CA1062573A - Compacted textured felt of tissue absorbable polymer - Google Patents
Compacted textured felt of tissue absorbable polymerInfo
- Publication number
- CA1062573A CA1062573A CA224,500A CA224500A CA1062573A CA 1062573 A CA1062573 A CA 1062573A CA 224500 A CA224500 A CA 224500A CA 1062573 A CA1062573 A CA 1062573A
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- CA
- Canada
- Prior art keywords
- felt
- tissue
- fibers
- compacted
- inches
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/64—Use of materials characterised by their function or physical properties specially adapted to be resorbable inside the body
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
- A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
- A61L27/58—Materials at least partially resorbable by the body
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L2400/00—Materials characterised by their function or physical properties
- A61L2400/04—Materials for stopping bleeding
Abstract
TITLE: COMPACTED TEXTURED FELT OF TISSUE ABSORBABLE
POLYMER
INVENTOR: ROY WILLIAM ROTH
Gray Squirrel Drive New Canaan, Fairfield County, Conn. 06840 ABSTRACT OF THE INVENTION
Tissue absorbable synthetic polymeric fibers, such as polyglycolic acid, are felted to form a thin mat with at least one, and preferably both, surfaces compacted by con-tact with a heated embossing surface such as a hot roller.
Porosity is reduced but the compacted felt retains its flex-ibility, and conforms readily to the surface of a bleeding wound to give effective rapid hemostasis. The hemostatic felt is conveniently but not necessarily allowed to remain in place during the healing process and is absorbed by liv-ing tissue.
POLYMER
INVENTOR: ROY WILLIAM ROTH
Gray Squirrel Drive New Canaan, Fairfield County, Conn. 06840 ABSTRACT OF THE INVENTION
Tissue absorbable synthetic polymeric fibers, such as polyglycolic acid, are felted to form a thin mat with at least one, and preferably both, surfaces compacted by con-tact with a heated embossing surface such as a hot roller.
Porosity is reduced but the compacted felt retains its flex-ibility, and conforms readily to the surface of a bleeding wound to give effective rapid hemostasis. The hemostatic felt is conveniently but not necessarily allowed to remain in place during the healing process and is absorbed by liv-ing tissue.
Description
24,2~6 -~
B~CKGROUND OF ~HE INVENTION
The problem of bleeding has caused complications in surgery or after traumatic damage for generations. Dif-ferent technigues have been used to control the flow of blood, such as the application of hot tar during a more barbaric age, or the use of sutures or ligatures to tie off bleeding vessels or a small cautery being used to burn bleeders, or assorted elamps, adapted for partieular surgical techniques. Various forms of dressings have been used to encourage clotting or otherwise eontrol the flow of blood. Various forms of ab-sorbable elements for eontaet with the wound surfaee have been suggested, ineluding such materials as foamed gelatin or knitted oxidized regenerated cellulose. The history of sur-gery shows many other materials have been used to eontrol bleeding.
In general, the desirable aspeets of hemostats are reeognized, but new and improved hemostats are in demand.
DESCRIP~ION OF THE PRIOR ART
Uses of polyglyeolie acid are disclosed in a series of patents and applieations to Sehmitt, et al:
U. S. Patent 3,297,033, Schmitt and Polistina, January 10, 1967, SURGICAL SUTURES, discloses polyhydroxy-aeetie ester absorbable sutures. The material is also ealled polyglyeolie aeid, and is disclosed as permitting small quanti-ties of eomonomers to be present, such as dl-laetie aeid, its optieally aetive forms, homologs and analogs. A small quan-tity is reeognized by the art as up to 15%, as shown by U. S.
Patent 2,668,1623 Lowe, February 2, 1954, PREPARATION OF HIGH
MOLECULAR WEIGHT POLYHYDROXY-ACETIC ES~ER.
U. S. Paten-t 3,463,158, Schmitt and Polistina, August 26, 1969, POLYGLYCOLIC ACID PROSTHETIC DEVICES, dis-eloses surgical uses of polyglycolic acid, and ineorporates -1- ~
definitions of some terms.
United States Patent 3,620,218,Schmitt and Polistina, November 16, 1971, CYLINDRICAL PROSTHETIC DEVI OE S OF POLY-GLYCOLIC ACID, lists many uses of polyglycolic acid.
United States Patent 3,736,646, Schmitt and Epstein, June 5, 1973, METHOD OF ATTACHING SURGICAL N~EDLES TO MULTIFILAMENT
POLYGLYCOLIC ACID ABSORBABLE SUTURES, discloses surgical elements of a copolymer containing from 15 to 85 mol percent glycolic acid and 85 to 15 mol percent lactic acid.
United States Patent 3,739,773g Schmitt and Polistina, June 19, 1973, POLYGLYCOLIC ACID PROSTHETIC DEVICES, claims particularly bone pins, plates, nails and screws of polygly-colic acid.
Un~ted States Patent No. 3,875,937, Schmitt and Polistina, May 31, 1973, SURGICAL DRESSINGS OF ABSORBABLE
POLYMERS, discloses additional subject matter on surgical dressings of polyglycolic acid.
United States Patent 3,739,773, supra, lists a number of United States patents on methods for preparing polyglycolic acid and starting materials therefor.
In United States Patent 3,620,218, supra, in Column 2 are listed a number of medical uses of polyglycolic acids, in-cluding in Column 2; line 52, knitted or woven fibrillar products, including velours, and mentioning specifically in line 53, burn dressings; line 57, felt or sponge for liver hemostasis; line 63, foam as an absorbable prosthesis; and in lines 74 and 75, burn dressings (in combination with other polymeric films).
United States Patent 3,783,093, Gallacher, January 1, 1974, FIBROUS POLYETHYLENE MATERIALS, discloses a fibrillated ma-terial, mentioning poly(glycolic acid) among others, in which one resin is mixed and fibrillated with another, and one leached out to give the product, a web of oriented, in-terconnected directional fiber-like strands, membranes, rib-bons, branched ribbons and fibrils. These can be used as bandages and for other medical purposes. Example 15 shows 25 parts of poly(glycolic acid) and 75 parts of poly-(methyl methacrylate) leached with acetone.
The use of gauzes, felts, and knitted fabrics as a wound dressing is quite conventional. The use of collagen-ous products as a sponge or pad has been disclosed.
Commercially, an oxidized regenerated cellulose is available as a hemostat. Also, a gelatin foam product is distributed in sheet form. Both of these are absorbable in tissues. Under some conditions, the gelatin foarn causes bile cysts. It is desirably wetted with saline at the time of use and to wet with saline, squeeze out, rewet and squeeze out again is time consuming, and renders the material limp and somewhat pasty so that it may stick to instruments and gloved fingers. In addition, on contact with blood the foam gelatin has a tendency to swell and unduly increase its bulk. Suction cannot be applied through the foam. The oxi-dized cellulose may acquire a gelatinous consistency and stick to gloves and instruments. As it is knitted, when cut, flakes of the material may scatter.
It is quite common for persons who have cut them-selves while shaving to stop bleeding by placing a smallpiece of toilet tissue on the wound. If the cut is small, tne tissue adheres to the skin, and bleeding stops. The tis-sue is trapped in the scab, and is later removed -- sometimes bleeding resumes. Often the tissue floats on accumulating ~062573 blood, and other measures are required to stop the bleeding.
S MMARY OF_ HE IN ENTION
This invention relates to a tissue absorbable syn-thetic polymeric fiber felt hemostat which is heat compacted on at least one surface. The compaction and heat embossing aid in causing the hemostatic surgical felt to adhere to the surface of a wound, and because it adheres so closely due to capillarity, hemorrhage is usually effectively controlled. If a ma~or blood vessel is severed, the hemostatic felt may be floated from the surface of a wound, but for many procedures, such as the excision of a part of a liver or neurosurgery, the adherence is such as to promptly cause hemostasis. The compacted hemostatic felt is preferably thick enough and com-pacted enough that blood does not flow from the outer surface;
and because of the absorbable characteristic of the felt, the hemostatic felt may be left in place when a wound is closed, to give effective blood flow control during the surgical pro-cedure, minimize subsequent bleeding and be readily absorb-able by living tissue so there is no need to remove the hemo-stat, which might cause renewed bleeding.
The hemostatic felt is produced by the random form-ation, as, for example, by air-scattering, of a felt followed by heat embossing. Conveniently, the fibers are within the range of 0.5 to 12 denier and a length of at least 1/4" con-tinuous fibers may be used, but chopping into a length of1/4" to 2" or 3" makes handling and air laying as a felt more convenient. The air laid web may then be felted, in accordance with conventional procedures, either using a non-oriented rubbing or a needling in which barbed needles cause interlocking of the polyglycolic acid fibers. If embossed, mechanical felting may be used but is not required.
Even if the laying or felting process introduces 24,2~6 106;~S73 some orientation, the compaction of the felt gives enough strength in all directions so that the compacted felt forms a good hemostat.
Whereas an ordinary felt, such as disclosed in 3,620,218, supra, gives at least some hemost~sis, uncompacted felted fibers give a felt which may float from a bleeding surface, and is too porous. ~he normal texture of the felt surface tends to be held from the wound surface by the random - orientation and soft surface of the conventional felted sur-face.
It has now been found that embossing and compacting the fibers on the tissue contacting surface aids in causing the felt to adhere sufficiently closely to hold the felt to the wound, and compacting the free surfaces reduces the ten-dency for blood to flow through the felt. The felt is thinner, which reduces the blood volume in the hemostat, so that absorption during healing is more rapid. lhe absorbable felt fibers, such as polyglycolic acid absorb readily during the healing process, but massive residual blood clots can be more of a problem. It is desirable that a minimum of pooled blood or blood clots be formed in the wound so that absorption of the clotted blood is more rapid.
~he fibers themselves are absorbable by living tissue so that any of the fibers within the wound are ab-sorbed by the living tissue without deleterious effects.
The present compacted absorbable felt may be used on almost any type of wound in which the skin is broken and body fluids, particularly blood and serum, are released by the wound. It is primarily designed for use as a hemostat on any bleeding surface, and is particularly adapted to procedures in which the compacted felt hemostat is closed into a wound, to be absorbed by living tissue as the wound heals. It is _~
also very effective on skin surface wounds, in which the compacted felt hemostat is on the skin surface, and at least part of the felt may be trapped within the wound.
