WO2004039267A1

WO2004039267A1 - Emergency set for emergency care

Info

Publication number: WO2004039267A1
Application number: PCT/EP2003/011994
Authority: WO
Inventors: Hans Sattler
Original assignee: Firma Hans Sattler
Priority date: 2002-10-29
Filing date: 2003-10-29
Publication date: 2004-05-13
Also published as: AU2003279328A1

Abstract

The invention relates to an emergency set (1) for performing emergency operations in the area of the upper respiratory tract in the event of respiratory distress, after stab incisions have been made in the throat area of patients or of the severely injured. The emergency set (1) comprises a bottom part (3) to which a cover (2) can be latched. An insert (4) that contains instruments (5, 6, 7, 8, 9 and 10) can be interchangeably accommodated in the bottom part (3) of the emergency set (1). The emergency set (1) contains at least one pair of knife-like scissors (7, 10) whose scissor blades (22, 23; 28, 31) are provided with at least one insertion retention element (20, 30).

Description

Emergency kit for emergency care

The present invention relates to an accident set for emergency care for surgeons, emergency physicians in the rescue operation or in the anesthesia area.

In the area of anesthesia, in intensive care units of hospitals or in the case of accidents with seriously injured people, there is often a need to open the patient's respiratory tract or a seriously injured person to prevent a life-threatening situation. For this purpose, a tracheotomy (tracheal incision) is usually performed, which is done with appropriately procured medical instruments. To this end, coniotomy trocars according to Denker or Ueckermann-Denker have been used. The thinker or Ueckermann thinker trocar enables the airways in the connective tissue to be opened quickly (ligamentum conicum). Ligamenta are strand-like or flat structures that serve to fasten parts of the human skeleton that move against one another. Strengthening tapes of the joint capsules secure the connection between the bones involved (adhesive tapes) and a movement that occurs in a joint or inhibit over-movement. The use of the Trocar thinker or Ueckermann thinker, however, requires a slender neck of the patient or the seriously injured person and a ligament that can be felt by the surgeon or otologist. The thinker or Ueckermann thinker trocar can be used directly without any additional instrument, which makes it easier to use. Furthermore, a tracheal indwelling cannula is provided at the thinker or Ueckermann thinker trocar.

A tracheotomy, ie a tracheal incision can only be performed with the thinker or Ueckermann thinker trocar if it is an extremely slim person who should also have a thin soft tissue cover. In many patients, due to anatomical peculiarities, the thinker or Ueckermann thinker trocar cannot be used or can only be used under extremely difficult conditions, for example if these Patients or seriously injured have a thick, short neck or a thick subcutaneous layer of fat makes access to a tracheotomy difficult.

In addition to the thinker or Ueckermann thinker Trokar, a set of instruments specially developed by the University of Kansas (USA) has been used. The advantages of the Kansas instrument, as it is generally called, are that it can be used to perform a so-called coniotomy as well as to perform a tracheotomy. The Kansas instrument set is a relatively extensive set with wound spreader and wound hook as well as with separate tracheostomy tubes. A disadvantage of the medical instruments used as Kansas instruments is the fact that if carelessly handled and if a very quick intervention is necessary, there is a high risk of injury, in particular for the tracheal posterior wall, i.e. for the wall that is immediately in front of the esophagus. If the Kansas instruments are used, the tracheal posterior wall may be injured if the procedure is carried out quickly, which may result in the risk of a fatal oesphago tracheal fistula, i.e. a connection between the esophagus and trachea can occur, which can lead to the immediate onset of death of the patient or the seriously injured. The Kansas instruments are therefore only suitable to a limited extent for the rapid procedure required in an emergency because they are too cumbersome to handle. Too many instruments and too many surgical steps are necessary to secure the respiratory tract and thus prevent a situation that is life-threatening for the patient or the seriously injured. When using the Kansas instruments, the first step is to open the airways with dagger scissors. In a second step, the dagger's weight is removed and replaced with a dagger dilator. Using the dagger dilator, the tracheal incision made with the dagger scissors is widened and the supply of breathing air into the trachea is ensured by spreading. As a third step, using the Kansas instruments, the insertion of tracheal cannulas is required to finally secure the airways into the expanded opening of the trachea. The tracheostomy tubes according to this set of instruments do not have an introductory part, which, particularly when a very fast procedure is required, does not make their use unproblematic.

