Part 22

The circumstances which follow division of an artery are these:—The immediate effect is retraction of its ends within the investing sheath, and a simultaneous contraction of the coats, so as to diminish the calibre. From the superior orifice there is necessarily a profuse flow of blood, which is discharged through the sheath that formerly enclosed that part of the vessel which has retracted. After considerable effusion of blood, the flow becomes slower and less profuse; particles of blood adhere to those filaments which previously connected the artery to the sheath, but which were lacerated by the sudden retraction of the divided extremity; these particles coagulate, and lessen the canal through which the blood is discharged, whilst they present an irregular surface, on which the blood continues to be deposited and to coagulate; and thus the aperture in the sheath is ultimately closed. This external coagulum is found to commence at the extremity of the artery, where it is of a cylindrical form, and shuts up the mouth of the vessel; it then extends along the canal in the sheath, frequently assuming a conical form; and, if a free discharge has been allowed for the blood, it will terminate at the cut margin of the sheath, otherwise it will be found continuous with the coagulum blocking up the external wound. Also, when hemorrhage has been resisted by the shutting of the external wound, blood is infiltrated into the cellular tissue around the bleeding point, and there coagulates; but this circumstance can be productive of little or no pressure on the parietes of the vessel, so as to assist those other natural means which obstruct it. The flow of blood through the divided vessel being prevented, the circulating fluid necessarily passes through the nearest collateral branches, leaving the blood in the extremity of the larger trunk in a state of comparative rest; consequently, coagulation occurs in this situation. The internal coagulum, however, is small, and not sufficient to occupy completely the cavity of the vessel; it is of a conical form, its apex being towards the heart, and opposite to the first collateral branch, and its base resting on the external coagulum, and there adhering to the internal surface of the artery. But, whilst this latter process is advancing, the capillary vessels supplying the cut margins of the artery have begun to act; they throw out coagulating lymph, and continue to do so until their secretion has completely filled the vessel immediately opposite to its divided margins; thus a third and more effectual coagulum is formed,—one of plastic matter, situated between the external and internal coagula of blood, and in general closely adherent to them. Lymph is also effused externally to the artery and its sheath, forming a dense stratum, which separates the extremity of the vessel from the external wound; it becomes organised, forms granulations, and thus the parts are consolidated, and the wound cicatrised. When the artery is permanently obstructed by the adhesion of its cut margins, the external coagulum can be dispensed with, and is gradually absorbed. Afterwards all the newly formed parts are condensed, and diminish in size; the artery contracts, its internal surface finally embraces the coagulated blood which lay loose in its canal; its coats appear to be thickened, and it is firm and hard. Ultimately, in consequence of the continuance of absorption, it becomes much more attenuated, so as scarcely to differ from the surrounding cellular tissue. Similar changes occur in the lower extremity of the divided artery; in general it retracts farther, its orifice is more contracted, and, the flow of blood being much less profuse than in the superior, the natural means for its temporary closure are sooner accomplished. When an artery has been divided close to the origin of a collateral branch, no bloody coagulum can form internally, for the blood in that situation is necessarily in a state of constant motion.

