CH616335A5 - Access device for a tube, in particular a drip - Google Patents

Abstract

The object of this device is to allow access to a drip tube by means of a needle making it possible to sample the liquid flowing in the tube or to inject substances into the tube. It comprises a drip tube (12), a segment of which is surrounded by an elastomer sleeve (14). An element (16) which cannot be perforated by a drip needle (18), surrounds a part of the sleeve (14) which it compresses. This element (16) protects the hand of the operator against any pricking by the needle (18) passing through the sleeve and the tube, and, furthermore, it compresses the elastomer sleeve (14) sufficiently to hermetically close the hole left by the needle (18) when the latter is withdrawn. <IMAGE>

Description

The invention relates to a device for accessing a tube, in particular an infusion tube, allowing for example the taking of samples of the fluid circulating in the tube or the injection of medicaments into this fluid without leaks. The invention also applies, for example, to sets of tubes intended for the circulation of blood between a patient and an artificial kidney, or to a device for oxygenating the blood.

Currently marketed sets of blood circulation tubes usually include one or more injection sites from which blood samples can be taken, or chemicals can be injected into the blood using a needle hypodermic piercing the wall of the tube. It is necessary to use a smooth, non-toxic blood flow tube for patient safety. Such a tube has a relatively thin wall, has a low elasticity and in general does not close hermetically by itself after being pierced. To avoid any leakage into the interior of the tube or to prevent blood from leaking from the tube pierced by a hypodermic needle, elastomers having a certain capacity for self-sealing have been used in the prior art. The elastomeric element is arranged relative to the blood flow tube so that the needle first pierces this self-sealing elastomeric element before piercing the tube. However, the self-sealing characteristics of the best commercially available material, namely natural rubber latex, are sometimes insufficient to prevent leakage into the interior of the blood flow tube under certain conditions. usage encountered periodically. For example, the difficulty in obtaining self-sealing increases with the size of the needle, with the duration of penetration of the needle and with the number of repeated injections performed at a particular injection site. In addition, it is known that the best material exhibiting self-sealing characteristics, namely natural rubber latex, also exhibits characteristics of blood coagulation and toxicity which make this material less desirable than other elastomers such as silicone rubber, polyurethane elastomers, etc.

To eliminate the problem of leaks while simultaneously avoiding intoxication or clotting of the blood, numerous devices intended for injection sites have been tried. One of these devices includes a latex sleeve surrounding a section of a blood flow tube. This embodiment uses the self-sealing feature of the latex sleeve to prevent leakage. In order to provide additional protection against leaks, a second thin latex sleeve is stretched over the first sleeve at the ends of which it protrudes in order to also apply in a leaktight manner to the blood flow tube. U.S. Patent No. 3,814,137 describes this latter embodiment. Although it has been relatively used, it nevertheless constitutes a source of leaks under difficult conditions of use. In addition, it presents the risk for the person pushing the needle into the elastomer sleeves and into the tube of piercing the hand holding the assembly.

U.S. Patent No. 3,889,988 describes a device for accessing blood and designed to eliminate the risk of injury to the person using the needle and also to eliminate the risk of leakage. This embodiment comprises a section of plastic tube which is placed in the blood flow conduit. This tube comprises a body of hard plastic material in the shape of a T, having a channel formed along the vertical part of the body and having a diameter sufficient to accommodate the ends of the blood flow tubes which are fixed by adhesive in said tube. channel. The diameter of the channel of the longitudinal central part of the tube is equal to the inside diameter of the blood flow conduits and the latter traverses the channel of this part of the hard plastic tube. An injection can be made through a cylindrical orifice in the upper surface of the T-tube, this orifice descending into the channel of the body of the tube in which the blood flows. The orifice is closed by a cylindrical plug fitted with a non-thrombogenic elastomer, for example polyurethane or silicone rubber, compressed in place in the orifice. This embodiment has significant defects, namely the contact of the lower end of the elastomer with the blood circulating in the tube and the risk of total disengagement of the cylindrical plug of elastomer when the hypodermic needle is withdrawn. Removal of the elastomer plug reveals a leak channel having the same diameter as that of the blood flow conduit, which is obviously unacceptable.

U.S. Patents Nos. 2129983, 2498831, 2832338, 3030955, 3112748, 3447570, 3463691, 3853127, 2053112, 2907351 and 3566868 describe other embodiments of the type to which the invention relates. None of these embodiments makes it possible to completely solve the problems of leaks into or out of a non-thrombogenic blood flow tube while simultaneously eliminating the risk of accidental punctures of the hand of the operator handling the needle.