In view of the outlined disadvantages of the thinker or Ueckermann thinker Trokar or the Kansas instrument set described above, the object of the invention is to provide an instrument set which is independent of the anatomical one The nature of the patient or a seriously injured allows the respiratory tract to be opened in a matter of seconds, even if a very quick procedure is required.

According to the invention, this object is achieved by the features of patent claim 1.

The instruments proposed according to the invention provide the surgeon or the emergency doctor in use with instruments that allow the respiratory tract of a patient or a seriously injured person to be opened in a matter of seconds under all anatomical conditions. The instruments proposed according to the invention are suitable for both coniotomy and emergency tracheotomy and combine two instruments in one. In the event of an emergency tracheotomy to be carried out under extreme time pressure, all that is required is an instrument for opening the trachea and for spreading it. For this purpose, a spread retention is formed on the instruments, a dagger-like pair of scissors. The expansion retention on the dagger-like scissors is formed by recesses on the outside of the scissor blades. The spreading retention is preferably carried out between an insertion retention and the tip of the dagger-like scissors lying on the outside.

An injury to the rear tracheal wall is avoided in that an insertion retention in the form of an abutment surface is formed on one of the straight or curved scissor blades of the dagger-like instruments. A risk of injury to the rear tracheal wall and the possible fatal consequences of an oesphago-tracheal fistula, i.e. a breakthrough from the posterior tracheal wall to the esophagus running behind the trachea can be excluded. The handling of the dagger-like instruments proposed according to the invention is much simpler and avoids the occurrence of an oesphago-tracheal fistula.

In addition, the emergency set according to the invention includes a tracheostomy tube with an insertion piece, which is safe and easy to handle under all circumstances and which can be inserted into the opened trachea. The airways are opened with the dagger-like scissors with spread retention and the configured according to the invention Rotate the instrument by 90 °. This causes the front wall of the trachea to expand, leaving the instrument in situ. The tracheal cannula is then inserted into the incision to finally secure the air supply to the airways below the larynx (larynx).

In an advantageous embodiment variant of the instruments proposed according to the invention, obliquely extending regions can be formed on the outer sides of the dagger-like instruments facing away from the cutting edges of the scissor blades, which areas have cut surfaces. These cut surfaces can be formed on the outer sides of the scissor blades, for example, as polished sections. These allow opening of the jugular fossa, fossa jugularis, through a medial longitudinal section and access to the suprasternal space with the arcus vernosus jugularis and on both sides of the anterior jugular vein. As soon as the longitudinal incision has been made, access to the trachea is possible, which runs in the fossa jugularis at a depth of 4 to 5 cm.

A curvature of the scissor blades of the dagger-like instruments in a dimension that takes human anatomy into account reduces the risk of injury to the rear tracheal wall when the longitudinal incision of the front wall of the trachea is made. The formation of the scissor blades in a radius of curvature adapted to the human anatomy permits a safer handling of the instruments proposed according to the invention with the greatest possible protection of the tissue.

The insertion retention formed on one or both of the scissor blades is arranged at a distance from the tip of the instrument at which the tracheal insertion depth of the instrument according to the invention is taken into account. The distance of the insertion retention from the tip of the dagger-like instrumentation prevents the instrumentation from being inserted too deeply through the front wall of the trachea and thus prevents injury to the tracheal rear wall. The insertion retention is advantageously rounded on its outer edge. The emergency set proposed according to the invention also contains a tracheostomy tube, which has an insertion piece. The tracheostomy tube can be placed on the dagger-like instruments and can be inserted quickly and safely thanks to the insertion piece designed on it. If the trachea is spread open while the dagger-like instruments are left in place, the tracheal cannula can be inserted after insertion of the insertion piece through the longitudinal incision in the front wall of the trachea and the respiratory air supply can be ensured. The leaf-shaped insertion piece is arranged at one of the ends of the tracheostomy tube, the tubular body of which is formed in a radius which favors the connection of a breathing air source. The tracheostomy tube can advantageously be designed as a 90 ° elbow.

