WO2000056214A1

WO2000056214A1 - Blood sampling device

Info

Publication number: WO2000056214A1
Application number: PCT/ZA2000/000052
Authority: WO
Inventors: Peter Hugh Harrison; William Alleyn Blake; Mirko Tappero; Jose Carlos Do Rego Loureiro
Original assignee: Anglo Operations Limited
Priority date: 1999-03-19
Filing date: 2000-03-20
Publication date: 2000-09-28
Also published as: AU4861200A

Abstract

This invention relates to a blood sampling device wherein a blood sampling cannula (1) and a delivery cannula (7) extend at an obtuse angle to each other from a base (2) which includes a transparent flashback chamber (3). A holder assembly (6) for a vacuum flask is integral with the base and a protective sheath (11) is movable co-axially with respect to the sampling cannula to optionally cover and expose it. The sheath and base have co-operant formations for providing a first holding position for the sheath in which it extends over the sampling cannula and a final lock position with the sheath receiving the sampling cannulae therein and in which position formations interact in an irreversible manner to hold the sheath in this locked position.

Description

BLOOD SAMPLING DEVICE

FIELD OF THE INVENTION

This invention relates to a blood sampling device and, more particularly, to a device which includes a medical needle or cannula (hereinafter referred to as a cannula) for insertion into the vein of a person in order to withdraw potentially several samples of blood for testing in known manner.

BACKGROUND TO THE INVENTION

The conventional blood sampling device widely employed at the present time includes a cannula passing completely through a base whereby it is supported with both ends of the cannula being sharpened with appropriate profiles and one, the front end, being longer than the other, the rear end. The base is adapted to fit releasably into a neck at one end of a cylindrical holder having an open opposite end. In use, the holder receives axially introduced vacuum sample tubes having a stopper through which the rear end of the cannula passes, in use, this stopper being of a self-sealing nature so that the tube is closed when the cannula is removed.

The base receives a cover on each end thereof so as to cover both forward and rear ends of the cannula for transport and storage purposes.

In order to use the device outlined above, a medical technician must firstly remove the cover from the rear end of the cannula, thereby exposing it and rendering it potentially dangerous in that it is capable of causing percutaneous in_jury and thus potentially communicating blood borne pathogens The rear end is then passed into the holder through the neck and the base is attached to the neck usually using a screwthreaded attachment requiring rotation of the base relative to the holder The cover over the forward end of the cannula is then removed thus rendering it potentially dangerous as indicated above

Whilst gripping the holder the medical technician will then very often bend the cannula to a slight incline to its original axial direction to facilitate its introduction into a person's vein, commonly on the arm, at a very small angle

The technician will then hold the patient with the free hand so as to stabilise the area of venipuncture throughout the procedure.

With the cannula now inserted into a vein, blood should be in communication through the cannula with the rear end thereof, but blood flow is prevented by an elastomeπc boot located over the rear end of the cannula and which acts as a closure valve.

One or more vacuum tubes are thereafter successively introduced into the holder with the stopper end inner-most so that the rear end of the cannula passes through the stopper to allow blood flow into the tube. After the required number of blood samples have been taken the device is removed from the patient The cover is often re-installed, with potential risk of injury, on the front end of the cannula preparatory to disposal thereof in what is known as a sharps container Generally, the holder itself is re-used repeatedly with obvious infection control implications

This procedure has various disadvantages and difficulties.

In the first place, there is appreciable effort required to configure the existing system for use. Secondly, there is considerable handling of the cannula with one or both ends thereof exposed, with the consequent danger of needlestick injuries with the accompanying possibility of infection communication.

When the base is released from the holder so that the latter can be re-used, this increases the dangers indicated above The holder can also become unhygienic, as it is seldom sterilised after each use A further disadvantage of this procedure is that until such time as the first vacuum tube is introduced into the holder and the stopper pierced by the rear end of the cannula, it is not known if there has been successful venipuncture If not. the vacuum tube will have to be discarded and the introduction of a cannula into the patient's vein carried out again

OBJECT OF THE INVENTION

it is the object of this invention to provide a blood sampling device which will greatly facilitate the task of a medical technician in taking blood samples and which may, if required, embody appreciable safety features.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention there is provided a blood sampling device comprising a blood sampling cannula and a delivery cannula extending from a base with the axes of the cannulae being at an obtuse angle to each other and the base being adapted to be associated with a holder assembly for a vacuum tube in use.

Further according to the invention the cannulae communicate with a flashback chamber in the base, at least part of the chamber being translucent and preferably transparent

Further features of the invention provide for the holder to be integral with the base and including an integral guide member fixed relative to the base and located in a plane including the axes of both cannulae so that the member, adjacent the base, passes through a slot in a protective sheath for the blood sampling cannula, the sheath being slidable axially on the base to optionally cover and expose the sampling cannula.

Still further features of the invention provide for the sheath and base or member to co-operate fπctionally or to have co-operant formations for providing a first holding position for the sheath in which it extends over the sampling cannula and a final lock position with the sheath receiving the sampling cannula therein and in which position formations interact in irreversible manner to hold the sheath in this locked position. Still further according to the invention the blood sampling device includes a holder for a vacuum tube integral with the base.

Still further according to the invention the flashback chamber includes a member which allows the escape of gas but not liquid therefrom and the device is a gas permeable member.

In order that the above and other features of the invention may be more fully understood one embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

FIGJ is a sectional elevation of the device according to the invention in the "as supplied" condition;

FIG.2 is a sectional plan of the device;

FIG.3 illustrates the device in a "ready to use" condition and showing a vacuum tube in position therein; and,

FIG.4(a) is a schematic plan of the sheath and locking

(b) & (c) mechanism.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the invention illustrated in the drawings the blood sampling device is made primarily of injection moulded plastics components each of which may be made in terms of current practise of suitable materials; and the most important of which are usually made of . colourless, transparent or at least translucent material.

