The coughing up of blood from the lungs is known as _haemoptysis_; vomiting of blood from the stomach, as _haematemesis_; the pa.s.sage of black-coloured stools due to the presence of blood altered by digestion, as _melaena_; and the pa.s.sage of b.l.o.o.d.y urine, as _haematuria_.
Haemorrhage is known as arterial, venous, or capillary, according to the nature of the vessel from which it takes place.
In _arterial_ haemorrhage the blood is bright red in colour, and escapes from the cardiac end of the divided vessel in pulsating jets synchronously with the systole of the heart. In vascular parts--for example the face--both ends of a divided artery bleed freely. The blood flowing from an artery may be dark in colour if the respiration is impeded. When the heart"s action is weak and the blood tension low the flow may appear to be continuous and not in jets. The blood from a divided artery at the bottom of a deep wound, escapes on the surface in a steady flow.
_Venous_ bleeding is not pulsatile, but occurs in a continuous stream, which, although both ends of the vessel may bleed, is more copious from the distal end. The blood is dark red under ordinary conditions, but may be purplish, or even black, if the respiration is interfered with. When one of the large veins in the neck is wounded, the effects of respiration produce a rise and fall in the stream which may resemble arterial pulsation.
In _capillary_ haemorrhage, red blood escapes from numerous points on the surface of the wound in a steady ooze. This form of bleeding is serious in those who are the subjects of haemophilia.
INJURIES OF ARTERIES
The following description of the injuries of arteries refers to the larger, named trunks. The injuries of smaller, unnamed vessels are included in the consideration of wounds and contusions.
#Contusion.#--An artery may be contused by a blow or crush, or by the oblique impact of a bullet. The bruising of the vessel wall, especially if it is diseased, may result in the formation of a thrombus which occludes the lumen temporarily or even permanently, and in rare cases may lead to gangrene of the limb beyond.
#Subcutaneous Rupture.#--An artery may be ruptured subcutaneously by a blow or crush, or by a displaced fragment of bone. This injury has been produced also during attempts to reduce dislocations, especially those of old standing at the shoulder. It is most liable to occur when the vessels are diseased. The rupture may be incomplete or complete.
_Incomplete Subcutaneous Rupture._--In the majority of cases the rupture is incomplete--the inner and middle coats being torn, while the outer remains intact. The middle coat contracts and retracts, and the internal, because of its elasticity, curls up in the interior of the vessel, forming a valvular obstruction to the blood-flow. In most cases this results in the formation of a thrombus which occludes the vessel.
In some cases the blood-pressure gradually distends the injured segment of the vessel wall and leads to the formation of an aneurysm.
The pulsation in the vessels beyond the seat of rupture is arrested--for a time at least--owing to the occlusion of the vessel, and the limb becomes cold and powerless. The pulsation seldom returns within five or six weeks of the injury, if indeed it is not permanently arrested, but, as a rule, a collateral circulation is rapidly established, sufficient to nourish the parts beyond. If the pulsation returns within a week of the injury, the presumption is that the occlusion was due to pressure from without--for example, by haemorrhage into the sheath or the pressure of a fragment of bone.
_Complete Subcutaneous Rupture._--When the rupture is complete, all the coats of the vessel are torn and the blood escapes into the surrounding tissues. If the original injury is attended with much shock, the bleeding may not take place until the period of reaction. Rupture of the popliteal artery in a.s.sociation with fracture of the femur, or of the axillary or brachial artery with fracture of the humerus or dislocation of the shoulder, are familiar examples of this injury.
Like incomplete rupture, this lesion is accompanied by loss of pulsation and power, and by coldness of the limb beyond; a tense and excessively painful swelling rapidly appears in the region of the injury, and, where the cellular tissue is loose, may attain a considerable size. The pressure of the effused blood occludes the veins and leads to congestion and dema of the limb beyond. The interference with the circulation, and the damage to the tissues, may be so great that gangrene ensues.