It may be used to wipe liquids from tissue surfaces as a sponge, with the advantage any fibers shed into and trap-ped within the wound are absorbed, and hence are innocu-ous .
For adequate conformation, the compacted feltmust be flexible so that it can conform to the topography of the wound and at the same time it must be sufficiently flexible that as the tissues move, the compacted felt can move with them. Usually, as a hemostat, the blood coagulates and may harden within the felt structure, and the characteristics of the clotted blood determine the flexibility of the healing structure.
The tissue absorbable fibers which may be used to provide the hemostatic surgical felt include those fibers which are reasonably rapidly absorbed in tissue, that is, within a period of less than about 90 days.
Polymers in which tissue absorption results from the hydrolytic degradation of glycolic acid ester linkages give good results. secause strength of the fibers is not a major requirement, a copolymer containing consider-able lactic acid makes a good hemostat. Such polymers are disclosed in 3,736,646, supra.
Another absorbable polymer which may be used for the hemostat is poly(N-acetyl-D-glucosamine).
24,23~
A preferred tissue absorbable fiber is made from homopolymeric polyglycolic acid, which among other polymers is described in the Schmitt patents above, and which is meet-ing with commercial success as a suture. Because this ma-terial is in current use as a suture, has been approved bygovernmental authorities, and is recognized as usable by the medical profession, most of the examples and description will be in connection with such a fiber; although it is to be understood that other tissue absorbable fibers may be used.
Because the felt is normally under a minimal load, a form of polyglycolic acid which is weaker than desirable for sutures is perfectly satisfactory in a hemostatic felt and additionally because the major reguirements for hemostatic action are during the course of an operation, a form of PGA
which loses its strength within 24 hours or less gives good results as a hemostat and is rapidly absorbed by tissues during the healing process. Once bleeding has been completely controlled and the wound closed, the likelihood of subsequent bleeding is markedly reduced and after a period of only a few days the healing process is sufficiently advanced that hemorrhage is not a problem. It is desirable that strength be retained for at least a few days to leave a margin for safety and some protection for the wound surface during a considerable portion of the healing process. Because of variations within species and because of variations in indi-vidual members of a species and variations in tissue char-acteristics of the site of use at which hemorrhage is con-trolled, minimum and maximum absorption times can vary con-siderably. ~o be on the safe side, it is desirable that the hemostatic felt be well within an acceptable range. A
material that retains a considerable portion of its strength for at least three days and is substantially completely ab-sorbed within ninety days gives highly advantageous re-sults.
It is important that the tissue absorbable poly-mer be of a material that is not deleterious to living hu-man tissue and that it be spinnable as a fiber which formsa fine structure such that blood and other fluids wet but do not flow rapidly therethrough. It needs sufficient strength to maintain its integrity as a hemostatic sponge during manufacturing and use. It ~ould be absorbed before it can act as a foreign body after the wound has healed.
Inasmuch as the useful characteristics of the present compacted felt are largely a function of the size, shape and structure, other tissue absorbable materials may be substituted for the homopolymeric polyglycolic acid fibers described in more detail in the following examples.
Polyglycolic acid is conveniently spun into the filaments of about 0.5 to 12 deniers per filament. Smaller filaments are quite difficult to spin and larger ones are stiffer than is desirable although there are many uses for which both larger and smaller are acceptable. Conveniently, from about 2 to 6 deniers per filament gives a good compro-mise between ease of spinning and sufficient flexibility to form a good felt and is preferred. Conveniently, but not necessarily, a group of fibers are spun together as a tow.
The tow may be twisted, or at least false twisted, and heat treated to give a crimped and textured configuration to the yarn after which it is preferably chopped into segments of 24,286-~
about 1/4" to about 3" using conventional cutting techniques to give a staple. It may be used straight--tha-t is, without crimping Other conventional methods of crimping may be used, such as a stuffer box, a knit-deknit process, or crimping gears, or a bicomponent fiber, in which different molecular weights of polymer are used as components. An uncrimped fiber gives good results if needle punched, a conventional felting technique. The cut fibers are sprinkled or air laid into a web having a density of from about 0.5 ounces per square yard to about 4 ounces per square yard. lhe densities above about 1.5 ounces per sguare yard are more effective hemostats over a wider range of surgical procedures than are the lighter webs.
~he webs may be felted by the usual rubbing or needling tech-niques to give a three dimensional configuration with inter-locked fibers which gives strength to the felt. It may be only heat embossed to give adequate strength.
The felt is embossed, preferably on both sides, to give a less porous felt and one in which the surface fibers are pressed down into the structure. By having the surface fibers pressed into the structure so that a smoother surface is obtained, the embossed felt when placed in contact with a wound surface can be drawn into closer conformity with the wound and reduce poc~ets in which blood or other fluids can accumulate, and by being drawn against the wound by capil-larity, the embossed hemostatic felt is held closely enough to the wound surface that it is drawn to the wound surface and does not float off.
The embossing may be accomplished conveniently by using a hot embossing roll which without melting the fibers gives them a permanent press and smooth flat surface. At faster speeds, a higher temperature can conveniently be used 24,28~
on the embossing roll. Good results are obtained using a roll temperature of 350~., a pressure of about 1050 pounds per linear inch of contact of rolls and a feed rate of 15 feet per minute. A stainless steel heated embossing roll is used against a nylon backing roll.
Embossing on the tissue contacting surface gives improved adherence to the tissues and increases the effective surface area exposed to blood. Blood can ooze through the - hemostatic embossed felt and pool on the free surface. If the free surface is also embossed, it gives a local increased compactness which aids in preventing blood from oozing through the free surface so that only the felt thickness between the two embossed surfaces is filled with blood. By having a minimum thickness of felt filled with blood, the later ab-sorption of the blood clot is expedited. ~he tissue absorb-able material, such as homopolymeric polyglycolic acid is ab-sorbed at such a rate that its presence in the wound presents no complications. A major blood clot may cause scar forma-tion or delayed absorption.
Although not limited thereto, it is convenient to make the present felt from fibers such as are used for su-tures. ~he breaking strength of such fibers varies from around 20,000 pounds per square inch to over 100,000 pounds per square inch. A weaker fiber is adequate for felts used as hemostats.
~he felts used as hemostats themselves are conven-iently formed by needling uncrimped fibers such as are used in sutures, but the felt may be embossed without needling.
~he stiffness of the felt may be determined by stan-dard methods such as set forth in Federal Test Method Stan-dard 191 of 31 December 196~, Method 5206. In this method a test specimen of rectangular cloth 6" long and 1" wide is 24,~G
placed on a horizontal platform and slid off under test con-ditions until the end of the fabric drops to an angle of 41 1/2 below the plane of the surface of the platform. The material is tested under standard conditions as set forth in the Federal Test Method Standard 191. Other test procedures may be used but the increase in relative stiffness of the em-bossed felt over the unembossed felt is one characteristic of a satisfactorily embossed felt hemostat.
If the felt is not needled, but merely the air laid web is used, it is somewhat more fle~ible than if needled but after embossing under heat using either a diamond or a burlap embossing roll, the felt is compressed and is a satisfactory hemostat.
Another measure of the effect of the heat embossing is the air permeability. The air permeability is conveniently measured by the standard method of test for air permeability of textile fabrics, AS~M Standards Designation D 737-69 (Oct. 3, 1969). In this method under standard conditions, air at a pressure of 0.5 inches of water is flowed through an orifice over which the fabric is finely spread, usually having a diameter of 2.75", and the rate of air flow is ex-pressed conveniently in cubic feet of air per minute per sguare foot of fabric at the pressure differential of 0.5"
of water. A Gurley Permeometer is one satisfactory device for this test method, and uses a guard ring to avoid leakage through the edges of the fabric. As shown below, the heat embossed fabric has a markedly lower air permeability than the felt before the heat embossing.
Conveniently, but not necessarily, the embossing roll has a plurality of small diamond-shaped engravings therein so that the fabric is embossed with a series of lines di-viding the felt surface into diamond-shaped raised portions.
24,2~ ~
Another good embossing roll has a configuration of the surface approximately that of burlap so that the finished felt has a general configuration of burlap. Other patterns may be used.
The effect of the embossing of the pressure roll is to give areas of different compression which gives a texture to the surface, improves the flexibility, and gives excellent control to the permeation of blood.
As a surgical device, it is obviously desirable, almost mandatory, that the hemostatic felt be sterile at the time of use. ~he felt may be sterilized by an appropriate sterilizing cycle using ethylene oxide as a sterilizing agent.
If ethylene oxide is used to sterilize, it is convenient that the ethylene oxide be diluted with carbon dioxide or a chloro-fluoroalkane to such an extent that the sterilizing gas is non-explosive. Radiation sterilization or heat sterilization may be used, where equipment for such processes is available.
For storage stability, it is desirable that the felt hemostat be protected from atmospheric influences. Parti-cularly, if the hemostatic felt contains hydrolyzable poly-glycolic acid ester linkages, the linkages can be hydrolyzed by ambient moisture under room storage. Because the strength reguirement for felt is comparatively low, a certain degree of degradation is acceptable and because the long time strength reguirement in tissue is very low, even if degraded to the point that the tissue absorbable fibers are absorbed in a comparatively short period of time, that is, under a few days, the surgical felt is still acceptable. It is de-sirable that such storage conditions be used so as to main-tain the hemostatic felt in a dry environment so that whether used immediately after packaging or after a storage period of several years, the felt has the same characteristics and, 24, ~8~
hence, has known predictable attributes as far ~s the using surgeon is concerned.
A good method o~ sterilizing and storage is the same as is used for polyglycolic acid sutures on a commercial scale and as disclosed in U. S. Patent 3,728,839, Arthur ~lick, April 24, 1973, S~ORAGE STABL~ SURGICA~Y ABSORBAB~
POLYGLYCOLIC ACID PRODUC~S. As there described, the polygly-colic acid product is stored in a moisture proof envelope in which conveniently the product is packaged except for one open side and sterilized using ethylene oxide diluted so as to be non-explosive, and then while protecting sterility, the product is vacuum dried and the envelope sealed. By having the foil envelope hermetically sealed, as there taught, the hemostatic felt may be maintained in a usable form with con-sistent characteristics for a period of at least several years.
Conveniently, but not necessarily, the felt may be placed be-tween two sheets of paper, or a single sheet of paper with a fold, so that the felt is held in flat condition between the sheets during storage and service to the using surgeon.
