DK150842B - BLOOD SAMPLING DEVICE - Google Patents

Description

150842

In a commonly used method of blood sampling, blood from a vein is passed through a cannula and into an evacuated container. This evacuated container provides the pressure drop necessary to facilitate blood flow to and collection in the container through the cannula apparatus.

In recent years, various improvements have been proposed in this method of blood sampling, such as inserting a valve into the apparatus for automatic opening and closing of the flow path as several evacuated containers are successively connected to the apparatus. In this way, a plurality of blood samples can be collected in a similar number of vessels from one and the same venous puncture.

Often, the evacuated containers contain chemical substances useful in the clinical laboratory studies to be performed after mixing with the patient's blood. However, these chemicals can be harmful to the patient and should therefore be prevented from flowing into the patient's bloodstream from the evacuated container. For example, some evacuated containers are partially filled with a nutrient substrate with protein, and if any of this protein material was transferred to the patient, it would be possible for it to cause anaphylactic shock only. Therefore, it is highly desirable to be able to do blood sampling using evacuated containers and in such a way as to avoid the risk of backflow in the patient during and after sampling.

To this end, it would be advantageous to be able to use an inexpensive non-return valve which responds to a pressure change and requires no significant force to open, while the valve is sensitive to small pressure drops to ensure that an evacuated container 35 is filled to the required degree before the valve closes. This 2 150842 applies especially in blood sampling, where different evacuated tubes must be filled with a precisely determined amount of blood relative to the chemical already present in the evacuated tube so as to obtain a predetermined blood-chemical ratio . This is a prerequisite for the subsequent investigation to be accurate.

In view of these conditions, in particular the demand for accurate regulation of the filling and the cost factor in mass production of evacuated pipes and cannula, it will be understood that an increase in the threshold value of the pressure difference required for opening or closing the valve direct increase in blood inaccuracy. A valve type, which requires the least possible differential pressure for opening and closing, and which is normally normally closed, will therefore be of great importance in the present technical field.

In the foregoing, the invention relates to an apparatus for blood sampling in a patient, comprising a housing containing a chamber and partly having a first, cannula fixed to the front of the housing, which with its tip end is adapted for insertion into the patient's blood vessel and with its rear end is connected to the chamber, and secondly a second cannula, which with its front end is connected to the chamber and extends therethrough through the rear of the housing and has a rearward-facing tip end for insertion into a replaceable, evacuated blood collection vessel, and wherein in chamber 30 there is a valve arrangement for interrupting the flow of blood upon replacement of the collecting vessel.

An apparatus of this kind is known from U.S.A. U.S. Patent No. 3,659,587, which discloses a valve arrangement with an elastic disc, which is clamped as a transverse wall in the chamber and contains a self-closing slot or slot which can be opened by a forward displacement of the second cannula thereby providing direct flow connection with the first needle. In this situation, backflow from the collecting container to the patient will not be ruled out, which means that the principal object of the present invention is not taken into account by the known construction.

From this, the apparatus according to the invention differs in that the second cannula is fixed to the rear of the housing 10 and that the valve arrangement is constituted by a resilient, elastic valve sleeve which is closed at its rear end and with its front end portion. the diameter of which in the unstressed state is less than the outer diameter of the cannula at this location, is inserted a short distance into the cannula for tightly enclosing it, the valve bushing between the part of the cannula and the closed end having at least one passage through the wall, which is normally closed to prevent blood flow but is adapted to be opened by elastic deformation only, as a result of a pressure reduction at the rear end of the second cannula, and independent of the device to allow blood flow and to be closed again at a predetermined pressure rise at the 25 rear end of the latter cannula. As a result, this pressure rise will cause the valve to automatically return to the closed position and prevent flow from the rear end of the device to the patient.

The invention is explained in more detail below with reference to the drawing, in which: FIG. 1 shows a side view, partly in section, of an embodiment of a cannula apparatus according to the invention, enclosed in a closed container; FIG. 2 is a side view of the apparatus shown in use and assembled with a holder, an evacuated container and a needle cap; FIG. 3 shows a longitudinal section in larger scale of the apparatus with the needle cap removed and with the apparatus in flow communication with a blood vessel immediately before taking a blood sample; FIG. 4 is an enlarged sectional view of the valve of the valve shown in FIG. 3; FIG. 5 is a view of FIG. Figure 3 is a sectional view of the cannula apparatus in use and with the valve open while collecting blood in an evacuated container; 6 is a cross-sectional view of the valve of the valve shown in FIG. 5 with the blood flow through the apparatus indicated by arrows; FIG. 7 is a view of FIG. 5 shows a sectional view of the cannula apparatus in use and inserted into the patient's vein as well as after collection of a blood sample in an evacuated container and after the valve has been closed, and FIG. 8 is an enlarged sectional view of the valve shown in FIG. 7, this valve is shown resealed after carrying out a blood sample.