_Treatment._--When an artery has been contused or ruptured, the limb must be placed in the most favourable condition for restoration of the circulation. The skin is disinfected and the limb wrapped in cotton wool to conserve its heat, and elevated to such an extent as to promote the venous return without at the same time interfering with the inflow of blood. A careful watch must be kept on the state of nutrition of the limb, lest gangrene occurs.
If no complications supervene, the swelling subsides, and recovery may be complete in six or eight weeks. If the extravasation is great and the skin threatens to give way, or if the vitality of the limb is seriously endangered, it is advisable to expose the injured vessel, and, after clearing away the clots, to attempt to suture the rent in the artery, or, if torn across, to join the ends after paring the bruised edges. If this is impracticable, a ligature is applied above and below the rupture. If gangrene ensues, amputation must be performed.
These descriptions apply to the larger arteries of the extremities. A good ill.u.s.tration of subcutaneous rupture of the arteries of the head is afforded by the tearing of the middle meningeal artery caused by the application of blunt violence to the skull; and of the arteries of the trunk--caused by the tearing of the renal artery in rupture of the kidney.
#Open Wounds of Arteries--Laceration.#--Laceration of large arteries is a common complication of machinery and railway accidents. The violence being usually of a tearing, twisting, or crushing nature, such injuries are seldom a.s.sociated with much haemorrhage, as torn or crushed vessels quickly become occluded by contraction and retraction of their coats and by the formation of a clot. A whole limb even may be avulsed from the body with comparatively little loss of blood. The risk in such cases is secondary haemorrhage resulting from pyogenic infection.
The _treatment_ is that applicable to all wounds, with, in addition, the ligation of the lacerated vessels.
#Punctured wounds# of blood vessels may result from stabs, or they may be accidentally inflicted in the course of an operation.
The division of the coats of the vessel being incomplete, the natural haemostasis that results from curling up of the intima and contraction of the media, fails to take place, and bleeding goes on into the surrounding tissues, and externally. If the sheath of the vessel is not widely damaged, the gradually increasing tension of the extravasated blood retained within it may ultimately arrest the haemorrhage. A clot then forms between the lips of the wound in the vessel wall and projects for a short distance into the lumen, without, however, materially interfering with the flow through the vessel. The organisation of this clot results in the healing of the wound in the vessel wall.
In other cases the blood escapes beyond the sheath and collects in the surrounding tissues, and a traumatic aneurysm results. Secondary haemorrhage may occur if the wound becomes infected.
The _treatment_ consists in enlarging the external wound to permit of the damaged vessel being ligated above and below the puncture. In some cases it may be possible to suture the opening in the vessel wall. When circ.u.mstances prevent these measures being taken, the bleeding may be arrested by making firm pressure over the wound with a pad; but this procedure is liable to be followed by the formation of an aneurysm.
_Minute puncture of arteries_ such as frequently occur in the hypodermic administration of drugs and in the use of exploring needles, are not attended with any escape of blood, chiefly because of the elastic recoil of the arterial wall; a tiny thrombus of platelets and thrombus forms at the point where the intima is punctured.
#Incised Wounds.#--We here refer only to such incised wounds as partly divide the vessel wall.
Longitudinal wounds show little tendency to gape, and are therefore not attended with much bleeding. They usually heal rapidly, but, like punctured wounds, are liable to be followed by the formation of an aneurysm.
When, however, the incision in the vessel wall is oblique or transverse, the retraction of the muscular coat causes the opening to gape, with the result that there is haemorrhage, which, even in comparatively small arteries, may be so profuse as to prove dangerous. When the a.s.sociated wound in the soft parts is valvular the haemorrhage is arrested and an aneurysm may develop.
When a large arterial trunk, such as the external iliac, the femoral, the common carotid, the brachial, or the popliteal, has been partly divided, for example, in the course of an operation, the opening should be closed with sutures--_arteriorrhaphy_. The circulation being controlled by a tourniquet, or the artery itself occluded by a clamp, fine silk or catgut st.i.tches are pa.s.sed through the outer and middle coats after the method of Lembert, a fine, round needle being employed.