For large sheets, the felt may be folded but for sheets up to 4" x 6" it is conveniently placed in an envelope large enough to hold the sheet flat. A plurality of sheets may be packaged in a single envelope if desired. Single sheets of about 4" x 6" are a surgically acceptable size, with the felt being cut to size by the surgeon, or an assistant, at the time of use. For many surgical procedures a single sheet is all that is required.
A double envelope, as described in 3,728,839, supra, is very convenient, and follows the techniques used in suture packages. The double envelope enables the sterile service of a sealed envelope, so that the surgeon or an assistant can open the inner envelope in a sterile area.
`` 1062573 A single envelope such as shown in United States Patent 3,017,990, Singerman, January 23, 1962, STERILE PAC~GE FOR
SURGICAL FABRIC, is also an economical and efficient package.
The inner paper wrap maintains the sterility of the felt until used by the surgeon.
The part, improvement or combination which is claimed as the invention herein comprises a hemostatic surgical felt comprising a sterile felt of fibers of 0.5 to 12 denier and 1/4 to 3 inch length of a tissue absorbable polymer subject to hydro-lytic degradation to non-toxic tissue compatible absorbable com-ponents, and which polymer has glycolic acid ester linkages, which felt has textured and partially compressed heat embossed surfaces, a weight of 0.5 to 4 ounces per square yard, a stiff-ness of 1.05 to 1.~3 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2 and which before embossing is too fragile for stiffness measurement, whereby the rate of penetra-tion of blood is reduced, and the adhesion to bleeding surfaces enhanced, and which is completely absorbed when enclosed in living tissue. The tissue absorbable polymer may be polyglycolic acid. Also claimed as the invention herein is a method of mak-ing a hemostatic surgical felt, having a textured and partially compressed heat embossed surface, of a tïssue absorbable polymer as described above, characterized by: melt spinning a tissue absorbable polymer into fibers of 0.5 to 12 denier, and cutting into segments of from about 1/4 to 3 inches in length, randomly laying said fibers into a mat having a uniform density of from 0.5 to 4 ounces per square yard, heating and compressing between heated embossing rolls, at least one of which has a textured surface to emboss said mat and bind the fibers to form a felt ~ - 14 --`- 1062S73 having a stiffness of 1.05 to 1.83 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2 and which before embossing is too fragile for stiffness measurement, and an air permeability of about 135 cubic feet per minute per square foot at 0.5 inches of water pressure differential and which before embossing has an air permeability of about 360 cubic feet per minute per square foot at 0.5 inches of water pressure differ-ential, cutting to form individual felt hemostats, and, in any order, packaging in contamination resistant packages, and sterilizing. In the method, the fibres may be air laid into a felt, and the individual felt hemostats may be packaged in mois-ture proof strippable packages, and sterilized by ethylene oxide.
THE DRAWINGS
In the attached drawings:
FIGURE 1 shows a diamond embossing pattern at an optical magnification of about 10 diameters;
FIGURE 2 shows a razor cut cross section of the embossed surgical felt of FIGURE 1, at 10 diameters optical magnification.
FIGURE 3 shows an embossed surgical felt with a burlap pattern, at 10 diameters optical magnification.
FIGURE 4 shows the embossed surgical felt of FIGURE 3 in a razor cut cross section, at 10 diameters optical magnific-ation.
FIGURE 5 is a composite scanning electron microscope photomicrograph at 30 diameters. The left side 5A shows the embossed felt. The right side 5B shows the air laid felt before embossing.
FIGURE 6 is a drawing showing the embossed felt hemostat in a double envelope.
Il ~ - 14a -,i lO~;Z573 FIGURE 7 is a drawing in pictorial, partly broken away showing the embossed felt hemostat in an envelope.
FIGURE 8 is a scanning electron microscope photo-micrograph at lOO diameters of the diamond embossed felt.
FIGURE 9 is a scanning electron microscope photo-micrograph at lOO diameters of an unembossed felt.
~ lhile the present invention is defined by the appended claims, it is illustrated by the following examples of specific constructions and usages of the present embossed surgical felt.
- 14b -24~86 --` 106Z573 Example 1 Polyglycolic acid having an inherent viscosity of about 1.05 was extruded into fibers of approximately 2 denier per filament using the following technique. 100 parts of re-crystallized glycolide (melting point 85.0 to 85.5C.) are intimately mixed with 0.02 part of methoxyacetic acid, 0.03 part of phenoldisulfide (Santo-Nox), and 0.03 part antimony trifluoride. Separate glass tubes are each charged with approximately 20 grams of the mixture, deoxygenated by re-peated evacuation and argon purging, then sealed under vacuum and heated to 185 to 190C. for 4 1/2 hours. On cooling a white opaque tough polyglycolic acid is produced in a 97.5%
yield with a melt viscosity at 245C. of 5,000 poises. The polymer is reheated and spun into fibers at a temperature of about 230C. at a speed of about 150 feet per minute. The fibers produced are cooled, then drawn at about 55C. When drawn to five times the original length a strong tough fiber is produced.
The continuous filaments are chopped into lengths of 1 1/2", fed into an air blast, suspended in air, and allow-ed to fall randomly onto a sheet of paper to a uniform den-sity of 2.25 oz. per square yard. The felt was then run under an embossing roll with the embossing roll having an engraved figured pattern of diamonds with about a 3/32" spacing. The felt was compressed against a nylon backing roll, with the embossing roll being operated at a temperature of 345-355F., a pressure of 1050 pounds per linear inch, and a speed of 15 feet per minute. After passing the free face of the felt under the embossing roll, the felt was turned ovre, the sup-port paper removed, and the felt passed again under the embos-sing roll to emboss the second side.
~ - 15 -'~4~ \
B~CKGROUND OF ~HE INVENTION
The problem of bleeding has caused complications in surgery or after traumatic damage for generations. Dif-ferent technigues have been used to control the flow of blood, such as the application of hot tar during a more barbaric age, or the use of sutures or ligatures to tie off bleeding vessels or a small cautery being used to burn bleeders, or assorted elamps, adapted for partieular surgical techniques. Various forms of dressings have been used to encourage clotting or otherwise eontrol the flow of blood. Various forms of ab-sorbable elements for eontaet with the wound surfaee have been suggested, ineluding such materials as foamed gelatin or knitted oxidized regenerated cellulose. The history of sur-gery shows many other materials have been used to eontrol bleeding.
In general, the desirable aspeets of hemostats are reeognized, but new and improved hemostats are in demand.
DESCRIP~ION OF THE PRIOR ART
Uses of polyglyeolie acid are disclosed in a series of patents and applieations to Sehmitt, et al:
U. S. Patent 3,297,033, Schmitt and Polistina, January 10, 1967, SURGICAL SUTURES, discloses polyhydroxy-aeetie ester absorbable sutures. The material is also ealled polyglyeolie aeid, and is disclosed as permitting small quanti-ties of eomonomers to be present, such as dl-laetie aeid, its optieally aetive forms, homologs and analogs. A small quan-tity is reeognized by the art as up to 15%, as shown by U. S.
Patent 2,668,1623 Lowe, February 2, 1954, PREPARATION OF HIGH
MOLECULAR WEIGHT POLYHYDROXY-ACETIC ES~ER.
U. S. Paten-t 3,463,158, Schmitt and Polistina, August 26, 1969, POLYGLYCOLIC ACID PROSTHETIC DEVICES, dis-eloses surgical uses of polyglycolic acid, and ineorporates -1- ~
definitions of some terms.
United States Patent 3,620,218,Schmitt and Polistina, November 16, 1971, CYLINDRICAL PROSTHETIC DEVI OE S OF POLY-GLYCOLIC ACID, lists many uses of polyglycolic acid.
United States Patent 3,736,646, Schmitt and Epstein, June 5, 1973, METHOD OF ATTACHING SURGICAL N~EDLES TO MULTIFILAMENT
POLYGLYCOLIC ACID ABSORBABLE SUTURES, discloses surgical elements of a copolymer containing from 15 to 85 mol percent glycolic acid and 85 to 15 mol percent lactic acid.
United States Patent 3,739,773g Schmitt and Polistina, June 19, 1973, POLYGLYCOLIC ACID PROSTHETIC DEVICES, claims particularly bone pins, plates, nails and screws of polygly-colic acid.
Un~ted States Patent No. 3,875,937, Schmitt and Polistina, May 31, 1973, SURGICAL DRESSINGS OF ABSORBABLE
POLYMERS, discloses additional subject matter on surgical dressings of polyglycolic acid.
United States Patent 3,739,773, supra, lists a number of United States patents on methods for preparing polyglycolic acid and starting materials therefor.
In United States Patent 3,620,218, supra, in Column 2 are listed a number of medical uses of polyglycolic acids, in-cluding in Column 2; line 52, knitted or woven fibrillar products, including velours, and mentioning specifically in line 53, burn dressings; line 57, felt or sponge for liver hemostasis; line 63, foam as an absorbable prosthesis; and in lines 74 and 75, burn dressings (in combination with other polymeric films).
United States Patent 3,783,093, Gallacher, January 1, 1974, FIBROUS POLYETHYLENE MATERIALS, discloses a fibrillated ma-terial, mentioning poly(glycolic acid) among others, in which one resin is mixed and fibrillated with another, and one leached out to give the product, a web of oriented, in-terconnected directional fiber-like strands, membranes, rib-bons, branched ribbons and fibrils. These can be used as bandages and for other medical purposes. Example 15 shows 25 parts of poly(glycolic acid) and 75 parts of poly-(methyl methacrylate) leached with acetone.
The use of gauzes, felts, and knitted fabrics as a wound dressing is quite conventional. The use of collagen-ous products as a sponge or pad has been disclosed.
Commercially, an oxidized regenerated cellulose is available as a hemostat. Also, a gelatin foam product is distributed in sheet form. Both of these are absorbable in tissues. Under some conditions, the gelatin foarn causes bile cysts. It is desirably wetted with saline at the time of use and to wet with saline, squeeze out, rewet and squeeze out again is time consuming, and renders the material limp and somewhat pasty so that it may stick to instruments and gloved fingers. In addition, on contact with blood the foam gelatin has a tendency to swell and unduly increase its bulk. Suction cannot be applied through the foam. The oxi-dized cellulose may acquire a gelatinous consistency and stick to gloves and instruments. As it is knitted, when cut, flakes of the material may scatter.
