WITH EXPERIMENTS ILLUSTRATING THE EFFECTS OF A VITIATED CONDITION OF
THE BLOOD.
I. John Hunter expressed his belief that the blood has "the power of
action within itself",[1] and that when it coagulates, it does so in
consequence of an "impression" which it receives. Such an impression
may be communicated by separation from the living vessels, or from
"cessation of natural action"[2] in them. In certain circumstances
also the living vessels themselves may be the means of exciting
coagulation.[3] In others, the admixture of extraneous substances may
either retard or hasten this operation.[4] The experiments made to
determine the last point, Mr. Hunter informs us, "were rather imagined
than fully carried out; and the subject rather broached and touched
upon, than prosecuted".[5] In these experiments, different articles
used in medicine were mixed with portions of blood taken from the body;
and it was found that, in some cases, they altered both "the time," and
"the firmness of the coagulation".[6] The circumstance of medicines
being used in such experiments, conveys the idea, that, in instituting
these researches, Hunter conceived that substances which would tend
to produce such actions out of the body, might likewise produce some
effect upon the blood in living animals. In endeavouring to prosecute
the idea thus thrown out, I have been led to try the effect of
different substances upon the blood, and to consider the changes which
may be produced in that fluid, by the admixture of animal secretions.
The experiments which will be hereafter detailed, not only confirm Mr.
Hunter's notion, that foreign substances may induce actions in the
blood when withdrawn from the body, but also show that some of these
effects may be produced still more rapidly in the living vessels.
[1] HUNTER on the Blood. Ed. 1794, p. 21.
[2] P. 25. [3] P. 24. [4] P. 97. [5] P. 94. [6] P. 98.
In these experiments, pus was used in preference to any other fluid;
first, because the power of coagulating the blood which it was found
to possess, enables its influence to be traced within the body; and
secondly, because, being an animal secretion, the results obtained are
likely to be analogous to those produced by the admixture of other
secretions with the blood.
When pus is mixed with blood, fresh-drawn from a healthy animal, it
is found in a marked manner to favour coagulation. This effect does
not take place immediately, as in the case of the mixture of an acid
with the blood; and I have reason to believe, that where the blood has
lost its natural power of coagulation, no visible change is produced
in it by the addition of pus. It appears, therefore, that this effect
depends rather upon a vital than a chemical influence. In some cases,
the coagulation takes place in less than two minutes; in others, after
a longer period; but in all the experiments made, the influence of pus,
when added to blood, in promoting its coagulation, was sufficiently
evident. Putrid pus was found to act more rapidly than healthy pus
(Exp. 1, _b_), but the admixture of water was found to retard the
operation; the result, in this respect, differing in some degree from
the conclusion drawn from a similar experiment performed by Hunter.[7]
The causes which usually favour coagulation out of the body, are rest,
and separation of the blood into small quantities. These conditions
are, in some degree, brought into play during the circulation of the
blood through the capillaries; and when the influence of the admixture
of pus with the blood is not sufficient to produce coagulation at once,
we should naturally expect the effect to be more readily induced,
where these two additional causes concur in favouring such an action.
When the pus introduced is in any large quantity, the coagulation of
the blood is at once determined, and the entrance of pus into the
circulation thereby prevented. The experiments VI, VII, and VIII,
appear to furnish evidence of the correctness of this opinion, and to
show that the result may be produced more quickly in the vessels than
elsewhere. In these cases, so sudden was the effect, that the mixture
of blood and pus coagulated before it could traverse the jugular vein,
as indicated by the induration and cord-like feeling of the vessel.
[7] Op. cit. p. 98.
In Experiment VIII, the obstruction formed was sufficient to resist
even firm pressure, and in a great measure, if not altogether, to
prevent the pus injected from finding its way along the vein. The
coagulum was felt in the vessel during the operation, and was there
found after death. One effect of the coagulation of the blood thus
immediately produced, is necessarily to retain the vitiated blood
in the part, and to prevent its being carried in the course of the
circulation. This intention may be interfered with, either by accident
or design. The coagulum, as in Experiment VI, may be broken up during
the process of its formation, or after it has formed, and the parts
of which it was composed carried forward with the circulating blood.
