Traumatic aneurism.—But if, as very fre quently happens, the accident that caused the aneurism has also created an external wound communicating with the injured vessel, and permitting the escape of a portion of the blood through it, although still a diffused aneurism, the leading circumstances of the case are essentially altered. This is the form of disease termed by the French traumatic aneurism, the name having reference not so much to the fact of its having been produced by violence, as to the co-existence with it of a solution of continuity in the skin and other structures external to the vessel. Thus, although an aneurism may be caused by the prick of a lancet in the bend of the arm, or by a bayonet wound in the thigh, yet if the external wound is healed, or, being unhealed, if it is so oblique or devious that the blood flowing from the artery does not escape from the limb, it may not be called traumatic, whilst a common pop liteal aneurism that had arisen spontaneously, if it is accidentally opened, assumes the cha racter just designated. The chief peculiarity of this case, then, is the external wound, and if it be conceded that it is the resistance of the unyielding structures that presses the coagu lum against the vessel, and thus accomplishes the cure of those forms of aneurism already described, it will be seen that a material part of the process must be deficient, and, therefore, that the principles applicable to the former cannot be made available here.
In order to the proper understanding of this part of the subject, it will be necessary to take a familiar case for illustration. A person in attempting to open a vein in the arm strikes his lancet into the artery, and is, perhaps, unconscious of the extent of the mischief he has occasioned. The arm is tied up, but it swells and becomes intolerably painful. When the bandage is removed, the wound is found not to have united, and a coagulum is pro bably seen plugging it up, which loosens occa sionally and allows the escape of a considerable quantity of red and florid blood. In the meantime the diffusion throughout the limb is extending in every direction, and the Immor rhages from the external aperture are more frequent. If this case is treated by ligature at a distance from the situation of the aneu rism, although the patient may appear relieved at the moment, that relief is but delusive. The blood may coagulate, but being unsupported by any external resistance, it cannot make suf ficient pressure on the orifice of the bleeding vessel. Fresh blood is carried round by the collateral circulation, and as it constantly oozes from the punctured artery, it disturbs the coagu lum in the neighbourhood, and bursts out into new and repeated haemorrhages until the sur geon is obliged to end where he ought to have begun, by cutting down (if he has still the opportunity) directly on the injured part of the vessel, and tying it above and below the aper ture. The great difference between the trau matic aneurism and the other forms of the dis ease is, that in it the haemorrhage is external as well as internal, and that the coagulum within the limb unsupported may press out wards through the wound more freely than inwards upon the vessel. The coagulum, therefore, is not available in the cure, and the treatment must have reference to the wounded artery alone. If the radial artery was opened arid bleeding freely from the ex ternal orifice, few surgeons would think of taking up the brachial high in the arm, know ing that the inosculating branches would still supply abundance of blood to the wound, and although the pathology of traumatic aneu rism is somewhat different, inasmuch as a portion of the blood lost still remains within the limb, yet the principle of treatment is unchanged.
It may be objected that in very many in stances of traumatic aneurism success has at tended the application of a ligature on a dis tant part of the artery ; but every one of these cases will require to be accurately examined before the treatment here laid down can be impeached. The definition of traumatic aneu rism must be borne in mind, and that it im plies not only the existence of a wound, but of one through which coagulated blood may pro trude and fluid blood may trickle. The only case in which such practice could succeed is, where, after the ligature had been tied, a suffi cient degree of pressure ab externo could be maintained to lay the opposite sides of the wounded artery together, and produce sufficient inflammation to procure its complete oblitera tion,—in short that it shall effect that which the resistance of the skin and fascia and other superincumbent structures would have accomplished in a limb less injured. Such pressure as this must occasion intolerable suf fering; and experience has proved, in nume rous instances, how little reliance can be placed on it.
Secondary heemorrhage.—Ilitherto the ap plication of a ligature has been noticed only as a curative process, its advantages have been discussed, and the manner in which it may be supposed to operate explained ; but it has been also stated that " the ligature is in itself not infrequently a cause of great and fearful mis chief," and as the consideration of the different cases that might require the operation has been just concluded, perhaps this may be a fit op portunity for examining' into the nature of these unfavourable cases. Secondary or consecutive haemorrhage occurs, as its name implies, at some period subsequent to the application of the ligature, and the blood flows from the place where the vessel has been tied. In many instances the patient has a kind of presenti ment of that which is about to happen, and becomes restless, uneasy, and agitated ; in other instances there is not the slightest warn ing, and the first notification of the mischief is the appearance of the dressings soaked in blood. In general it has been stated that it is on the separation of the ligature that this bleeding takes place, but this is not the fact, for com monly it happens whilst the cord is fixed and firm, and three or four days before its fall ought to be expected. The longer the ligature remains, provided no nerve or fascia had been included with the vessel, the safer the patient is, and it must be rare to meet with secondary hae morrhage after the cord has become detached and been quietly withdrawn. It is remarkable that the blood comes from the inferior portion of the artery; it wells up abundantly from the bottom of the wound, and never flows with a gush or per saltum ; it is easily restrained by pressure on the bleeding orifice; and if such pressure is accurately applied, and can be maintained during a very few days, the cure is permanent, and the patient would be safe but for a number of collateral circumstances, which, however important in the management of the case, form, properly speaking, no portion of the pathology of arteries.