The sheath of the vessel or an adjacent fascia should be st.i.tched over the line of suture in the vessel wall. If infection be excluded, there is little risk of thrombosis or secondary haemorrhage; and even if thrombosis should develop at the point of suture, the artery is obstructed gradually, and the establishment of a collateral circulation takes place better than after ligation. In the case of smaller trunks, or when suture is impracticable, the artery should be tied above and below the opening, and divided between the ligatures.
#Gunshot Wounds of Blood Vessels.#--In the majority of cases injuries of large vessels are a.s.sociated with an external wound; the profusion of the bleeding indicates the size of the damaged vessel, and the colour of the blood and the nature of the flow denote whether an artery or a vein is implicated.
When an artery is wounded a firm _haematoma_ may form, with an expansile pulsation and a palpable thrill--whether such a haematoma remains circ.u.mscribed or becomes diffuse depends upon the density or laxity of the tissues around it. In course of time a _traumatic arterial aneurysm_ may develop from such a haematoma.
When an artery and its companion vein are injured simultaneously an _arterio-venous aneurysm_ (p. 310) may develop. This frequently takes place without the formation of a haematoma as the arterial blood finds its way into the vein and so does not escape into the tissues. Even if a haematoma forms it seldom a.s.sumes a great size. In time a swelling is recognised, with a palpable thrill and a systolic bruit, loudest at the level of the communication and accompanied by a continuous venous hum.
If leakage occurs into the tissues, the extravasated blood may occlude the vein by pressure, and the symptoms of arterial aneurysm replace those of the arterio-venous form, the systolic bruit persisting, while the venous hum disappears.
_Gangrene_ may ensue if the blood supply is seriously interfered with, or the signs of _ischaemia_ may develop; the muscles lose their elasticity, become hard and paralysed, and anaesthesia of the "glove" or "stocking" type, with other alterations of sensation ensue. Apart from ischaemia, _reflex paralysis_ of motion and sensation of a transient kind may follow injury of a large vessel.
_Treatment_ is carried out on the same lines as for similar injuries due to other causes.
INJURIES OF VEINS
Veins are subject to the same forms of injury as arteries, and the results are alike in both, such variations as occur being dependent partly on the difference in their anatomical structure, and partly on the conditions of the circulation through them.
#Subcutaneous rupture# of veins occur most frequently in a.s.sociation with fractures and in the reduction of dislocations. The veins most commonly ruptured are the popliteal, the axillary, the femoral, and the subclavian. On account of the smaller amount of elastic and muscular tissue in the wall of a vein, the contraction and retraction of its walls are less than in an artery, and so bleeding may continue for a longer period. On the other hand, owing to the lower blood-pressure the outflow goes on more slowly, and the gradually increasing pressure produced by the extravasated blood is usually sufficient to arrest the haemorrhage before it becomes serious. As an aid in diagnosing the source of the bleeding, it should be remembered that the rupture of a vein does not affect the pulsation in the limb beyond. The risks are practically the same as when an artery is ruptured, excepting that of aneurysm, and the treatment is carried out on the same lines, but it is seldom necessary to operate for the purpose of applying a ligature to the injured vein.
#Wounds# of veins--punctured and incised--frequently occur in the course of operations; for example, in the removal of tumours or diseased glands from the neck, the axilla, or the groin. They are also met with as a result of accidental stabs and of suicidal or homicidal injuries. The haemorrhage from a large vein so damaged is usually profuse, but it is more readily controlled by external pressure than that from an artery.
When a vein is merely punctured, the bleeding may be arrested by pressure with a pad of gauze, or by a lateral ligature--that is, picking up the margins of the rent in the wall and securing them with a ligature without occluding the lumen. In the large veins, such as the internal jugular, the femoral, or the axillary, it is usually possible to suture the opening in the wall. This does not necessarily result in thrombosis in the vessel, or in obliteration of its lumen.
