FI60125B - SURGICAL FOERBAND - Google Patents

Description

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Patent and regulatory framework Anteku utltgd och uti.ikrtften publktrsd 31 * 06.81 (32) (33) (31) P) 7 ** «y utueikmit — Begird priority li + .05.73 USA (US) 359802 Toteennäytetty-Styrkt ( 71) Johnson & Johnson, 501 George Street, New Brunswick, SJ, USA (72) Norman Eisdorfer, East Brunswick, NJ, John Lesniak, Englishtown, NJ, Bernard Lichstein, Elizabeth, NJ, USA (7l) This invention relates to a surgical dressing comprising a plurality of layers of a textile-like nonwoven fabric having a dressing absorbency of at least equal to the absorbency per gram of the fabric per gram of fabric. and a degree of separation of less than 12.1+ mg of particulate matter per visible surface area.

Surgical dressings are used in the operating room for a variety of purposes, e.g., to stop blood flow, administer drugs, isolate organs, and separate and dry tissue. The basic requirement is that the dressing used for these purposes be able to absorb liquids and still maintain its structural integrity. Unfortunately, these requirements are somewhat contradictory, as highly absorbent materials often have poor structural stability. For example, cotton wadding, wood wool, etc., which are highly absorbent, do not in themselves retain their structural integrity, and as a result, a compromise has been made in the art using a loosely woven fabric, and cotton gauze is generally chosen.

There are several disadvantages to using cotton gauze. First, the single or double gauze layer is relatively low absorbent, resulting in the use of multiple gauze layers, e.g., 16, in surgical dressings to achieve the required absorbency 2,60125. This method of obtaining a higher absorbency has proven to be uneconomical because it has been found that although the overall absorbency increases with each new layer of gauze, the absorbency per unit weight of the dressing decreases. In other words, the additional layers increase the absorbency less and less. In addition, gauze bandages have proven unsatisfactory in many applications because they tend to leave harmful fluff amounts behind. By flocculant is meant here a particulate matter that differs from the bandage in use. A fluff that remains in the wound can cause inflammation, adhesions, and the formation of grain growths.

The danger of fluff is the greatest so-called. in "full-thickness openings" which occur, for example, in tracheal opening and cardiovascular surgery, in which case the fluff may form a colony for the growth of thrombi, which in turn may lead to the formation of blood clots, and in the abdominal opening and thoracic opening,

Due to the disadvantages of gauze, there have long been attempts in the art to devise suitable substitutes. For example, U.S. Patent 3,081,515, issued to H. W. Griswold and others on March 19, 19 ^ 3, describes a perforated, nonwoven fabric that can be used in place of gauze in surgical dressings. This fabric has been found to be highly absorbent in the unbonded state (i.e., when no additional binder has been added). However, when the fabric is used in a bandage, it is not able to retain its structural integrity at all, which is why it is very unsatisfactory for this purpose. To compensate for this poor side Griswold proposes the establishment of an adhesive binder material. Although a useful surgical dressing can be made in this way, it has been found that the dressing greatly impairs the absorbency of the sponge, and this method of making the dressings thus does not remedy the disadvantages associated with cotton gauze.

So far, therefore, no bandage has been available to avoid the poor absorbency of previous gauze bandages and the detachment of the fluff, while keeping the structure intact under stress.

It has now been discovered that it is possible to develop a surgical dressing that overcomes the disadvantages associated with cotton gauze dressings. The bandage of the present invention is characterized in that the fabric consists of substantially unbonded, mechanically entangled fibers intertwined in an irregular shape with local entangled regions and connecting fibers extending between adjacent entangled regions having a fiber length of 0.6 g. ... 3.80 cm and a denier of 0.5 ·. · 3.0, and having a fabric breaking energy 2 absorption value of at least 1 U, 6 J / m in both the machine direction and the transverse direction.

3,60125 Such a bandage and method of making the same is described in U.S. Patent No. 3 1 * 85 706, issued December 23, 1969 to Franklin Jones Evans. When a cut-off energy absorption value of at least 6 J / m is selected for the fabric according to the Evans patent, the surgical dressing retains its structural integrity at least as well as the gauze and the detachment from it is considerably more than about half of the corresponding value of the gauze. This lower detachment of the scar is particularly important in surgical dressings, e.g., abdominal surgeries used in critical surgeries.

