«NEW ABSORBABLE HEMOSTATIC AGENTS* VIRGINIA KNEELAND FRANTZ Department of Surgery, College of Physicians and Surgeons, Columbia University, New York ...»
10 TH ULEI
NEW ABSORBABLE HEMOSTATIC
VIRGINIA KNEELAND FRANTZ
Department of Surgery, College of Physicians and Surgeons, Columbia University, New York
2ITH the end of combat in World War II the new hemo-
static agents developed in various research laboratories, developed under the pressure of the emergency, were almost ready for general surgical use. The preliminary 5isesesas~srsW experimental work had been done, clinical investigation had confirmed the laboratory reports and enough observers in general and special fields of surgery had tested the materials to appreciate the possibilities of a new technique for checking hemorrhage. The clinical investigation already done included trial by military surgeons, both British and American, in several theaters of operation. Fortunately, the carnage ceased earlier than some of us had dared hope, and before com- plete comparative studies of the different agents could be made in com- bat zones. In civilian surgery, critical evaluation of these new agents may take somewhat longer, as hemorrhage which makes packing man- datory is, happily, less commonly encountered in peace than in war.
The novelty of these agents, stressed in the title of this presentation, may be questioned. The need for staunching of blood goes back beyond history and many techniques have been tried, discarded, tried again and accepted. As an example of the aphorism that there is nothing new under the sun, it should be recalled that in i9ii Cushing, who, as a neuro- surgeon needs must be, was pre-occupied with hemostasis, not only advocated the use of muscle to accelerate clotting, thus anticipating thrombin, but also predicted that "fibrin from whipped blood might be so prepared that it could be immediately plastered on bleeding surfaces"
-which is just the application of fibrin foam. As to another "new" agent, oxidized cellulose, it may be that Halsted* encountered its fore- * The work described in this paper was done under a contract, recommended by the Committee on Medical Research, between the Office of Scientific Research and Development and Columbia University. The gauze and cotton were supplied by Eastman Kodak Research Laboratories, Roches.
ter, N. Y. (U. S. Pat. No. 2,232,990) through Parke, Davis and Company, Detroit, Michigan.
Presented October 16, 1945 before the Eighteenth Graduate Fortnight of The New York Academy of Medicine.
* This reference in Surgical Papers, William Stewart Halste(l, Baltimore, The Johns Hopkins Press, 1924, was brought to my attention by Dr. Jerome Webster.
New Absorbable Hemostatic Agents 03 I runner in 1879 for he writes that he observed that penghawar djambi was used quite frequently in the clinic of Billroth, particularly for checking hemorrhage in papillary cysts of the thyroid. This material consisted of the root hairs of the East Indian bullock tree and was said to be styptic. Certainly it was cellulose. Thus in the field of "new" materials, of the three selected for this discussion, only gelatin sponge deserves this adjective, and it seems wholly probable that careful study of the literature would turn up some early trial of this homely substance.
The impetus for the development of an absorbable hemostatic packing for lacerated vessels in a cavity or for application to surface oozetwo forms of bleeding which present somewhat different technical problems-came partly because of the development of thrombin, particularly the highly potent, purified, water-soluble form obtained from beef plasma by Seegers and his associates.' Their reports of its experimental use as a hemostatic spray appeared in 1938 and a year later it was used clinically with promising results. Again neurosurgeons were those most eager to develop a suitable technique for use of this aid to clotting.
Their cotton patties were more effective when soaked in thrombin, but difficulty still arose when the patties were removed. Needless to say, the clots which close torn or cut vessels, large or small, are those on which ultimate hemostasis and wound healing depend. If these clots, formed rapidly because of the additional enzyme activity of the thrombin, are stuck to the cotton patty, bleeding naturally begins again, however gently the patty is removed. There was need, therefore, for an absorbable patty which could be left in place.
