SI9800177A - Artificial vein - Google Patents

Abstract

The invention refers to an artificial vein, especially a permanent short-circuit connection of an artery to the vein (shunt), for example in the arm, intended for a repetitious connecting and disconnecting of tubes attaching a patient to a dialysis apparatus. It comprises three length sections where between the first length section intended to be sewn on the artery, and the third length section intended to be sewn on the vein, the second length section, in the present case a throttling one is foreseen. The inner cross-section of the second, i.e. the throttling length section is not smaller than the flow cross-section of the first/third length section reduced by the projection area of a stuck-in outlet/inlet needle which is a part of the dialysis apparatus tubing. The artificial vein of a constant cross-section can be transformed into the artificial vein as defined here by the application of a well-known principle of a clamp.

Description

BUTUROVIC-PONIKVAR Jadranka Ljubljana, Slovenia

Artificial vein (MPK: A 61 F 2/06)

The subject of the invention is an artificial vein, in particular for the permanent short-circuiting of the artery and vein (shunf), for example in the hand, intended for the recurrent connection and removal of the patient's conduit for dialysis.

The artificial vein, its incorporation into the patient for the above purpose and the accompanying medical phenomena are illustrated and illustrated in a 1995 book in English. language entitled LONG-TERM HEMODYALISIS by N.K. Man et al. (all from Paris, France), published by Kluwer Academic Publishers, Dordrecht, The Netherlands, especially in Chapter 3, entitled BLOOD ACCESS.

It is a cut length plastic tube as a single product of a single clear section, which for blood-process reasons is smaller than the clear cross-section of the artery at the site of implantation and not larger than the clear cross-section of the vein at the site of implantation.

The current state of the art in a contracted arterial-venous vascular system of a patient with a built-in artificial vessel of the type discussed here is predominant in time, i.e., when the patient is not connected to the dialysis apparatus, and the rest of the time, i.e., when connected to it, is in each case different.

At least three arterial-related, blood-independent thresholds for blood flow are counted:

(1) Removal of arterial blood into and through the artificial vein into the vein should not reduce the residual arterial flow when the supply of blood distal to the artificial vein would be compromised;

(2) The flow of arterial blood through an artificial vein into a vein must be in both conditions, ie in a condition when the patient is not connected to the dialysis apparatus and in a condition when it is connected to it, sufficient to prevent blood clotting in it; and (3) The flow of arterial blood through the dialysis apparatus must satisfy the minimum operating flow for the smooth operation of the dialysis apparatus (which again depends on the process properties of the blood).

The critical, therefore relevant, flow member in the above flow chart is the needle.

In fact, the needle, with its soaked wet projection surface, occupies part of the bright section of the artificial vein. In order for the dialysis apparatus to meet the threshold value below (2) when the dialysis apparatus is connected, the residual cross-section of the artificial vessel, i.e. the section between the wall of the artificial vein and the needle.

With the above findings, it becomes apparent in itself that the cross-section of the artificial vein from the prior art must satisfy the criteria under (2) and (3). It follows that at a time when the patient is not connected to the dialysis machine, i.e. in the vast majority of the patient's life, the bright section of the artificial vein is oversized (with many negative consequences for the patient).

In the foregoing, the invention is intended to create an artificial vein that will at least alleviate, if not eliminate, the identified deficiency with which a patient wearing an artificial vein of the prior art must live.

The stated object of the invention is achieved by an artificial core designed to have a basic, expedient, but not necessarily uniform, cross-section, in the case of one which satisfies the above criteria in (2) and (3), and in essentially anywhere along its length dimension, expediently in the middle, a damping place, i the location of the reduced bright cross-section, if appropriate, which satisfies the above criterion under (2).

It is understood that the location of the reduced clear section of the artificial vessel according to the invention does not cause current irregularities in blood flow, especially congestion and / or swirls, which would cause clots or otherwise damage the blood.

According to the invention, therefore, a new, composite artificial vein is provided, consisting of a first length section intended for sewing to the artery, a second, optionally damping, length section, and a third length section intended for sewing to a vein.

Here the bright cross-section of the other, i.e. of the damping, length section of the artificial vein not less than the flow cross-section of the first / third length section, reduced by the wetted projection surface of the dialysis apparatus insertion / return needles inserted therein.

The accompanying drawing clearly illustrates the short-circuit connection of the artery with the vein of the patient's arm through an artificial vein of the prior art, which indicates the site of damping as contemplated by the present invention.

According to the first embodiment, the known continuous transformation of the circular section of the artificial vein into an elliptical cross section of the artificial vein is advantageously utilized to form the damping section of the artificial vein. The extent of the contour of the section of the vein is constant. The surface of a bright elliptical section of an artificial vein is a multiple of the area of the bright circular section of an artificial vein with a coefficient corresponding to the ratio of the small axis of the ellipse to its large axis. For example, if this ratio is equal to '/ ί, then the elliptical cross section of the vein is half round. Importantly, it is ensured that the continuous passage of the circular cross section of the first length section into the elliptical section of the second length section and forward in the circular (in the third length section of the artificial vein) does not cause the aforementioned current irregularities.

In another embodiment, the articulation of the smaller diameter diameter of the artificial vessel is advantageously utilized to form the damping section of the artificial vein.

The constant-section artificial vein can be converted into the artificial vein from the preceding paragraph by the use of the known compression principle.

Under the authority of:

Patent Offices ^ 'ύ ^ Ι'.ό. For her: Vinko Skubic

Claims (3)

Patent claims 1. Artificial veins, in particular for permanent short-circuiting of the artery and vein (shunt), for example in the hand, intended for the recurrent connection and removal of the patient's conduit for dialysis apparatus, characterized in that it has three length sections, between the first length sections intended to be stitched to the artery and the third length sections intended to be stitched to the vein, provided a second, in this case, damping, length section. The artificial vessel of claim 1, wherein the illuminated cross-section of the second, i.e. of the damping length section not less than the flow cross section of the first / third length section, reduced by the wetted projection surface of the dialysis apparatus receiving / returning needles inserted therein. 3. The conversion of a constant-section artificial vein to the artificial vein of claim 2 using the principle of clamping known per se.