In such a case, the vein in which the coagulum first formed, is found
in its natural condition (except at the part where it may have been
mechanically injured), and dark patches of congestion may be found in
distant systems of capillaries. If the coagulum be allowed to remain,
the vein in which it is formed soon becomes thickened; but, as the
experiments cited prove, _this thickening is the effect and not the
cause of the stagnation of the vitiated blood in the vessel_.
II. When blood coagulates in a serous cavity, a thin pellicle forms
upon its surface, and, becoming thickened by deposition from the
fibrin of the blood, forms a cyst, which completely circumscribes the
effusion. This point has not probably received the attention which it
deserves; and as it is believed to be of primary importance in the
investigation of the present subject, a short space will be devoted
to the purpose of fully establishing it, and tracing its connexion
with other and subsequent changes. Every layer of lymph observed upon
dissection, has perhaps too generally been considered as the result
of inflammation; and hence there has arisen a confusion in the terms
employed. That lymph may be derived from the blood directly, and
deposited in the form of a membrane, without being secreted by any
vessel, has been fully shown by a paper in the _Medico-Chirurgical
Transactions_.[8] Such layers of lymph assume so much the appearance
of others, derived by secretion from inflamed capillaries, that they
have been described as identical. But the mode of their formation in
the two instances is altogether different. In the one case, the process
is a local one, confined to the blood itself, and subsequently to the
membrane with which it happens to be in contact. In the other case,
it is an effort of the constitution, accompanied by constitutional
symptoms. The former of these processes was clearly described by
Hunter. In describing the process of union by the first intention,
"Coagulation", he says, "I imagine to proceed upon exactly the same
principle as the union by the first intention. It is particle uniting
with particle by the attraction of cohesion, which, in the blood, forms
a solid; and it is this coagulum uniting to the surrounding parts
which forms the union by the first intention: for union by the first
intention is no more than the living parts when separated, whether
naturally, or by art, forming a reciprocal attraction of cohesion
with the intermediate coagulum, which immediately admits of mutual
intercourse, and, as it were, one interest."[9] "When the blood has
coagulated, so as to adhere to both surfaces and to keep them together,
it may be said that union has begun."[10] "The uniting medium becomes
immediately a part of ourselves, and the parts not being offended at
it, no irritation is produced." "If the quantity of blood extravasated
be large, the whole will not become vascular, but the surface only,
which is in contact with the surrounding parts."[11] The process thus
described in general terms may take place in serous cavities. In the
third plate at the end of Mr. Hunter's work, is represented a coagulum
of blood adhering to the _tunica vaginalis_. "The adhesion was firm,
though it admitted of a separation at one end; when separated, fibres
were seen running between it and the testis."
[8] Vol. x, p. 45-82. [9] Op. cit. p. 26. [10] P. 200.
[11] P. 205.
It might seem unnecessary to dwell upon this process further, had
not some of the highest authorities in surgery, both here and on the
continent, described it as identical with adhesive inflammation. Thus
Bichat[12] says, "The cicatrization of wounds in veins after bleeding
is a result of inflammation." Now, it is submitted, that when the blood
coagulates, either in serous cavities or in veins, the process of union
is not usually one of inflammation, or one in which the powers of the
constitution are called into increased activity. It is true, that in
both cases, inflammation may take place, and lymph, as the result of
such inflammation, may be secreted; but this is only when, to use Mr.
Hunter's language, the "primary intention" has not been fulfilled.[13]
[12] Anatomie Générale, vol. ii, p. 423.
[13] In speaking of the two principles, I shall use the term by "first
intention", to designate that the fibrin is derived from coagulated
blood; and restrict the term "adhesive inflammation" to indicate the
effusion of lymph from inflamed vessels.
When a membranous layer of lymph is deposited from effused blood, it
adheres with some firmness to the surface with which it is in contact;
but, as there is at first no vascular connexion established between
them, it may be separated, leaving the part to which it adhered in its
natural condition. Lymph derived from adhesive inflammation, on the
other hand, when separated, leaves the surface upon which it was formed
rough and uneven. Coagulated fibrin, when recently deposited, may thus
be distinguished from effused lymph.