The present invention further relates to a set of instruments for performing a coniotomy or a tracheotomy with a first and a second scissor blade, which have mutually facing cutting edges, the scissor blades being connected to one another at a joint. The instruments are dagger-like and there is an insertion retention on at least one of the scissor blades. The insertion retention is arranged at a distance determining the insertion depth of the dagger-like instrumentation on at least one of the scissor blades, the scissor blades being able to extend both parallel to the joint connecting them and in a radius of curvature relative to the latter. In order to carry out a medial longitudinal section and to access the jugular fossa, cut surfaces are formed at the tip of the dagger-shaped instrument set.

The invention is described in more detail below with reference to the drawing.

It shows:

FIG. 1 the content of an emergency set equipped according to the invention,

FIG. 2 shows the top view of the lower part of the emergency set according to FIG. 1 with a removable insert, Figure 3 shows a first embodiment of a dagger-like scissors

Einführretention,

FIG. 4 shows a second embodiment variant of a dagger-like scissors with retention,

FIG. 5 shows a further embodiment variant of a dagger-like scissors with an anatomically improved radius of curvature,

FIG. 6 shows an embodiment variant of the dagger-like scissors according to FIG. 5 with recesses in the scissor blades,

FIG. 7 shows the tip of a dagger-like pair of scissors with constriction and retention designed to be angled to form a scissor blade,

FIG. 8 shows a precisely fitting tracheostomy tube that can be placed on a dagger-like pair of scissors

FIG. 9 shows an opened fossa jugular länopinzision as well as further incisions opening the airways.

Models:

FIG. 1 shows the content of an emergency set equipped according to the invention.

An emergency set 1 is accommodated in a container, which comprises a cover element 2 and a lower part 3. In the lower part 3, an insert 4 is inserted, which holds various instruments. In the insert 4 there are spreading scissors 5 as well as anatomical tweezers 6 and a dagger-like pair of scissors 7. In addition, a scalpel handle 8 and a tracheal cannula 9, on which an insertion piece 38 is formed, are accommodated in the insert 4. In addition, the emergency set 1 proposed according to the invention contains baby scissors which are designed to be comparable to dagger-like scissors 7; this is identified by reference number 10.

The lid 2 and the lower part 3 of the emergency set 1 can be closed via a first snap lock 11 and a second snap lock 12, each of which contains a joint 13. Optionally, the emergency set 1 shown in FIG. 1 can also include a needle holder 14. The insert 4 of the lower part 3 is connected at its corners to recessed grips 15, which facilitates the sterilization of the instruments. To sterilize the instruments, the closed emergency set is inserted into an autoclave and sterilized by inflowing steam at 140 ° C. The instruments 5, 6, 7, 8, 9 and 10 accommodated in the insert 4 in the lower part 3 are sterilized at the same time, so that the sterilized emergency set is prepared for use.

FIG. 2 shows the top view of the lower part of the emergency set according to FIG. 1 with a removable insert.

The lower part 3 is enclosed by a metallic ring 16. The insert 4 embedded in the lower part 3 has the grip recesses 15 already mentioned at its corners. In addition to the anatomical tweezers 6 and the scalpel handle 8, dagger-like scissors 7 and 10 are inserted into the lower part 3. The dagger-like scissors 7 and 10 each have a straight first scissor blade 22 and a second scissor blade 23 arranged parallel to it. An insertion retention 20 is received on one of the scissor blades 22 or 23 of the dagger-like scissors 7, 10. The insertion retention 20, which is arranged on the dagger-like scissors 7, offers a larger area compared to the area of the insertion retention 20 of the dagger-like baby scissors 10 opposite a dagger tip 29.

The dagger-like instruments 7 and 10 differ from one another only by their length. Due to the human anatomy, the first dagger-like scissors 7 are used to perform tracheal cuts in adults, while the second dagger-like scissors 10 can be used to perform tracheal cuts in children or adolescents. Since the diameter of the trachea is smaller in children and adolescents, the insertion retention 20 lies on one of the scissor blades 22 and 23 on the second dagger-like scissors (baby scissors) further towards the tip 29 of the second dagger-like scissors 10 , Each of the two scissors 7, 10 with insertion retention 20 comprises bevelled areas 24 and 25 at the tip 29, which have cut surfaces 26, for performing a medial longitudinal cut to expose the trachea between the arcus venosus juguli and vena jugularis exterior. With the inventive design of the first dagger-like scissors 7 or the second dagger-like scissors 10, the opening of the fossa jugularis and the tracheal incision in the front wall of the trachea can be performed with an instrument, after which the tracheal cannula 9 can be inserted directly into the front wall of the trachea ,

In the lower part 3 of the emergency kit 1, a needle holder 14 can also be provided, the two legs of which are connected to one another at an articulation point 21.