Figure 1 shows a perspective view of a fabric of the present invention before being folded into an embodiment of a bandage of the invention; Figure 2 shows a perspective view of a bandage of the invention; Fig. 3 shows a partially fragmentary perspective view of another embodiment of a bandage of the invention; Fig. b shows a perspective view of an abdominal incision using the structure shown in Fig. 3; and Fig. 5 is a graph showing the preferred absorbent properties of the dressings of the present invention.

The unique surgical dressings of the invention include nonwoven textile fabrics made as taught in U.S. Patent 3,885,706 to F. J. Evans issued December 23, 1969. According to this description, these fabrics (hereinafter referred to as "mechanically entangled" fabrics) contain fibers that lock in place by the interaction of the fibers to form a strong, cohesive structure that maintains its structural integrity without the need for adhesive binders or yarn melting. The fabrics have entangled areas of fiber having a density (weight per unit area) greater than the average density of the entire fabric, and the interconnecting fibers extend between dense, entangled areas and are randomly entangled in dense, entangled areas. As described in the Evans patent, entanglement is achieved by first preparing a loose fibrous layer and then treating the layer with a liquid that is sprayed with at least 1 U, 06 kg / 2. ......

cm of pressure from a row of small holes, to directly convert the layer into nonwoven fabrics that can be used in the surgical dressings of this invention.

In accordance with the present invention, it has been found that the use of a specific, mechanically messed fabric of Evans in a multilayer sponge dressing avoids many of the disadvantages of prior gauze dressings. The bandages of the invention must generally use wettable fibers or fibers that have been treated so that they can be wetted. In some cases, wettable fibers may be used in conjunction with small amounts of non-wettable fibers. Useful 60125 fibrous structures include cotton, spreader, polyethylene terephthalate, polyamide, cellulose acetate, polyacrylonitrile, acrylonitrile vinyl chloride copolymer, reconstituted protein and polyolefin fibers, and mixtures thereof.

This group includes hydrophobic fibers that have been treated to have hydrophilic properties. Such treatment is, for example, the incorporation of polymeric materials onto fibrous surfaces by means of radiant energy, free radicals and other polymerization methods known in the art. Other treatment examples include the use of wetting agents, the use of rewetting agents, and surface modification by chemical reaction, e.g., mercerization of cotton and alkaline treatment of polyethylene terephthalate. In this context, it is, of course, important to avoid the use of modification methods that are unsuitable for the surgical use of the fibers, e.g., methods that leave residual chemicals that may be extracted out of the dressing into body wounds.

The fibers should have a length and denier such that the stated strength and lower release of the particulate matter is achieved. The denier can generally vary in the range Q, 5 ”3.0, preferably in the range 1.0-2.0. The lengths of the fibers can range from 6.35 to 38.1 mm, preferably from 12, T-31, T5 mm. The weight of the fabric per unit area may vary in the range of 17_102 g / m depending on the desired degree of stick in the product. The weight per unit area should preferably be about 25-68 g / m 2.

In many applications, it is desirable for the fabric to be perforated. The openings can give the bandage a desirable greater fluff without the need for additional fibers. The perforated fabric is less smooth, wads less wet, and is more useful in surgical procedures such as tissue separation, where the dressing should be slightly abrasive. From an aesthetic point of view, perforated fabrics are more reminiscent of familiar gauze bandages. Holes can be made in the fabric by means well known in the art, e.g., by piercing with a needle or a jet of fluid that strikes the fabric supported by the patterned substrate.

The proportion of the open area of the opening varies depending on the intended use of the product. A suitable open area is generally about 10-100 holes / cm 2, with about 20-80 holes / cm 2 being preferred.

In order to be useful as a surgical dressing, the fibers must be sufficiently mechanically entangled for the product to maintain its structural integrity under the conditions of use. It has been found that the cutting energy absorption value of the fabric should be at least 1 U, 6 J / m in both the machine and transverse directions, and preferably at least about 29.2 J / m. The breaking energy absorption value is defined as the area under its stress curve that develops when the fabric is stressed under tensile stress according to the method described in the TU9I + - SU-6U test designed by the Technical Association of the Pulp and Paper Institute (TAPPi) I96U.