The changes which blood undergoes when effused in serous cavities, may
likewise take place when it is detained in injured or exposed veins.
The coagulation of the blood in such cases (Exp. VII and VIII) serves
as a bond of union between the sides of the veins (which may be either
temporary or permanent), so as to prevent the entrance of any foreign
matter into the circulation. When the blood thus coagulates in veins,
changes may be produced analogous to those mentioned as occurring in
serous cavities. If the quantity of blood be large, a thin pellicle is
at first formed upon its surface (see Preparations 1523-25 and 1525-64,
in the Museum of Guy's Hospital). This membrane becomes thickened
and adheres to the internal surface of the vein (see plate No. 13,
Cooper and Travers' _Surgical Essays_, Part I, and Prep. No. 1736, in
the Pathological Museum of the College of Surgeons). It then becomes
vascular, and finally so firmly united to a part of the circumference
of the vessel as to be inseparable from it, without lacerating its
lining membrane.
If the wounded vessel be small, or if the animal be strong and robust,
the whole of the blood in the vein may at once coagulate and become
united to its sides. The usual economy of nature, however, is here
exercised, with a precision proportionate to the strength of the
patient. A simple wound in a vein, in healing by the first intention,
will not obstruct the circulation through the vessel under ordinary
circumstances. A coagulum will form, sufficient to unite together the
divided edges, and the circulation of blood through the vessel will be
uninterrupted; but if the wound does not readily heal, coagula may
form, which encroach more or less upon the cavity of the vein. There
are then three ways in which a coagulum may obstruct the circulation
through a vein. 1. By the outer layer of the coagulum forming a
membrane, which contains the more fluid parts of the blood. 2. By the
whole of the blood contained in the vessel forming a solid coagulum. 3.
By a coagulum adhering to the injured side only of the vessel.
In whichever of these ways the process of repair is commenced, it
may be interfered with, and the union dissolved. This is practically
known to farriers; who, when they want to bleed a second time from
the same orifice, break down the "union by the first intention" by a
blow upon the vein. During the time that the parts are united only by
the fibrin from the blood, any violence must tend to produce the same
effect. If the constitution is good, and the coagulating power of the
blood unimpaired, the union may be frequently interrupted, and yet
be as frequently re-established in the same way. When from any local
cause, or from any constitutional peculiarity, the union by the first
intention fails at the seat of the injury, it may yet be attempted at
some distance up the vein; and then we have coagula formed at different
distances along the vessel. If these coagula fill the vein, are firm,
and remain undisturbed by violence, the union may be complete, and
the vessel sealed at those parts, even although the original wound
should suppurate. But it sometimes happens, that the same peculiarity
of constitution, or the same local cause, which prevented the union at
the original wound, may prevent complete union by the first intention
at any other point of the vein; and then its canal is open to any
secretion that may be introduced into it. Foreign matter may thus
find its way along a vein; but still there is a provision against
its being carried the round of the circulation. It has been already
shown that the blood, when in a natural condition, has a tendency to
coagulate around pus, and, probably, many other fluids, even out of
the body (Experiments I, V), and that this property is exercised in
a still more remarkable manner in the living vessels (see Experiments
VII, VIII). Foreign matter, even after it has got into the veins, may
then, by the same means, be prevented from proceeding farther towards
the centre of circulation. The process that takes place under such
circumstances, is strictly analogous to union by the first intention.
The blood may coagulate and adhere to the sides of any part of the
vascular system. The union thus formed may be permanent, or the
coagulum may be again broken up and carried with the blood in the
course of the circulation, as shown in Experiment vi. When this occurs,
as is shown in the same experiment, other changes supervene in remote
parts of the body. This tendency to coagulate around the foreign matter
once impressed upon the blood, cannot be destroyed by the coagulum
being mechanically broken up, as indeed is proved by the fact already
mentioned, that after one attempt at union in a vein (in consequence
of the introduction of foreign matter) has failed, another attempt is
made immediately farther up the vessel. Under these last circumstances,
we may find a vein partially obliterated at different points, leaving
intervals where lymph or pus are secreted. If the purulent matter
introduced is allowed to remain a short time only in the vein, no
inflammation is produced (Experiment VI). But when any irritating fluid
is detained there in consequence of the blood coagulating around it,
adhesive, ulcerative, or suppurative inflammation, will be excited
(Experiments VII and VIII).
