When a ligature is tied tightly round an artery, every thing included within its noose is killed, but this is only a very small ring of the cellular coat, the internal and middle being as completely divided as if it had been done with a knife. When the absorbents have de tached the connection of this ring with the remainder of the cellular coat, there is nothing (so far as the vessel is concerned) to retain it farther, nor is it of use in preventing hemor rhage : it might be withdrawn, only that being entangled in lymph or granulations from the adjacent parts, such a proceeding would dis turb the divided vessel before the curative process was complete. This process is in some instances, perhaps, never attempted in the inferior portion, although such a deviation from the usual course is probably not frequent ; when it does happen, the cure is more tedious and longer of accomplishment, and when inter terrupted prematurely, of course it is from this portion that the blood is poured out.
Whatever the process is by which the ex tremities of the two segments are closed, it is certainly not the same in both. This fact I was enabled to verify in one of the cases al ready alluded to,—namely, that of the man who died on the sixteenth day after the operation for popliteal aneurism, and whilst the ligature still remained undetached from the artery. The vessel was carefully removed from the body, and on being slit up, the lining mem brane of the portion at the cardiac side of the ligature was of a pale yellow colour and nearly of its natural appearance, with the exception of one or two broad spots of a very light pink colour. A large coagulum extended upwards from the seat of the ligature, the base of which was attached to the lymph situated there. The ligature was still firm, but on attempting to tear it away, the lower portion of the vessel easily separated from it, leaving it still fixed firmly on the upper section : a circumstance which explained a fact I had frequently wit nessed, that of secondary haemorrhage occur ring before the final separation of the cord. Below the spot where it had been tied the vessel appeared to be of a deep pink colour approaching to carmine, the seat of which colouring matter was in the cellular tissue between the fibrous and internal coats. This cellular substance seemed to be hypertrophied and largely congested with blood, whilst it caused the lining membrane to be thrown into transverse rugee or folds. On pulling off this membrane, it was pale, transparent, and colour less—devoid of any proper vascularity : and on looking along the slit-side of the vessel the fibrous coat and the internal membrane were seen like white lines with the congested cellu lar tissue between them. There was not a particle qf coagulum either of blood or lymph in any portion of the vessels below the liga ture.
It may be objected that in this very dissec tion, the appearances would warrant a belief that a more active form of inflammation was present in the distal portion of the vessel, because of the deeper tint of colour and the superior thickness of the cellular tissue there observed. Such, however, was not the im pression of those who witnessed the dissection. There was no result of inflammation visible after seventeen days, neither adhesion, nor sup puration, nor ulceration : there was merely a congested condition of the part—a condition not found in other structures or situations to lead to any of the usual products of inflam mation.
An artery, the coats of which have been divided by a ligature, is subject to the same conditions as if it had been severed with a knife : its cavity must be obliterated from the wounded spot to the next collateral branch above and below. Now, the constitutional causes that can delay or impede this oblite ration, if any, are not sufficiently known; but it is obvious that any local interference may (as in a case of open hemorrhage) prove sin gularly perilous. During the first few days, whilst the continuity of the cellular coat is still unbroken, there is no cause for apprehen sion ; but afterwards, any irregularity of diet, any excitement of the circulation, any unwary motion, any injudicious meddling with the ligature; in short, any one circumstance that can interfere with or disturb the operations of nature within the part before they are perfect and complete, will have a much more intimate connexion with the production of secondary haemorrhage than any of the causes hitherto advanced. Hence it is, that the bleeding occurs some two or three days earlier than the period at which the ligature naturally separates and comes from the wound.
When the bleeding has commenced, it is a case of haemorrhage from an open wound, and must be managed on similar principles, that is, pressure to a sufficient extent must be applied directly on the orifice of the vessel. I have never seen a second ligature applied on the mouth of the vessel, either in consequence of the difficulty of finding the artery in a wound swollen and matted up with lymph and gra nulations, or from an apprehension of the ex istence of such a diseased condition of its coats as would cause it again to break down under the cord. But I have frequently witnessed the effective operation of direct pressure, par ticularly in three cases, which occurred within the last few months, two of which were patients in the Meath Hospital, and all of whom recovered. In the application of this pressure, however, much caution is required. It should not be greater than is absolutely necessary to command the haemorrhage; it ought to be maintained by means of some me chanical contrivance, and be independent of all bandages which are liable to stretch, to loosen, or to slip, and it should be removed the very moment this can be done with safety. If the bleeding has been perfectly restrained during three or four days, it is probable it never will return. The sequelm of secondary haemor rhage ought always to have been regarded as more important and more perilous than the bleeding itself. I have invariably found the wound to become the seat of unhealthy sup puration : very frequently abscesses form in different parts of the limb, and occasionally gangrene supervenes. It is sometimes diffi cult to connect any of these occurrences with a lesion of any structure within the limb ; but too frequently the mischief can be evidently traced to the pressure being directed on the vein, and being either too forcible or too long continued.