In the present invention, it is important that the minimum tensile strength determined above is achieved with a substantially sufficient degree of mechanical entanglement and not by the use of adhesive binders. These binders, which are usually either a latex that is applied in the form of an emulsion to a weak fibrous tissue, or a crosslinked resin structure, are detrimental because they tend to impair the absorbency of the dressing made. Although the reason for this is not fully known, it is possible that the binder impairs the connection between the capillary spaces of the nonwoven fabric, as this connection is believed to be important for a good absorbent material. Another possibility is that ordinary binders are less hydrophilic than fibers, resulting in a general deterioration in absorbent properties. Perhaps an even more important reason for using the substantially unbonded dressings of this invention is that because these dressings are used with body wounds, substantial binderlessness prevents substances from entering the body by extraction or direct contact that could cause adverse tissue reactions, e.g., toxic or allergic reactions.

According to the present invention, a mechanically messed fabric is incorporated into a surgical sponge using multiple layers. Figure 1 shows a single rectangular piece 10 of this mechanically tangled fabric that can be folded to form a multilayer surgical sponge, e.g., the eight-layer sponge 12 of Figure 2. The piece 10 is folded first along line A-A and then along line. B-B so that the lines C-C and C-C 'coincide. The finished product, sponge 12, is obtained by folding once more around the converging lines C-C and C-C '. Attached to the piece 10 is an X-ray detectable portion 13, e.g., a polyolefin wire coated with barium sulfate or other suitable X-ray opaque material. Figure 1 shows that the part 13 is preferably located close to the line A-A, so that it is in the middle of the finished product.

Figures 3 and 1 * show yet another embodiment of the present invention in which the required mechanically messed fabric is included in the abdominal surgery sheath 1U. These sheaths are usually used inside the body cavities during larger surgical procedures as absorbent pieces, in addition to insulating the organs and covering the outer edges of the wounds.

Abdominal surgical patches must therefore have a certain wet elasticity in order to retain their fluff when performing these non-suction functions. The embodiment of the invention shown in Figure 3 includes thin thermoplastic nets 16 and 17 interposed between layers 18, 19 and 20 of the required mechanically tangled fabric. The best crosslinking agent may be, for example, made of polyolefin, e.g. polypropylene, which may weigh about 0.155 * 0.5 ^ 2 g / m 2. The degree of openness of the net shall be sufficient so that the net does not impair the absorbency of the vagina or its flexibility. The best quantities are considered to be 12 x 20, 20 x 20, 36 x 36 or 1 * 8 x 1 + 8 holes / 10 cm. The entire laminate formed by the fabric layers and the intervening thermoplastic nets can be bonded together as best shown in Figure U by heat-sealing at least at the edge 11 of the mandrel 11 + to melt the nets 16 and 17 and form a unitary bond with the fabric layers. To ensure even greater integrity of the laminate structure, additional heat-sealing points 20 are used inside the edges 18 and are shown in cross-section in Figure 1+. In this connection, it should be noted that instead of a thermoplastic mesh, thermoplastic fibers can be incorporated into the fabric, i.e. e.g. polyethylene terephthalate fiber. which can form a fusible material for binding. One skilled in the art will appreciate that other shapes and arrangements of heat seal points may be used. One skilled in the art will also appreciate that the layers of the vagina may be bonded together by other means than heat sealing, e.g., ultrasonic sealing or sewing. The abdominal surgical sheath 11 + is provided with a handle 22, which can also be heat sealed to the sheath or alternatively sewn on. As in the previous embodiment, the abdominal surgical sponge can be provided with X-ray detected portions 2h and 26.

The bandages of this invention have properties that are completely surprising compared to prior multilayer bandages. It has been found that both the suction properties and the fluff removal rate of the multilayer structure are surprisingly improved.

With respect to absorbent properties, it has been found that when the number of layers is greater than one, the average total absorbency per unit weight of the dressing does not deteriorate. · When more than two layers are used, the absorbency per gram actually increases. This result is particularly surprising when compared to commonly used cotton gauze bandages, which have the exact opposite result, i. the average total ability to absorb liquid per unit weight of gauze deteriorates with increasing number of layers. The amount of such reduction in absorbency in previous h 2 -cosols is considerable, e.g. up to 10% of the value of one layer, and in extreme cases up to 25% of the value of one layer. In contrast, no such decrease in absorbency is observed in the dressings of this invention.