The slowness with which veins inflame when cut, tied, or bruised, has
been made a subject of comment by different authors; and Mr. Travers,
in particular, has endeavoured to reconcile "the infrequency of its
occurrence" with the rapid and violent character of the inflammation in
certain cases. Although, under ordinary circumstances, a wounded vein
does not inflame, yet the annexed experiments show, that pus introduced
into its cavity will produce inflammation, in which the system will
sympathize. Other fluids besides pus will no doubt produce similar
effects; but those of pus are here particularly noticed, as affording a
good illustration of the series of changes produced by the introduction
of foreign matter into the blood.
What the symptoms are which characterize the presence of pus, as
distinguished from other secretions in the blood, it would probably
be difficult to determine in cases as they occur in practice.
The examination of the blood in these instances affords no very
satisfactory information; for the characters of pus, when the blood has
once coagulated round it, are so altered, that I know of no means by
which a small quantity can be recognized, when it has once entered the
circulation. The conclusions drawn from the different facts now stated
are,--first, that inflammation of a vein, or phlebitis, is no essential
part of the primary affection which precedes constitutional symptoms,
even when morbid matter has found its way into the circulation through
a vein. Secondly, that when inflammation of a vein does occur, in some
instances at least, it is not the cause, but the consequence of the
introduction of diseased or foreign matter into the blood. Thirdly,
that although veins are with difficulty inflamed by any mechanical
injury, they are susceptible of rapid inflammation, accompanied with
constitutional disorder, whenever any irritating fluids are introduced
into their cavities.
III. When the principal veins in a part become obstructed, it is
natural to suppose that changes should be produced in the smaller veins
which supply them. These changes may be expected in a more marked
degree, when the obstruction depends upon coagulation of the blood,
than when it arises from other causes, inasmuch as the coagulum usually
extends to several veins at the same time.
In the experiments that have been made upon animals, it has been a
matter of surprise that, while extreme pain was evinced upon the
injection of irritating fluids into the veins, comparatively little
or no suffering was produced, when similar experiments were performed
upon the arteries. The foreign matter introduced in these cases would
probably have the effect of coagulating the blood, as in the instances
already mentioned. If this occurred in an artery, the supply of blood
below the obstruction would be diminished; but if in a vein, the return
of blood would be prevented: in the latter case, the continued influx
of blood to the part would necessarily distend the capillaries.
In M. Cruveilhier's[14] experiment, of injecting ink into the veins of
dogs, he found, that in thirty-six hours the legs swelled, and a number
of bloody patches (_foyers apoplectiques_) were found in the substance
of the muscles and the cellular tissues of the limb. The large veins
were distended with adherent coagula of blood, and the smaller veins
around the livid patches were also filled with coagulated blood. If
the animal were allowed to live, the congested spots suppurated. The
appearances thus produced in the muscles and cellular tissue of the
limb were evidently not those of inflammatory action propagated along
the coats of the veins, for the affection in the capillaries was
circumscribed, and terminated in many places abruptly, leaving the
veins in the immediate neighbourhood perfectly healthy; still less
could the appearance produced depend upon the injected fluid finding
its way through the veins (contrary to the course of the circulation)
to the capillary system; nor, lastly, could it depend upon the ink
finding its way into the general circulation, and producing its effects
in its course a second time through the limb; for, not to mention that
the capillaries of the lungs and other parts would be equally liable to
be affected, one essential condition of the success of the experiment
is mentioned to have been, that the fluid injected should _not_ find
its way along the vein in the usual course of the blood. We therefore
conclude, that it was the coagulation of the blood in the large veins
which caused the congestion of the capillaries, those veins remaining
unaffected which could discharge their contents by some collateral
channel.
[14] CRUVEILHIER'S Path. Liv. XI.