The invention is designed to solve these two problems. To this end, the invention relates to a device for accessing a tube, in particular an infusion tube, comprising a tube, an elongated elastomer sleeve which surrounds a section of this tube, and a C-shaped element which cannot be perforated by the needles, surrounding the sleeve and arranged substantially over the entire length and over a part of the periphery of said sleeve, in order to reveal a part of this sleeve comprised between the inner edges of the branches of said C-shaped element, the latter having a diameter inside smaller than the outside diameter of the sleeve and compressing it around the tube, over its entire length, the branches of the C-shaped element exerting a combination of radial and transverse forces inside

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laughing at the part of the elastomer sleeve not covered by said element, these forces being sufficient to prevent the appearance of leaks in the tube while a needle pierces the sleeve and the tube and after the needle has been withdrawn.

The device according to the invention differs from previous embodiments by the presence of a C-shaped element, which cannot be perforated by the needles and disposed substantially over the entire length of the sleeve which it surrounds over part of the periphery, so that this C-shaped element compresses said sleeve and achieves, using the characteristics of the elastomer constituting said sleeve, an effective seal preventing for example air from entering the blood flow tube or the blood leaking from this tube when a needle is inserted into it or after the needle has been removed. The access device according to the invention protects against any accidental injury to the operator holding the C-shaped element, which cannot be punctured by the needles, during the introduction of a needle into the sleeve, and it has a large access surface allowing several needle introductions and facilitating the placement of the needles at any desired angle for the injection of drugs and the taking of blood samples. The access device according to the invention also has increased resistance to leaks in conditions of use much more difficult than those encountered in the normal use of sets of tubes in which blood circulates between a patient and an artificial kidney. or a blood oxygenator. The device according to the invention is also useful during transfusions of blood or any other fluid, for example saline solutions, etc.

The invention will be described in more detail with reference to the drawing appended by way of example in which:

fig. 1 is a plan view of an advantageous form of the device according to the invention;

fig. 2 is a partial section along line 2-2 of FIG. 1; fig. 3 is a section along line 3-3 of FIG. 2;

fig. 4 is a perspective view, with partial cutaway, of the device during the introduction of a needle;

fig. 5 is a partial axial section of the device of FIG. 4, showing a needle which passes through the elastomer sleeve and the wall of the blood flow tube, this figure also showing in broken lines two other locations for piercing by a needle;

fig. 6 is an axial section of the access device showing two locations from which the needles have been removed, and a third needle partially removed;

fig. 7 is a cross section on an enlarged scale of the device shown in FIG. 1;

fig. 8 is a partial cross-section, on an enlarged scale, showing the part of penetration of the needle shown in FIG. 7 and also showing the distribution of forces in the elastomer sleeve when the needle is withdrawn, and FIG. 9 is a partial axial section, on an enlarged scale, along line 9-9 of FIG. 6, showing the distribution of forces inside the elastomer sleeve and acting on the needle inserted at an angle less than 90 ° relative to the axis of the blood flow tube.

The figures represent an access device according to the invention, indicated at 10 in FIG. 1. This device 10 comprises a blood flow or perfusion tube 12 which, during normal use, is part of a set of tubes connecting an artery or a vein of a patient to an artificial kidney, a blood oxygenator or an organ perfusion device. The tube 12 can be made of any one of several non-toxic plastic materials sold, for example polyvinyl plastics, polyurethanes or silicone rubber. The tube 12 is advantageously made of plasticized polyvinyl chloride.

