THE BLOOD VESSELS
Anatomy--INJURIES OF ARTERIES: _Varieties_--INJURIES OF
VEINS: _Air Embolism_--Repair of blood vessels and natural
arrest of hæmorrhage--HÆMORRHAGE: _Varieties_;
_Prevention_; _Arrest_--Constitutional effects of
hæmorrhage--Hæmophilia--DISEASES OF BLOOD VESSELS:
Thrombosis; Embolism--Arteritis: _Varieties_;
Arterio-sclerosis--Thrombo-phlebitis--Phlebitis:
_Varieties_--VARIX--ANGIOMATA--Nævus: _Varieties_;
_Electrolysis_--Cirsoid aneurysm--ANEURYSM: _Varieties_;
_Methods of treatment_--ANEURYSMS OF INDIVIDUAL ARTERIES.
#Surgical Anatomy.#--An _artery_ has three coats: an internal coat--the
_tunica intima_--made up of a single layer of endothelial cells lining
the lumen; outside of this a layer of delicate connective tissue; and
still farther out a dense tissue composed of longitudinally arranged
elastic fibres--the internal elastic lamina. The tunica intima is easily
ruptured. The middle coat, or _tunica media_, consists of non-striped
muscular fibres, arranged for the most part concentrically round the
vessel. In this coat also there is a considerable proportion of elastic
tissue, especially in the larger vessels. The thickness of the vessel
wall depends chiefly on the development of the muscular coat. The
external coat, or _tunica externa_, is composed of fibrous tissue,
containing, especially in vessels of medium calibre, some yellow elastic
fibres in its deeper layers.
In most parts of the body the arteries lie in a sheath of connective
tissue, from which fine fibrous processes pass to the tunica externa.
The connection, however, is not a close one, and the artery when divided
transversely is capable of retracting for a considerable distance within
its sheath. In some of the larger arteries the sheath assumes the form
of a definite membrane.
The arteries are nourished by small vessels--the _vasa vasorum_--which
ramify chiefly in the outer coat. They are also well supplied with
nerves, which regulate the size of the lumen by inducing contraction or
relaxation of the muscular coat.
The _veins_ are constructed on the same general plan as the arteries,
the individual coats, however, being thinner. The inner coat is less
easily ruptured, and the middle coat contains a smaller proportion of
muscular tissue. In one important point veins differ structurally from
arteries--namely, in being provided with valves which prevent reflux of
the blood. These valves are composed of semilunar folds of the tunica
intima strengthened by an addition of connective tissue. Each valve
usually consists of two semilunar flaps attached to opposite sides of
the vessel wall, each flap having a small sinus on its cardiac side.
The distension of these sinuses with blood closes the valve and
prevents regurgitation. Valves are absent from the superior and inferior
venæ cavæ, the portal vein and its tributaries, the hepatic, renal,
uterine, and spermatic veins, and from the veins in the lower part of
the rectum. They are ill-developed or absent also in the iliac and
common femoral veins--a fact which has an important bearing on the
production of varix in the veins of the lower extremity.
The wall of _capillaries_ consists of a single layer of endothelial
cells.
HÆMORRHAGE
Various terms are employed in relation to hæmorrhage, according to its
seat, its origin, the time at which it occurs, and other circumstances.
The term _external hæmorrhage_ is employed when the blood escapes on the
surface; when the bleeding takes place into the tissues or into a cavity
it is spoken of as _internal_. The blood may infiltrate the connective
tissue, constituting an _extravasation_ of blood; or it may collect in a
space or cavity and form a _hæmatoma_.
The coughing up of blood from the lungs is known as _hæmoptysis_;
vomiting of blood from the stomach, as _hæmatemesis_; the passage of
black-coloured stools due to the presence of blood altered by digestion,
as _melæna_; and the passage of bloody urine, as _hæmaturia_.
Hæmorrhage is known as arterial, venous, or capillary, according to the
nature of the vessel from which it takes place.
In _arterial_ hæmorrhage 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_ hæmorrhage, 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 hæmophilia.
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 hæmorrhage 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 association 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 œdema 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 illustration 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 associated with much hæmorrhage, 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 hæmorrhage 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
hæmostasis 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 hæmorrhage. 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
hæmorrhage 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
circumstances 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 hæmorrhage, which, even in comparatively small
arteries, may be so profuse as to prove dangerous. When the associated
wound in the soft parts is valvular the hæmorrhage 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 stitches are passed 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 stitched
over the line of suture in the vessel wall. If infection be excluded,
there is little risk of thrombosis or secondary hæmorrhage; 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 associated 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 _hæmatoma_ may form, with an expansile
pulsation and a palpable thrill--whether such a hæmatoma remains
circumscribed 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 hæmatoma.
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 hæmatoma as the arterial blood finds
its way into the vein and so does not escape into the tissues. Even if a
hæmatoma forms it seldom assumes 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 _ischæmia_ may develop; the muscles lose their
elasticity, become hard and paralysed, and anæsthesia of the "glove" or
"stocking" type, with other alterations of sensation ensue. Apart from
ischæmia, _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 association
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
hæmorrhage 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
hæmorrhage 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 massage of the heart
might be tried.
THE NATURAL ARREST OF HÆMORRHAGE AND THE REPAIR OF BLOOD
VESSELS
#Primary Hæmorrhage.#--The term primary hæmorrhage is applied to the
bleeding which follows immediately on the wounding of a blood vessel.
The natural process by which such hæmorrhage is arrested varies with the
character of the wound in the vessel and may be modified by accidental
circumstances.
(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 constitute what is known as the _temporary arrest of
hæmorrhage_, 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 mass,
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.
In course of time the collateral branches of the vessel above and below
the level of section enlarge and their inter-communication becomes more
free, so that even when large trunks have been divided the vascular
supply of the parts beyond may be completely restored. This is known as
the development of the _collateral circulation_.