In cases of phlegmasia dolens after child-birth, the same principle
can sometimes be traced; thus, in a dissection performed by Mr.
Lawrence,[15] the external and common iliac veins were filled with
a substance like the laminated coagulum of an aneurism. "The tube
was completely obstructed by this matter, adhering as firmly as the
coagulum does in any part of an old aneurismal sac. In its centre was a
cavity containing about a teaspoonful of thick fluid of the consistence
of pus, of a light brownish red tint, and pultaceous appearance." The
femoral vein was in this case also filled with a coagulum; but, as is
observed in the account of the dissection, the red colour of that vein
might have been caused by the clot everywhere in contact with it, and
therefore cannot be deemed a proof of inflammation.
[15] Medico-Chirurgical Transactions, vol. xii.
Mr. Guthrie[16] has published a case of inflammation of the veins
after amputation, resembling phlegmasia dolens, in which the veins
of the opposite limb, even down to the foot, had become affected. In
this case, on the fourteenth and fifteenth days after amputation of
the right thigh, the left leg began to swell, and became intolerably
painful. "The swelling was elastic, yielding to the pressure of the
finger, but not in any manner like an oedematous limb. _Upon a
careful examination, no pain was felt in the course of the iliac
vessels upon that side_; the stump looked well, save at one small
point, corresponding to the termination of the femoral vein." On
examination after death, the termination of the vein on the surface of
the stump _was open_, and in a sloughy condition. At the left groin,
the iliac vein was greatly distended with pus. Sir Henry Halford[17]
has also mentioned three cases of what he has termed phlegmasia dolens,
occurring in the male, in one of which the iliac vein was found
obliterated after death. In this case, the patient had suffered, for
several years before his death, from swelling of the left leg and
thigh. In the interior of the obliterated vessel there is a coagulum,
which has lost its colour, and become firm and completely adherent to
the inner surface of the vein. (See Prep. No. 1732, Path. Mus. Coll.
of Surgeons.) The rapid swelling and general pain of the limb in such
cases, indicate a sudden obstruction to the circulation, while the
absence of tenderness in the course of the vessels during the first
stages of the disease, tends to show that the contents of the vessels,
and not the vessels themselves, are primarily interested in its
production.
[16] Medical and Physical Journal, vol. lvi.
[17] London Medical Gazette.
The foregoing remarks have appeared necessary, in order to explain a
circumstance mentioned by Hunter, upon which considerable stress has
been laid by subsequent writers. Mr. Hunter observed that the whole
side of the head in horses that had been bled would frequently become
swollen and inflamed. The explanation of this fact appears very simple,
when viewed in relation to the general principle illustrated by the
above cases. The horse has only one jugular vein upon each side;
and, although in the usual operation of bleeding, its channel is not
obstructed, yet if the wound do not readily heal, its contents will
coagulate. The circulation will then be obstructed in all the distant
branches, and the blood, if long retained, will coagulate in them also.
It will then part with its serum, and give rise to all the symptoms
of inflammation in the distant vessels; a pulpy elastic swelling,
accompanied with great pain, will then be the principal symptom, while
the turgescence on the surface will be less than where the superficial
veins have been mechanically compressed. It will, however, very
frequently happen, that a vein in a part may be felt distended without
any symptom of inflammation being present; and, in other cases, the
pain and swelling will appear and disappear too rapidly to allow the
idea that they depend upon inflammation of the coats of the vein.
It has occurred to the author, to feel a vein in the arm and hand
distended during life, and after death, to find it empty, and its coats
of their natural colour and thickness; in such a case, the coagulum
gives way, becomes broken up, and mixed with the circulating blood.