The first answer to the absorbable carrier of thrombin was human fibrin foam. This was only one of many developments as a result of the large scale study of the fractionation of human blood plasma undertaken in the Department of Physical Chemistry of Harvard University. Plasma in amounts suitable for this project were, as is obvious, available because of the Red Cross blood donations. From this source, fibrin foam was separated and processed to form a dry, porous, brittle, cream-colored textile-if the term may be allowed. Another fraction was human thrombin, slightly less potent perhaps than the bovine form, but free of any suggestion of possible antigenicity. Extensive experimental trials in animals, mostly monkeys, were carried out, which confirmed the expectation that immediate control of bleeding from oozing surfaces could be achieved, that the wounds could be closed with impunity and that I104 THE B ULLETIN 10 H BLEI the foam would be absorbed with a minimum of inflammatory response and of residual scar.
Following this experimental work these two products of human blood were used together for hemostasis in neurosurgical procedures with highly gratifying results.2 Slight ooze in the closed cranial cavity may be a serious complication where a similar amount might scarcely impede wound healing elsewhere. The challenge of the absorbable carrier of thrombin had been met for this special field.
Controversy at once arose, as was to be expected, as to the advantage of thrombin of human origin. Theoretically it was to be expected that bovine thrombin might have antigenic properties for humans. The experimental laboratory studies on this point need not be discussed here.
The very large series of clinical cases in which bovine thrombin has been used without untoward effect, used in many instances more than once in the same patient, have led competent critics to feel that as it is employed it is without significant hazard.* It was an obvious sequence of thought, once the properties of fibrin foam had been demonstrated, that sources other than human blood might offer absorbable materials simpler in preparation, more readily available and equally effective. There was no priority in this concept, and a great many different substances were proposed. Some of these were irritating. Some preparations were unsuitable in texture, too friable, hard to moisten and difficult to handle. Many suggestions were made as to the possibility of combining not only antibacterial agents with the absorbable materials for an additional safeguard in the wound, but even growth promoting substances to speed wound healing. Imaginations ran riot at the possibility of achieving in one simple application a triple miracle-the control of bleeding, the prevention of infection and the acceleration of repair.
These proposals became at once the subject of intensive study at a pace somewhat more brisk than was always consistent with the highest scientific critique. With the new term "beach-head," the desire for quick practical hemostasis was obvious to laymen as well as to physicians. Much of the work was done in various institutions under OSRD contract. This, because of the policy of the Committee on Medical * On July 6, 1945 it was recommended by the Committee on Surgery of the National Research Council, Division of Medical Sciences acting for the Committee on Medical Research of the Office of Scientific Research and Development that bovine thrombin be made available to the armed forces.
New Absorbable Hemostatic Agents I 05 Research to disseminate information in related fields of study and so speed investigation and prevent duplication of effort, made it possible for one laboratory to receive and use as control materials under study elsewhere. It was for this purpose that Lattes devised a simple and reliable technique for testing aborbability and the irritant qualities of various substances in a small and inexpensive laboratory animal, the rat.
Unsuitable samples could be eliminated by this means and the more elaborate operative procedures in larger animals, monkeys and dogs, could be reserved for the promising materials.
The second absorbable substance to be considered in this presentation is one of those proposed somewhat later than others, much later than the absorbable cellulose which has been the subject of our own investigation at Columbia. At the suggestion of the Committee on Surgery we had the privilege of seeing this early in its development.
It is the gelatin sponge, or as it is now named to indicate its similarity to the human fibrin sponge, "Gelfoam." It was developed by Correll and Wise3 in the Upjohn Research Laboratories. Gelatin is denatured by a process not yet made public, so that it is rendered slowly absorbable.
The process prevents its immediate digestion in tissue fluids, but must not be carried too far or absorption is too long delayed. The satisfactory product is determined by the speed with which a standardized pepsin solution will dissolve a cube of the material. The finished sponge is a glistening white porous mass which is elastic and can be sterilized by autoclave. Moistened, it becomes absorbent and pliable.
