Sampling Apparatus

Abstract

A holder for a sealed container of the type having a piercable self-sealing cap is slidably mounted at a lower end of an inclined slideway. The slideway is pivotally mounted at its upper end to a stationary base. A housing mounted to an upper end of the slideway includes a pair of needles positioned to pierce the cap of the container. The needles are disposed one above the other and the uppermost needle is longer than the lower most needle. Actuating means are provided for causing reciprocal movement of the holder and simultaneous pivotal movement of the slideway so that the cap is pierced by the needles. As the uppermost needle pierces the cap it enters a bubble formed above fluid contained in the container for purposes of equalizing the pressure within the container. The second needle then pierces the cap as the container passes through a horizontal position so that the second needle enters the fluid contained in the container which flows to a position adjacent the cap as the container is tilted. Means are provided for applying a negative pressure to the second needle for drawing fluid out of the container. The actuating means is then used to withdraw the holder and container from the needles which are wiped clean by the action of the self-sealing cap.

Description

SUMMARY OF THE INVENTION

The present invention relates to a method of and apparatus for withdrawing a sample of fluid from a sealed container.

It is known to take a sample of blood from a vein by introducing a needle into the vein and then applying an evacuated self-sealing container to the outer end of the needle so that the vacuum in the container draws a specific quanatity of blood from the vein into the container. The container is then withdrawn from the outer end of the needle and the cap on the container which is made from a synthetic plastics material seals the hole left by the withdrawal of the needle. A self-sealing container of this type is sold under the Registered Trademark "VACUTAINER."

The blood sample is then contained in the sealed partially evacutated container and testing procedures can only be carried out on the sample by withdrawing small quantities of the fluid from the container. Since it is normally desirable to carry out several tests on one sample it is often necessary to withdraw several small samples of blood from the sealed container. In the past, this has been done by removing the sealed cap, placing a tube in the container and withdrawing a small sample through the tube.

This method has the disadvantage that the cap has to be removed from the container and may often be smeared with blood from the container. In addition, the end of the tube which has been placed in the blood may drip blood before it has been wiped clean. As a result of both of these factors there is a risk of cross infection occurring from the blood which is left on the cap or on the end of the tube.

It is an object of the present invention to provide a method of withdrawing samples of fluid from a sealed container without removing the cap from the container and in a manner such that the member used to withdraw the sample is automatically wiped as it is withdrawn and the container resealed.

It is a further object of the present invention to provide a method of removing fluid from a sealed container and apparatus therefor such that the pressure in the sealed container is equalized with the atmospheric pressure before the sample is withdrawn so as to prevent any risk of too large a quantity of fluid being withdrawn into pressure sensitive testing equipment.

According to one aspect of the present invention there is provided a method of withdrawing a sample of fluid from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn, comprising the steps of: inserting a sampling needle through the cap and into the fluid in the container, withdrawing a sample of fluid from the container by applying a negative pressure in the sampling needle and withdrawing the sampling needle through the cap allowing the cap to wipe the sampling needle as it is withdrawn and thereafter reseal the container.

If the sample is being withdrawn from the container automatically into a piece of testing apparatus and it is important to ensure that the pressure in the container before the sample is withdrawn is approximately equal to atmospheric pressure then the container is vented through the cap before the sampling needle passes through the cap.

The present invention also provides apparatus for withdrawing a sample from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn comprising a housing, a sampline needle mounted on the housing, means for connecting the sampling needle to a source of negative pressure, a holder for the container mounted on the housing and adapted to hold the container with the cap spaced from and facing the tip of the sampling needle and manually or automatically operable actuating means for producing relative linear reciprocal movement between the container and the sampling needle to cause the sampling needle to pierce the cap and enter the fluid in the container and thereafter be withdrawn from the cap.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section through a connector of the present invention.

FIG. 2 is an end view of the connector of FIG. 1.

FIG. 3 is an elevation, partly in section of an applicator for applying the connector of FIGS. 1 and 2 to a fluid container in the withdrawn position.

FIG. 4 is an elevation similar to FIG. 3 but showing the applicator in the forward position.

FIG. 5 is a plan view of the applicator in the forward position.

FIG. 6 is a view similar to FIGS. 3 and 4, but showing the applicator in an intermediate position.

DESCRIPTION OF THE INVENTION

In the drawings, a connector is indicated generally at 10 which is adapted to connect a withdrawal tube 11 to the fluid in a container 12 so that a measured quantity of the fluid can be withdrawn from the container through the tube 11.

The connector 10, which is shown in detail in FIGS. 1 and 2, comprises a main body 13, a needle holder 14 which carries two needles 15 and 16, a threaded cap 17 which secures the needle holder 14 to the main body 13 and a threaded pin 18.