In fact, there is at least about a 3% increase in the five-layer bandage and even greater growth in the ten-layer bandage. This is advantageous because less material can be used to achieve the desired absorbency. This has the advantage that the use of a smaller amount of material, i.e. the use of fewer fabric layers, means that less fabric surface is included in each sponge.

Since the degree of detachment of the fluff, i.e. the detachment of the particulate matter, is for the most part a function of the surface area of the substance used, the significantly lower degree of detachment of the fluff is a consequence of the smaller surface area used and the other properties described. The degree of detachment or separation of the fluff or particulate matter of the fungus prepared according to the invention is less than 12, b mg 2 per bare area m when used in a multilayer structure. In contrast, the degree of loosening of the cotton gauze fungus is about 22 mg of particulate matter 2 per exposed area m. This comparison has been made after the usual precautions have been taken to limit the fluffy detachment of the gauze bandages. Due to the nature of the cut gauze, a lot of particle material comes off the cut edges, so these are usually folded in and hidden inside the folded bandage. In addition, cutting the gauze before folding must be performed in the so-called by a punch-cutting method, in which the cut ends of the gauze yarns are closed by punching into an elliptical, inverted shape so that the loose fibers cannot come off. All of these back-up procedures are performed on the gauze bandages tested, but are not required for the mechanically tangled fabric bandages of this invention. Had these precautions not been taken with gauze bandages, the difference in the degree of fluff detachment would have been considerably greater.

The advantages of the present invention are further illustrated by the following examples:

Example 1

From three fabric types, binder samples are prepared with different number of layers. The first type consists of a surgical, bleached and abraded cotton gauze (U.S. Pharmacopoeia Type VII) with a yarn count of 20 warp yarns per 12 weft yarns and a weight of 20.0 g / m 2. The second type consists of a surgical, bleached and abraded cotton gauze (US Pharmacopoeia Type III) with a yarn count of 28 warp yarns per 2 h weft yarn and a weight of 3 g / m 2. with a denier of 1.5 and a length of 19.05 mm. The mechanically entangled fabric weighs 3 g / m 2 and is perforated so that the open area is about 55 holes / cm.

The samples are prepared in a round mold with a diameter of 68.5 mm. The samples are tested to determine their total absorbency with distilled water and using a device consisting of a smooth, Teflon-coated plate through which an opening with a diameter of 0,076 mm extends. The orifice is in flow communication with the distilled water tank and means are used to ensure that the hydraulic pressure of the liquid in the orifice, which is substantially at the same level as the top surface of the smooth plate, is substantially zero throughout the test period. Means for ensuring hydraulic pressure are described in the description of the constant flow burette (Journal of Chemical Education, Part U7, pages 8U1-8U2, December 1970). Each sample was placed on the top surface of the plate above the opening and allowed to absorb the liquid and lower the height of the liquid surface in the tank until no 8 60125 change was observed in the tank. The volume of liquid absorbed by each sample was recorded.

Table I summarizes the results of these experiments and in addition the number of layers used in each sample, the type of absorbent used, and the absorbency of each sample, expressed as the total capacity of each layered sample as a percentage of the absorption capacity of one layer.

cm of liquid per gram of dressing.

Table I

Total capacity per gram as a percentage of the capacity of one layer per gram

Layers 20 x 12 gauze 28 x 2b gauze Mechanically tangled fabric 1 100 100 100 2 100 100 100 4 89.5 100 103 8 73.6 91.5 103 7 103 9 106 12 73.6 95.7 16 73.6 91 , 5

Figure 5 shows a graphical representation of this data and shows the number of layers in the abscissa and the ordinate is the total absorbency per gram as a percentage of the capacity of one layer per gram. The values of 20 x 12 gauze, 28 x 2b gauze, and mechanically messed fabric are plotted as X, triangles, and circles, respectively. It can be seen from Figure 5 and Table I that in both gauze samples the total absorbency per gram decreases with increasing number of layers, and this decrease is evident after four layers. In clear contrast, the ratio is reversed in the novel mechanically entangled samples of this invention, where the absorbency per gram increases with the number of layers, with growth evident after two layers and even more evident at four layers.

Example II

Eight samples of different types of surgical fungi are prepared here. The first and second types are conventional cotton gauze sponges consisting of the 20 x 12 and 28 x 2b gauze described in the previous example, respectively. Other types are made in accordance with the present invention and contain 9,601,25 mechanically entangled fibers, the different types of which are given in Table II below and the different weights per unit area are also given in Table II. Eight samples of each type are tested for particulate matter by immersing the sample in 1 000 ml of distilled water in a beaker. The sample, held at the edge with crucible forceps, is immersed in water and removed five times. Each time the sample is immersed, it is shaken back and forth five times.