_Imperfect Collateral Circulation._--While the development of the
collateral circulation after the ligation or obstruction from other
cause of a main arterial trunk may be sufficient to prevent gangrene of
the limb, it may be insufficient for its adequate nourishment; it may be
cold, bluish in colour, and there may be necrosis of the skin over bony
points; this is notably the case in the lower extremity after ligation
of the femoral or popliteal artery, when patches of skin may die over
the prominence of the heel, the balls of the toes, the projecting base
of the fifth metatarsal and the external malleolus.
If, during the period of reaction, the blood-pressure rises
considerably, the occluding clot at the divided end of the vessel may be
washed away or the ligature displaced, permitting of fresh bleeding
taking place--_reactionary_ or _intermediary hæmorrhage_ (p. 272).
In the event of the wound becoming infected with pyogenic organisms, the
occluding blood-clot or the young fibrous tissue may become
disintegrated in the suppurative process, and the bleeding start
afresh--_secondary hæmorrhage_ (p. 273).
(b) If an artery is only _partly cut across_, the divided fibres of
the tunica muscularis contract and those of the tunica externa retract,
with the result that a more or less circular hole is formed in the wall
of the vessel, from which free bleeding takes place, as the conditions
are unfavourable for the formation of an occluding clot. Even if a clot
does form, when the blood-pressure rises it is readily displaced,
leading to reactionary hæmorrhage. Should the wound become infected,
secondary hæmorrhage is specially liable to occur. A further risk
attends this form of injury, in that the intra-vascular tension may in
time lead to gradual stretching of the scar tissue which closes the gap
in the vessel wall, with the result that a localised dilatation or
diverticulum forms, constituting a _traumatic aneurysm_.
(c) When the injury merely takes the form of a _puncture_ or _small
incision_ a blood-clot forms between the edges, becomes organised, and
is converted into cicatricial tissue which seals the aperture. Such
wounds may also be followed by reactionary or secondary hæmorrhage, or
later by the formation of a traumatic aneurysm.
_Conditions which influence the Natural Arrest of Hæmorrhage._--The
natural arrest of bleeding is favoured by tearing or crushing of the
vessel walls, owing to the contraction and retraction of the coats and
the tendency of blood to coagulate when in contact with damaged tissue.
Hence the primary hæmorrhage following lacerated wounds is seldom
copious. The occurrence of syncope or of profound shock also helps to
stop bleeding by reducing the force of the heart's action.
On the other hand, there are conditions which retard the natural arrest.
When, for example, a vessel is only partly divided, the contraction and
retraction of the muscular coat, instead of diminishing the calibre of
the artery, causes the wound in the vessel to gape; by completing the
division of the vessel under these circumstances the bleeding can often
be arrested. In certain situations, also, the arteries are so intimately
connected with their sheaths, that when cut across they were unable to
retract and contract--for example, in the scalp, in the penis, and in
bones--and copious bleeding may take place from comparatively small
vessels. This inability of the vessels to contract and retract is met
with also in inflamed and œdematous parts and in scar tissue. Arteries
divided in the substance of a muscle also sometimes bleed unduly. Any
increase in the force of the heart's action, such as may result from
exertion, excitement, or over-stimulation, also interferes with the
natural arrest. Lastly, in bleeders, there are conditions which
interfere with the natural arrest of hæmorrhage.
#Repair of a Vessel ligated in its Continuity.#--When a ligature is
applied to an artery it should be pulled sufficiently tight to occlude
the lumen without causing rupture of its coats. It often happens,
however, that the compression causes rupture of the inner and middle
coats, so that only the outer coat remains in the grasp of the ligature.
While this weakens the wall of the vessel, it has the advantage of
hastening coagulation, by bringing the blood into contact with damaged
tissue. Whether the inner and middle coats are ruptured or not, blood
coagulates both above and below the ligature, the proximal clot being
longer and broader than that on the distal side. In small arteries these
clots extend as far as the nearest collateral branch, but in the larger
trunks their length varies. The permanent occlusion of those portions of
the vessel occupied by clot is brought about by the formation of
granulation tissue, and its replacement by cicatricial tissue, so that
the occluded segment of the vessel is represented by a fibrous cord. In
this process the coagulum only plays a passive rôle by forming a
scaffolding on which the granulation tissue is built up. The ligature
surrounding the vessel, and the elements of the clot, are ultimately
absorbed.
#Repair of Veins.#--The process of repair in veins is the same as that
in arteries, but the thrombosed area may become canalised and the
circulation through the vessel be re-established.
HÆMORRHAGE IN SURGICAL OPERATIONS
The management of the hæmorrhage which accompanies an operation includes
(a) preventive measures, and (b) the arrest of the bleeding.
#Prevention of Hæmorrhage.#--Whenever possible, hæmorrhage should be
controlled by _digital compression_ of the main artery supplying the
limb rather than by a tourniquet. If efficiently applied compression
reduces the immediate loss of blood to a minimum, and the bleeding from
small vessels that follows the removal of the tourniquet is avoided.
Further, the pressure of a tourniquet has been shown to be a material
factor in producing shock.
In selecting a point at which to apply digital compression, it is
essential that the vessel should be lying over a bone which will furnish
the necessary resistance. The common carotid, for example, is pressed
backward and medially against the transverse process (carotid tubercle)
of the sixth cervical vertebra; the temporal against the temporal
process (zygoma) in front of the ear; and the facial against the
mandible at the anterior edge of the masseter.
In the upper extremity, the subclavian is pressed against the first rib
by making pressure downwards and backwards in the hollow above the
clavicle; the axillary and brachial by pressing against the shaft of the
humerus.
In the lower extremity, the femoral is controlled by pressing in a
direction backward and slightly upward against the brim of the pelvis,
midway between the symphysis pubis and the anterior superior iliac
spine.