It is quite common for persons who have cut them-selves while shaving to stop bleeding by placing a smallpiece of toilet tissue on the wound. If the cut is small, tne tissue adheres to the skin, and bleeding stops. The tis-sue is trapped in the scab, and is later removed -- sometimes bleeding resumes. Often the tissue floats on accumulating ~062573 blood, and other measures are required to stop the bleeding.
S MMARY OF_ HE IN ENTION
This invention relates to a tissue absorbable syn-thetic polymeric fiber felt hemostat which is heat compacted on at least one surface. The compaction and heat embossing aid in causing the hemostatic surgical felt to adhere to the surface of a wound, and because it adheres so closely due to capillarity, hemorrhage is usually effectively controlled. If a ma~or blood vessel is severed, the hemostatic felt may be floated from the surface of a wound, but for many procedures, such as the excision of a part of a liver or neurosurgery, the adherence is such as to promptly cause hemostasis. The compacted hemostatic felt is preferably thick enough and com-pacted enough that blood does not flow from the outer surface;
and because of the absorbable characteristic of the felt, the hemostatic felt may be left in place when a wound is closed, to give effective blood flow control during the surgical pro-cedure, minimize subsequent bleeding and be readily absorb-able by living tissue so there is no need to remove the hemo-stat, which might cause renewed bleeding.
The hemostatic felt is produced by the random form-ation, as, for example, by air-scattering, of a felt followed by heat embossing. Conveniently, the fibers are within the range of 0.5 to 12 denier and a length of at least 1/4" con-tinuous fibers may be used, but chopping into a length of1/4" to 2" or 3" makes handling and air laying as a felt more convenient. The air laid web may then be felted, in accordance with conventional procedures, either using a non-oriented rubbing or a needling in which barbed needles cause interlocking of the polyglycolic acid fibers. If embossed, mechanical felting may be used but is not required.
Even if the laying or felting process introduces 24,2~6 106;~S73 some orientation, the compaction of the felt gives enough strength in all directions so that the compacted felt forms a good hemostat.
Whereas an ordinary felt, such as disclosed in 3,620,218, supra, gives at least some hemost~sis, uncompacted felted fibers give a felt which may float from a bleeding surface, and is too porous. ~he normal texture of the felt surface tends to be held from the wound surface by the random - orientation and soft surface of the conventional felted sur-face.
It has now been found that embossing and compacting the fibers on the tissue contacting surface aids in causing the felt to adhere sufficiently closely to hold the felt to the wound, and compacting the free surfaces reduces the ten-dency for blood to flow through the felt. The felt is thinner, which reduces the blood volume in the hemostat, so that absorption during healing is more rapid. lhe absorbable felt fibers, such as polyglycolic acid absorb readily during the healing process, but massive residual blood clots can be more of a problem. It is desirable that a minimum of pooled blood or blood clots be formed in the wound so that absorption of the clotted blood is more rapid.
~he fibers themselves are absorbable by living tissue so that any of the fibers within the wound are ab-sorbed by the living tissue without deleterious effects.
The present compacted absorbable felt may be used on almost any type of wound in which the skin is broken and body fluids, particularly blood and serum, are released by the wound. It is primarily designed for use as a hemostat on any bleeding surface, and is particularly adapted to procedures in which the compacted felt hemostat is closed into a wound, to be absorbed by living tissue as the wound heals. It is _~
also very effective on skin surface wounds, in which the compacted felt hemostat is on the skin surface, and at least part of the felt may be trapped within the wound.
It may be used to wipe liquids from tissue surfaces as a sponge, with the advantage any fibers shed into and trap-ped within the wound are absorbed, and hence are innocu-ous .
For adequate conformation, the compacted feltmust be flexible so that it can conform to the topography of the wound and at the same time it must be sufficiently flexible that as the tissues move, the compacted felt can move with them. Usually, as a hemostat, the blood coagulates and may harden within the felt structure, and the characteristics of the clotted blood determine the flexibility of the healing structure.
The tissue absorbable fibers which may be used to provide the hemostatic surgical felt include those fibers which are reasonably rapidly absorbed in tissue, that is, within a period of less than about 90 days.
Polymers in which tissue absorption results from the hydrolytic degradation of glycolic acid ester linkages give good results. secause strength of the fibers is not a major requirement, a copolymer containing consider-able lactic acid makes a good hemostat. Such polymers are disclosed in 3,736,646, supra.
Another absorbable polymer which may be used for the hemostat is poly(N-acetyl-D-glucosamine).
24,23~
A preferred tissue absorbable fiber is made from homopolymeric polyglycolic acid, which among other polymers is described in the Schmitt patents above, and which is meet-ing with commercial success as a suture. Because this ma-terial is in current use as a suture, has been approved bygovernmental authorities, and is recognized as usable by the medical profession, most of the examples and description will be in connection with such a fiber; although it is to be understood that other tissue absorbable fibers may be used.
Because the felt is normally under a minimal load, a form of polyglycolic acid which is weaker than desirable for sutures is perfectly satisfactory in a hemostatic felt and additionally because the major reguirements for hemostatic action are during the course of an operation, a form of PGA
which loses its strength within 24 hours or less gives good results as a hemostat and is rapidly absorbed by tissues during the healing process. Once bleeding has been completely controlled and the wound closed, the likelihood of subsequent bleeding is markedly reduced and after a period of only a few days the healing process is sufficiently advanced that hemorrhage is not a problem. It is desirable that strength be retained for at least a few days to leave a margin for safety and some protection for the wound surface during a considerable portion of the healing process. Because of variations within species and because of variations in indi-vidual members of a species and variations in tissue char-acteristics of the site of use at which hemorrhage is con-trolled, minimum and maximum absorption times can vary con-siderably. ~o be on the safe side, it is desirable that the hemostatic felt be well within an acceptable range. A
material that retains a considerable portion of its strength for at least three days and is substantially completely ab-sorbed within ninety days gives highly advantageous re-sults.
It is important that the tissue absorbable poly-mer be of a material that is not deleterious to living hu-man tissue and that it be spinnable as a fiber which formsa fine structure such that blood and other fluids wet but do not flow rapidly therethrough. It needs sufficient strength to maintain its integrity as a hemostatic sponge during manufacturing and use. It ~ould be absorbed before it can act as a foreign body after the wound has healed.
Inasmuch as the useful characteristics of the present compacted felt are largely a function of the size, shape and structure, other tissue absorbable materials may be substituted for the homopolymeric polyglycolic acid fibers described in more detail in the following examples.
Polyglycolic acid is conveniently spun into the filaments of about 0.5 to 12 deniers per filament. Smaller filaments are quite difficult to spin and larger ones are stiffer than is desirable although there are many uses for which both larger and smaller are acceptable. Conveniently, from about 2 to 6 deniers per filament gives a good compro-mise between ease of spinning and sufficient flexibility to form a good felt and is preferred. Conveniently, but not necessarily, a group of fibers are spun together as a tow.
The tow may be twisted, or at least false twisted, and heat treated to give a crimped and textured configuration to the yarn after which it is preferably chopped into segments of 24,286-~
about 1/4" to about 3" using conventional cutting techniques to give a staple. It may be used straight--tha-t is, without crimping Other conventional methods of crimping may be used, such as a stuffer box, a knit-deknit process, or crimping gears, or a bicomponent fiber, in which different molecular weights of polymer are used as components. An uncrimped fiber gives good results if needle punched, a conventional felting technique. The cut fibers are sprinkled or air laid into a web having a density of from about 0.5 ounces per square yard to about 4 ounces per square yard. lhe densities above about 1.5 ounces per sguare yard are more effective hemostats over a wider range of surgical procedures than are the lighter webs.
~he webs may be felted by the usual rubbing or needling tech-niques to give a three dimensional configuration with inter-locked fibers which gives strength to the felt. It may be only heat embossed to give adequate strength.
The felt is embossed, preferably on both sides, to give a less porous felt and one in which the surface fibers are pressed down into the structure. By having the surface fibers pressed into the structure so that a smoother surface is obtained, the embossed felt when placed in contact with a wound surface can be drawn into closer conformity with the wound and reduce poc~ets in which blood or other fluids can accumulate, and by being drawn against the wound by capil-larity, the embossed hemostatic felt is held closely enough to the wound surface that it is drawn to the wound surface and does not float off.
The embossing may be accomplished conveniently by using a hot embossing roll which without melting the fibers gives them a permanent press and smooth flat surface. At faster speeds, a higher temperature can conveniently be used 24,28~
on the embossing roll. Good results are obtained using a roll temperature of 350~., a pressure of about 1050 pounds per linear inch of contact of rolls and a feed rate of 15 feet per minute. A stainless steel heated embossing roll is used against a nylon backing roll.
Embossing on the tissue contacting surface gives improved adherence to the tissues and increases the effective surface area exposed to blood. Blood can ooze through the - hemostatic embossed felt and pool on the free surface. If the free surface is also embossed, it gives a local increased compactness which aids in preventing blood from oozing through the free surface so that only the felt thickness between the two embossed surfaces is filled with blood. By having a minimum thickness of felt filled with blood, the later ab-sorption of the blood clot is expedited. ~he tissue absorb-able material, such as homopolymeric polyglycolic acid is ab-sorbed at such a rate that its presence in the wound presents no complications. A major blood clot may cause scar forma-tion or delayed absorption.
Although not limited thereto, it is convenient to make the present felt from fibers such as are used for su-tures. ~he breaking strength of such fibers varies from around 20,000 pounds per square inch to over 100,000 pounds per square inch. A weaker fiber is adequate for felts used as hemostats.
~he felts used as hemostats themselves are conven-iently formed by needling uncrimped fibers such as are used in sutures, but the felt may be embossed without needling.
~he stiffness of the felt may be determined by stan-dard methods such as set forth in Federal Test Method Stan-dard 191 of 31 December 196~, Method 5206. In this method a test specimen of rectangular cloth 6" long and 1" wide is 24,~G
placed on a horizontal platform and slid off under test con-ditions until the end of the fabric drops to an angle of 41 1/2 below the plane of the surface of the platform. The material is tested under standard conditions as set forth in the Federal Test Method Standard 191. Other test procedures may be used but the increase in relative stiffness of the em-bossed felt over the unembossed felt is one characteristic of a satisfactorily embossed felt hemostat.