The main body 13 of the connector has a threaded boss 19 at one end and an internally threaded, axial recess 20 at its other end. The end face of the boss 19 is formed with a central frustoconical recess 21 and with an annular groove 22 which surrounds the recess 21. An axial bore 23 communicates between the recess 21 in the end face of the boss and the axial recess 20 in the other end of boss. A conduit 24, which communicates between the groove 22 and the atmosphere forms an air vent to the groove 22 and extends through the main body 13 at an angle to the axis of the connector.

The needle holder 14 is cylindrical and has a collar 25 at one end forming an abutment which seats in the cap 17. The needles 15 and 16 are mounted in bores which extend through the holder 14 and are fixed in place by soldering or any other suitable means. The needle 16 is mounted on the axis of the holder 14 and a portion 16a projects a short distance outwardly from the rear face of the holder whereas the needle 15 is offset from the axis and terminates flush with the rear face of the holder 14. Both of the needles 15 and 16 are hollow and sharply pointed and the needle 15, which is offset from the axis of the holder, is substantially longer than the needle 16.

In order to attach the needle holder 14 to the main body 13, the holder 14 is positioned against the end face of the boss 19 with a pin 26, which projects forwardly from the end face of the boss, located in a hole 27 formed in the collar 25 and the portion 16a located in the recess 21 and surrounded by an O-ring seal 28 which is housed in the recess 21. The location of the pin 26 in the hole 27 ensures that the longer needle 15 is angularly aligned with a radially projecting pin 29 on the main body 13, the purpose of which is explained below. When the holder 14 is positioned against the end face of the boss 19 the cap 17 is threaded home to secure the holder 14 on the boss and it will be seen from FIG. 1 that, when assembled, the needle 15 communicates through the groove 22 and conduit 24 with a tube 72. The tube 72 leads to a vessel 74 which is closed by a lid 76 and which contains a small quantity of antiseptic fluid. The tube 72 passes through the lid 76, which is readily removable from the vessel. It will be noted that the volume of the vessel 74 is substantially greater than the volume of the container 12.

The pin 18, which is threadedly mounted in the recess 20 retains an O-ring seal 30 at the end of the recess and is formed with a stepped through bore 31 forming a continuation of the axial bore 23 is the main body. The withdrawal tube 11 is a slide fit through the bore 31 and the O-ring seal 30 into the axial bore 23 when the pin 18 is unscrewed and is clamped in position by the O-ring seal 30 when the pin 18 is tightened home on to the O-ring seal.

In order to connect the tube 11 with the fluid in the container 12 to enable a quantity of the fluid to be withdrawn from the container, the container and the connector are mounted on an applicator which is indicated generally at 40 in FIGS. 3 to 5.

The applicator 40 comprises a channel shaped housing 41 having side walls 42 and 43. The housing 41 is mounted on a support 44 so that it is inclined to the horizontal at an angle of approximately 30.degree. with its forward end 45 substantially higher than its trailing end 46. Pivotally mounted at 62 between the side walls 42 and 43, at the forward end 45 of the housing is a cross-bar 47 which is adapted to receive the connector 10. A clamp 48 is hinged to the cross-bar 47 and a screw 49 is provided to tighten the clamp 48 so as to firmly mount the connector on the cross-bar. The clamp 48 is provided with a hole which is adapted to receive the pin 29 on the main body 13 of the connector to ensure that the needle 15 is located vertically above the needle 16.

Two parallel rods 50 project rearwardly from the cross-bar 47 and are slidable engaged through two bores formed in a mount 51. The rear end of the mount 51 is pivotally linked at 63 to the lower end of a handle 52 which is pivotally mounted at 64 between upwardly projecting extensions 53 and 54 of the side walls 42 and 43 respectively.

The mount 51 is formed with an upwardly opening recess 55 adapted to receive the container 12. The contaienr 12 is not a close fit in the recess 55 and a gap is formed between a forward end wall 56 of the mount and the end face of the cap on the container. The extent of this cap will depend upon the length of the container and the length of the container cap.

An aperture 58 is formed in the end wall 56 and as can be seen from FIGS. 3 to 6, the size and position of the aperture 58 is such that the needles 15 and 16 can pass through the aperture and into the container 12.

When the connector 10 and the container 12 are mounted on the applicator 40, as shown in FIG. 3, the tip of the upper, longer needle 15 is located partly in the aperture 58 but spaced from the container 12.

In order to actuate the applicator, the handle 52 is depressed and the rods 50 and mount 51, which is carrying the container 12 are pivoted upwardly about the pivot point 62. At the same time, an elbow 52a at the bottom end of the handle drives the mount forwardly along the rods 50 towards the needles 15 and 16.