The abdominal aorta may be compressed against the bodies of the lumbar
vertebræ opposite the umbilicus, if the spine is arched well forwards
over a pillow or sand-bag, or by the method suggested by Macewen, in
which the patient's spine is arched forwards by allowing the lower
extremities and pelvis to hang over the end of the table, while the
assistant, standing on a stool, applies his closed fist over the
abdominal aorta and compresses it against the vertebral column.
Momburg recommends an elastic cord wound round the body between the
iliac crest and the lower border of the ribs, but this procedure has
caused serious damage to the intestine.
When digital compression is not available, the most convenient and
certain means of preventing hæmorrhage--say in an amputation--is by the
use of some form of _tourniquet_, such as the elastic tube of Esmarch or
of Foulis, or an elastic bandage, or the screw tourniquet of Petit.
Before applying any of these it is advisable to empty the limb of blood.
This is best done after the manner suggested by Lister: the limb is held
vertical for three or four minutes; the veins are thus emptied by
gravitation, and they collapse, and as a physiological result of this
the arteries reflexly contract, so that the quantity of blood entering
the limb is reduced to a minimum. With the limb still elevated the
tourniquet is firmly applied, a part being selected where the vessel can
be pressed directly against a bone, and where there is no risk of
exerting injurious pressure on the nerve-trunks. The tourniquet should
be applied over several layers of gauze or lint to protect the skin, and
the first turn of the tourniquet must be rapidly and tightly applied to
arrest completely the arterial flow, otherwise the veins only are
obstructed and the limb becomes congested. In the lower extremity the
best place to apply a tourniquet is the middle third of the thigh; in
the upper extremity, in the middle of the arm. A tourniquet should never
be applied tighter or left on longer than is absolutely necessary.
The screw tourniquet of Petit is to be preferred when it is desired to
intermit the flow through the main artery as in operations for aneurysm.
When a tourniquet cannot conveniently be applied, or when its presence
interferes with the carrying out of the operation--as, for example, in
amputations at the hip or shoulder--the hæmorrhage may be controlled by
preliminary ligation of the main artery above the seat of operation--for
instance, the external iliac or the subclavian. For such contingencies
also the steel skewers used by Spence and Wyeth, or a special clamp or
forceps, such as that suggested by Lynn Thomas, may be employed. In the
case of vessels which it is undesirable to occlude permanently, such as
the common carotid, the temporary application of a ligature or clamp is
useful.
#Arrest of Hæmorrhage.#--_Ligature._--This is the best means of securing
the larger vessels. The divided vessel having been caught with forceps
as near to its cut end as possible, a ligature of catgut or silk is tied
round it. When there is difficulty in applying a ligature securely, for
example in a dense tissue like the scalp or periosteum, or in a friable
tissue like the thyreoid gland or the mesentery, a stitch should be
passed so as to surround the bleeding vessel a short distance from its
end, in this way ensuring a better hold and preventing the ligature from
slipping.
If the hæmorrhage is from a partly divided vessel, this should be
completely cut across to enable its walls to contract and retract, and
to facilitate the application of forceps and ligatures.
_Torsion._--This method is seldom employed except for comparatively
small vessels, but it is applicable to even the largest arteries. In
employing torsion, the end of the vessel is caught with forceps, and the
terminal portion twisted round several times. The object is to tear the
inner and middle coats so that they curl up inside the lumen, while the
outer fibrous coat is twisted into a cord which occludes the end of the
vessel.
_Forci-pressure._--Bleeding from the smallest arteries and from
arterioles can usually be arrested by firmly squeezing them for a few
minutes with artery forceps. It is usually found that on the removal of
the forceps at the end of an operation no further hæmorrhage takes
place. By the use of specially strong clamps, such as the angiotribes of
Doyen, large trunks may be occluded by pressure.
_Cautery._--The actual cautery or Paquelin's thermo-cautery is seldom
employed to arrest hæmorrhage, but is frequently useful in preventing
it, as, for example, in the removal of piles, or in opening the bowel in
colostomy. It is used at a dull-red heat, which sears the divided ends
of the vessel and so occludes the lumen. A bright-red or a white heat
cuts the vessel across without occluding it. The separation of the
slough produced by the charring of the tissues is sometimes attended
with secondary bleeding.
_Hæmostatics_ or _Styptics_.--The local application of hæmostatics is
seldom to be recommended. In the treatment of epistaxis or bleeding from
the nose, of hæmorrhage from the socket of a tooth, and sometimes from
ulcerating or granulating surfaces, however, they may be useful. All
clots must be removed and the drug applied directly to the bleeding
surface. Adrenalin and turpentine are the most useful drugs for this
purpose.
Hæmorrhage from bone, for example the skull, may be arrested by means of
Horsley's aseptic plastic wax. To stop persistent oozing from soft
tissues, Horsley successfully applied a portion of living vascular
tissue, such as a fragment of muscle, which readily adheres to the
oozing surface and yields elements that cause coagulation of the blood
by thrombo-kinetic processes. When examined after two or three days the
muscle has been found to be closely adherent and undergoing
organisation.
#Arrest of Accidental Hæmorrhage.#--The most efficient means of
temporarily controlling hæmorrhage is by pressure applied with the
finger, or with a pad of gauze, directly over the bleeding point. While
this is maintained an assistant makes digital pressure, or applies a
tourniquet, over the main vessel of the limb on the proximal side of the
bleeding point. A useful _emergency tourniquet_ may be improvised by
folding a large handkerchief _en cravatte_, with a cork or piece of wood
in the fold to act as a pad. The handkerchief is applied round the
limb, with the pad over the main artery, and the ends knotted on the
lateral aspect of the limb. With a strong piece of wood the handkerchief
is wound up like a Spanish windlass, until sufficient pressure is
exerted to arrest the bleeding.