If the felt is not needled, but merely the air laid web is used, it is somewhat more fle~ible than if needled but after embossing under heat using either a diamond or a burlap embossing roll, the felt is compressed and is a satisfactory hemostat.
Another measure of the effect of the heat embossing is the air permeability. The air permeability is conveniently measured by the standard method of test for air permeability of textile fabrics, AS~M Standards Designation D 737-69 (Oct. 3, 1969). In this method under standard conditions, air at a pressure of 0.5 inches of water is flowed through an orifice over which the fabric is finely spread, usually having a diameter of 2.75", and the rate of air flow is ex-pressed conveniently in cubic feet of air per minute per sguare foot of fabric at the pressure differential of 0.5"
of water. A Gurley Permeometer is one satisfactory device for this test method, and uses a guard ring to avoid leakage through the edges of the fabric. As shown below, the heat embossed fabric has a markedly lower air permeability than the felt before the heat embossing.
Conveniently, but not necessarily, the embossing roll has a plurality of small diamond-shaped engravings therein so that the fabric is embossed with a series of lines di-viding the felt surface into diamond-shaped raised portions.
24,2~ ~
Another good embossing roll has a configuration of the surface approximately that of burlap so that the finished felt has a general configuration of burlap. Other patterns may be used.
The effect of the embossing of the pressure roll is to give areas of different compression which gives a texture to the surface, improves the flexibility, and gives excellent control to the permeation of blood.
As a surgical device, it is obviously desirable, almost mandatory, that the hemostatic felt be sterile at the time of use. ~he felt may be sterilized by an appropriate sterilizing cycle using ethylene oxide as a sterilizing agent.
If ethylene oxide is used to sterilize, it is convenient that the ethylene oxide be diluted with carbon dioxide or a chloro-fluoroalkane to such an extent that the sterilizing gas is non-explosive. Radiation sterilization or heat sterilization may be used, where equipment for such processes is available.
For storage stability, it is desirable that the felt hemostat be protected from atmospheric influences. Parti-cularly, if the hemostatic felt contains hydrolyzable poly-glycolic acid ester linkages, the linkages can be hydrolyzed by ambient moisture under room storage. Because the strength reguirement for felt is comparatively low, a certain degree of degradation is acceptable and because the long time strength reguirement in tissue is very low, even if degraded to the point that the tissue absorbable fibers are absorbed in a comparatively short period of time, that is, under a few days, the surgical felt is still acceptable. It is de-sirable that such storage conditions be used so as to main-tain the hemostatic felt in a dry environment so that whether used immediately after packaging or after a storage period of several years, the felt has the same characteristics and, 24, ~8~
hence, has known predictable attributes as far ~s the using surgeon is concerned.
A good method o~ sterilizing and storage is the same as is used for polyglycolic acid sutures on a commercial scale and as disclosed in U. S. Patent 3,728,839, Arthur ~lick, April 24, 1973, S~ORAGE STABL~ SURGICA~Y ABSORBAB~
POLYGLYCOLIC ACID PRODUC~S. As there described, the polygly-colic acid product is stored in a moisture proof envelope in which conveniently the product is packaged except for one open side and sterilized using ethylene oxide diluted so as to be non-explosive, and then while protecting sterility, the product is vacuum dried and the envelope sealed. By having the foil envelope hermetically sealed, as there taught, the hemostatic felt may be maintained in a usable form with con-sistent characteristics for a period of at least several years.
Conveniently, but not necessarily, the felt may be placed be-tween two sheets of paper, or a single sheet of paper with a fold, so that the felt is held in flat condition between the sheets during storage and service to the using surgeon.
For large sheets, the felt may be folded but for sheets up to 4" x 6" it is conveniently placed in an envelope large enough to hold the sheet flat. A plurality of sheets may be packaged in a single envelope if desired. Single sheets of about 4" x 6" are a surgically acceptable size, with the felt being cut to size by the surgeon, or an assistant, at the time of use. For many surgical procedures a single sheet is all that is required.
A double envelope, as described in 3,728,839, supra, is very convenient, and follows the techniques used in suture packages. The double envelope enables the sterile service of a sealed envelope, so that the surgeon or an assistant can open the inner envelope in a sterile area.
`` 1062573 A single envelope such as shown in United States Patent 3,017,990, Singerman, January 23, 1962, STERILE PAC~GE FOR
SURGICAL FABRIC, is also an economical and efficient package.
The inner paper wrap maintains the sterility of the felt until used by the surgeon.
The part, improvement or combination which is claimed as the invention herein comprises a hemostatic surgical felt comprising a sterile felt of fibers of 0.5 to 12 denier and 1/4 to 3 inch length of a tissue absorbable polymer subject to hydro-lytic degradation to non-toxic tissue compatible absorbable com-ponents, and which polymer has glycolic acid ester linkages, which felt has textured and partially compressed heat embossed surfaces, a weight of 0.5 to 4 ounces per square yard, a stiff-ness of 1.05 to 1.~3 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2 and which before embossing is too fragile for stiffness measurement, whereby the rate of penetra-tion of blood is reduced, and the adhesion to bleeding surfaces enhanced, and which is completely absorbed when enclosed in living tissue. The tissue absorbable polymer may be polyglycolic acid. Also claimed as the invention herein is a method of mak-ing a hemostatic surgical felt, having a textured and partially compressed heat embossed surface, of a tïssue absorbable polymer as described above, characterized by: melt spinning a tissue absorbable polymer into fibers of 0.5 to 12 denier, and cutting into segments of from about 1/4 to 3 inches in length, randomly laying said fibers into a mat having a uniform density of from 0.5 to 4 ounces per square yard, heating and compressing between heated embossing rolls, at least one of which has a textured surface to emboss said mat and bind the fibers to form a felt ~ - 14 --`- 1062S73 having a stiffness of 1.05 to 1.83 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2 and which before embossing is too fragile for stiffness measurement, and an air permeability of about 135 cubic feet per minute per square foot at 0.5 inches of water pressure differential and which before embossing has an air permeability of about 360 cubic feet per minute per square foot at 0.5 inches of water pressure differ-ential, cutting to form individual felt hemostats, and, in any order, packaging in contamination resistant packages, and sterilizing. In the method, the fibres may be air laid into a felt, and the individual felt hemostats may be packaged in mois-ture proof strippable packages, and sterilized by ethylene oxide.
THE DRAWINGS
In the attached drawings:
FIGURE 1 shows a diamond embossing pattern at an optical magnification of about 10 diameters;
FIGURE 2 shows a razor cut cross section of the embossed surgical felt of FIGURE 1, at 10 diameters optical magnification.
FIGURE 3 shows an embossed surgical felt with a burlap pattern, at 10 diameters optical magnification.
FIGURE 4 shows the embossed surgical felt of FIGURE 3 in a razor cut cross section, at 10 diameters optical magnific-ation.
FIGURE 5 is a composite scanning electron microscope photomicrograph at 30 diameters. The left side 5A shows the embossed felt. The right side 5B shows the air laid felt before embossing.
FIGURE 6 is a drawing showing the embossed felt hemostat in a double envelope.
Il ~ - 14a -,i lO~;Z573 FIGURE 7 is a drawing in pictorial, partly broken away showing the embossed felt hemostat in an envelope.
FIGURE 8 is a scanning electron microscope photo-micrograph at lOO diameters of the diamond embossed felt.
FIGURE 9 is a scanning electron microscope photo-micrograph at lOO diameters of an unembossed felt.
~ lhile the present invention is defined by the appended claims, it is illustrated by the following examples of specific constructions and usages of the present embossed surgical felt.
- 14b -24~86 --` 106Z573 Example 1 Polyglycolic acid having an inherent viscosity of about 1.05 was extruded into fibers of approximately 2 denier per filament using the following technique. 100 parts of re-crystallized glycolide (melting point 85.0 to 85.5C.) are intimately mixed with 0.02 part of methoxyacetic acid, 0.03 part of phenoldisulfide (Santo-Nox), and 0.03 part antimony trifluoride. Separate glass tubes are each charged with approximately 20 grams of the mixture, deoxygenated by re-peated evacuation and argon purging, then sealed under vacuum and heated to 185 to 190C. for 4 1/2 hours. On cooling a white opaque tough polyglycolic acid is produced in a 97.5%
yield with a melt viscosity at 245C. of 5,000 poises. The polymer is reheated and spun into fibers at a temperature of about 230C. at a speed of about 150 feet per minute. The fibers produced are cooled, then drawn at about 55C. When drawn to five times the original length a strong tough fiber is produced.
The continuous filaments are chopped into lengths of 1 1/2", fed into an air blast, suspended in air, and allow-ed to fall randomly onto a sheet of paper to a uniform den-sity of 2.25 oz. per square yard. The felt was then run under an embossing roll with the embossing roll having an engraved figured pattern of diamonds with about a 3/32" spacing. The felt was compressed against a nylon backing roll, with the embossing roll being operated at a temperature of 345-355F., a pressure of 1050 pounds per linear inch, and a speed of 15 feet per minute. After passing the free face of the felt under the embossing roll, the felt was turned ovre, the sup-port paper removed, and the felt passed again under the embos-sing roll to emboss the second side.
~ - 15 -'~4~ \
2~-286 " 106~73 FIGURES 1, 2, 5A, and 8 are of the thus heat embos-sed felt.
FIGURE 2 shows a cross section at a magnification of about 10 diameters.
FIGURES 5A and 5B show the felt for a hemostat be-fore and after embossing. The figure at the right, 5~, is of the air laid web showing the individual fibers in random configuration as a comparatively thick soft felt. FIGURE 5A
shows the same felt which has been heat embossed which re-sults in heating to incipient fusion and pressing together the felt along certain lines so that the individual fibers adhere to each other giving a compacted zone which aids in keeping the felt hemostat thin, aids in preventing the later-al transfer of liquids, and gives a desirable stiffne~s to the structure.
15a -i ,' 2~ 6 ~he picture is at a magnification of 30 diameters and is taken with a scanning electron microscope which gives far greater depth of focus than an optical system. FIGURES 8 and 9 are similar photographs with an electron microscope showing the embossed and unembossed felt at about 100 dia~eters en-largement. The mashing together and fusion of the indivi-dual fibers can be seen in FIGURE 8. FIGURE 9 shows a random - unoriented structure before the heat embossing. Before heat embossing, the fibers are springy and tend to stand up so that the felt has a soft fuzzy finish so that it is impracti-cal to attempt to measure its thickness.