IV. When pus, or other diseased fluid, is confined to the cavity of
a vein, the constitutional symptoms produced are comparatively mild,
as long as it remains limited and circumscribed by adherent coagula;
that is to say, so as to be excluded from the rest of the circulating
system. (Compare the frequency of the respiration in Experiments VI and
VII.) But the tendency of a clot of blood is to contract; and a time
comes when the coagulum is either broken up, or shrinks, so that if no
further changes are produced, the current of blood through the vein is
re-established.[18] Meanwhile, however, the coats of the veins have
undergone changes corresponding to the degree of irritation produced
by the contained fluids, and the intention or result to which the
inflammation tends. If the coagula have long remained, the coats of
the veins are always found thickened, sometimes to three or four times
their natural thickness, and sometimes so as to completely obliterate
the vessels. The contents of the veins are occasionally found to
consist, as far as can be seen, simply of coagulated blood; at other
times, they are found filled with soft yellowish coagula, deprived,
more or less perfectly, of their colouring matter; more rarely, the
cavity of a vein will be found filled with dark-coloured membranous
layers, leaving still a channel through the vessel; and occasionally it
will be found completely obstructed by "dense, dark-coloured, bluish
membranes."
[18] This remark I have had opportunities of verifying in cases,
where needles have been introduced under varicose veins in the lower
extremities, and allowed to remain, with a ligature around them, for
ten days or a fortnight. The circulation through the vein will in such
cases be obstructed; but, in a year or two, will be found to have
become completely re-established.
As the coagulum contracts in a vein, if the intention is to obliterate
the vessel, its sides are gradually approximated. In the smaller
veins, and in the divided extremities of large veins, the sides are
soon completely drawn together. But the latter, if not wounded, may
for a long time (see Prep. 1732, Path. Mus., Coll. of Surg.) retain
coagulated blood in their contracted, but not completely closed,
cavities. In both cases, the coagula which close the veins are liable
to be displaced by accident, or to have their adhesions loosened by the
changes which they undergo. The position of a vein, and the structure
of the organ through which it passes, may be unfavourable to its
healthy reparation. The process of repair goes on frequently during
a continued flow of blood over the part, and sometimes during the
constant action of the muscles in the neighbourhood: at other times, an
injured vein will be situated immediately in the bend of a joint, and
will be subject to be continually bent and extended with the motions of
the limb. In the structure of the bones, the veins lie in unyielding
channels, and are consequently deprived of the assistance derived from
the approximation of their sides, as in soft parts, during the process
of reparation. As the coagula contract in such a case, there is danger
lest the union by the first intention should be disturbed, and that the
cavities of the injured veins should be left exposed.
Again, in the uncontracted uterus after child-birth, the veins which
open upon the placental surface, pass through the firm texture of
the organ, and are incapable of contraction independently of the
muscular structure which surrounds them. The coagula which close their
extremities secure them against the entrance of any foreign matter;
but should these coagula be removed before the vessels are otherwise
protected, their open mouths are exposed to any secretions that the
uterus may happen to contain. In these cases, if a coagulum is not
firmly formed, or if it is displaced by violence, it may be broken
up, and portions of it mixed with the fluid blood. Subsequent coagula
may form in the veins and offer fresh obstructions to the admission
of any foreign matter, but these may, as in the first instance, be
disturbed, and carried, together with any admixture of the secretions
of the part, in the course of the circulation. The period at which
the union of a coagulum in a vein is dissolved, is sometimes marked
with great precision. In a case recorded by Dr. Davis,[19] a patient
was convalescent from an attack of phlegmasia dolens, when death took
place instantaneously, while the patient was in the act of changing
the sitting for the recumbent posture; the left external iliac vein
was thickened, and its internal tunic was studded in several places
with deposits of adherent lymph. The portion most remarkable for this
incrustation, as well as for other disease, was immediately beneath
Poupart's ligament; the vein, although contracted, was _manifestly
pervious_.
[19] Medico-Chirurgical Transactions, vol. xii.
V. It has been shown in the previous sections, that secretions mixed
with the blood will alter its properties, and influence the period
of its coagulation: that when the blood is thus altered, it may pass
through a vessel without leaving any trace of its passage; but that
if it coagulates and remains in a vein, the coats of the vessel will
then take on increased action. The exciting cause of the inflammation
in such cases appears to be conveyed by means of the contents of the
vessels to the vessels themselves. But, as in post-mortem examinations,
the changes produced in the vessels are much more easily recognized
than the alterations in their contents, the former have of late years
almost exclusively occupied the attention of pathologists. The cases in
which constitutional symptoms follow inflammation of the veins, will
be found to divide themselves principally into three large classes. 1.