When hæmorrhage is taking place from a number of small vessels, its
arrest may be effected by elevation of the bleeding part, particularly
if it is a limb. By this means the force of the circulation is
diminished and the formation of coagula favoured. Similarly, in wounds
of the hand or forearm, or of the foot or leg, bleeding may be arrested
by placing a pad in the flexure and acutely flexing the limb at the
elbow or knee respectively.
#Reactionary Hæmorrhage.#--Reactionary or intermediary hæmorrhage
is really a recurrence of primary bleeding. As the name indicates, it
occurs during the period of reaction--that is, within the first twelve
hours after an operation or injury. It may be due to the increase in the
blood-pressure that accompanies reaction displacing clots which have
formed in the vessels, or causing vessels to bleed which did not bleed
during the operation; to the slipping of a ligature; or to the giving
way of a grossly damaged portion of the vessel wall. In the scrotum, the
relaxation of the dartos during the first few hours after operation
occasionally leads to reactionary hæmorrhage.
As a rule, reactionary hæmorrhage takes place from small vessels as a
result of the displacement of occluding clots, and in many cases the
hæmorrhage stops when the bandages and soaked dressings are removed. If
not, it is usually sufficient to remove the clots and apply firm
pressure, and in the case of a limb to elevate it. Should the hæmorrhage
recur, the wound must be reopened, and ligatures applied to the bleeding
vessels. Douching the wound with hot sterilised water (about 110° F.),
and plugging it tightly with gauze, are often successful in arresting
capillary oozing. When the bleeding is more copious, it is usually due
to a ligature having slipped from a large vessel such as the external
jugular vein after operations in the neck, and the wound must be opened
up and the vessel again secured. The internal administration of heroin
or morphin, by keeping the patient quiet, may prove useful in preventing
the recurrence of hæmorrhage.
#Secondary Hæmorrhage.#--The term secondary hæmorrhage refers to
bleeding that is delayed in its onset and is due to pyogenic infection
of the tissues around an artery. The septic process causes softening and
erosion of the wall of the artery so that it gives way under the
pressure of the contained blood. The leakage may occur in drops, or as a
rush of blood, according to the extent of the erosion, the size of the
artery concerned, and the relations of the erosion to the surrounding
tissues. When met with as a complication of a wound there is an
interval--usually a week to ten days--between the receipt of the wound
and the first hæmorrhage, this time being required for the extension of
the septic process to the wall of the artery and the consequent erosion
of its coats. When secondary hæmorrhage occurs apart from a wound, there
is a similar septic process attacking the wall of the artery from the
outside; for example in sloughing sore-throat, the separation of a
slough may implicate the wall of an artery and be followed by serious
and it may be fatal hæmorrhage. The mechanical pressure of a fragment of
bone or of a rubber drainage tube upon the vessel may aid the septic
process in causing erosion of the artery. In pre-Listerian days, the
silk ligature around the artery likewise favoured the changes that lead
to secondary hæmorrhage, and the interesting observation was often made,
that when the collateral circulation was well established, the leakage
occurred on the _distal_ side of the ligature. While it may happen that
the initial hæmorrhage is rapidly fatal, as for example when the
external carotid or one of its branches suddenly gives way, it is quite
common to have one, two or more _warning hæmorrhages_ before the leakage
on a large scale, which is rapidly fatal.
The _appearances of the wound_ in cases complicated by secondary
hæmorrhage are only characteristic in so far that while obviously
infected, there is an absence of all reaction; instead of frankly
suppurating, there is little or no discharge and the surrounding
cellular tissue and the limb beyond are œdematous and pit on pressure.
The _general symptoms_ of septic poisoning in cases of secondary
hæmorrhage vary widely in severity: they may be so slight that the
general health is scarcely affected and the convalescence from an
operation, for example, may be apparently normal except that the wound
does not heal satisfactorily. For example, a patient may be recovering
from an operation such as the removal of an epithelioma of the mouth,
pharynx or larynx and the associated lymph glands in the neck, and be
able to be up and going about his room, when, suddenly, without warning
and without obvious cause, a rush of blood occurs from the mouth or the
incompletely healed wound in the neck, causing death within a few
minutes.
On the other hand, the toxæmia may be of a profound type associated with
marked pallor and progressive failure of strength, which, of itself,
even when the danger from hæmorrhage has been overcome, may have a fatal
termination. The _prognosis_ therefore in cases of secondary hæmorrhage
can never be other than uncertain and unfavourable; the danger from loss
of blood _per se_ is less when the artery concerned is amenable to
control by surgical measures.
_Treatment._--The treatment of secondary hæmorrhage includes the use of
local measures to arrest the bleeding, the employment of general
measures to counteract the accompanying toxæmia, and when the loss of
blood has been considerable, the treatment of the bloodless state.
_Local Measures to arrest the Hæmorrhage._--The occurrence of even
slight hæmorrhages from a septic wound in the vicinity of a large blood
vessel is to be taken seriously; it is usually necessary to _open up the
wound_, clear out the clots and infected tissues with a sharp spoon,
disinfect the walls of the cavity with eusol or hydrogen peroxide, and
_pack_ it carefully but not too tightly with gauze impregnated with some
antiseptic, such as "bipp," so that, if the bleeding does not recur, it
may be left undisturbed for several days. The packing should if possible
be brought into actual contact with the leaking point in the vessel, and
so arranged as to make pressure on the artery above the erosion. The
dressings and bandage are then applied, with the limb in the attitude
that will diminish the force of the stream through the main artery, for
example, flexion at the elbow in hæmorrhage from the deep palmar arch.
Other measures for combating the local sepsis, such as the irrigation
method of Carrel, may be considered.
If the wound involves one of the extremities, it may be useful; and it
imparts confidence to the nurse, and, it may be, to the patient, if a
Petit's tourniquet is loosely applied above the wound, which the nurse
is instructed to tighten up in the event of bleeding taking place.