A similar section of the felt was run under the same speed and pressure conditions at the same temperature with an embossed roll having a burlap configuration. This gives to the surface of the felt the configuration resembling that of burlap. ~his is shown in FIGURES 3 for a face view and FIGURE 4 for a cross section, at about 10 diameters.
Sections of the felt were cut to approximately
FIGURE 2 shows a cross section at a magnification of about 10 diameters.
FIGURES 5A and 5B show the felt for a hemostat be-fore and after embossing. The figure at the right, 5~, is of the air laid web showing the individual fibers in random configuration as a comparatively thick soft felt. FIGURE 5A
shows the same felt which has been heat embossed which re-sults in heating to incipient fusion and pressing together the felt along certain lines so that the individual fibers adhere to each other giving a compacted zone which aids in keeping the felt hemostat thin, aids in preventing the later-al transfer of liquids, and gives a desirable stiffne~s to the structure.
15a -i ,' 2~ 6 ~he picture is at a magnification of 30 diameters and is taken with a scanning electron microscope which gives far greater depth of focus than an optical system. FIGURES 8 and 9 are similar photographs with an electron microscope showing the embossed and unembossed felt at about 100 dia~eters en-largement. The mashing together and fusion of the indivi-dual fibers can be seen in FIGURE 8. FIGURE 9 shows a random - unoriented structure before the heat embossing. Before heat embossing, the fibers are springy and tend to stand up so that the felt has a soft fuzzy finish so that it is impracti-cal to attempt to measure its thickness.
A similar section of the felt was run under the same speed and pressure conditions at the same temperature with an embossed roll having a burlap configuration. This gives to the surface of the felt the configuration resembling that of burlap. ~his is shown in FIGURES 3 for a face view and FIGURE 4 for a cross section, at about 10 diameters.
Sections of the felt were cut to approximately
3 x 51~ and placed in a sheet of glassine paper folded to en-close the embossed felt with a slight margin all around. ~hefelt in the folded paper was placed in a slightly larger en-velope of foil stock of the type as described in Patent 3~728~839~ supra, and the slightly open envelope, arranged to be sealed by parallel sealing clamps across the open face, 25 was placed in an ethylene oxide oven, evacuated, 12% ethylene oxide in 88% dichlorodifluoromethane passed into the oven and allowed to stand for two hours, the oven was again evacu-ated, and held under vacuum until the ethylene oxide and any moisture was removed, and then the vacuum broken with dry nitrogen. Using precautions to preserve sterility, the en-velope was then sealed across the open end, packaged in a larger strippable envelope, the inter envelope space sterilized 24,286 ~06Z573 and the thus doubly packaged absorbable surgical felt was storage stable and ready for use. As so packaged, the material will retain its characteristics for periods of at least several years and probably much longer. ~ests conducted to date have not established the end of its useful life.
Such a package is shown in FIGURES 6 and 7 in which the hemostatic felt 11 is shown in a folded paper shield 12 with the paper shield extending slightly beyond the hemostatic felt on all sides and the paper shield in an inner moisture proof envelope 13. The inner moisture proof envelope in turn is sealed in a strippable outer envelope 14. The use of a paper shield in an outer envelope is shown in U. S. Patent 3,017,990, Singerman, STERILE PACKAGE FOR SURGICAL FABRIC, January 23, 1962. The sterilizing cycle and double envelope, including descriptions of materials of construction, for polyglycolic acid products, is set forth in detail in U. S.
3,728,839, supra.
Example 2 A fast screening test for a hemostat is the rabbit "vena cava test" in which a slit approximately a quarter of an inch is formed longitudinally in the vena cava of a rabbit, the hemostat material placed over the opening and held by the finger of the surgeon for approximately 15 seconds, after which as the finger is removed, the hemostat is examined to see if it stops the flow of blood. The present hemostat with either the diamond or burlap embossing passes this test.
~x~
Stiffness and air Porosit~ of hemostat Using the procedure of Method of 5206 of Federal Test Method Standard 191, sections of embossed felt were 3o tested by placing them on the test stand and extending out until the end of the specimen dropped to an angle of 41 i/20.
24,286 ~he drape stiffness is reported as 1/2 the length of the over-hang of the specimen when it reaches 41 1/2 slope.
In the material of Example 1 this is found to be:
Diamond embossed:
Horizontal (machine direction) 1.05 inches Vertical (perpendicular to machine direction) 1.15 inches Burlap embossed:
Horizontal 1.35 inches Vertical 1.83 inches Unembossed web:
~oo fragile to be measured.
Similar tests were run following ASTM Method D-737-69 for air permeability. ~he results are reported as cubic feet per minute per square foot of fabric at 0.5" water pressure differential:
Diamond embossed:
2.25 oz. per square yard, air permeability 133 cubic feet per minute per sguare foot of fabric at 0.5" water pressure differ-ential.
Burlap embossed:
2.25 oz. per square yard, air permeability 135 cubic feet per minute per sguare foot f fabric at 0 5 water pressure differen-tial.
Unembossed web:
2.25 oz. per square yard, air permeability 360 cubic feet per minute per square foot of fabric at 0.5" water pressure differen-3o tial.
24j286 ~xample 4 Hepatectomies Sub-total hepatectomies were performed on a total of 15 randomly sexed New Zealand white rabbits weighing two to three Xg. The operation w~s as follows:
The animals were anesthetized with sodium pento-barbital intravenously. The abdomen was shaved and a trans-verse incision made just posterior to the costal margin to expose the liver. The right medial, left medial, and left lateral liver lobes were identified, a Stockman penis clamp placed on each of two or three of the lobes as close to the hilum as possible, and the lobe excised distal to the clamp.
The clamp was removed and bleeding proceeded until it stopped spontaneously or the animal expired. If the animal was alive when bleeding stopped, the laparotomy was repaired in the usual manner and the animal returned to its cage. The animal was protected with one ml. of penicillin and dihydrostrepto-mycin administered intro-muscularly as a prophylactic measure.
Similarly, groups of ten rabbits of about the same weight and randomly sexed were tested using the polyglycolic acid hemostat of ~xample l; an absorbable gelatin foam, an absorbable oxidized regenerated cellulose knit; and mattress sutures of 2/0 chromic surgical gut. Twenty to thirty percent of the liver was removed in each case and with the hemostats, the appropriate material was cut to a size slightly larger than the cut surface and secured with two or three stay sutures of 5/0 polyglycolic acid placed through the parenchyma about 5 mm. below the cut and tied with surgeons' knots on top of the material. The clamp was then removed. ~he sur~ace 3 area covered varied from animal to animal, but was about 12-13 square cm. For the suture group, two or three mattress sutures were placed parallel to the cut surface and knotted 24,286 1(~6ZX73 on the ventral surface of the lobe.
The laparotomy incisions were closed with 3/0 poly-glycolic acid sutures in the standard manner and the animals returned to cages without further treatment.
Results Of the animals without hemostatic treatment, 7~Yo died between six minutes and twelve hours after surgery.
- Of the hemostats, the effectiveness was somewhat similar in all groups. After the clamp release, there was usually some minor oozing from around the edges for a short time. Seldom was there any leakage of blood through the ma-terial. ~he polyglycolic acid felt hemostat, on contact with the blood, became translucent but was otherwise unchanged in appearance and dimension. ~he gelatin foam became swollen as its interstices filled with blood. ~he oxidized regenerated cellulose turned black and acquired a gelatinous consistency.
The gelatin foam had to be pretreated by wetting the saline, squeezing out, rewetting and resqueezing, which is time consuming and the material is limp and pasty such that it sticks to instruments and gloves. ~he knitted oxidized regenerated cellulose shredded at the edges and also stuck to instruments and gloves. ~he mattress sutures were diffi-cult to place tightly enough to stop bleeding without tearing through the liver capsule.
Results With the polyglycolic acid felt hemostat, there was no evidence of post-operative hemorrhage or unusual gross pathologic finding. Gross findings included minor focal infarction directly beneath the material and some of the hemostat was stained with bile but there was no evidence of peritoneal irri-tation due to bile leakage. At ~5 days focal necrosis was largely resolved and the polyglycolic acid 24,286 showed some absorption.
At 30 days very little of the polyglycolic acidfelt hemostat was grossly identifiable and tissue response was unremarkable.
At 60 and 90 days the reaction was unremarkable except for a thin fibrous coating at the operative sites and regeneration of liver.
One animal in the group never recovered from anes-thesia. There was no evidence of hemorrhage at the operative site.
Under similar conditions using the gelatin foam, at 3 days the implant was engorged with blood and bile and there was minor sub-implant infarction. ~he reaction at 7 days was similar but more diffuse.
At 15 days reaction was characterized by fibroplasis at the operative site, areas of focal necrosis, and bile cysts.
The gelatin foam was largely intact.
~ he gelatin foam appeared to be absorbed by about 30 days although there were bile cysts in one of the animals and fiberplasia.
Sixty and 90 day reactions showed resolution of the above findings with liver regeneration. At 60 days, partially resorbed clots were found in the abdomen of one animal and bile cysts in the other. ~wo animals were found dead of pulmonary congestion and edema secondary to anesthesia overdose. No evidence of post-operative hemorrhage was noted.
Oxidized Re~enerated Cellulose ~he three day findings included minor focal self-3 -implant infarction and blood clot distal to the oxidized regenerated cellulose implant indicating post-operative bleeding through the material.
24,2~6 The seven day reaction was similar.
The findings for fifteen days was similar to those of three and seven days. In addition, there was inflammatory exudate into some intra-hepatic spaces, fibroplasia and partially resorbed clots. The oxidi%ed regenerated cellulose appeared to be about 50% absorbed. The findings at 30, 60, and 90 days were largely unremarkable, except for traces of the regenerated cellulose in the 60 and 90 day animals.
Sutures as Hemostats With the sutures, there was severe hepatic infarc-tions surrounding the mattress sutures at three days, and at seven days the findings were similar. At 15 through 90 days there was progressive resolution of the above responses. One animal was found dead on the fourth day from a technical error unrelated to the liver injury. Another was found dead on the first day with large clots on the liver and serosan-guinous fluid throughout the abdomen.
It appears that although there were 73% deaths from the liver injury when untreated, when treated with the poly-glycolic acid hemostatic felt, or the gelatin foam, or theregenerated oxide cellulose, there were no deaths attributable to hemorrhage. The embossed non-woven polyglycolic felt com-pared favorably with the conventional materials used for treatment. ~here appeared to be less post-operative bleeding using the embossed non-woven polyglycolic acid felt.
