Cannula

Abstract

The invention relates to a cannula comprising a tip and an outlet, the cannula having a reduction in the internal diameter, which reduction is designed as a conically tapering tip the end of which has a length that is shorter than the internal diameter of the adjoining portion of the cannula.

Claims

1. An arterial cannula comprising: a tip; an outlet; a first cylindrical cannula section having a first internal diameter from 15 Fr to 19 Fr; a second cylindrical cannula section having a second internal diameter from 13 Fr to 17 Fr; a diameter reduction section forming a caliber narrowing transition between the first and second cylindrical cannula sections; and a valve having at least one flap arranged in the diameter reduction section; wherein the arterial cannula has an insertion length, wherein the diameter reduction section is located 25% to 40% of the insertion length away from the tip of the arterial cannula to enable the arterial cannula to be inserted past a branching area of a blood vessel without blocking blood flow to surrounding branches of the blood vessel.

2. The arterial cannula according to claim 1, wherein the arterial cannula has lateral holes and the diameter reduction section is arranged between the lateral holes and the tip of the arterial cannula.

3. The arterial cannula according to claim 1, wherein the valve has several flaps.

4. The arterial cannula according to claim 1, wherein the at least one flap has a spring mechanism.

5. The arterial cannula according to claim 2, wherein one base of the at least one flap is arranged in the diameter reduction section.

6. The arterial cannula according to claim 1, wherein the diameter reduction section is in the form of a conically tapering section.

7. The arterial cannula according to claim 1, wherein a conical end of the tip has a length which is shorter than that of the internal diameter of the area of the arterial cannula adjoining the tip.

8. The arterial cannula according to claim 1, the insertion length is 20 to 50 cm.

9. The arterial cannula according to claim 1, wherein on an inner side of the arterial cannula, at least in sections, the arterial cannula comprises a spiral-shaped structure.

10. The arterial cannula according to claim 9 wherein the spiral-shaped structure is an elevation.

11. The arterial cannula according to claim 9, wherein the spiral-shaped structure is a recess.

12. The arterial cannula according to claim 9, wherein the spiral-shaped structure is multiple-threaded.

13. The arterial cannula according to claim 9, wherein the spiral-shaped structure is formed by a wire reinforcement of the arterial cannula.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of embodiments of cannulas according to the invention are shown in the drawing and will be described in more detail below. In this:

(2) FIG. 1 shows a side view of a cannula with tapering and a prolonged tip,

(3) FIG. 2 shows a side view of a cannula with a conical tip,

(4) FIG. 3 shows a side view of a cannula with several holes on its circumference,

(5) FIG. 4 shows a side view of a cannula with holes arranged offset with regard to each other on the circumference

(6) FIG. 5 schematically shows the function of an open valve in a partially cross-sectional side view,

(7) FIG. 6 schematically shows a front view of the valve shown in FIG. 5,

(8) FIG. 7 schematically shows a side view of a partially closed valve,

(9) FIG. 8 schematically shows a front view of the valve shown in FIG. 7,

(10) FIG. 9 schematically shows a cross-section through a cannula with a convex spiral-shaped elevation,

(11) FIG. 10 schematically shows a cross-section through a cannula with two opposite spiral-shaped elevations and

(12) FIG. 11 schematically shows a cross-section through a cannula with four concavely designed spiral-shaped recesses.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) The cannula 1 shown in FIG. 1 has a cylindrical basic body 2, a cylindrical cannula tip 3 and in between as a diameter reduction concave tapering 4 which forms a transition between the cylindrical basic body 2 with the larger diameter and the cylindrical tip 3 with the smaller diameter. The position of the tapering 4 is selected so that the length 5 is two thirds of the cannula or insertion length.

(14) FIG. 2 shows an alternative front end of the cannula 6 in which a conical tapering 7 forms the front end of the cannula 6 so that the cannula 6 has a conical cannula tip with length 8.

(15) Holes 9, 10 can be provided within the cannula and preferably in the basic body 2 of the cannula with the larger diameter. FIG. 3 shows an arrangement of holes each offset by 90° in the longitudinal direction of the cannula. In the example of embodiment there are thus four rows 11, 12 of holes slightly offset with regard to each other, each of which has three holes 13-15, 16-18 and 19-21.

(16) In the embodiment example shown in FIG. 4 the entire rows 22, 23, 24 are each arranged offset with regard to each other. In the embodiment example each of the rows has three holes. However, two or more holes can also be provided.

(17) In the valve 30 shown in FIGS. 5-8 three valve leaflets 34, 35, 36 are provided in the tapering area 31 between a cannula section 32 with a larger diameter and a cannula section 33 with a smaller diameter, which are attached to the inner wall of the cannula in the tapering area 31. These valve leaflets 34-36 are opened by a volumetric flow 37 so that an opening 38 comes about through which a fluid can flow from cannula section 32 to cannula section 33.

(18) If the pressure of the volumetric flow 37, as shown in FIGS. 7 and 8 decreases the valve leaflets 34-36 are forced inwards through their material stiffness so that the opening 38 closes in that the valve leaflets 34-36 are in contact with each other at point 39 and hinder or stop the throughflow.

(19) Different variants for applying a rotating movement within the cannula are shown in FIGS. 9-11. These are only schematically shown embodiment variants for indicating the possibility of applying a rotating movement within the cannula. FIG. 9 shows a cannula 40 with an elevation 41 bulging radially inwards which extends in a helical manner within the cannula. A double-threaded form of embodiment is shown in FIG. 10. Here, a first elevation 43 and a second elevation 44 opposite the elevation 43 are provided within the cannula 42. Both elevations form part of a double-threaded spiral formed within the cannula 42.

(20) In FIG. 11, using the example of four recesses, it is shown how a rotating movement can be applied to a fluid being conveyed in the cannula by means of recesses 45-48 within the cannula 49.