_Ligation of the Artery._--If the hæmorrhage recurs in spite of packing
the wound, or if it is serious from the outset and likely to be critical
if repeated, ligation of the artery itself or of the trunk from which it
springs, at a selected spot higher up, should be considered. This is
most often indicated in wounds of the extremities.
As examples of proximal ligation for secondary hæmorrhage may be cited
ligation of the hypogastric artery for hæmorrhage in the buttock, of the
common iliac for hæmorrhage in the thigh, of the brachial in the upper
arm for hæmorrhage from the deep palmar arch, and of the posterior
tibial behind the medial malleolus for hæmorrhage from the sole of the
foot.
_Amputation_ is the last resource, and should be decided upon if the
hæmorrhage recurs after proximal ligation, or if this has been followed
by gangrene of the limb; it should also be considered if the nature of
the wound and the virulence of the sepsis would of themselves justify
removal of the limb. Every surgeon can recall cases in which a timely
amputation has been the means of saving life.
The _counteraction of the toxæmia_ and the _treatment of the bloodless
state_, are carried out on the usual lines.
#Hæmorrhage of Toxic Origin.#--Mention must also be made of hæmorrhages
which depend upon infective or toxic conditions and in which no gross
lesion of the vessels can be discovered. The bleeding occurs as an
oozing, which may be comparatively slight and unimportant, or by its
persistence may become serious. It takes place into the superficial
layers of the skin, from mucous membranes, and into the substance of
such organs as the pancreas. Hæmorrhage from the stomach and intestine,
attended with a brown or black discoloration of the vomit and of the
stools, is one of the best known examples: it is not uncommonly met with
in infective conditions originating in the appendix, intestine,
gall-bladder, and other abdominal organs. Hæmorrhage from the mucous
membrane of the stomach after abdominal operations--apparently also due
to toxic causes and not to the operation--gives rise to the so-called
_post-operative hæmatemesis_.
#Constitutional Effects of Hæmorrhage.#--The severity of the symptoms
resulting from hæmorrhage depends as much on the rapidity with which the
bleeding takes place as on the amount of blood lost. The sudden loss of
a large quantity, whether from an open wound or into a serous
cavity--for example, after rupture of the liver or spleen--is attended
with marked pallor of the surface of the body and coldness of the skin,
especially of the face, feet, and hands. The skin is moist with a cold,
clammy sweat, and beads of perspiration stand out on the forehead. The
pulse becomes feeble, soft, and rapid, and the patient is dull and
listless, and complains of extreme thirst. The temperature is usually
sub-normal; and the respiration rapid, shallow, and sighing in
character. Abnormal visual sensations, in the form of flashes of light
or spots before the eyes; and rushing, buzzing, or ringing sounds in the
ears, are often complained of.
In extreme cases, phenomena which have been aptly described as those of
"air-hunger" ensue. On account of the small quantity of blood
circulating through the body, and the diminished hæmoglobin content of
the blood, the tissues are imperfectly oxygenated, and the patient
becomes extremely restless, gasping for breath, constantly throwing
about his arms and baring his chest in the vain attempt to breath more
freely. Faintness and giddiness are marked features. The diminished
supply of oxygen to the brain and to the muscles produces muscular
twitchings, and sometimes convulsions. Finally the pupils dilate, the
sphincters relax, and death ensues.
Young children stand the loss of blood badly, but they quickly recover,
as the regeneration of blood takes place rapidly. In old people also,
and especially when they are fat, the loss of blood is badly borne, and
the ill effects last longer. Women, on the whole, stand loss of blood
better than men, and in them the blood is more rapidly re-formed. A few
hours after a severe hæmorrhage there is usually a leucocytosis of from
15,000 to 30,000.
#Treatment of the Bloodless State.#--The patient should be placed in a
warm, well-ventilated room, and the foot of the bed elevated. Cardiac
stimulants, such as strychnin or alcohol, must be judiciously
administered, over-stimulation being avoided. The inhalation of oxygen
has been found useful in relieving the urgent symptoms of dyspnœa.
The blood may be emptied from the limbs into the vessels of the trunk,
where it is more needed, by holding them vertically in the air for a few
minutes, and then applying a firm elastic bandage over a layer of cotton
wool, from the periphery towards the trunk.
_Introduction of Fluids into the Circulation._--The most valuable
measure for maintaining the circulation, however, is by transfusion of
blood (_Op. Surg._, p. 37). If this is not immediately available the
introduction of from one to three pints of physiological salt
solution (a teaspoonful of common salt to a pint of water) into a vein,
or a 6 per cent. solution of gum acacia, is a useful expedient. The
solution is sterilised by boiling, and cooled to a temperature of about
105° F. The addition of 5 to 10 minims of adrenalin solution (1 in 1000)
is advantageous in raising the blood-pressure (_Op. Surg._, p. 565).
When the intra-venous method is not available, one or two pints of
saline solution with adrenalin should be slowly introduced into the
rectum, by means of a long rubber tube and a filler. Satisfactory,
although less rapidly obtained results follow the introduction of saline
solution into the cellular tissue--for example, under the mamma, into
the axilla, or under the skin of the back.
If the patient can retain fluids taken by the mouth--such as hot coffee,
barley water, or soda water--these should be freely given, unless the
injury necessitates operative treatment under a general anæsthetic.
Transfusion of blood is most valuable as _a preliminary to operation_ in
patients who are bloodless as a result of hæmorrhage from gastric and
duodenal ulcers, and in bleeders.
HÆMOPHILIA
The term hæmophilia is applied to an inherited disease which renders the
patient liable to serious hæmorrhage from even the most trivial
injuries; and the subjects of it are popularly known as "bleeders."