The solution is then filtered into a vacuum flask through a crucible with a porous glass bottom and first rinsed with distilled water, dried in an oven at 105 ° C for three hours and then cooled in a desiccator for one hour. The weight of the chilled and dried crucible is recorded. The filtered solution is returned to the beaker and the other samples of the same type of dressing are again subjected to the described immersion, shaking, removal and filtration.

The crucible is then dried to constant weight in an oven at 105 ° C and weighed again and the difference in weight is noted. This difference in weight is divided by the total bare surface of all fungal samples and is expressed in Table II as the weight of particulate matter released per unit area of fungal area.

Table II

2 2

Fungus type Fibers Weight g / m Particulate matter mg / cm

Gauze Cotton yarn 20 x 12 20, h 0.002 ^ 5

Gauze cotton yarn 28 x 2b 3 ^ 0.00205

Mechanically tangled 100% Säteri, 0.00088

Mek. messed up 100% Säteri, 68 0.001009

Mek. entangled 75% Säteri, 25% PET1) 37 0.0010 ^

Mek. entangled 75% Säteri, 25% PET2) 37 0.0011

Mek. entangled 10% Säteri, 90% PET1) 3b 0.00073

Mek. messy 10% Sinter, 90% PET2) 3 ^ 0.000807 1) Polyethylene terephthalate 2) Polyethylene terephthalate with added polyacrylic acid

Table II shows that in all the mechanically entangled fungi of this invention, the release of particulate matter is significantly lower than in conventional gauze dressings. The release of particulate matter is usually reduced by a factor greater than two. In addition, it should be noted that the nature of the particulate matter released from the gauze fungus differs from the particulate matter of the mechanically entangled fungi of this invention. The fluff detached from the gauze sponges consists essentially of pieces of yarn, 10 60125 with a diameter of about 0.13-0.32 mm and most of which are about 1 mm long, if 6 and 7 lengths are also present. These pieces of yarn are mixed with loose short fibers, which are parts of said yarns, and impurities, such as pieces of cotton web, leaf and stem. In contrast, the mechanically entangled sponge releases fluff particles that are substantially smaller and dusty.

Example III

This example illustrates the advantages of the present invention over previous attempts to make nonwoven surgical sponges. Here, two samples of a single ply fabric are prepared by the method described in U.S. Patent 3,081,515, issued to H. W. Grisvold et al. On March 19, 1963, using 100% filaments having a denier of 1.5 and a length of 19.05 mm. The first sample is made of carded fabric and used in the unbound state. The second sample is likewise made of a single-layer, carded fabric and is then impregnated with a crosslinkable acrylic emulsion polymer in an amount of about 30% by weight of the unbound fabric. The absorbency of both samples is tested according to Example I. In addition, the breaking energy absorption values of both samples are investigated by the method described by The Technical Association of the Pulp and Paper Industries (TAPPI), the proposed method T ^ 9 ^ SU-6U, 196U. Samples of the single-ply, mechanically tangled fabric of the present invention, similar to Example I, are tested in the same manner, and the results are reported in Table III.

Table III

j g 2 sample I Weight g / m Absorbency «m / g Machine K E ^ A 1) j direction J / in! _j_ Transverse direction j ICarded, unbound 3 * + 8.5 0.3 0.11 + 6 1 O")

Carded, bound 37 5.6 7.975 63.33

Mek. messed up 3 ^ 8.3 6.3,758 1 * 1, 0 ^ ^ Cutting energy absorption value 2) Without binder

The table shows that unbound specimens have good absorbency, but do not withstand sufficient tensile stress to be used as a structural material in a surgical sponge. This substance is, in fact, so weak that when an attempt was made to determine the particulate matter removed by a fungus made from this fabric, using the method described in the previous example, the fungus lost its structural integrity.

11 60125

According to Grivold's proposal, unbound substances were strengthened by impregnating them with a binder. In this form, the samples examined had sufficient ability to withstand tensile stresses. However, as the table above clearly shows, the absorbency decreases very much. Compared to both of the above samples, the agent of this invention had both satisfactory strength and satisfactory absorbency.