The FIG. 1, 2 and 3, the device 20 has a housing 21 which carries at the front end a forward cannula 22 for venous puncture and which at the rear end has a second collar 23.

The housing 21 has a front end portion 24 with a through passage 25 into which the rear end portion of the venous puncture cannula 22 is disposed. This cannula may be securely held in the housing, e.g. by means of an adhesive 26.

The portion 24 of the housing 21 has a hollow cone-shaped rear end 27 in which the rear end of the cannula 22 extends from the passage 25. The forward end of the cannula 22 protrudes from the housing 21 and has an obliquely cut tip 28 for insertion into a patient's vein. The rear end 29 of the cannula 22 is blunt, and on the portion of the cannula extending beyond the passage 25 an elastomeric cap or valve body 30 is provided.

The valve body 30 is closed at the rear end, but is open forward and encloses the cannula 22 in a tight manner. Between the blunt end 29 of the cannula 22 and the rear end of the valve 30, it has a central cavity 31 which communicates with the passage through the cannula 22. The valve 30 consists of a self-closing, elastomeric material and contains one or more 10 slots 32 next to the cavity 31. The inside diameter of the valve 30 is smaller than the outer diameter of the cannula 22, so that the bushing or valve 30, when inserted on the cannula 22, expands into the contact area and thereby provides a tight abutment against the outside of the cannula.

The housing 21 is composed of two parts, the slightly tapered exterior 27 of the front portion 24 having suitable friction being inserted into the likewise tapered interior of the rear portion of the housing 33. This portion 33 has a hollow outer cylindrical portion 34 of 20 a tapered inner surface that fits with the front portion 24 of the housing and, on the opposite side, the housing portion 33 has a stud 35 with a through passage 36. The stud 35 has an external thread 37 for screwing together with a holder to be discussed in detail therein. following. When the two parts 24 and 33 of the housing 21 are stitched together, they together form a chamber 38. To this chamber 38 there is access through the cannula 22 in the passage 25 or through the cannula 23 which is in the passage 36. This cannula 23 can be fixed in a conventional manner, for example by means of an adhesive 39. The front end of the cannula 23 lies inside the passage 36 and its rear end extends out from the socket 35 and has a sharpened tip 40 for insertion into an evacuated container which 35 will be discussed later. As shown, the cap or valve 30 is inside the chamber 38 of the housing 21.

6 150842

In FIG. 1, it can be seen how the cannula can be packaged for shipping and storage under aseptic conditions until use. The packaging consists of a hollow capsule 41 of rigid material, e.g. a rigid plastic package consisting of two parts. The front portion 42 covers the front portion of the cannula 20 to a point between the ends of the housing 33. The rear portion 43 of the package covers the rear end of the cannula and ends below the lower end of its housing 21. The two portions 42 and 43 of the capsule or the packaging 41 is closed at the distant ends, but is open at the opposite ends and can be stitched together under friction to form a closed capsule 41 containing the cannula device. At the point of connection between the parts 42 and 43, these cylindrical outer surfaces are similar to each other and on which a piece of adhesive tape 144 is applied. As long as this adhesive tape 144 is intact, the capsule 41 is unbroken and the apparatus 20 located in the capsule 20 can is expected to be in aseptic condition. The rigidity of the capsule 41 excludes the risk of damage to the appliance during shipment, storage and handling before use. The apparatus 20 is disposable, so that after opening the capsule 41 25 and after completing the blood sampling, it can be discarded.

During use, the belt 144 is broken or removed and the capsule 41 is opened by removing the rear portion 43 from the front portion 42 and from the rear end 30 of the apparatus 20. The front portion 42 of the capsule 41 remains in its position above the venous puncture cannula 22 in order to reduce the risk of contamination during the preparatory work prior to use.

Upon removal of the rear portion 43 of the capsule 41 ', the cannula 23 and the socket 35 are exposed so that a holder 44 can be slid in over the cannula 23 and screwed together with the housing 7. 2, the needle 23 is disposed within the holder 44.