The cause of the disease and its true nature are as yet unknown. There
is no proof of any structural defect in the blood vessels, and beyond
the fact that there is a diminution in the number of blood-plates, it
has not been demonstrated that there is any alteration in the
composition of the blood.
The affection is in a marked degree hereditary, all the branches of an
affected family being liable to suffer. Its mode of transmission to
individuals, moreover, is characteristic: the male members of the stock
alone suffer from the affection in its typical form, while the tendency
is transmitted through the female line. Thus the daughters of a father
who is a bleeder, whilst they do not themselves suffer from the disease,
transmit the tendency to their male offspring. The sons, on the other
hand, neither suffer themselves nor transmit the disease to their
children (Fig. 64). The female members of a hæmophilic stock are often
very prolific, and there is usually a predominance of daughters in their
families.
FIG 64.--Genealogical Tree of a Hæmophilic Family.
Great-Great-Grandmother Great-Great-Grandfather
Mrs D. (Lancashire) F M (History not known
.| | as to bleeding)
.| |
.+----------+-------+
............|
.|
....|
.+---------+--------+
Great-Grandmother .| | |
(Married three .F MB MB
times) .|
.|
.|
By First Husband .| By Second By Third
..............| Husband Husband
+-----------+------------+----------+-------+-------+-----------+------+
| .| | | +-------+-----------+------+
M .F F F | | +------+
| .| | | MB F Died in No
Died Grandmother | | | Childbed Family
æt. .| | +-----------+ +----+---
70 .| +------+ |had family | |
.| | | |but history| |
.| MB MB |not known | MB
.|
.|
.|.............................
+-----+----------+------------+------------+------------+-------------+
| | | | |. | |
| | | | |. | |
M M M MB F. F F
| |. | |
| Mother +--+--+---+--+--+ |
+----+ |. | | | | | | |
| | |. M M MB F F F |
M F |. |
Not Married |. +---+---+---+---+
|. | | | | |
|. MB M MB M M
.............|.
+-----+-----+-----+-----+-----+
| .| .| | | |
| .|* .|* | | |
M MB MB F F F
F = Females. M = Males (not bleeders). MB = Males (bleeders)
** the patients observed by the authors. The dotted line shows the
transmission of the disease to our patients through four
generations.
The disease is met with in boys who are otherwise healthy, and usually
manifests itself during the first few years of life. In rare instances
profuse hæmorrhage takes place when the umbilical cord separates. As a
rule the first evidence is the occurrence of long-continued and
uncontrollable bleeding from a comparatively slight injury, such as the
scratch of a pin, the extraction of a tooth, or after the operation of
circumcision. The blood oozes slowly from the capillaries; at first it
appears normal, but after flowing for some days, or it may be weeks, it
becomes pale, thin, and watery, and shows less and less tendency to
coagulate.
Female members of hæmophilia families sometimes show a tendency to
excessive hæmorrhage, but they seldom manifest the characteristic
features met with in the male members.
Sometimes the hæmorrhage takes place apparently spontaneously from the
gums, the nasal or the intestinal mucous membrane. In other cases the
bleeding occurs into the cellular tissue under the skin or mucous
membrane, producing large areas of ecchymosis and discoloration. One of
the commonest manifestations of the disease is the occurrence of
hæmorrhage into the cavities of the large joints, especially the knee,
elbow, or hip. The patient suffers repeatedly from such hæmorrhages, the
determining injury being often so slight as to have passed unobserved.
There is evidence that the tendency to bleed is greater at certain times
than at others--in some cases showing almost a cyclical
character--although nothing is known as to the cause of the variation.
After a severe hæmorrhage into the cellular tissue or into a joint, the
patient becomes pale and anæmic, the temperature may rise to 102° or
103° F., the pulse become small and rapid, and hæmic murmurs are
sometimes developed over the heart and large arteries. The swelling is
tense, fluctuating, and hot, and there is considerable pain and
tenderness.
In exceptional cases, blisters form over the seat of the effusion, or
the skin may even slough, and the clinical features may therefore come
to simulate closely those of an acute suppurative condition. When the
skin sloughs, an ulcer is formed with altered blood-clot in its floor
like that seen in scurvy, and there is a remarkable absence of any
attempt at healing.
The acute symptoms gradually subside, and the blood is slowly absorbed,
the discoloration of the skin passing through the same series of changes
as occur after an ordinary bruise. The patients seldom manifest the
symptoms of the bloodless state, and the blood is rapidly regenerated.
The _diagnosis_ is easy if the patient or his friends are aware of the
family tendency to hæmorrhage and inform the doctor of it, but they are
often sensitive and reticent regarding the fact, and it may only be
elicited after close investigation. From the history it is usually easy
to exclude scurvy and purpura. Repeated hæmorrhages into a joint may
result in appearances which closely simulate those of tuberculous
disease. Recent hæmorrhages into the cellular tissue often present
clinical features closely resembling those of acute cellulitis or
osteomyelitis. A careful examination, however, may reveal ecchymoses on
other parts of the body which give a clue to the nature of the
condition, and may prevent the disastrous consequences that may follow
incision.
These patients usually succumb sooner or later to hæmorrhage, although
they often survive several severe attacks. After middle life the
tendency to bleed appears to diminish.
_Treatment._--As a rule the ordinary means of arresting hæmorrhage are
of little avail. From among the numerous means suggested, the following
may be mentioned: The application to the bleeding point of gauze soaked
in a 1 in 1000 solution of adrenalin; prolonged inhalation of oxygen;
freezing the part with a spray of ethyl-chloride; one or more
subcutaneous injections of gelatin--5 ounces of a 2½ per cent.
solution of white gelatin in normal salt solution being injected at a
temperature of about 100° F.; the injection of pituitary extract. The
application of a pad of gauze soaked in the blood of a normal person
sometimes arrests the bleeding.