Figure 3 shows a first embodiment of a dagger-like scissors with insertion retention in the form of a stop surface.

The dagger-like scissors shown in FIG. 3 comprise a joint 21, on which a first straight scissor blade 22 and a second, also straight scissor blade 23 are connected to one another in an articulated manner. The insertion retention 30 is arranged on the second scissor blade 23 at a distance 47 from the tip 29. The insertion retention 30 can be, for example, as a plate with a rounding 44 welded onto the second scissor blade 23 at a 90 ° angle. With respect to the cutting edge 46 of the second scissor blade 23, the insertion retention 30 is formed in a 90 ° position, indicated by the arrow 27.

The dagger-like scissors 7 according to the illustration in FIG. 3 is in a slightly opened state, in which the mutually facing cutting edges 45 and 46 of the first and second scissor blades 22, 23 are opposite one another. In the area of the tip 29 of the dagger-like scissors 7 there are beveled edges 24 and 25, respectively, which are each provided with a cut surface 26 (abutment surface) and allow the neck surface of a patient or a seriously injured person to be opened. Figure 4 shows a second embodiment of a dagger-like scissors with insertion retention.

In the embodiment variant of a dagger-like pair of scissors shown in FIG. 4, there are recesses 33, 34 between the tip 29 of the first scissor blade 22 and the second scissor blade 23. The recesses 33, 34 are located approximately in the middle between the side of the tip 29 and the tip 29 Insertion retention 30 and the tip 29 of the scissor blades 22, 23.

The recesses 33, 34 represent an expansion retention in order to push cartilage and bone aside and to expose the access to the trachea.

The embodiment variant of a dagger-like pair of scissors shown in FIG. 4, which is included in the emergency set 1 proposed according to the invention, also comprises oblique end regions 24, 25, on each of which a cut surface 26 is implemented.

FIG. 5 shows a further embodiment variant of a pair of scissors configured in the manner of a dagger, the scissor blades of which are provided with a radius of curvature which takes human anatomy into account.

The first scissor blade 22 and the second scissor blade 23 are connected to one another at a joint (not shown in FIG. 5) and are designed as curved scissor blades 28 or 31. The curved scissor blades 28 and 31 have cutting edges 45 and 46 on their mutually facing sides. The cutting edges 45 and 46 of the curved scissor blades 28 and 31 run according to the radius of curvature 32 of the curved scissor blades 28 and 31.

On the first curved scissors blade 28 of the dagger-like scissors 7 and 10 is a plate 47 representing an insertion retention 30 at a distance 47 from the tip 29 of the dagger-like scissors. The plate comprises a curve 44 and extends over the width of the first curved scissor blade 28. The curved scissor blades 28 and 31 of the dagger-like scissors 7 also extend 10 and 10 have beveled surfaces 24, 25 in the region of the tip 29 of the instrument 7 and 10, on which a cut surface 26 can be formed in each case. The cut surfaces 26 on each of the curved scissor blades 28 and 31 can be used to make a medial longitudinal cut to expose the fossa jugularis. Due to the radius of curvature 32 of the first curved scissor blade 28 and the second curved scissor blade 31, injury to the rear tracheal wall when inserting the dagger-like scissors 7 or 10 through the opened front wall of the trachea is excluded. The distance 47 between the side of the insertion retention 30 facing the tip 29 and the tip 29 of the dagger-like scissors 7, 10 determines the insertion depth up to which the tip 29 of the dagger-like scissors 7, 10 can be inserted into the trachea. The distance 47 is larger in scissors that are used in the tracheotomy of adult patients or seriously injured than the corresponding distance on a dagger-like scissors 10 that is used to perform a tracheal cut in children or adolescents.

6 shows an embodiment variant of the dagger-like scissors with curved scissor blades according to FIG. 5, which contains recesses in the scissor blades.