An elastomer sleeve 14 surrounds a section of the tube 12 at one or more points along its length, for example on several sections of about 2.5 to 6.5 cm in length. The characteristics of the elastomer of the sleeve 14 are important for eliminating leaks of the type indicated above. The elastomer must be relatively soft while having sufficient elasticity and internal resistance to allow the introduction of a needle without shredding or disintegrating during penetration or withdrawal of the needle. It must also have maximum elastic memory or maximum ability to return to its original shape after being stretched or deformed, and it must have maximum resistance to fatigue or changes in elasticity with reuse or over time. It is important that the elastomer can transmit forces, in particular compression forces, from the point of application to neighboring areas located inside the body of the elastomer sleeve. These general considerations can be used for the selection of the best elastomer suitable for particular conditions of use which may differ significantly, as regards the pressure of the fluid flowing in the tube 12 or the diameter of the needle used, or else the needle retention time during blood sample collection or during the introduction of drugs into the blood flow tube, conditions normally encountered when using access devices mounted on blood pressure sets blood flow tubes used to subject a patient to dialysis using an artificial kidney. There are a certain number of types of elastomers which can be used for the production of the sleeve 14, these elastomers having the appropriate degree of elasticity for a given group of conditions of use, for example elastomers based on polyurethane, elastomers silicone, synthetic latex and natural rubber latex. To perform dialysis on human patients using an artificial kidney, in particular using an artificial kidney of the type containing hollow fibers as a dialysis element, for example the artificial kidney produced by the company Cordis Dow Corporation under the name C-DAK, it is preferable to use, as an elastomer, natural rubber latex.

The third and main element of an advantageous access device according to the invention is a C-shaped element 16, which cannot be crossed by the needles and partially surrounding, but more than half of the periphery of the sleeve 14, advantageously from about 65 to 90% of the periphery of this sleeve. The element 16 has the primary function of preventing accidental and total crossing of the sleeve 14 and the tube 12 by a needle 18 and, consequently, the penetration by this needle of the hand of the operator holding the access device , as shown in dashed lines in FIG. 4. A second and more important function of the C-shaped element 16 is to exert a certain compression on the part of the sleeve 14 which it surrounds, this compression being sufficient to improve the natural elastic characteristics of the part. of the sleeve which is not covered by the element 16, so that said sleeve 14 prevents any leakage towards the inside of the tube 12 while the needle 18 passes through the upper parts of the wall of the sleeve 14 and of the wall of the tube 12, as shown in FIG. 5. Another function of the element 16, less important than the preceding ones, is to exert a continuous force on the body of the element 16 and through it, so as to interrupt almost immediately any leak of fluid to the outside through the hole made in the tube 12 when the needle 18 is withdrawn from the interface between the exterior surface of the wall of the tube 12 and the interior surface of the sleeve 14, as shown in FIG. 6. Then, when the needle 18 is withdrawn from the body or from the upper wall of the sleeve 14, in the orientation of the figures, the force exerted on the sleeve 14 by the element 16 causes the hole previously sealed to be sealed. the introduction of needle 18, as shown by lines 20 and 22 in FIG. 6. This der5

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nier force is applied mainly by the parts 16A and 16B of the element 16, that is to say by the upper ends of the branches which extend above a horizontal plane tangent to the upper surface of the tube 12 and indicated by the dashed lines 17 in FIG. 7.

The force applied by the element 16 on the sleeve 14 comes from the resistance presented by the material constituting this element 16 to deformations relative to the initial circular circular cross section of the C formed by said element when the latter surrounds the part of the periphery. of the sleeve 14 which it covers, as shown in FIGS. 3 and 7. Fig. 7 is an end view on an enlarged scale of an advantageous form of the access device 10 according to the invention, showing the degree of deformation of the element 16 relative to its initial circular cross section when the material of the tube 12 is plasticized polyvinyl chloride, that of the sleeve 14 is natural rubber latex and that of the element 16 is a polypropylene. Before assembly, the outside diameter of the tube 12 is 6.42 + 0.08 mm, the inside diameter of the latex sleeve 14 is 5.56 ± 0.41 mm, the thickness of the wall of the sleeve is 3.18 + 0.25 mm and its nominal outside diameter is 11.91 mm. The sleeve 14 is mounted on the tube 12 and its internal diameter is slightly increased when said sleeve arrives at the predetermined position on the tube 12 for the access device 10. The sleeve 14 simultaneously applies a slight compression to the outside diameter of the tube 12. Similarly, before assembly, the element 16, injection molded of polypropylene, has a circular cross section having an inside diameter of 10.15 mm. , a wall thickness between 1.32 and 1.52 mm and a slot, between the upper parts 16A and 16B of its wall, with a width of 3.18 mm, as shown in FIGS. 3 and 7. The element 16 is mounted on the sleeve 14 by spacing the parts 16A and 16B with sufficient force to allow this element 16 to surround the external surface of the sleeve 14. The resistance of the polypropylene to deformation by spacing, sufficient for the element 16 to tightly surround the part shown of the periphery of the sleeve 14, causes a bulge in the part of the sleeve 14 indicated by the arrow 23 and situated between the inner edges 24A and 24B of the element 16. Due of the final spacing presented by the branches 16A and 16B of the element 16 once assembled, the part of the wall of this element 16 indicated by the arrow 25 is slightly flattened relative to its profile, in cross-section, circular, which causes a slight elongation of the C formed by the element 16, as it appears when FIG. 7 is rotated until the edge 16B is located at the top of the figure.