If the hemorrhage is suppressed artificially, either by ligature, or by otherwise well-applied pressure, no external coagulum is formed; there appears only the internal bloody coagulum, the lymphatic effusion, and consolidation of the compressed part. The natural contraction and retraction cannot occur in vessels partially divided; hemorrhage, therefore, is more violent and dangerous from a partial than from a complete section. Again, transverse wounds are more dangerous than longitudinal; in the latter, the edges of the wound are spontaneously approximated on account of the structure of the vessels, whilst, from the same cause, the margins of the latter continue separate, and, in fact, the aperture is a complete circle; the lips of an oblique wound will be more or less apart, in proportion as it approaches to the transverse direction. When an artery has been punctured, the wound in the sheath perhaps does not correspond with that in the vessel; blood, therefore, accumulates between the vessel and its sheath, and there coagulates. The wound is thus compressed, its edges kept in contact, and the farther escape of blood prevented; the lips of the incision are then agglutinated by effused lymph, and cicatrisation occurs. This, however, cannot be expected to take place unless methodical pressure has been applied from the first. Even from small punctures blood is effused under the sheath and into the neighbouring cellular tissue, rapidly, and in such quantity as to prevent adhesion. The effusion continues, and a false aneurism is formed. If a considerable part of the circumference has been divided, the lymph may be, and generally is, superabundant, and often to such an extent as to close up the canal of the artery at that point; but, if the aperture is minute and in a longitudinal direction, lymph will seldom be effused in greater quantity than is sufficient for the cicatrisation; and, though it should be superabundant, it is afterwards removed by the absorbents. In all cases, the cellular tissue round the wounded point is much thickened and condensed by the deposition of lymph, but this gradually disappears after cicatrisation has been completed. Sometimes, and generally when the wound has been transverse and large, the process of adhesion is disturbed, and suppuration occurs; in this case the wound in the vessel communicates with the fistulous track in the externally effused lymph, and may be the source of troublesome hemorrhage. In other instances of extensive transverse wounds, the undivided slip ulcerates, and the artery becomes obliterated, by means of the same natural processes that occur in complete division. In cases of laceration of an artery, when its coats have been forcibly torn rather than divided, little or no bleeding takes place. The vessel retracts; the lacerated margins of its inner coat become puckered up, so as to contract greatly the orifice of the vessel; the lacerated sheath is pulled out to a point, and closed at a little distance from the divided inner coats. If a large artery is torn asunder in the dead body, this stretching out and contraction of the sheath will prevent injection passing; in short, the immediate effects of the injury are such as to favour the instant formation of coagula, by which the hemorrhage is arrested until the orifices of the vessel be permanently closed by the adhesive process. Thus, in instances where the whole of an extremity has been torn off, the patients have generally lost but a very small quantity of blood.

From wounds of veins the blood flows, not in a sub-saltatory but in a uniform stream: its colour is dark, and the flow is easily suppressed. The common opinion is, that to place a ligature on a vein is dangerous, and to be scrupulously avoided. The process of reparation, besides, in a wounded vein, is different from that in an artery. Veins are less disposed to the secreting action by which adhesion is perfected; and, when inflamed, the inflammation is extremely apt to extend along the coats of the vessel; which latter circumstance has been ascribed to the great proportion of cellular tissue in their coats. When punctured longitudinally, the lips of the wound remain in contact, and cicatrisation, by means of effused lymph, is soon effected; in fact, the wound heals by the first intention. But if opened obliquely or transversely, not to a great extent, the immediate result is discharge of blood, and, when this has ceased, a coagulum forms in the wound, the margins of which remain separate; and this coagulum generally communicates with blood effused into the sheath of the vessel. After some time, the lips of the wound, encircling the coagulum which occupies the aperture, and which has temporarily averted the hemorrhage, become somewhat turgid, and increased in vascularity; they then appear to assume a secreting action, by which a membranous substance, of extreme delicacy, is produced; and the extent of this membrane is increased until it form an expansion, investing the outer surface of the clot; it then becomes thickened, by addition of matter, similar to itself, from the recent vessels which ramify in it. At the same time it forms adhesions to the surrounding cellular tissue, and resembles the original tunics of the vein. After being consolidated, so as to prevent the flow of blood through that part, the coagulum, formed to arrest the hemorrhage until a more complete barrier should be furnished, is gradually absorbed. But the membrane long remains smooth, thin, and diaphanous, and can be thereby readily distinguished from the original coats. This reparative process is much longer in being finished than the corresponding one in arteries; and, from what has been stated, it is evident that the two actions differ in other respects than the time requisite to complete them. When a vein has been completely divided, the extremities are closed by means similar to those which have been already detailed in regard to arteries.

In many, nay in most, instances of hemorrhage from a wounded artery, the surgeon cannot wait for the natural processes by which the flow of blood is arrested, but must have recourse to immediate and certain means. In division of the smaller arteries, or in minute wounds of the larger, pressure, well applied, will often be sufficient. In both cases it immediately stops the flow: in the former, it prevents the blood from penetrating into that portion of the sheath which has been vacated by the retracted artery; and it being thereby confined, and kept in a state of rest, coagulation soon takes place. At the same time, the compression brings the divided margins of the vessel into close apposition, and thereby permanent closure, by adhesion, is quickly accomplished. In the latter, the mere circumstance of the escape of blood being prevented, naturally hastens the closure of the minute aperture by the natural process; and, if the compression be accurate and very firm, the opposite surfaces of the vessel, being brought in contact, may adhere, and the canal be obliterated at the wounded point. It is obvious that, in this latter class, pressure can only be of advantage immediately after the infliction of the wound, and not when blood is extravasated to a great extent.

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.