DE1810804A1 - Plastic cannula for injection and infusion - Google Patents

Abstract

The tubes are prevented from flexure during puncturing by providing the plastics tube, which is guided in an external guide tube, with an axially extending radially inwardly directed fold.

Description

Dr. med. G-. Metz September 11th 1968

Freiburg i. Br. ^ _Λ " _{Λ Λ Λ} #

Iivolistr. 16 1810804

Plastic cannulas for puncture, injection and infusion

The invention relates to plastic cannulas for puncture, injection and infusion, which are more spacious than the previous ones and are more atraumatic and cannot bend up at the front when piercing because they are looking for a new one Principle to be introduced into the blood vessel.

In surgery it depends on the type of procedure and the condition prolonged infusion treatment of the patient required, not only during the operation to compensate for blood loss, but also preoperatively and postoperatively to fight shock, to normalize the water and Electrolyte balance, for parenteral nutrition and for the easier administration of medication.

The usefulness of an infusion cannula depends on two conditions: The lumen should be as large as possible, the badge and needle tip as atraumatic as possible in terms of material and shape. A large lumen is the primary goal exposure for faster infusion entry when needed «. »

At the same density and pressure, the flow rate per unit of time is proportional to the square of the ion diameter, but only with the same density and the same diameter proportional to the square root of the pressure. D. II. a doubling of the diameter brings a fourfold influx per unit of time, while for it an increase in the pressure 16 times that would be required.

The second requirement, atraumatic "material, and a similar one Pinpoint, is intended to prevent the formation of thrombi, that affect the patency of the cannula or vein. A small-lumen cannula is used again

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rather than one with a large inner diameter. For the latter reason, long-term infusion treatments are required Increasingly, instead of the conventional metal cannulas, those made of plastic are being used, vein and cannulas The cannula remain open longer, with the advantage of that the cannula does not have to be replaced too often.

A plastic tube is usually inserted into the vein ρercutane, less often through vena esectio; to pierce the Skin and venous wall, plastic alone would be too soft that temporarily The necessary stability is therefore achieved with an additional guide cannula made of steel, which is inserted after the insertion into the vein is removed again. The guide cannula can either be as a jacket around the plastic tube or in the lumen.

Plastic cannulas with external guide .

So far, the exterior guidance has not allowed it, as intended, insert as large a plastic tube as possible into the vein, because the lumen of the guide cannula is relatively narrow.

This Hachteil can (Fig. 1) by using a Avoid thin-walled plastic tubes a that first folded lengthways in the metal guide cannula b and only after it has been withdrawn, through the infusion expanded to its full lumen. By pulling back the metal jacket, the plastic tube can be pulled out of the kit in this way avoid that it is first held behind the guide cannula and then at the tip by finger pressure on the vein as soon as the tip of the plastic tube is free in the vein. If necessary, unfolding the plastic tube with a sterile button probe get supported.

Plastic cannulas with inner guides .

The plastic cannulas with Ixraenführung have a different one Haohteili The puncture fails if the Skin the cannula is compressed and its front edge is bent up}

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with the thinner plastic tubes, which have a lower wall stability this is particularly common. A completely stepless transition from the protruding metal tip this defect would become the leading edge of the plastic tube fix, but this is not possible even with the most precise production. Between the metal and plastic tubes a win- Z'ig-er sliding gap remain in order to pull out the inner one To allow metal cannula. The width of this gap also increases with the outside temperature, because plastic is stronger expands than steel and the heating usually takes place from the outside, z. B-. when touching the skin. By changing the technical principle, the deficiency ™ avoid that the tube is compressed and bent open at the front. , The cause of the upsetting is that the plastic tube is pushed, that of the bending up, especially in the transverse course of its front edge to the stitch direction. at In the models described below, the plastic tube is therefore not pushed but pulled when piercing, the edge of the opening runs along the direction of pull if possible. The pull principle also has the advantage that the wall of the plastic cannula no longer has to have substantial stability in order to counteract compression; it can be thinner, the lumen wider, according to its o. g. primary meaning for the inflow per unit of time. At Jj In addition, the use of a cannula as a guide can be dispensed with in all models; v-shaped cross-section replaced. The blood return to check the position The plastic cap in the vein after the puncture is made in the plastic cannula itself, in the gap between Metal guide and plastic tube, dejjaach the puncture through Slackening of the train becomes sufficiently far again. The thinner wall means material savings and the need to replace the cannula .by a metal rod also a reduction in manufacturing costs.