Comparable to the embodiment variant of a dagger-like scissors 7 according to FIG. 4, there with straight scissor blades 22, 23, in the dagger-like scissors according to the embodiment variant in FIG. 6 there are recesses 33, 34 on the outside of the first curved one between the insertion retention 30 and the tip 29 Scissor blade 28 and on the outside of the second curved scissor blade 31. The recess 33 on the first curved scissor blade 28 lies approximately midway between the tip 29 and the side of the insertion retention 30 facing it. The recess 34 on the second curved scissor blade 31 lies approximately on same height as the recess 33 on the outside of the first curved scissor blade 28. FIG. 7 shows the tip of a dagger-like scissors with constriction and an insertion retention angled on a scissor blade.

In the embodiment according to the schematic illustration in FIG. 7, the first scissor blade 22 and the second scissor blade 23 have a curvature, compare FIGS. 5 and 6. On the second scissor blade 23, a laterally protruding insertion retention 30 is carried out below the tip of the dagger-like scissors. This can (see illustrations according to FIGS. 3, 4, 5 and 6) also be designed as a small plate which is at a distance 47, which determines the insertion depth of the dagger-like scissors 7, 10, from the tip 29.

A dagger thickening 35 is formed in the region of the tip 29, which is separated by a tapered diameter region 36 of the curved scissor blades 28 and 31, respectively. The tapered diameter region 36 below the dagger thickening 35 according to FIG. 7 represents an embodiment variant of an expansion retention, which in this embodiment variant is formed on curved scissor blades 28 or 31.

FIG. 8 shows a precisely fitting tracheostomy tube that can be placed on a dagger-like pair of scissors.

The tracheal cannula 37 shown in FIG. 8 essentially corresponds to the cannula 9 shown in connection with the description of the emergency kit 1 in FIG. 1. An insertion piece 38 is formed on the lateral surface 43 on one of the ends 40, 41 of the tubular body of the tracheal cannula 37 , The insertion piece 38 can be plate-shaped and can be provided with a rounding 44. The rounding 44 on the periphery of the insertion piece 38 allows the tracheal cannula 37 to be inserted easily and securely into a trachea opened by the dagger-like scissors 7 and 10. Advantageously, the body of the tracheal cannula 37 is curved to describe a 90 ° arc, which, on the one hand, is favorable with regard to the handling of the tracheal cannula 37 and, on the other hand, should allow an optional, simple connection of an external breathing air source to supply the respiratory airways of a patient or a seriously injured person this may be necessary. The end region 40 or 41 of the Tracheal cannula 37 are rounded, as is the outer circumferential surface of the insertion piece 38 in order to avoid further tissue injuries on the patient or on the seriously injured. The radius of curvature 39 of the tracheal cannula 37 is denoted by r.

Figure 9 shows an opened fossa jugularis.

The illustration according to FIG. 9 shows a first trachea access 50 (cross section) between the cartilago cricoidea 61 and the cartilago thyroidea 60. The first trachea access 50 (cross section) is expediently to be carried out within the ligamentum cricothyreoideum. Instead of the first tracheal access 50 designed as a cross section, a second tracheal access 51 (longitudinal section) can also be opened. This is made as a longitudinal section through the arch of the cricoid cartilage (cartilago cricoidea 61) (cricotomy).

When performing the first access to the trachea 50 (cross-section), also known as a coniotomy, the trachea 58 is reached approx. 1 cm below the vocal cord (ligamentum vocalia, conus elasticus).

If one follows the course of trachea 58 according to FIG. the course of the human neck in the direction of the chest, a median incision 54 can also be made below the cartilago cricoidea 61. For this purpose, the median incision 54 can be made with the dagger-like scissors 7 and 10 designed according to the invention and the cutting surfaces 29 formed at the tip 29 thereof. There is an opening of the jugular fossa and access to the suprasternal space with the arcos venosus jugularis 55 and on both sides of the jugular vein 56. The cut surface in which the front wall of the trachea 58 is to be opened is identified by reference numeral 54 and is indicated by the course the blood vessels 55 and 56 limited. The trachea 58 is located in the fossa jugularis 53 at a depth of 4 to 5 cm.

After the median incision 54 has been made, a longitudinal incision of the front wall of the trachea 58 is made through the cut surfaces 26 of the dagger-like scissors 7, 10, be it with straight scissor blades 22, 23 or be it with curved scissor blades 28, 31 (compare representations according to FIGS. 5 and 6). When performing the tracheal cut with dagger-like scissors 7, 10 with curved scissor blades 28, 31, injury to the tracheal posterior wall of the trachea 58 is excluded. The instrument 7, 10 rotated 90 ° in situ in its position limited by the insertion retention 20 or 30, the surgeon or the emergency doctor can insert the tracheal cannula 9, 37 contained in the emergency set 1 proposed according to the invention into the trachea 58 on the insertion piece 38 insert without removing the scissors 7 or 10 designed according to the invention from the trachea 58.

