1. Contusion or laceration without perforation.—(a)The vessel may be struck laterally, the injured portion then forming a part of the bounding wall of the wound track, or (b) one or more layers of the vessel wall may be destroyed over a limited area. Given primary union, these conditions are only of importance in so far as subsequent contraction of the lumen of the vessel may result from implication in the neighbouring cicatrix. One of the most striking features of the wounds as a whole was seen in the hair-breadth escapes of the large limb vessels with no subsequent ill effects, and such injuries were seen in every situation.
In a certain proportion of wounds in close proximity to large vessels, however, a diminution of the normal calibre of the arteries was observed, either shortly after the injury or later in the advanced stages of cicatrisation. As an example of early obstruction, the following may be related. A Mauser bullet passed from the inner side of the thigh across the neck and great trochanter of the femur beneath the femoral vessels, and probably struck and grooved the bone, since the aperture of exit was large and irregular, some 3/4 of an inch in diameter. One week later no pulse was palpable in either anterior or posterior tibial arteries at the ankle, and pulsation which was strong in the common femoral artery was very weak in the superficial femoral. Slight fulness existed in the hollow of Scarpa's triangle, but not sufficient to make any serious difference in the contour of the two limbs. No thrill or abnormal murmur was discoverable. There was no œdema of the limb, which was also normal in temperature. The patient was kept at rest in the supine position for three weeks, during which time the tibial pulses gradually returned. Three weeks later he was invalided home, the pulses, however, still remaining considerably smaller than normal.
In the advanced stages of cicatrisation narrowing of the lumen of the trunk vessels was far from uncommon, especially in cases of wounds of the arm crossing the course of the brachial artery; in many of these the radial pulse was diminished almost to imperceptibility. How far this condition may prove permanent there has been little opportunity of judging; nor as to the possible ultimate weakening of the vessel wall and the development of a secondary aneurism has time allowed the acquisition of experience. In the light of the observation of so many cases in which large vessels were wounded without the occurrence of severe hæmorrhage, either primary or secondary, it is impossible to be certain whether some of the cases of arterial obstruction were not secondary to perforating lesions of the vessels.
Pressure on, or minor lesion of the vessel was sometimes evidenced by the development of a murmur, as in the following case. A Mauser bullet entered immediately within and below the left coracoid process, and emerged at the back of the arm at its inner margin, 2½ inches above the junction of the right posterior axillary fold. During the first week dysphagia and some pain and soreness in the episternal notch, with pain and difficulty of respiration, were noticed. Eight weeks later no trouble with the pharynx or œsophagus remained, but a short sharp systolic murmur was audible over the first part of the left axillary artery, which could be extinguished by pressure on the subclavian; the radial pulse was normal.[14]
When primary union failed or was prevented by infection and suppuration, lesions, although incomplete, of the vessel coat naturally frequently gave rise to secondary hæmorrhage.
2. Perforation of the vessels.—(a) This may be oblique or transverse to the long axis of a trunk; when the vessel is impinged upon laterally, an oval or circular notch, as the case may be, is produced; or (b) the bullet may strike more or less in the centre of the vessel, perforating both in front and behind, while lateral continuity is maintained; (c) beyond these degrees a vessel may, of course, be completely divided. Cases of notching of the vessel will be referred to under the heading of traumatic aneurism; those of perforation under that of aneurismal varix and varicose aneurism, the perforations in these cases affecting a parallel artery and vein.
Results of Injury to the Vessels
1. Hæmorrhage.—The fact that hæmorrhage was not a prominent feature in the wounds received during this campaign can scarcely be regarded as an experience confined to injuries caused by bullets of small calibre. The same observation was often made in the case of larger bullets in old days, and the absence of severe hæmorrhage has previously been regarded as a special characteristic of gunshot wounds. None the less, as high a proportion as 50 per cent. of deaths occurring on the field in earlier days has been ascribed to this cause.
Unfortunately no new facts can be furnished on this point, although a few cases of rapid death from primary hæmorrhage will be found recounted under the heading of visceral injuries. Beyond these the general evidence offered by observations on men brought in from the field with vascular injuries, was opposed to the frequent occurrence of death from hæmorrhage, at any rate of an external nature. This subject will be dealt with under the classical three headings of primary, recurrent, and secondary hæmorrhage.
Primary hæmorrhage.—A marked distinction needs to be drawn between external and internal hæmorrhage. External hæmorrhage from the great vessels of the limbs, or even of the neck, proved responsible for a remarkably small proportion of the deaths on the battlefield. This statement may be made with confidence, since it is not only my own experience, but coincides with what I was able to glean from many medical officers with the Field bearer companies. It is, moreover, supported by the facts that cases in which primary ligature had been resorted to were extremely rare at the Base hospitals, while, on the other hand, traumatic aneurisms and aneurismal varices of any one of the great trunks of the neck and limbs were comparatively common. Again, primary amputation for small-calibre bullet wounds, except when complicated by severe injury to the bones, was so rare as to render more than doubtful the frequent occurrence of severe primary hæmorrhage on the field. Only one case of rapid death due to bleeding from a limb artery was recounted to me. In this a wound of the first part of the axillary artery proved fatal in the twenty minutes occupied by the removal of the patient to the dressing station. The amount of hæmorrhage in many instances was no doubt checked by the application of pressure at the time of the first field dressing; but it can scarcely be argued that such dressings as were applied were of sufficient firmness to control bleeding from such trunks as the brachial, femoral, or carotid arteries.