Pressure may be used along with styptics, or along with escharotics, actual or potential. They may be often employed when pressure ought not; styptics promote the contraction and retraction of the divided extremities, and thereby expedite the formation of a coagulum. Escharotics form a slough, which, adhering to the extremity of the vessel, stops the flow of blood, and the cut margins of the vessel, being stimulated by the application, soon cohere. Active stimulating applications merely cause effusion quickly of coagulated lymph, and thus often arrest hemorrhage from very vascular surfaces better than the so-called styptics. Not unfrequently, after the separation of the slough, it is found that union has not taken place, and hemorrhage is renewed; from this circumstance, the remedy cannot be trusted to, except when the divided vessels or vessel are of small size. It may be stated, generally, that these means are of little avail without methodical pressure. In oozing from small vessels, pressure may be applied by means of agaric, sponge, or lint. In bleeding from small vessels, where there is general oozing from the surface, and pressure cannot readily be made, applications tending to produce effusion of lymph—stimulants, such as turpentine or creosote, are often remarkably efficacious, and very speedily so; but in wounds of the larger vessels, the most efficient mean is a graduated compress of lint placed immediately on the external wound, and supported by a firmly-applied bandage. The bandage ought to encircle not only the wounded part, but every part of the limb with a uniform tightness, not so great as to arrest the general circulation; the parts are thereby supported, and engorgement prevented. This method, when employed previously to the effusion of much blood into the cellular tissue, has proved effectual in wounds even of the brachial, femoral, and carotid arteries. When blood has been extensively injected into the limb, when the aperture in the vessel has remained pervious, and when a large diffused aneurism exists, bandaging is worse than useless. By its application in such a case the limb becomes discoloured and swells extensively; there is a risk of mortification from impeded circulation. If a small quantity only of blood has escaped, its diffusion and increase may be prevented by the bandage: but a cyst will nevertheless be formed in the cellular tissue; its parietes will communicate with the margins of the aperture in the artery, its cavity with the canal of the vessel; an aneurism of the false kind will be established, and will run the course of one arising spontaneously.
A ligature, well applied, is the only means that can be relied on. The immediate effect of a tightly-drawn ligature is to avert the flow of blood, to divide the internal and middle coats at the deligated point, the cellular coat remaining entire, and to narrow the canal for some extent above the point at which it is applied. Coagulation then occurs within the vessel above the ligature, provided there is no collateral branch in the immediate vicinity. The ruptured margins of the internal coat effuse lymph and cohere; lymph is effused also in the cellular tissue, exterior to the artery and to the ligature; by the compression of the ligature, ulceration occurs in those parts which it envelopes, and the foreign body is discharged; but before this occurs the canal of the vessel has been obliterated by an internal coagulum, and by the effused lymph. Afterwards, the same absorption and consolidation occur as in a divided artery, the orifice of which has closed permanently and spontaneously.
When from a punctured wound profuse hemorrhage ensues, there is reason to suspect that an important vessel has been hurt, and the bleeding point must be sought for. After the artery giving out the blood has been discovered, the external wound must be enlarged, so as to expose the vessel, and admit of the convenient application of a ligature. It will not be sufficient to include the vessel above the wounded point, for the lower part will, after some time, be supplied with blood by the collateral branches almost as freely as by the large trunk, and, consequently, bleeding will be renewed. Two ligatures are to be employed, one above, the other below, the wound. The wounded vessel must be exposed, as already stated, but not detached more than is sufficient for the application of the ligature; and at the same time the ligatures ought to enclose nothing but the vessel. Neither ought the ligatures to be placed at any considerable distance, but as close to the wounded point as possible; otherwise circulation in the included part may be restored. The ligature, round, narrow, and firm, ought to be tightly applied. Cases of hemorrhage have occurred in which the tying of the vessel immediately above the wound has been successful; but these are few, and by no means afford any authority for the general adoption of such a measure. If the vessel is merely punctured, it is necessary to apply the ligature by means of a blunt pointed needle, and the parts are to be disturbed as little as possible. If, however, the artery is completely divided, its cut extremities are to be drawn out of their sheath by a hook or forceps, and the ligatures applied close to the connections of the vessel; the vasa vasorum, in the immediate vicinity of the deligated point, being left to carry on those processes by which obliteration is accomplished. In punctured or partial wounds of arteries, it deserves consideration whether the hemorrhage may not be restrained by the application of slight pressure, so regulated as to prevent the flow of blood laterally through the wound, but not so forcibly applied as to stop the onward current of the blood along the vessel, from the part of the tube above to that below the puncture. Some experiments made by Dr. Davy seem favourable to this view; as bleeding from the carotid arteries, partially divided transversely, in dogs was easily arrested by the means above-mentioned, the wound of the vessel readily healing, so as to preserve its tube entire; whereas, when the pressure was increased, the hemorrhage became violent. The subject is mentioned as one worthy of a further experimental investigation. The instrument which will generally be found most useful for laying hold of the vessel is the common dissecting forceps, but a tenaculum will, in certain circumstances, be more convenient. By far the most convenient machine is that here represented.
When no assistant is at hand, and in cases of emergency, the surgeon provided with this little instrument can tie vessels without the least difficulty; and in operation, when many vessels spring, several of these forceps can be applied; there is besides this great advantage in their employment, that a clumsy assistant can scarcely include the point of the instrument with the vessel. Hemorrhage from the smaller vessels soon ceases; and, before reaction occurs, their orifices have generally become so obstructed as to resist the effusion of blood.