The container 12 is provided with a known self-sealing cap 60, which can for example be formed from a butyl rubber material. As the mount and container are initially moved forwardly the container is held with the cap uppermost and with the air bubble adjacent the cap so that the needle 15 pierces the cap 60 and enters the air bubble. This position is shown in FIG. 6. The needle 15 communicates through a tube 72 with interior of the vessel 74, which is kept approximately at atmospheric pressure. Since the volume of the air bubble in the container 12 is substantially less than the volume of the vessel 74, the air pressure in the container will be immediately equalized approximately with atmospheric pressure.

As the container and the mount continue to move forwardly the shorter needle 16 pierces the cap 60 and the container is tilted through the horizontal so that the air bubble moves away from the cap 60 and the needle 16 pierces the cap, and enters the fluid which is now adjacent the cap, the air bubble having risen to the opposite end of the container. This condition is shown in FIG. 4.

When the handle 52 is fully depressed, a negative pressure is applied to the tube 11 so as to withdraw a determined quantity of fluid from the container. When the sample has been withdrawn from the container, the handle 52 is raised so as to withdraw the container from the connector. As the needles 15 and 16 are withdrawn, the container is lowered through the horizontal so that the air bubble in the container moves along the container towards the cap. The needle 15 is withdrawn immediately before the air bubble reaches the cap but the needle 16 is withdrawn through the air bubble so that pressure in the container is again equalized approximately with atmospheric pressure.

As the mount 51 and the container are drawn away from the needles the friction exerted on the needles by the cap initially holds the container and the cap in position until such time as the end wall 56 of the mount engages the outer face of the cap and draws the container and the cap away from the needles. As the needles are withdrawn through the cap they are wiped substantially clean and the cap then reseals the container. The container can then be removed from the applicator until a further sample is required.

Under some operating conditions, fluid from the container 12 has been found to creep back along the needle 15. The reason for this is not yet known. If this occurs, the fluid will pass along the tube 72 into the vessel 74 where it drips into the antiseptic fluid. The lid of the vessel 74 can be readily removed to replace the antiseptic fluid and also to ensure that the pressure in the vessel 74 is kept approximately at atmospheric pressure.

If the problem of creep back along the needle 15 should not occur then the needle 15 can communicate directly with the atmosphere via the groove 22 and conduit 24.

The connector 10 and applicator 40 enable a sample to be withdrawn from the container 12 without any substantial spillage of fluid from the container. The cap 60 remains on the container throughout the operation and the needles which enter the fluid are automatically wiped as they are withdrawn through the cap. The tube 11, which may form a permanent part of a piece of testing apparatus does not enter the container and can be removed from the connector clean, thus eliminating the need for wiping.

The connector 10 and the applicator 40 also ensure that the pressure in the sealed container 12 is approximately equal to atmospheric pressure before any fluid is withdrawn through the tube 11. This is particularly important if the tube 11 is connected to apparatus, such as a Coulter counter, which is an automatic blood count apparatus and which is sensitive to pressure differences in the container. Many pieces of testing equipment of this kind apply a negative pressure to the container to draw off a measured quantity of fluid and are set to work against atmospheric pressure. Consequently if there is a vacuum in the container the quantity of fluid drawn into the testing equimpment will vary. This problem does not arise if a sample is drawn from an open container but if a sealed container is used then a pressure is normally created whenever liquid is withdrawn through the cap and also whenever the cap is removed and then replaced.

The applicator 40, by tilting the container 12 throuh the horizontal also enables substantially all of the fluid to be withdrawn from a container by the shorter needle so that none of the sample in a container need be wasted.

It will be appreciated that the use of the second needle 15 to equalize the pressure in the container is only essential if the fluid is bein withdrawn into apparatus that is sensitive to pressure differences in the container and if this is not the case then the second air venting needle can be omitted.

It will also be understood that it is within the scope of the present invention to provide a switch mechanism on the applicator 40 which automatically actuates apparatus connected to the tube 11 when the handle 52 is fully depressed. Additionally, it will be understood that the applicator 40 can itself be automatically operated and that other modifications can be made both to the applicator 40 and the connector 10 without departing from the spirit and scope of the present invention.

Claims

What we claim is:

1. A method of withdrawin a sample of fluid from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn, comprising the steps of:

venting the container through the cap while maintaining the container in substantially upright position before the sampling needle passes through the cap, whereby the pressure in the container is approximately equalized with atmospheric pressure;

inserting a sampling needle through the cap and into the container;

tilting the container subsequent to venting of the container so that the fluid is positioned adjacent the cap and the sampling needle extends into the fluid;

withdrawing a sample of fluid from the container by applying suction to the sampling needle; and

withdrawing the sampling needle through the cap, whereby the cap wipes the sampling needle as it is withdrawn and thereafter reseals the container.