As illustrated in the drawings the device comprises a sampling cannula (1) extending from a plastics base (2) located at its rear end. The open rear end of the cannula communicates with a transparent flashback chamber (3) having at its end opposite the cannula a gas permeable plug (4). The base (2) is injection moulded integral with a central guide memoer or wall (5) of material which connects it to the inside of the wall of an integral cylindrical holder (6), the axis x of which extends at an obtuse angle to the axis y of the sampling cannula (1) The holder is thus laterally off-set to one side of the axis of the cannula (1)

Co-axial with the holder (6) is a delivery cannula (7) fitted with a conventional rubber sealing boot (8) over its delivery end (9) The opposite end (10) of the delivery cannula extends into the flashback chamber (3) so as to be in communication via the chamber with the blood sampling cannula

Slidable axially on the base is a substantially rigid plastics tubular protective sheath (11) having a longitudinally extending guide slot (12) for locating the guide wall (5) connecting the holder to the base and on which guide wall the sheath can slide The sheath has a finger grip (14) at its rearward end (15) to facilitate movement The sheath is slidable between three basic positions In a first position (Figures 1 and 2) the sheath extends over or covers the sampling cannula (1) to prevent inadvertent contact with, and to protect the point (13) of the sampling cannula This is the position in which the sampling device is supplied. The second position (Figure 3) is one in which the sheath is withdrawn as illustrated in Figure 3 and the sampling cannula is fully exposed The guide wall (5) and slot (12) are provided with cooperating holding and locking formations Thus the wall (5) at its edge (16) remote from the sampling cannula (1) is provided with an enlarged formation (17) which fits within the width of the guide slot (12) The guide slot (12) itself terminates in two constrictions in its width The first holding constriction (18) is adapted to hold the enlarged formation (17) in the "ready to use" or packing position as shown in Figure 1 and Figure 4

(a) Movement of the enlarged formation (17) and of this constriction (towards the left in the drawings) and into the major portion of the length of the slot (12) escapes the sampling cannula (1) and in this position the sheath (11) is freely movable and is shown in Figure 4 (b).

The guide slot (12) terminates in a terminal undercut locking constriction (19)

Movement of the sheath (11) and slot (12) on the guide wall (5) so that the enlarged formation (17) enters the locking constriction (19) covers the sampling cannula (1) with the sheath (11) and locks the sheath (11) in this final condition prior to disposal. This is shown in Figure 4 (c) The slot has inwardly directed tabs (20) longitudinally spaced relative to each other at its forward end and which overlap with each other in plan view as shown in Figure 2 The purpose of these tabs is to prevent the pointed end (13) of the sampling cannula from moving laterally out of the slot for example in the event that, in spite of it being unnecessary, a medical technician has bent the needle to an incline to its original axis

In use, a medical technician simply slides the sheath rearwardly from the position illustrated in Figure 1 and Figure 4 (a) to that illustrated in Figure 3 and Figure 4 (b) in order to render the blood sampling device ready for use. As a result of the fact that the holder is integral with the base and is laterally offset by virtue of the construction of the device it will be unnecessary to apply a bend to the sampling cannula (1) The cannula (1) can then be introduced into a person's vein and successful venipuncture can be observed by the arrival of blood in the transparent flashback chamber (3) One or more vacuum sampling tubes (21) can then be used to collect blood in the usual way with the boot (8) serving as a valve over the delivery end (9) of the delivery cannula (7) as in the case of known devices

After sampling has been completed the sampling cannula is withdrawn in the normal way and the sheath slid fully forwardly for the enlarged formation (17) to engage the irreversible co-operating constriction (19) and thereby render the entire device safe for disposal

It will be understood that numerous variations may be made to the embodiment of the invention described above without departing from the scope hereof

Claims

1. A blood sampling device comprising a blood sampling cannula and a delivery cannula extending from a base with the axes of the cannulae being at an obtuse angle to each other and the base being adapted to be associated with a holder assembly for a vacuum tube in use.

2. A blood sampling device as claimed in claim 1 in which the cannulae communicate with a flashback chamber in the base.

3. A blood sampling device as claimed in claim 2 in which the flashback chamber includes a member which allows the escape of gas but not liquid therefrom.

4. A blood sampling device as claimed in claim 3 in which the member is a gas permeable member.

5. A blood sampling device as claimed in claim 2 in which at least part of the flashback chamber is at least translucent.

6. A blood sampling device as claimed in claim 5 in which at least part of the flashback chamber is transparent.

7. A blood sampling device as claimed in any of the preceding claims which includes a holder integral with the base.

8. A blood sampling device as claimed in claim 7 in which the base and holder include an integral guide member fixed relative to the base and located in a plane including the axes of both cannulae.

9. A blood sampling device as claimed in any of the preceding claims which includes a protective sheath axially slidable with respect to the sampling cannula to optionally cover and expose the sampling cannula.

10. A blood sampling device as claimed in claim 4 read with claim 8 in which the sheath includes a guide slot co-operable with the integral guide member.

11. A blood sampling device as claimed in claim 10 in which the guide slot and guide member have co-operant formations for providing a first holding position for the sheath in which it extends over the sampling cannula and a final lock position with the sheath receiving the sampling cannula therein and in which position formations interact in irreversible manner to hold the sheath in this locked position.

12. A blood sampling device substantially as herein described will refer to accompany drawings