Due to the deformation of the element 16 with respect to its initial circular cross-section, multidirectional forces are constantly applied by this element 16 to the sleeve 14. The arrows 26 of FIG. 8 represent these forces with respect to a needle 18 passing through the sleeve 14, perpendicular to the longitudinal axis of the tube 12. It appears that the forces thus exerted, coming mainly from the upper edges 16A and 16B, include components oriented radially towards the inside, that is to say towards the sleeve 12, and other components resulting from the pressure exerted by the surfaces 24A and 24B on the external surface of the sleeve 14 and causing the bulge 23, these latter forces having components which vary from the radial direction towards the axially centered area of the bulge 23, gradually rising and passing through the horizontal, in the orientation of FIG. 8.

Fig. 9 shows in particular the distribution of forces exerted further to seal leakage of a needle introduced through the sleeve 14 at an angle less than 90 °, for example of about 40 °, as shown, by relative to a horizontal plane passing through the axis of the tube 12, this angle being indicated at 28 in FIG. 6. The arrows 30 show the forces oriented vertically and acting on the upper and lower surfaces of the hole made by the needle 18 due to the inclined introduction of the latter. The best seal is obtained, with the access device described, when the penetration of the needle takes place at an angle of about 45 ± 10 ° relative to a horizontal plane passing through the axis of the tube 12. The access device shown in fig. 7 and made with the materials indicated above constitutes the best embodiment according to the invention currently known. However, the element 16 can be made satisfactorily from materials other than polypropylene. The important criterion to be satisfied is that the material used has a relatively high rigidity and a resistance to deformation making it pass from an initial circular cross section to a C-shaped cross section, as described above for the polypropylene element 16. . It is desirable to choose a material having sufficient resistance to deformation so that the element 16 has a relatively thin wall, for example of a thickness less than 2.5 mm, in order to exert sufficient force to oppose leaks in difficult to use conditions. Materials which can be used satisfactorily in place of polypropylene include other plastics such as synthetic polyamides sold under the name nylon, acetal resins available under the designation Delrin, and acrylonitrile / butadiene / styrene resins produced by various manufacturers. It is also possible to use metals such as steel, stainless steel, aluminum and magnesium, especially under the most difficult conditions of use. Metals have the advantage of allowing easy manufacture of elements of initial cross section other than circular, in order to allow an increase in the pressure exerted by the upper parts of the wall of these elements corresponding to parts 16A, 16B. For example, these parts 16A and 16B can be curved initially towards the inside of the circular profile, so as to exert forces oriented downwards and adding to those indicated by the arrows 26 in FIG. 8.

The data indicated below and resulting from a comparative test show the effectiveness of the preferred embodiment according to the invention, the materials and initial dimensions of which and in the assembled state have been indicated with reference to FIG. 7, to prevent air leakage. The access device described was compared, during a test, with the access device of the type described in the aforementioned US Patent No. 3,814,137, marketed by the firm Travenol Laboratories Ine, under the designation Travenol Dialysis Blood Set. Each of these embodiments is particularly suitable for the sets of blood flow tubes used in dialysis with an artificial kidney, and therefore the test conditions chosen for comparison are much more severe than the conditions encountered in normal clinical use. during dialysis actually performed on patients. The test conditions used are indicated in the following table to allow a comparison with normal conditions encountered in clinical use during dialysis performed with an artificial hollow fiber kidney of the C-DAK type.

(Table at the top of the next page)

It is obvious that the increase in the diameter of the needle, the angle of piercing and the negative and positive pressures, as well as the use of water instead of blood constitute appreciably more difficult conditions than those normally encountered. .

The test consisted of the following operations:

1. Connecting the blood lines to a suction and heating device at body temperature, ie 37 "C.

2. At a water flow rate of 200 ml / min, establishment of a pressure of —150 mm of mercury, which is roughly double the maximum depression generally used in dialysis.