The effects of ligature on a vein are somewhat different from those on an artery. The inner coat of the former is more dense and elastic, and remains entire, whilst the external and middle are divided. It is puckered by the ligature, and its opposite surfaces are placed in immediate contact; but there is no breach of surface, and adhesion does not occur till the tunic has been divided by ulceration; then the opposite margins cohere, the vessel is obliterated, and undergoes changes resembling those in an artery similarly circumstanced. The coagulum between the ligature and extremity is of considerable extent, dense, and completely filling the canal of the vein, and consequently, of a cylindrical form.
The edges of the wound, in the soft parts, ought not to be approximated till the bleeding has entirely ceased, and the surface become glazed, for the interposition of the slightest quantity of blood prevents union by the first intention. When bleeding has ceased, the divided edges are to be brought together as accurately as possible, and adhesion promoted. The minute vessels assume an action greater than in the healthy state, though not equal to inflammatory action; they effuse coagulating lymph, by which the opposed surfaces are agglutinated, though the union is at first feeble and easily broken up. Soon the lymph is firmly attached, by newly-formed vessels, to the surface from which it was secreted; in effect, it becomes organised, and rendered capable of undergoing, through its inherent powers, the changes necessary for its perfection and stability. Similar processes go on in it as in any sound part of the body; new matter is deposited, and the superfluous is absorbed. The process of nutrition, however, is not the same in all parts of its substance, that is, the new matter deposited is not exactly similar at all points; but, according as the new secreting vessels proceed from the different tissues of which the margins of the recent wound are composed, so, in various parts of the new formation, these vessels assume peculiar modes of action, one set forming muscular, another cellular tissue, and a third a substitute for skin, formations corresponding to the primary tissues from which the secreting vessels proceed.
Thus the vasa vasorum, ramifying on the divided ends of the minute vessels, secrete a substance which is transformed into a set of minute capillaries, and these also, assuming a secretive action, produce an arterial or venous tube, similar to that nourished by the original vasa vasorum. By this process the lymph becomes well supplied with bloodvessels, those from the opposite surfaces meeting, and freely inosculating with each other. These bloodvessels, as already stated, have been produced from arteries possessing different powers, and hence the newly-formed assume actions similar to those of the primary, and thereby interstitial matter is deposited of its proper kind and in its proper place, a cuticular membrane superficially, then cellular tissue, afterwards muscular, and so on according to the primary tissues which had been divided; these parts do not at first resemble exactly the corresponding natural tissues, but, by the continued action of the new vessels and capillaries, they are moulded and prepared for the due performance of their respective functions. If the degree of action necessary for the accomplishment of these processes increase to inflammation, adhesion is interrupted till the action be lowered to its previous standard.
From this view it is evident, that, besides a certain excitement of the bloodvessels, it is necessary that the raw margins be in close apposition, and carefully retained so, for, by ever so slight movement of the parts, the recent and delicate bond of union will be ruptured; and, if this motion be allowed to continue, adhesion may be at divers times begun, but can never be perfected. Whereas, if the necessary precautions are adopted, union is often completed in thirty or forty hours, sometimes sooner, seldom later. From a knowledge of the astonishing powers of nature in repairing injuries, many and important improvements have of late years been made in the practice of surgery. In the majority of instances it is also requisite that the parts be brought in contact soon after division, otherwise granulation will have commenced in the different parts of the wound, and the surfaces then approximated will not so readily adhere: pus is formed, and, having lodged between the surfaces, acts as an extraneous substance, keeping them apart, and separating them still farther by its accumulation. All foreign bodies in the wound must be removed before adhesion can occur; and, on the same principle, care ought to be taken that no effused blood be interposed. In many cases the margins of the wound can be accurately adjusted by careful attention to the position of the part, or by the application of a few strips of adhesive plaster; but the latter, from indiscriminate use, often prove the source of much irritation, and totally frustrate the end for which they are designed. When employed, they ought to be narrow and few. If such means be considered insufficient, recourse must be had to a few points of interrupted suture, and these are not productive of bad consequences which have been by some attributed to them. When neatly applied, they can produce but little irritation, more especially if removed as soon as their presence is unnecessary, that is, as soon as adhesion has fairly commenced, and the natural bond of union is of such strength as to need no artificial assistance. By these the edges of the wound are more neatly and suitably placed than by any other means; they meet easily, without the puckering or overlapping of each other; and, from the circumstance of sutures obtaining a more just coaptation, they can be sooner discontinued. In most wounds no other dressing is required; but in some a combination of sutures, adhesive plaster, and compress, is necessary.
Of late, I have greatly dispensed with stitches and the common adhesive plaster, using, instead of the latter, slips of glazed riband smeared with a saturated solution of isinglass in brandy, which is much less irritating and more tenacious than the common adhesive compost. The parts are fixed temporarily with a single stitch, or two at most, and cloths dipped in cold water are placed over the wound; the ribands are not applied till the adhesive substance has partly congealed, and the oozing of blood ceased. The divided margins being approximated by the fingers of an assistant, the ribands are laid gently over, and held for a few seconds. Soon after a sufficient number have been applied the stitches are withdrawn, being no longer necessary. No other dressing is required unless suppuration occur; the ribands will adhere firmly till the completion of the cure, and thus the pain and irritation caused by frequent dressing is avoided. Even the largest wounds, as after amputation, are treated in this manner with the most satisfactory results. Of late years a plaster, made by coating oiled silk with a solution of isinglass, has been used instead; the glazed surface of the slips is moistened, and applied as here directed.