To prevent bleeding in hæmophilics, intra-venous or subcutaneous
injections of fresh blood serum, taken from the human subject, the
sheep, the dog, or the horse, have proved useful. If fresh serum is not
available, anti-diphtheritic or anti-tetanic serum or trade
preparations, such as hemoplastin, may be employed. We have removed the
appendix and amputated through the thigh in hæmophilic subjects without
excessive loss of blood after a course of fresh sheep's serum given by
the mouth over a period of several weeks.
The chloride and lactate of calcium, and extract of thymus gland have
been employed to increase the coagulability of the blood. The patient
should drink large quantities of milk, which also increases the
coagulability of the blood. Monro has observed remarkable results from
the hypodermic injection of emetin hydrochloride in ½-grain doses.
THROMBOSIS AND EMBOLISM
The processes known as thrombosis and embolism are so intimately
associated with the diseases of blood vessels that it is convenient to
define these terms in the first instance.
#Thrombosis.#--The term _thrombus_ is applied to a clot of blood formed
in the interior of the heart or of a blood vessel, and the process by
which such a clot forms is known as _thrombosis_. It would appear that
slowing or stagnation of the blood-stream, and interference with the
integrity of the lining membrane of the vessel wall, are the most
important factors determining the formation of the clot. Alterations in
the blood itself, such as occur, for example, in certain toxæmias, also
favour coagulation. When the thrombus is formed slowly, it consists of
white blood cells with a small proportion of fibrin, and, being
deposited in successive layers, has a distinctly laminated appearance on
section. It is known as a _white thrombus_ or laminated clot, and is
often met with in the sac of an aneurysm (Fig. 72). When rapidly formed
in a vessel in which the blood is almost stagnant--as, for example, in a
pouched varicose vein--the blood coagulates _en masse_, and the clot
consists of all the elements of the blood, constituting a _red thrombus_
(Fig. 66). Sometimes the thrombus is _mixed_--a red thrombus being
deposited on a white one, it may be in alternate layers.
When aseptic, a thrombus may become detached and be carried off in the
blood-stream as an embolus; it may become organised; or it may
degenerate and undergo calcification. Occasionally a small thrombus
situated behind a valve in a varicose vein or in the terminal end of a
dilated vein--for example in a pile--undergoes calcification, and is
then spoken of as a _phlebolith_; it gives a shadow with the X-rays.
When infected with pyogenic bacteria, the thrombus becomes converted
into pus and a localised abscess forms; or portions of the thrombus may
be carried as emboli in the circulation to distant parts, where they
give rise to secondary foci of suppuration--pyæmic abscesses.
#Embolism.#--The term _embolus_ is applied to any body carried along in
the circulation and ultimately becoming impacted in a blood vessel. This
occurrence is known as _embolism_. The commonest forms of embolus are
portions of thrombi or of fibrinous formations on the valves of the
heart, the latter being usually infected with micro-organisms.
Embolism plays an important part in determining one form of gangrene, as
has already been described. Infective emboli are the direct cause of the
secondary abscesses that occur in pyæmia; and they are sometimes
responsible for the formation of aneurysm.
Portions of malignant tumours also may form emboli, and their impaction
in the vessels may lead to the development of secondary growths in
distant parts of the body.
Fat and air embolism have already been referred to.
ARTERITIS
_Pyogenic._--Non-suppurative inflammation of the coats of an artery may
so soften the wall of the vessel as to lead to aneurysmal dilatation. It
is not uncommon in children, and explains the occurrence of aneurysm in
young subjects.
When suppuration occurs, the vessel wall becomes disintegrated and gives
way, leading to secondary hæmorrhage. If the vessel ruptures into an
abscess cavity, dangerous bleeding may occur when the abscess bursts or
is opened.
_Syphilitic._--The inflammation associated with syphilis results in
thickening of the tunica intima, whereby the lumen of the vessel becomes
narrowed, or even obliterated--_endarteritis obliterans_. The middle
coat usually escapes, but the tunica externa is generally thickened.
These changes cause serious interference with the nutrition of the parts
supplied by the affected arteries. In large trunks, by diminishing the
elasticity of the vessel wall, they are liable to lead to the formation
of aneurysm.
Changes in the arterial walls closely resembling those of syphilitic
arteritis are sometimes met with in _tuberculous_ lesions.
#Arterio-sclerosis# or #Chronic Arteritis#.--These terms are applied to
certain changes which result in narrowing of the lumen and loss of
elasticity in the arteries. The condition may affect the whole vascular
system or may be confined to particular areas. In the smaller arteries
there is more or less uniform thickening of the tunica intima from
proliferation of the endothelium and increase in the connective tissue
in the elastic lamina--a form of obliterative endarteritis. The
narrowing of the vessels may be sufficient to determine gangrene in the
extremities. In course of time, particularly in the larger arteries,
this new tissue undergoes degeneration, at first of a fatty nature, but
progressing in the direction of calcification, and this is followed by
the deposit of lime salts in the young connective tissue and the
formation of calcareous plates or rings over a considerable area of the
vessel wall. To this stage in the process the term _atheroma_ is
applied. The endothelium over these plates often disappears, leaving
them exposed to the blood-stream.
Changes of a similar kind sometimes occur in the middle coat, the lime
salts being deposited among the muscle fibres in concentric rings.
The primary cause of arterio-sclerosis is not definitely known, but its
almost constant occurrence, to a greater or less degree, in the aged
suggests that it is of the nature of a senile degeneration. It is
favoured by anything which throws excessive strain on the vessel walls,
such as heavy muscular work; by chronic alcoholism and syphilis; or by
such general diseases as tend to raise the blood-pressure--for example,
chronic Bright's disease or gout. It occurs with greater frequency and
with greater severity in men than in women.