An evacuated container 45 is then partially pushed into the holder 44 to the tip 40 of the cannula. The evacuated container may be of a conventional nature and has a tubular body 46 which is open at one end and which is covered and sealed by a permeable, self-closing plug 47. The apparatus is now ready for actual blood sampling, and the front or cap portion 42 of the capsule 41 can be removed while overcoming the friction against the housing 21, thereby exposing the cannula 22. As shown in FIG. 3, the needle 28 of the needle 22 is then inserted into a patient's vein 48. Since the valve 30 locks the posterior, blunt 15 end 29 of the needle 22, no blood can escape from the cavity 31 of the valve 30 under the effect of venous pressure alone.

The evacuated container 45 is then further pushed forward until the tip 40 of the cannula 23 has pierced the stopper 47, thereby connecting the space of the evacuated tube 45 with the central chamber 38 of the housing 21. Between the inside and the outside of the valve 30, Because of the vacuum prevailing in the container 45, a pressure difference 25 arises which automatically opens the slots 32, whereby blood can flow from the vein through the cannula 22 and the slots 32 as well as the chamber 38 and further through the cannula 23 to the container * 45. This blood flow will continue as long as the pressure difference or pressure drop is maintained. When the vacuum suppressed in the container 45 is exhausted or equalized, the valve 30 will automatically return to its normal shape, whereby the slots 32 return to the closed position thereby blocking the blood flow at the blunt end 29 of the cannula 22. Similarly, an optional 35 counter pressure, which builds up during the filling of the container 45 with blood, abolishes the pressure difference, and the increased pressure on the outside of the valve 30 will cause closure of the slots 32, thereby eliminating any risk of flow into the valve 30 and 5 into the cannula 22 toward the patient.

As mentioned above, this is particularly important in the event that harmful substances to be used later in chemical analysis are already present in the tube 45, as it is extremely important to avoid the possibility of such 10 harmful substances entering the patient. .

FIG. 3-8 shows the sequence of operations when taking a blood sample without the risk of a recurrent flow of blood or other media through the cannula and into the patient.

FIG. 3 and 4 show the situation after puncture of the patient's vein 48. As the valve 30 is closed, the venous pressure will not be able to induce any blood flow past the valve 30 in the apparatus.

The evacuated tube 45 is shown in a short distance away from the rear needle of the device.

Then complete connection of the cannula device 20 with the evacuated tube 45 is made. 5 and 6 so that the tip 40 of the cannula 23 will be inside the evacuated tube. This vacuum causes a 25 pressure drop by reducing the pressure in the chamber 38 so that the slots 32 in the valve 30 open and allow blood to flow through the cannula 20 and into the evacuated tube 46 for collection. If during this procedure a pressure increase occurs behind the valve 30, its slots 32 will again close, thereby preventing flow both forward and backward through the apparatus.

When the vacuum in the tube 46 is exhausted or equalized, the pressures on the two sides of the valve 30 35 will be equal and this valve 30 will return to

Claims (2)

150842, its normal, unstressed position, in which the slots 32 block the passage through the apparatus 20. Thereafter, no flow can occur between the two cannula tips 28 and 40. The evacuated container 45 5 can then be removed from the cannula apparatus as shown in FIG. 7 and 8 and subjected to analysis or other treatment as desired. A new evacuated container can then be coupled to the apparatus 20 in a similar manner for collection of a further sample. 10 An apparatus for blood sampling in a patient, comprising a housing (21) containing a chamber (38) and having, in part, a first needle (22) secured to the front of the housing (24), as with its tip end (28). is adapted for insertion into the patient's blood vessel and with its posterior end is connected to the chamber, and secondly a cannula (23) which is connected with its anterior end and extends therethrough through the posterior portion (33) of the housing 20 and has a rearward facing tip end (40) for insertion into a replaceable, evacuated blood collection vessel (45), and wherein there is a valve arrangement for interrupting blood flow upon replacement of the collecting vessel, characterized in that the second needle (23) is secured to the rear of the housing (33), and that the valve arrangement is constituted by an elastic valve sleeve (30) seated on the rear end of the first cannula (22), which is closed at its rear end and with its front end portion, whose diameter in unstressed condition is less than outer the diameter of the cannula at this location is inserted a distance into the cannula for tightly enclosing it, wherein the valve sleeve between the portion attached to the cannula and the closed end has at least one 35 slot (32) passage normally closed for obstruction of blood flow but is adapted to be opened by elastic deformation only to allow blood flow and again to be closed by a predetermined pressure rise at the posterior end of the second cannula (23) and independently of the orientation of the device. the posterior end of the latter cannula (23). Apparatus according to claim 1, characterized in that the second cannula (23) is secured in an external threaded stud (35) on the housing for screwing together with a holder (44) for the evacuated collector (46).