~ rom the standpoint of performance in surgery, the embossed non-woven polyglycolic acid felt did not stick to instruments or gloves, maintained its integrity better, and could be handled, manipulated, and repositioned when wet 3o without tearing or sticking to the instruments. The material was stiff enough that it could be sutured if desired, and used as a bolster.
24,2~6 xample 5 ~ amples of the polyglycolic acid embossed hemostatic felt were tested in neuro-surgery on the brains of test ani-mals. Small portions of the hemostatic felt were placed on the surfaces of the brain where hemorrhage was observed and held in place by the finger of the surgeon. A fine suction tube was used to remove blood which oozed through the hemostat or around the hemostat. After a short period, the flow of blood was effectively controlled with very little blood being absorbed in the hemostatic felt because it had been removed by suction. The flow of blood into and around the felt could be readily observed during the operating procedure. By con-trast, when a gelatin foam is used for the same procedure, it is customary to hold it in place with a pad of cotton which prevents ready observation and interferes with removal of blood and introduces the possibility of cotton fibers being trapped within the wound. On closing the embossed non-woven polyglycolic acid felt hemostat within the wound, there ap-peared to be minimal risk of hemorrhage and recovery was un-eventful. Autopsy showed no hemorrhage and rapid absorptionof the polyglycolic acid felt within the animal and a minimal of interference with the healing of the wound.
In humans, where the brain or other neural tissue was damaged, the present embossed polyglycolic acid surgical felts are found to give good hemostasis and permit regenera-tion at least as rapidly as more conventional surgical proced-ures.
The denier per filament, the thickness of the felt sponge, its stiffness, and handling characteristics can be varied by using different size filaments, different lengths of filaments and different temperatures and pressure during the embossing operation to present felts with a thickness 24,2~6 1C~62~S73 and stiffness which is preferred by a surgeon in connection with a specific operating procedure. As different surgeons have different preferences and there is a wide variation of surgical procedures in which hemostasis is desired, a range of thicknesses and stiffnesses may be provided.
Usually, the sponge of Example 1 is sufficiently versatile to cover most operative procedures and most surgeons' preferences and, hence, permits effective wide range hemo-stasis with a minimum of inventory and supply problems.
Such a package is shown in FIGURES 6 and 7 in which the hemostatic felt 11 is shown in a folded paper shield 12 with the paper shield extending slightly beyond the hemostatic felt on all sides and the paper shield in an inner moisture proof envelope 13. The inner moisture proof envelope in turn is sealed in a strippable outer envelope 14. The use of a paper shield in an outer envelope is shown in U. S. Patent 3,017,990, Singerman, STERILE PACKAGE FOR SURGICAL FABRIC, January 23, 1962. The sterilizing cycle and double envelope, including descriptions of materials of construction, for polyglycolic acid products, is set forth in detail in U. S.
3,728,839, supra.
Example 2 A fast screening test for a hemostat is the rabbit "vena cava test" in which a slit approximately a quarter of an inch is formed longitudinally in the vena cava of a rabbit, the hemostat material placed over the opening and held by the finger of the surgeon for approximately 15 seconds, after which as the finger is removed, the hemostat is examined to see if it stops the flow of blood. The present hemostat with either the diamond or burlap embossing passes this test.
~x~
Stiffness and air Porosit~ of hemostat Using the procedure of Method of 5206 of Federal Test Method Standard 191, sections of embossed felt were 3o tested by placing them on the test stand and extending out until the end of the specimen dropped to an angle of 41 i/20.
24,286 ~he drape stiffness is reported as 1/2 the length of the over-hang of the specimen when it reaches 41 1/2 slope.
In the material of Example 1 this is found to be:
Diamond embossed:
Horizontal (machine direction) 1.05 inches Vertical (perpendicular to machine direction) 1.15 inches Burlap embossed:
Horizontal 1.35 inches Vertical 1.83 inches Unembossed web:
~oo fragile to be measured.
Similar tests were run following ASTM Method D-737-69 for air permeability. ~he results are reported as cubic feet per minute per square foot of fabric at 0.5" water pressure differential:
Diamond embossed:
2.25 oz. per square yard, air permeability 133 cubic feet per minute per sguare foot of fabric at 0.5" water pressure differ-ential.
Burlap embossed:
2.25 oz. per square yard, air permeability 135 cubic feet per minute per sguare foot f fabric at 0 5 water pressure differen-tial.
Unembossed web:
2.25 oz. per square yard, air permeability 360 cubic feet per minute per square foot of fabric at 0.5" water pressure differen-3o tial.
24j286 ~xample 4 Hepatectomies Sub-total hepatectomies were performed on a total of 15 randomly sexed New Zealand white rabbits weighing two to three Xg. The operation w~s as follows:
The animals were anesthetized with sodium pento-barbital intravenously. The abdomen was shaved and a trans-verse incision made just posterior to the costal margin to expose the liver. The right medial, left medial, and left lateral liver lobes were identified, a Stockman penis clamp placed on each of two or three of the lobes as close to the hilum as possible, and the lobe excised distal to the clamp.
The clamp was removed and bleeding proceeded until it stopped spontaneously or the animal expired. If the animal was alive when bleeding stopped, the laparotomy was repaired in the usual manner and the animal returned to its cage. The animal was protected with one ml. of penicillin and dihydrostrepto-mycin administered intro-muscularly as a prophylactic measure.
Similarly, groups of ten rabbits of about the same weight and randomly sexed were tested using the polyglycolic acid hemostat of ~xample l; an absorbable gelatin foam, an absorbable oxidized regenerated cellulose knit; and mattress sutures of 2/0 chromic surgical gut. Twenty to thirty percent of the liver was removed in each case and with the hemostats, the appropriate material was cut to a size slightly larger than the cut surface and secured with two or three stay sutures of 5/0 polyglycolic acid placed through the parenchyma about 5 mm. below the cut and tied with surgeons' knots on top of the material. The clamp was then removed. ~he sur~ace 3 area covered varied from animal to animal, but was about 12-13 square cm. For the suture group, two or three mattress sutures were placed parallel to the cut surface and knotted 24,286 1(~6ZX73 on the ventral surface of the lobe.
The laparotomy incisions were closed with 3/0 poly-glycolic acid sutures in the standard manner and the animals returned to cages without further treatment.
Results Of the animals without hemostatic treatment, 7~Yo died between six minutes and twelve hours after surgery.
- Of the hemostats, the effectiveness was somewhat similar in all groups. After the clamp release, there was usually some minor oozing from around the edges for a short time. Seldom was there any leakage of blood through the ma-terial. ~he polyglycolic acid felt hemostat, on contact with the blood, became translucent but was otherwise unchanged in appearance and dimension. ~he gelatin foam became swollen as its interstices filled with blood. ~he oxidized regenerated cellulose turned black and acquired a gelatinous consistency.
The gelatin foam had to be pretreated by wetting the saline, squeezing out, rewetting and resqueezing, which is time consuming and the material is limp and pasty such that it sticks to instruments and gloves. ~he knitted oxidized regenerated cellulose shredded at the edges and also stuck to instruments and gloves. ~he mattress sutures were diffi-cult to place tightly enough to stop bleeding without tearing through the liver capsule.
Results With the polyglycolic acid felt hemostat, there was no evidence of post-operative hemorrhage or unusual gross pathologic finding. Gross findings included minor focal infarction directly beneath the material and some of the hemostat was stained with bile but there was no evidence of peritoneal irri-tation due to bile leakage. At ~5 days focal necrosis was largely resolved and the polyglycolic acid 24,286 showed some absorption.
At 30 days very little of the polyglycolic acidfelt hemostat was grossly identifiable and tissue response was unremarkable.
At 60 and 90 days the reaction was unremarkable except for a thin fibrous coating at the operative sites and regeneration of liver.
One animal in the group never recovered from anes-thesia. There was no evidence of hemorrhage at the operative site.
Under similar conditions using the gelatin foam, at 3 days the implant was engorged with blood and bile and there was minor sub-implant infarction. ~he reaction at 7 days was similar but more diffuse.
At 15 days reaction was characterized by fibroplasis at the operative site, areas of focal necrosis, and bile cysts.
The gelatin foam was largely intact.
~ he gelatin foam appeared to be absorbed by about 30 days although there were bile cysts in one of the animals and fiberplasia.
Sixty and 90 day reactions showed resolution of the above findings with liver regeneration. At 60 days, partially resorbed clots were found in the abdomen of one animal and bile cysts in the other. ~wo animals were found dead of pulmonary congestion and edema secondary to anesthesia overdose. No evidence of post-operative hemorrhage was noted.
Oxidized Re~enerated Cellulose ~he three day findings included minor focal self-3 -implant infarction and blood clot distal to the oxidized regenerated cellulose implant indicating post-operative bleeding through the material.
24,2~6 The seven day reaction was similar.
The findings for fifteen days was similar to those of three and seven days. In addition, there was inflammatory exudate into some intra-hepatic spaces, fibroplasia and partially resorbed clots. The oxidi%ed regenerated cellulose appeared to be about 50% absorbed. The findings at 30, 60, and 90 days were largely unremarkable, except for traces of the regenerated cellulose in the 60 and 90 day animals.
Sutures as Hemostats With the sutures, there was severe hepatic infarc-tions surrounding the mattress sutures at three days, and at seven days the findings were similar. At 15 through 90 days there was progressive resolution of the above responses. One animal was found dead on the fourth day from a technical error unrelated to the liver injury. Another was found dead on the first day with large clots on the liver and serosan-guinous fluid throughout the abdomen.
It appears that although there were 73% deaths from the liver injury when untreated, when treated with the poly-glycolic acid hemostatic felt, or the gelatin foam, or theregenerated oxide cellulose, there were no deaths attributable to hemorrhage. The embossed non-woven polyglycolic felt com-pared favorably with the conventional materials used for treatment. ~here appeared to be less post-operative bleeding using the embossed non-woven polyglycolic acid felt.
~ rom the standpoint of performance in surgery, the embossed non-woven polyglycolic acid felt did not stick to instruments or gloves, maintained its integrity better, and could be handled, manipulated, and repositioned when wet 3o without tearing or sticking to the instruments. The material was stiff enough that it could be sutured if desired, and used as a bolster.