When an _artery and vein are simultaneously wounded_, the features peculiar to each are present in greater or less degree. In the limbs gangrene may ensue, especially if the wound is infected. Punctured and gun-shot wounds implicating both artery and vein are liable to be followed by the development of arterio-venous aneurysm.
#Entrance of Air into Veins--Air Embolism.#--This serious, though fortunately rare, accident is apt to occur in the course of operations in the region of the thorax, neck, or axilla, if a large vein is opened and fails to collapse on account of the rigidity of its walls, its incorporation in a dense fascia, or from traction being made upon it. If the wound in a vein is thus held open, the negative pressure during inspiration sucks air into the right side of the heart. This is accompanied by a hissing or gurgling sound, and with the next expiration some frothy blood escapes from the wound. The patient instantly becomes pale, the pupils dilate, respiration becomes laboured, and although the heart may continue to beat forcibly, the peripheral pulse is weak, and may even be imperceptible. On auscultating the heart, a churning sound may be heard. Death may result in a few minutes; or the heart may slowly regain its power and recovery take place.
_Prevention._--In operations in the "dangerous area"--as the region of the root of the neck is called in this connection--care must be taken not to cut or divide any vein before it has been secured by forceps, and to apply ligatures securely and at once. Deep wounds in this region should be kept filled with normal salt solution. Immediately a cut is recognised in a vein, a finger should be placed over the vessel on the cardiac side of the wound, and kept there until the opening is secured.
_Treatment._--Little can be done after the air has actually entered the vein beyond endeavouring to maintain the heart"s action by hypodermic injections of ether or strychnin and the application of mustard or hot cloths over the chest. The head at the same time should be lowered to prevent syncope. Attempts to withdraw the air by suction, and the employment of artificial respiration, have proved futile, and are, by some, considered dangerous. In a desperate case ma.s.sage of the heart might be tried.
THE NATURAL ARREST OF HaeMORRHAGE AND THE REPAIR OF BLOOD VESSELS
#Primary Haemorrhage.#--The term primary haemorrhage is applied to the bleeding which follows immediately on the wounding of a blood vessel.
The natural process by which such haemorrhage is arrested varies with the character of the wound in the vessel and may be modified by accidental circ.u.mstances.
(a) _Repair of completely divided Artery._--When an artery is _completely_ divided, the circular fibres of the muscular coat contract, so that the lumen of the cut ends is diminished, and at the same time each segment retracts within its sheath in virtue of the recoil of the elastic elements in its walls, the tunica intima curls up in the interior of the vessel, and the tunica externa collapses over the cut ends. The blood that escapes from the injured vessel fills the interstices of the tissues, and, coagulating, forms a clot which temporarily arrests the bleeding. That part of the clot which lies between the divided ends of the vessel and in the cellular tissue outside, is known as the _external clot_, while the portion which projects into the lumen of the vessel is known as the _internal clot_, and it usually extends as far as the nearest collateral branch. These processes const.i.tute what is known as the _temporary arrest of haemorrhage_, which, it will be observed, is effected by the contraction and retraction of the divided artery and by clotting.
The _permanent arrest_ takes place by the transformation of the clot into scar tissue. The internal clot plays the most important part in the process; it becomes invaded by leucocytes and proliferating endothelial and connective-tissue cells, and new blood vessels permeate the ma.s.s, which is thus converted into granulation tissue. This is ultimately replaced by fibrous tissue, which permanently occludes the end of the vessel. Concurrently and by the same process the external clot is converted into scar tissue.
If a divided artery is _ligated at its cut end_, the tension of the ligature is usually sufficient to rupture the inner and middle coats, which curl up within the lumen, the outer coat alone being held in the grasp of the ligature. An internal clot forms and, becoming organised, permanently occludes the vessel as above described. The ligature and the small portion of vessel beyond it are subsequently absorbed.