Those in which one of the larger veins has been opened. 2. Those in
which some portion of bone has been involved in the original lesion. 3.
Those that occur after child-birth.
In each of these three classes of cases, a free communication will be
found to exist between the injured part and the general circulation.
The natural mode of sealing this communication, when it is no longer
proper, is the coagulation of the blood in the veins of the injured
part. When, from some constitutional affection, or from some local
peculiarity of structure, this intention is not fulfilled, a ready
passage remains open, through which the blood may become infected.
When pus has been injected into the veins, it has frequently happened,
that no great constitutional disturbance, and no signs of secondary
inflammation, have been produced; but this is believed to have depended
upon the coagula in the veins having prevented (as probably occurred
in Experiments VII and VIII) the foreign matter from finding its way
along the vessels. But if this obstruction be not offered, or be
overcome, then the appearance of secondary inflammation, accompanied by
corresponding constitutional symptoms, will be produced.
If water be injected into the cancellous structure of bone, it will
find its way out in drops through the apertures of the nutritious
vessels. The ready communication which is thus shown to exist
between the interior of bones and the veins, has been but too often
exemplified by M. Cruveilhier's experiments of introducing mercury
into their cancellous structure, and finding it subsequently in the
vascular system. This fact assumes peculiar significance, when taken
in conjunction with the very large proportion of cases, in which some
portions of bone will be found to have been involved in the primary
lesion, in those who have died of secondary inflammations. Of fifty-two
consecutive cases, occurring in surgical hospital practice, of which I
have preserved notes, in no less than forty-one was some portion of the
osseous system implicated.
Again, in the third class of cases above-mentioned, if the vena cava be
injected after parturition, the injection will very speedily find its
way into the uterus.[20] The ready communication which is thus shown to
exist between the vascular system and the local affection, in each of
the three large classes of cases which usually give rise to subsequent
disease, would of itself afford at least a very remarkable coincidence.
But more direct evidence presents itself of the way in which the system
becomes contaminated in these affections: thus, after an operation
for hæmorrhoidal tumours, an effusion of lymph and pus has been found
in the hæmorrhoidal veins,[21] from thence the same appearances have
been traced to the inferior mesenteric vein, and the severity of the
secondary affection, indicated both by the symptoms and the post-mortem
appearances, has fallen upon the liver. These circumstances all tend to
point to the venous system as the means by which morbid matter in such
instances is introduced: and the still more conclusive facts afforded
in the production of secondary disease, by injecting fluids into the
veins,[22] allow scarcely a doubt to remain upon the mind, that the
unprotected veins are the channels, in a very large proportion of
cases, through which the blood becomes infected.
[20] DANCE. Archives Générales de Méd. vol. xviii, p. 480, Dec. 1828.
[21] In cases where pus has been found in veins surrounded by coagula,
its presence and detention there have been differently accounted for.
M. Cruveilhier appears to have imagined that the loose coagula act as
filters, through which the blood passes, while the pus is retained.
(_Dict. de Méd. et de Chir._ t. xii, p. 641.) The true explanation of
the way in which coagula form round pus in the veins has already been
given.
[22] See M. Gaspard's experiments.
VI. The cancellous structure of bone may be compared to the cellular
tissue in soft parts. When inflamed, its intervals become filled up
by effusion from the vessels, and an abscess may be as accurately
circumscribed in the hard as in the soft structures of the body. In
a healthy constitution, the adhesive inflammation will, in this way,
always precede the suppurative; but where the inflammation is not
circumscribed by adhesion, the secretions may permeate from cell to
cell in unadhering parts. In soft structures, a remedy is at hand for
allowing the escape of the matter, by a free division of the parts; but
in bone, where the same thing takes place, the hard unyielding sides
offer an effectual obstruction to the escape of any effused fluid. The
cells of the bone then may become infiltrated, and, unless the veins
of the part have been closed, there is nothing to prevent the diseased
secretions from finding their way into the circulation.