24,2~6 xample 5 ~ amples of the polyglycolic acid embossed hemostatic felt were tested in neuro-surgery on the brains of test ani-mals. Small portions of the hemostatic felt were placed on the surfaces of the brain where hemorrhage was observed and held in place by the finger of the surgeon. A fine suction tube was used to remove blood which oozed through the hemostat or around the hemostat. After a short period, the flow of blood was effectively controlled with very little blood being absorbed in the hemostatic felt because it had been removed by suction. The flow of blood into and around the felt could be readily observed during the operating procedure. By con-trast, when a gelatin foam is used for the same procedure, it is customary to hold it in place with a pad of cotton which prevents ready observation and interferes with removal of blood and introduces the possibility of cotton fibers being trapped within the wound. On closing the embossed non-woven polyglycolic acid felt hemostat within the wound, there ap-peared to be minimal risk of hemorrhage and recovery was un-eventful. Autopsy showed no hemorrhage and rapid absorptionof the polyglycolic acid felt within the animal and a minimal of interference with the healing of the wound.
In humans, where the brain or other neural tissue was damaged, the present embossed polyglycolic acid surgical felts are found to give good hemostasis and permit regenera-tion at least as rapidly as more conventional surgical proced-ures.
The denier per filament, the thickness of the felt sponge, its stiffness, and handling characteristics can be varied by using different size filaments, different lengths of filaments and different temperatures and pressure during the embossing operation to present felts with a thickness 24,2~6 1C~62~S73 and stiffness which is preferred by a surgeon in connection with a specific operating procedure. As different surgeons have different preferences and there is a wide variation of surgical procedures in which hemostasis is desired, a range of thicknesses and stiffnesses may be provided.
Usually, the sponge of Example 1 is sufficiently versatile to cover most operative procedures and most surgeons' preferences and, hence, permits effective wide range hemo-stasis with a minimum of inventory and supply problems.
Claims (5)
1. A hemostatic surgical felt comprising a sterile felt of fibers of 0.5 to 12 denier and 1/4 to 3 inch length of a tissue absorbable polymer subject to hydrolytic degrada-tion to non-toxic tissue compatible absorbable components, and which polymer has glycolic acid ester linkages, which felt has textured and partially compressed heat embossed sur-faces, a weight of 0.5 to 4 ounces per square yard, a stif-fness of 1.05 to 1.83 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2° and which before embossing is too fragile for stiffness measurement, whereby the rate of penetration of blood is reduced, and the adhesion to bleed-ing surfaces enhanced, and which is completely absorbed when enclosed in living tissue.
2. The hemostatic felt of Claim l in which the tis-sue absorbable polymer is polyglycolic acid.
3. A method of making a hemostatic surgical felt, having a textured and partially compressed heat embossed sur-face, of a tissue absorbable polymer of Claim 1 characterized by:
melt spinning a tissue absorbable polymer into fibers of 0.5 to 12 denier, and cutting into segments of from about l/4 to 3 inches in length, randomly laying said fibers into a mat having a uniform density of from 0.5 to 4 ounces per square yard, heating and compressing between heated embossing rolls, at least one of which has a textured surface to emboss said mat and bind the fibers to form a felt having a stif-fness of 1.05 to 1.83 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2° and which before embossing is too fragile for stiffness measurement, and an air permeability of about 135 cubic feet per minute per square foot at 0.5 inches of water pressure differential and which before embossing has an air permeability of about 360 cubic feet per minute per square foot at 0.5 inches of water pressure differential, cutting to form individual felt hemostats, and, in any order, packaging in contamination resistant packages, and sterilizing.
melt spinning a tissue absorbable polymer into fibers of 0.5 to 12 denier, and cutting into segments of from about l/4 to 3 inches in length, randomly laying said fibers into a mat having a uniform density of from 0.5 to 4 ounces per square yard, heating and compressing between heated embossing rolls, at least one of which has a textured surface to emboss said mat and bind the fibers to form a felt having a stif-fness of 1.05 to 1.83 inches, measured as one half the length of the overhang of a specimen on a flat horizontal surface which drops to an angle of 41 1/2° and which before embossing is too fragile for stiffness measurement, and an air permeability of about 135 cubic feet per minute per square foot at 0.5 inches of water pressure differential and which before embossing has an air permeability of about 360 cubic feet per minute per square foot at 0.5 inches of water pressure differential, cutting to form individual felt hemostats, and, in any order, packaging in contamination resistant packages, and sterilizing.
4. The method of Claim 3 in which the fibers are air laid into a felt.
5. The method of Claim 3 or 4 in which the individual felt hemostats are packaged in moisture proof strippable pack-ages, and sterilized by ethylene oxide.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/462,559 US3937223A (en) | 1974-04-19 | 1974-04-19 | Compacted surgical hemostatic felt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062573A true CA1062573A (en) | 1979-09-18 |
Family
ID=23836875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA224,500A Expired CA1062573A (en) | 1974-04-19 | 1975-04-14 | Compacted textured felt of tissue absorbable polymer |
Country Status (27)
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| US (2) | US3937223A (en) |
| JP (1) | JPS5829105B2 (en) |
| AT (1) | AT343821B (en) |
| AU (1) | AU499869B2 (en) |
| BE (1) | BE828135A (en) |
| BR (1) | BR7502011A (en) |
| CA (1) | CA1062573A (en) |
| CH (1) | CH614118A5 (en) |
| CS (1) | CS213324B2 (en) |
| DD (1) | DD118527A5 (en) |
| DE (1) | DE2515970A1 (en) |
| DK (1) | DK144553C (en) |
| ES (1) | ES436723A1 (en) |
| FR (1) | FR2267794B1 (en) |
| GB (1) | GB1453265A (en) |
| HU (1) | HU171852B (en) |
| IE (1) | IE41111B1 (en) |
| IL (1) | IL46934A (en) |
| IT (1) | IT1035318B (en) |
| NL (1) | NL7504645A (en) |
| PH (1) | PH11073A (en) |
| PL (1) | PL100801B1 (en) |
| RO (1) | RO70496A (en) |
| SE (1) | SE411299B (en) |
| SU (1) | SU691066A3 (en) |
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-
1974
- 1974-04-19 US US05/462,559 patent/US3937223A/en not_active Expired - Lifetime
-
1975
- 1975-03-21 ZA ZA00751805A patent/ZA751805B/en unknown
- 1975-03-25 AU AU79491/75A patent/AU499869B2/en not_active Expired
- 1975-03-26 IL IL46934A patent/IL46934A/en unknown
- 1975-04-03 BR BR2561/75A patent/BR7502011A/en unknown
- 1975-04-04 PH PH17017A patent/PH11073A/en unknown
- 1975-04-08 IE IE796/75A patent/IE41111B1/en unknown
- 1975-04-11 DE DE19752515970 patent/DE2515970A1/en not_active Withdrawn
- 1975-04-14 CA CA224,500A patent/CA1062573A/en not_active Expired
- 1975-04-14 GB GB1530675A patent/GB1453265A/en not_active Expired
- 1975-04-15 IT IT49108/75A patent/IT1035318B/en active
- 1975-04-15 DD DD185451A patent/DD118527A5/xx unknown
- 1975-04-16 CH CH484875A patent/CH614118A5/xx not_active IP Right Cessation
- 1975-04-16 HU HU75AE00000442A patent/HU171852B/en unknown
- 1975-04-17 AT AT294075A patent/AT343821B/en not_active IP Right Cessation
- 1975-04-17 YU YU00980/75A patent/YU98075A/en unknown
- 1975-04-18 RO RO7582022A patent/RO70496A/en unknown
- 1975-04-18 NL NL7504645A patent/NL7504645A/en not_active Application Discontinuation
- 1975-04-18 FR FR7512229A patent/FR2267794B1/fr not_active Expired
- 1975-04-18 ES ES436723A patent/ES436723A1/en not_active Expired
- 1975-04-18 CS CS752729A patent/CS213324B2/en unknown
- 1975-04-18 SE SE7504548A patent/SE411299B/en unknown
- 1975-04-18 DK DK168175A patent/DK144553C/en not_active IP Right Cessation
- 1975-04-18 PL PL1975179758A patent/PL100801B1/en unknown
- 1975-04-18 BE BE155570A patent/BE828135A/en not_active IP Right Cessation
- 1975-04-18 SU SU752133101A patent/SU691066A3/en active
- 1975-04-19 JP JP50048095A patent/JPS5829105B2/en not_active Expired
- 1975-11-03 US US05/628,029 patent/US4128612A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5829105B2 (en) | 1983-06-20 |
| FR2267794B1 (en) | 1979-06-29 |
| IE41111L (en) | 1975-10-19 |
| DK144553B (en) | 1982-03-29 |
| SE7504548L (en) | 1975-12-23 |
| ATA294075A (en) | 1977-10-15 |
| BR7502011A (en) | 1976-03-09 |
| GB1453265A (en) | 1976-10-20 |
| IL46934A0 (en) | 1975-05-22 |
| ES436723A1 (en) | 1977-05-01 |
| DD118527A5 (en) | 1976-03-12 |
| IE41111B1 (en) | 1979-10-24 |
| JPS50146182A (en) | 1975-11-22 |
| ZA751805B (en) | 1976-02-25 |
| CH614118A5 (en) | 1979-11-15 |
| DK144553C (en) | 1982-09-20 |
| PL100801B1 (en) | 1978-11-30 |
| DE2515970A1 (en) | 1975-10-30 |
| FR2267794A1 (en) | 1975-11-14 |
| CS213324B2 (en) | 1982-04-09 |
| PH11073A (en) | 1977-10-25 |
| AT343821B (en) | 1978-06-26 |
| NL7504645A (en) | 1975-10-21 |
| HU171852B (en) | 1978-04-28 |
| SE411299B (en) | 1979-12-17 |
| RO70496A (en) | 1981-07-30 |
| DK168175A (en) | 1975-10-20 |
| US3937223A (en) | 1976-02-10 |
| AU7949175A (en) | 1976-09-30 |
| IT1035318B (en) | 1979-10-20 |
| YU98075A (en) | 1982-05-31 |
| SU691066A3 (en) | 1979-10-05 |
| IL46934A (en) | 1978-03-10 |
| US4128612A (en) | 1978-12-05 |
| BE828135A (en) | 1975-10-20 |
| AU499869B2 (en) | 1979-05-03 |
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