When preliminary tests in rats had convinced the originators that the gelatin sponge was non-irritant and absorbable, experimental studies were then undertaken by Light.4 A series of craniotomies was performed in monkeys. Bleeding was initiated and then controlled. The animals were sacrificed at varying time intervals and the tissues were studied by Prentice. The gelatin sponge combined with bovine thrombin was found to be an effective hemostatic, easily handled and in general similar to fibrin foam in rate of absorbability and lack of significant tissue reaction. Our own experience with this material entirely confirmed these findings, as did Light's later clinical trial and the experimental and clinical investigations of Pilcher and Meacham,5 working under OSRD contract at Vanderbilt University. They report clinical trial of gelatin sponge and human thrombin in neurosurgery by sixteen surgeons working in eleven different clinics here and in Canada. In a total of 291 cases i o6 THE B ULLETIN BULLETIN there were eight unsatisfactory results. In 134 of these cases a comparison was made with fibrin foam.
It has seemed to us that one factor will influence the neurosurgeon's preference for one of these two carriers of thrombin, provided each is equally available. That factor is the ease of handling. Sterile thrombin solution must be made up in each case, constituting a time factor which, however, is of no consequence in a neurosurgical procedure of choice.
Some time is necessary to moisten the gelatin sponge and mold it to express air from its meshes. This, however, can also be done in advance of the moment when it is to be applied. Some of the fibrin foam preparations when wet have been more friable than others. The nature of the bleeding is a consideration which may influence the choice of material. The gelatin sponge has more body and in our hands packed somewhat more readily into freely bleeding deep lacerations. Both substances controlled surface ooze and became adherent with gratifying rapidity.
Our own investigation of oxidized cellulose-or, in more accurate chemical designation-cellulosic acid, began in 1941. For some years previous to this we had been searching for a non-irritating absorbable membrane to assist in the prevention of adhesions, particularly in the repair of a tendon in its sheath. A number of substances had been proposed by Dr. Hans Clarke, Professor of Biochemistry, College of Physicians and Surgeons, but had not been found suitable. He had been apprised, in advance of publication, of the work of Kenyon and his collaborators in the Research Laboratories of the Eastman Kodak Company where oxidized cotton had been produced. This had been prepared by oxidizing long-fibered cotton with nitrogen dioxide which resulted in the formation of carboxyl groups-COOH-in the long carbohydrate chain. The physical and chemical properties of the processed cotton depended on the length of time of oxidation. The texture was somewhat altered and the material was soluble in dilute alkali. In its present surgical form-and this is true of oxidized gauze also-it is soluble in dilute bicarbonate of soda, 0.15 Molar solution, approximately the pH of the blood.
In this early stage of investigation it was proposed for use as a blood substitute. Accordingly studies were undertaken by Kabat, but with disappointing results from the standpoint of the usefulness of this possible cheap substitute for plasma. The material, in solution, introduced New Absorbable Hemostatic Agents 07 I in large quantities directly into the blood stream of rabbits had no deleterious effects, but it was eliminated, unaltered, too rapidly through the kidneys to be useful. This constituted, however, a convincing proof of the harmlessness of the material to the organism as a whole. Whether or not it would prove irritating locally in the tissues remained to be investigated and it was this study which Dr. Clarke proposed to us.
In our preliminary observations, published in I943, small amounts of cotton, and later gauze and paper-all oxidized cellulose-were introduced into almost every tissue of the body in experimental animals.
Nowhere, except in bone was any untoward effect observed. In repair of a clean experimental wound of bone, or simple fracture, there was some delay in the early callus, as might be expected from the acidity of the material.
This demonstration of the absorbable and non-irritating properties of oxidized cellulose came just at the time when the hunt was on for carriers of thrombin. It was tried at once as such by Putnam of the Neurological Institute and later by Uihlein at the Mayo Clinic. Both authors reported favorably on it as an absorbable patty with thrombin added.