LIST OF REFERENCE NUMBERS

Emergency Kit

cover

lower part

commitment

Spreading scissors anatomical tweezers

dagger scissors

scalpel handle

Cannula with stop

Baby dagger scissors first lock second lock

joint

needle holder

grip

metal ring

Einführretention

Scissor joint first scissor blade second scissor blade first angled end second angled end

section

90 ° orientation Retention of the first curved scissor blade

dagger tip

Insertion retention second curved scissor blade

Cutting radius of curvature

First scissor blade recess (spread retention)

Second scissor blade recess (spread retention)

dagger thickening

constriction tracheostomy

insertion piece

Radius of curvature tracheal cannula first end second end

tube

lateral surface

Rounding retention

Cut from 22, 31

Cut from 23, 28

Distance (tracheal insertion depth)

first trachea access (cross-section) second trachea access (longitudinal section) third trachea access

Jugular fossa

Medianinzision

Arcus venosus Juguli

Jugular vein

section

trachea

Os hyoid

Cartilago thyroidea

Cartilago cricoidea

Claims

claims

1. Emergency set for performing emergency operations after stab incisions in the neck area of patients or seriously injured, with a cover (2) which can be locked on a lower part (3), instruments (5, 6, 7, 8, 9, 10), characterized in that the emergency set (1) comprises at least one dagger-like scissors (7, 10), on the scissor blades (22,

31; 28, 31) at least one insertion retention (20, 30) is formed.

2. Emergency set according to claim 1, characterized in that on the scissor blades (22, 23; 28, 31) there are recesses (33, 34) forming a spreading retention.

3. Emergency set according to claim 1, characterized in that on the scissor blades (22, 23; 28, 31) of the dagger-like scissors (7, 10) at the tip (29) angled sections (24, 25) with cut surfaces (26 ) are trained.

4. Emergency kit according to claim 3, characterized in that the cut surfaces (26) on the tip (29) on the cutting edges (45, 46) of the scissor blades (22, 23; 28, 31) are facing away from the sides.

5. Emergency set according to claim 1, characterized in that the scissor blades (28, 31) of the dagger-like scissors (7, 10) are curved in a radius of curvature (32).

6. Emergency set according to claim 3, characterized in that the cut surface (26) on the scissor blades (22, 23; 28, 31) are designed as grindings.

7. Emergency set according to claim 1, characterized in that the insertion retention (20, 30) is arranged at a distance corresponding to a tracheal insertion depth (47) on one or both of the scissor blades (22, 23; 28, 31).

Emergency case according to claim 1, characterized in that the insertion retention (20, 30) is provided with a rounded outer edge (44).

9. Emergency kit according to claim 1, characterized in that it contains a tracheostomy tube (37) which has an insertion piece (38).

10. Emergency kit according to claim 9, characterized in that the insertion piece (38) is arranged at one of the ends (40, 41) of the tracheal cannula (37), the tubular body of which is curved in a radius of curvature (39).

11. Instrument set for performing a coniotomy or a tracheotomy with a first scissor blade (22, 28) and a second scissor blade (23, 31) which have mutually facing cutting edges (45, 46) and the scissor blades (22, 23; 28, 31 ) are connected to one another at a joint (21), characterized in that the instruments (7, 10) are dagger-like and an insertion retention (20, 30) is formed on at least one of the scissor blades (22, 23; 28, 31).

12. Instrument set according to claim 11, characterized in that the insertion retention (20, 30) is arranged at a distance (47) determining the insertion depth on at least one of the scissor blades (22, 23; 28, 31).

13. Instrument according to claim 11, characterized in that the scissor blades (28, 31) are curved in a radius of curvature (32).

14. Instrument according to claim 11, characterized in that the scissor blades (22, 23; 28, 31) have end regions (24, 25), on the outside of which cut surfaces (26) are formed.

15. Instrument set according to claim 11, characterized in that the scissor blades (22, 23; 28, 31) have recesses (33, 34) forming a spreading retention.