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Needle diameter Piercing angle Pressure, below that of the atmosphere

Positive pressure gauge Fluid flow rate Fluid temperature

Test condition selected

1.27 mm 90 °

-150 to —400 mm Hg 0.35; 0.70; 1.05 bar 200 ml / min 37 ° ± 1 ° C Water

Normal range in clinical dialysis

0.91 to 0.41 mm 45 °

0 to - 80 mm Hg 0.028 to 0.21 bar 100 to 300 ml / min 35 ° to 39 ° C Blood

3. Introduction of a 1.27 mm diameter needle through the latex sleeve and the tube, at an angle of 90 ° formed with a horizontal plane passing through the axis of the blood flow tubes; holding the needle in place for 1 min; 20 removal and examination for the detection of possible leaks under bright light. If there are no leaks, after 1 minute, repeat the previous operations and re-examine.

4. When no leak is visible after the second examination, increase the water depression to —400 mm of mercury. 25 Repeat operation 3 consisting of two piercings and holding the needle for 1 min before examination.

5. When no leakage appears after the four holes made during operations 3 and 4, adjust the water pressure to a pressure value of 0.35 bar and repeat operation 3.

6. If no leakage appears after the sixth piercing made during operation 5, increase in pressure to a pressure value of 0.7 bar and repeat operation 3.

7. If no leakage appears after the eighth piercing made during operation 6, rise in pressure to the manometric value of 1.05 bar and repeat operation 3. When a fall appears under the form of one or more visible bubbles formed in water during operations 3

or 4, or around the needle or at the location of the hole 40 left by the needle after its withdrawal, and after 1 min of examination time, the test is stopped and the number of piercings carried out before the appearance of the leak is recorded. The test is then stopped.

Twenty access devices of the type shown in FIG. 2 of US Pat. No. 3,814,137, sold under the trademark Travenol Dialysis Blood Set, were tested under the conditions selected and as described above, so as to be compared to the preferred embodiment of the invention. access device according to the invention, shown in particular in FIG. 7 and the dimensions of which have been indicated previously. The results are presented in the form of the average number of perforations carried out by a needle before the appearance of a leak resulting, for each access device, from a cycle of perforations under increasingly difficult test conditions, until the appearance of a fault. The average number of perforations before the appearance of a leak, obtained with the 20 access devices of the type described in the aforementioned US Patent No. 3,814,137, is equal to 5.25. The average number of perforations obtained before the appearance of a leak with the 72 access devices according to the invention tested is 7.66.

Another series of tests was carried out in order to show the need for the element which cannot be punctured by the needles to exert sufficient forces in the body of the latex sleeve to prevent leaks. These tests were also carried out so that their results were compared with those obtained with the advantageous embodiment described above. These tests related to devices in which the tube, the latex sleeve and the element which cannot be perforated by the needle are made of the same materials as those used during the test carried out on the preferred embodiment. . The only change concerns the size of the latex sleeve which has been reduced to an outside diameter of 11.12 mm and an inside diameter of 4.75 mm. This change results in a decrease in the difference between the outside diameter of the latex sleeve and the inside diameter of the non-perforable member and, together, an increase in the difference between the outside diameter of the tube and the inside diameter of the latex. Seventy-two access devices thus produced, tested under the same conditions and by implementing the same process as those indicated above, gave an average number of perforations before the appearance of a leak equal to 2.53.

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2 sheets of drawings

Claims (4)

616,335 1. Device for accessing a tube, in particular an infusion tube, characterized in that it comprises a tube, an elongated elastomer sleeve which surrounds a section of this tube, and a C-shaped element which cannot be perforated by needles, surrounding the sleeve and arranged substantially over the entire length and over a part of the periphery of said sleeve, in order to reveal a part of this sleeve comprised between the inner edges of the branches of said C-shaped element, the latter having a diameter inside smaller than the outside diameter of the sleeve and compressing it around the tube, over its entire length, the branches of the C-shaped element exerting a combination of radial and transverse forces inside the part of the sleeve made of elastomer not covered by said element, these forces being sufficient to prevent the appearance of leaks in the tube while a needle pierces the sleeve and the tube and after the needle has been withdrawn. 2. Device according to claim 1, characterized in that the tube is made of non-toxic material and the C-shaped element is made of polypropylene. 2 3. Device according to claim 1, characterized in that the tube is in plasticized polyvinyl chloride and the C-shaped element is in polypropylene. 4. Device according to claim 1, characterized in that the infusion tube is in plasticized polyvinyl chloride, the elastomer sleeve is in natural rubber latex, and the C-shaped element is in polypropylene.