2. A method as described in claim 1, wherein the container is vented by means of a vent needle, the vent needle being passed through the cap before the sampling needle so as to communicate an air bubble formed above the fluid in the container with atmospheric pressure.

3. A method as claimed in claim 2 including the additional steps of holding the container with the cap uppermost as the vent needle pierces the cap so that the vent needle enters the air bubble above the fluid and thereafter tilting the container through a horizontal position as the sampling needle passes through the cap so that the air bubble in the container moves away from the cap and the sampling needle enters the fluid positioned adjacent the cap.

4. Apparatus for withdrawing a fluid sample from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn, comprising:

a housing;

a samapling needle mounted on the housing;

means for connecting the sampling needle to a suction source;

a holder for the container mounted on the housing and adapted to hold the container with the cap spaced from and facing the tip of the sampling needle;

actuating means for producing relative linear reciprocal movement between the container and the sampling needle to cause the sampling needle to pierce the cap and enter the fluid in the container and thereafter be withdrawn from the cap;

the holder for the container being normally disposed at an angle to the horizontal with the cap end of the holder upppermost and the said actuating means being adapted to tilt the holder through the horizontal before the sampling needle passes through the cap; and

means being provided for venting the container through the cap whereby the pressure in the cap is approximately equalized with atmospheric pressure before the container is tilted into a horizontal position.

5. Apparatus as claimed in claim 4, wherein the said means for venting the container comprises a venting needle adapted to pierce the cap before the sampling needle and enter an air bubble formed above the fluid to vent the container.

6. Apparatus as claimed in claim 5, wherein the venting needle is longer than the sampling needle and the venting needle is arranged above the sampling needle and in parallel with the sampling needle.

7. Apparatus as claimed in claim 4, wherein abutment means is provided on the holder to retain the container in the holder when the sampling needle is withdrawn.

8. Apparatus as claimed in claim 4, wherein the sampling needle is mounted substantially rigidly in a connector which is adapted to readily connect the sampling needle to a source of suction.

9. Apparatus as described in claim 5, wherein the sampling needle and the venting needle are mounted substantially rigidly in a connector which is adapted to readily connect the sampling needle to a source of suction and to connect the venting needle to a pressure source approximately equal to atmospheric pressure.

10. Apparatus as claimed in claim 9, wherein the sampling needle and the venting needle are readily removable from the connector for cleaning or replacement purposes.

11. Apparatus for withdrawing a fluid sample from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn, comprising:

a housing;

a sampling needle mounted on the housing;

means for connecting the sampling needle to a suction source;

a holder for the container mounted on the housing and adapted to hold the container with the cap spaced from and facing the tip of the sampling needle;

actuating means for producing relative linear reciprocal movement between the container and the sampling needle to cause the sampling needle to pierce the cap and enter the fluid in the container and thereafter be withdrawn from the cap;

the holder for the container being normally disposed at an angle to the horizontal with the cap end of the holder uppermost and the said actuating means being adapted to tilt the holder through the horizontal before the sampling needle passes through the cap;

means being provided for venting the container through the cap before the container is tilted into a horizontal position;

the means for venting the container comprising a venting needle adapted to pierce the cap before the sampling needle and enter an air bubble formed above the fluid to vent the container;

the venting needle being longer than the sampling needle and the venting needle being arranged above the sampling needle and in parallel with the sampling needle; and

the needles being mounted at the upper end of an inclined slideway on the housing, the holder for the container is slidably mounted at the lower end of the inclined slideway for reciprocal movement toward and away from the needles, the slideway being pivotally mounted at its upper end to the housing and the actuating means being operable to pivot the slideway through the horizontal for tilting movement of the container.

12. Apparatus for withdrawing a fluid sample from a container which is sealed by a cap formed from a material which can be readily pierced by a sampling needle and which will reseal the aperture formed by the sampling needle when the sampling needle is withdrawn, comprising:

a housing;

a sampling needle mounted on the housing;

means for connecting the sampling needle to a suction source;

a holder for the container mounted on the housing and adapted to hold the container with the cap spaced from and facing the tip of the sampling needle;

actuating means for producing relative linear reciprocal movement between the container and the sampling needle to cause the sampling needle to pierce the cap and enter the fluid in the container and thereafter be withdrawn from the cap;

the holder for the container being normally disposed at an angle to the horizontal with the cap end of the holder uppermost and the said actuating means being adapted to tilt the holder through the horizontal before the sampling needle passes through the cap;

the sampling needle being mounted substantially rigidly in a connector which is adapted to readily connect the sampling needle to a suction source; and

the sampling needle being readily removable from the connector for cleaning or replacement purposes.