invention also relates to a holder intended for coaction with a cannula of the kind described above. The holder is illustrated in Figure 6, although in a smaller scale than the cannula 1 illustrated in Figure 5. The holder 13 includes a centrally projecting first part 14 in which an axially extending recess 15 is formed. Spaced from the first part 14 is at least one second outwardly projecting part 16 and a slot 17 is provided between the parts 14, 16 parallel with the longitudinal axis of the first part 14. The recess 15 has an internal shape which corresponds to the external shape of the protective sleeve 10. The width and length of the slot 17 cor¬ respond respectively to the thickness and length of the guide sleeve 8, so as to enable the guide sleeve to be fitted onto the first part.

According to one preferred embodiment of the invention, the holder 13 is provided with two second outwardly projecting parts 16, 18, which are positioned symmetrically in relation to the longitudinal axis of the first outwardly projecting part 14. Figure 7 shows the holder 13 from above. The aforesaid second outwardly projecting parts 16, 18 may have the form shown in Figure 7.

As before mentioned, the holder 8 is illustrated in Figure 8. The holder 8 includes at the bottcm end thereof a flange 19 which projects further on mutually opposite sides of one diameter line of the guide sleeve and which projects less on mutually opposite sides of another diameter line which extends perpendicular to the first mentioned diameter line, as illustrated in Figure 9. The container may alterna¬ tively be configured so that flanges are present solely at two diametrically opposed locations, with no flange therebetween. The slot 17 has a width such as to enable the guide sleeve 8, including the presence of any smaller outwardly projecting flange to be inserte into the slot.

When the protective sleeve 8 is fitted over the first outwardly projecting part 15, those parts of the aforesaid flange which project further than the other flange part will engage the walls 20, 21 of the second outwardly projecting parts 16, 18 upon twisting the guide sleeve relative to the holder 13. The guide sleeve 8 fitted to the holder is thus locked rotationally in relation thereto.

When seen in cross-section, the protective sleeve 10 has a peripheral shape which deviates from a circular shape. This cross-sectional shape is preferably square, although any appropriate cross-sectional shape can be used. The object is to enable the protective sleeve 10 to be locked rotationally relative to the holder 13, when placing the holder in the recess 15.

The inventive cannula and holder operate in the following manner.

When a cannula is to be used, the cannula is removed from its packing and the protective sleeve 10 is screwed onto the cannula. A guide sleeve 8 is then fitted onto the first part 14 of the holder. The cannula, together with the protective sleeve fitted thereto, is then passed through a screw threaded hole 22 in the guide sleeve 8, so that the protective sleeve 10 will be pushed down into the holder recess 15, where the sleeve is locked rotationally in relation to the holder 13, as before described. The cannula is then screwed onto the guide sleeve, through the mutual coaction of the screw threads 6 and 7. Since the first screw thread 9 on the cannula is threaded in the opposite direction to the second screw thread 6 of the cannula, the protective sleeve 10 will be unscrewed from the cannula as the cannula is screwed onto the guide sleeve 8. Provided in the bottom of the recess 15 is a spring 23 which is compressed when the protective sleeve 10 is unscrewed from the cannula. When the cannula is screwed onto the guide sleeve, the cannula and guide sleeve 8 connected thereto are lifted from the holder, whereas the protective sleeve 10 remains in the recess 15.

Blood is then tapped or drained into the container, in the aforedes- cribed manner. When removing the container from the guide sleeve, the guide sleeve is again moved to the first part 14 of the holder, whereafter the cannula is unscrewed from the guide sleeve 8 and the protective sleeve 10 is screwed onto the cannula in conjunction therewith.

It will be evident from the aforegoing that nursing personnel need never come into contact with the rear pointed-part 4 of the cannula. Furthermore, the invention eliminates two working steps, namely the step of first removing the protective sleeve 10 and the step of then refitting said protective sleeve, since these steps are carried out autcmatically when fitting and removing the guide sleeve 8 respectiv¬ ely.

The present invention therefore greatly enhances safety in handling a cannula and also makes handling of the cannula easier to accomplish. It will be understood that the present invention can also be applied to cannulas which lack an axially moveable protective sleeve 3, even though it is preferred to use a cannula which is provided with an axially moveable protective sleeve.

It will also be understood that the present invention can be modified with respect to the form of the holder 13 and to the form of the protective sleeve 10, without departing from the described function.

The present invention shall not therefore be considered limited to the aforedescribed exemplifying embodiments thereof, since modifica¬ tions can be made within the scope of the following Claims.

Claims

1. A cannula of the kind that coπprises a front part which is provided with a point for insertion into a patient, and a back part which is provided with a point for insertion into a blood collecting container, and which includes between said points a screw threaded part which is intended to coact with a corresponding screw thread in a container guide sleeve; char ac t e r i z e d in that the cannula (1) is provided with a further screw thread (9) which is located adjacent the first mentioned screw thread (6) but closer to the rear pointed- part (4) ; in that the further screw thread (9) has a smaller diameter than the first mentioned screw thread (6); and in that the further screw thread (9) is threaded in an opposite direction to the first mentioned screw thread (6) , said further screw thread (9) being intended to coact with a protective sleeve (10) provided with a corresponding, internal screw thread (11) .

2. A cannula according to Claim 1, ch a r a ct e r i z e d in that both the first mentioned screw thread (6) and the further screw thread (9) have the same or substantially the same pitch.

3. A cannula according to Claim l αr 2, ch a r a c t er i z ed in that the peripheral form of the protective sleeve (10) differs from a circular form, as seen in cross-section through the sleeve.

4. A holder for coaction with a cannula according to Claim 1, ch a r a c t e r i z ed in that the holder (13) includes a central, outwardly projecting first part (14) having an axially extending recess (15) ; at least one second outwardly projecting part (16; 18) located at a distance from the first outwardly projecting part (14) ; a slot (17) which extends parallel with the longitudinal axis of the first outwardly projecting part (14) and which is located between respective outwardly projecting parts; in that said recess (15) has an inner form which corresponds to the outer form of the protective sleeve (10) ; and in that the width and length of the slot (17) cor¬ respond respectively to the thickness and length of the guide sleeve (8) , such as to enable the guide sleeve to be fitted onto the first outwardly projecting part (14) .

5. A holder according to Claim 4, c h a r a c t e r i z e d in that the holder (8) includes two second outwardly projecting parts (16; 18) which are located symmetrically in relation to the longi- tudinal axis of the first outwardly projecting part (14) .