Atheromatous degeneration is most common in the large arterial trunks,
and the changes are most marked at the arch of the aorta, opposite the
flexures of joints, at the mouths of large branches, and at parts where
the vessel lies in contact with bone. The presence of diseased patches
in the wall of an artery diminishes its elasticity and favours
aneurysmal dilatation. Such a vessel also is liable to be ruptured by
external violence and so give rise to traumatic aneurysm. Thrombosis is
liable to occur when calcareous plates are exposed in the lumen of the
vessel by destruction of the endothelium, and this predisposes to
embolism. Arterio-sclerosis also interferes with the natural arrest of
hæmorrhage, and by rendering the vessels brittle, makes it difficult to
secure them by ligature. In advanced cases the accessible arteries--such
as the radial, the temporal or the femoral--may be felt as firm,
tortuous cords, which are sometimes so hard that they have been aptly
compared to "pipe-stems." The pulse is smaller and less compressible
than normal, and the vessel moves bodily with each pulsation. It must be
borne in mind, however, that the condition of the radial artery may fail
to afford a clue to that of the larger arteries. Calcified arteries are
readily identified in skiagrams (Fig. 65).
[Illustration: FIG. 65.--Radiogram showing Calcareous Degeneration
(Atheroma) of Arteries.]
We have met with a chronic form of arterial degeneration in elderly
women, affecting especially the great vessels at the root of the neck,
in which the artery is remarkably attenuated and dilated, and so friable
that the wall readily tears when seized with an artery-forceps,
rendering ligation of the vessel in the ordinary way well-nigh
impossible. Matas suggests infolding the wall of the vessel with
interrupted sutures that do not pierce the intima, and wrapping it
round with a strip of peritoneum or omentum.
The most serious form of arterial _thrombosis_ is that met with _in the
abdominal aorta_, which is attended with violent pains in the lower
limbs, rapidly followed by paralysis and arrest of the circulation.
THROMBO-PHLEBITIS AND THROMBOSIS IN VEINS
#Thrombosis# is more common in veins than in arteries, because slowing
of the blood-stream and irritation of the endothelium of the vessel wall
are, owing to the conditions of the venous circulation, more readily
induced in veins.
Venous thrombosis may occur from purely mechanical causes--as, for
example, when the wall of a vein is incised, or the vessel included in a
ligature, or when it is bruised or crushed by a fragment of a broken
bone or by a bandage too tightly applied. Under these conditions
thrombosis is essentially a reparative process, and has already been
considered in relation to the repair of blood vessels.
In other cases thrombosis is associated with certain constitutional
diseases--gout, for example; the endothelium of the veins undergoing
changes--possibly the result of irritation by abnormal constituents in
the blood--which favour the formation of thrombi.
Under these various conditions the formation of a thrombus is not
necessarily associated with the action of bacteria, although in any
of them this additional factor may be present.
The most common cause of venous thrombosis, however, is inflammation of
the wall of the vein--phlebitis.
#Phlebitis.#--Various forms of phlebitis are met with, but for practical
purposes they may be divided into two groups--one in which there is a
tendency to the formation of a thrombus; the other in which the
infective element predominates.
In surgical patients, the _thrombotic form_ is almost invariably met
with in the lower extremity, and usually occurs in those who are
debilitated and anæmic, and who are confined to bed for prolonged
periods--for example, during the treatment of fractures of the leg or
pelvis, or after such operations as herniotomy, prostatectomy, or
appendectomy.
_Clinical Features._--The most typical example of this form of phlebitis
is that so frequently met with in the great saphena vein, especially
when it is varicose. The onset of the attack is indicated by a sudden
pain in the lower limb--sometimes below, sometimes above the knee. This
initial pain may be associated with shivering or even with a rigor, and
the temperature usually rises one or two degrees. There is swelling and
tenderness along the line of the affected vein, and the skin over it is
a dull-red or purple colour. The swollen vein may be felt as a firm
cord, with bead-like enlargements in the position of the valves. The
patient experiences a feeling of stiffness and tightness throughout the
limb. There is often œdema of the leg and foot, especially when the limb
is in the dependent position. The acute symptoms pass off in a few days,
but the swelling and tenderness of the vein and the œdema of the limb
may last for many weeks.
When the deep veins--iliac, femoral, popliteal--are involved, there is
great swelling of the whole limb, which is of a firm almost "wooden"
consistence, and of a pale-white colour; the œdema may be so great that
it is impossible to feel the affected vein until the swelling has
subsided. This is most often seen in puerperal women, and is known as
_phlegmasia alba dolens_.
_Treatment._--The patient must be placed at absolute rest, with the foot
of the bed raised on blocks 10 or 12 inches high, and the limb
immobilised by sand-bags or splints. It is necessary to avoid handling
the parts, lest the clot be displaced and embolism occur. To avoid
frequent movement of the limb, the necessary dressings should be kept in
position by means of a many-tailed rather than a roller bandage.
To relieve the pain, warm fomentations or lead and opium lotion should
be applied. Later, ichthyol-glycerin, or glycerin and belladonna, may be
substituted.
When, at the end of three weeks, the danger of embolism is past,
douching and gentle massage may be employed to disperse the œdema; and
when the patient gets up he should wear a supporting elastic bandage.
The _infective_ form usually begins as a peri-phlebitis arising in
connection with some focus of infection in the adjacent tissues. The
elements of the vessel wall are destroyed by suppuration, and the
thrombus in its lumen becomes infected with pyogenic bacteria and
undergoes softening.
_Occlusion of the inferior vena cava_ as a result of infective
thrombosis is a well-known condition, the thrombosis extending into the
main trunk from some of its tributaries, either from the femoral or
iliac veins below or from the hepatic veins above.
Portions of the softened thrombus are liable to become detached and to
enter the circulating blood, in which they are carried as emboli. These
may lodge in distant parts, and give rise to secondary foci of
suppuration--pyæmic abscesses.