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Modification of the conventional plastic cannulas .

Fig. 2 shows a conventional plastic cannula. The obstructive one The gap between the inner cannula b and the outer a at the front opening can be completely for the time of the piercing or in several places with a physiological adhesive locked and thus secured against bending open. After the puncture, the splices are h by turning the ' Loosened again inside against the outer cannula.

Plastic cannulas based on the pull principle.

Fig. 3-7 show plastic cannulas based on the new pulling principle, which differ only in terms of position, size and shape of their opening and the type of pulling.

In Fig. 3 is the thin-walled plastic tube a with a Tab d on the metal guide b above the tip c suspended in an indentation e that receives the tab d, like this that a smooth piercing is guaranteed.

Fig. 4 shows a plastic cannula in which the plastic tube a is pulled on the upper edge d of the front opening, which reaches over the metal guide.

In Fig. 5 the front part of the metal guide b is conical, and the front opening of the plastic tube 'a is in diameter smaller than the full cross section of the metal guide b, so that the tube a when piercing the entire front edge is pulled into the vein »Because of its smaller front opening an additional side opening for »

Abb..6 shows a plastic tube a and including b the corresponding metal guide whose apex c as in Fig. 5 "is conical, but which has an annular step j, in which the front edge reinforcement comes to lie i of the plastic tube a so that The stylet and the tube together form a stepless “conical tip”. Apart from the fact that the reinforced edge i secures the hold of the tube a on the metal guide b during the puncture, it also stabilizes the shape

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front and side opening so that these are not just "at." an injection and an infusion, but also with a blood sample would remain constant **.

Fig. 7 shows, like Fig. 1, an Ealt cannula. The plastic tube However, a has no outer guide channels, but lies over an inner, v-shaped metal guide b, being an the points d that reach over the metal guide are pulled into the vein * Bas unfolding of the tube takes place both by the elasticity of its material, as well as by the infusion flowing in.

Summary and advantages:

While in the conventional plastic cannulas, for. B. the Braunüle from Sirma Braun-Melsungen, the gap between plastic tubes and metal guide can be protected against bending open during puncture by temporary gluing, offer the new plastic cannulas for puncture, injection and infusion the following advantages: With an outer guide channel made of metal an internal plastic tube can be opened by folding it lengthways Bring it with a larger inner diameter into the vessel accordingly its primary importance for unhindered influx the infusion

With an internal metal guide, the plastic cannula when piercing no longer from the rear as before. End here pushed, but rather pulled into the vein at its tip. This eliminates the need to compress and bend the front opening, that obstructs venipuncture. In addition, the wall of the plastic tubing can no longer have any significant inherent stability needs to have to be thinner and softer, which has the advantages of a larger inner diameter and less Iraumatisierung the inner wall of the vessel, and with it the danger reduces the fact that the vessel or cannula is occluded thrombotically will. ! Previous stabilization for grooving an internal metal cannula can be replaced by a metal rod. The thinner plastic wall and the simpler metal guide mean a cost reduction.

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A folding cannula with an inner V-shaped metal guide combines the advantages of both principles, that of longitudinal folding
and that of pulling instead of pushing when piercing.

The new cannulas are also advantageous for vena esectio
to use. You can pierce the exposed vein or through your previously opened vein
temporary greater longitudinal stability can be better introduced than the usual soft plastic tubes.

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Claims (1)

Claims: Plastic cannulas for puncture, injection and infusion, which are more spacious and atraumatic compared to the "previous ones and can no longer bend up at the front when piercing, characterized by: 1.) That a thin-walled plastic tube to insert Folded lengthways in an outer guide cannula or around a inner metal guide lies. 2 ·) That a thin-walled plastic tube with a temporary Internal stabilization is introduced by pulling from the tip. 3 ·.) That with conventional plastic cannulas the gap between inner metal guide and outer plastic st off tube is sealed at the front edge of the cannula for the time of the piercing by adhesive points. 009823/1038 Blank page