M. Cruveilhier assures us, that a single drop of mercury introduced
into the cancellous structure of living bone, may subsequently be
detected in the capillaries of the lung, where it becomes the centre
of one or more patches of livid congestion. This experiment appears to
afford a perfect illustration of the way in which diseased secretion
may be conveyed into the circulation, when the natural processes of
repair in bone are abortive. These processes are the same in bone as in
the other structures of the body; viz., union by the first intention,
and adhesive inflammation. In soft parts, as the fibrin, which forms
the bond of union in the first of these, is absorbed, the divided veins
collapse, and thus continue closed; but in bony structures, where the
injured vessels are held open, as the fibrin which at first closed
their extremities becomes removed, their channels may be left as much
open to the diseased secretions of the part, as to the globule of
mercury in M. Cruveilhier's experiment.
The low degree of organization in bone, and the comparative slowness
with which actions are there carried on, render it, in a peculiar
degree, liable to interruptions in the process of repair; especially
when, as not unfrequently happens, there is reason to believe that the
vitality of some portion of the bone has been threatened. The offensive
smell of the bone, as well as the appearance of its cancellous
structure infiltrated with puriform matter, will frequently show in
such cases, that the processes above-named have not followed their
natural course.
VII. As a necessary deduction from the accompanying experiments, and
those of M. Cruveilhier, alluded to in the previous section, we arrive
at the conclusion, that a vitiated condition of the blood may give
rise to inflammation of the veins in different parts of the body. The
circumstances which occasionally attend reparation of the uterine
veins after child-birth, will be found to lead to the same inference;
and the same general proposition will derive fresh support from the
consideration of this class of cases.
The veins which terminate upon the placental surface of the uterus
are necessarily open when this organ is distended, and become more or
less perfectly closed when it contracts. In cases when the contraction
is incomplete, innumerable open-mouthed orifices are left bathed in
secretions, which are often offensive and undergoing decomposition;
the natural protection to the vessels then, is the coagulation of the
blood in them. If examined, the uterine veins will be found filled with
coagula for some distance. But in cases where this power is impaired,
all the uterine veins and arteries recently separated from the placenta
may be found bathed in the secretions of the part, under circumstances
most favourable for their absorption. The passage of diseased
secretions through the vessels cannot always be traced in this, any
more than in the other forms of the disease. Many of the substances
introduced artificially into the circulation by M. Gaspard, produced no
action upon the coats of the veins through which they passed, and yet
the general symptoms were precisely similar to those originating from
genuine phlebitis. In accordance with this, it may be observed that the
uterine veins are often found perfectly healthy when the spermatic,
or renal, or still more distant veins are thoroughly disorganized.
In either case, the healthy condition of the veins near the original
lesion forbids the idea of inflammation having been propagated along
the coats of the vessels, while all analogy appears in favour of the
disease being transmitted through their contents.
In a certain number of cases no lesion will be found in any of the
veins of the body, but the uterine veins will be found to contain some
unnatural fluid; at other times coagula of blood, which have lost
their elasticity, gritty to the feel, and greyish or light brown in
appearance, will be found filling the veins or leaving intervals in
them, where lymph or pus may be recognized. It matters little whether
the unnatural fluids, thus found in the uterine vessels, have been
absorbed from the cavity of the uterus, or are the product of venous
inflammation. The effect upon the blood in either case would be the
same.
When obstructions form in the spermatic veins, they are not indicated
by any external symptoms; but when the veins opening into the internal
iliac are similarly affected, the coagula are liable to extend into its
cavity, and even beyond it to the external and common iliac vessels.
The free return of the blood from the inferior extremity, will then be
prevented. The effects of this have already been described (sec. III.)
The connection of this form of disease with affections in distant parts
of the body, has been noticed by several eminent writers. Legallois
has expressed his conviction, that phlegmasia dolens, puerperal fever,
and many other puerperal ailments, are solely dependent upon the
absorption of pus from the uterine surface. This opinion appears to
have been formed upon too hasty a generalization, inasmuch as other
fluids besides pus, as evinced by some of the annexed experiments, may
produce similar effects upon the blood. But that pus, when absorbed,
will determine the coagulation of the blood in the iliac as well as
in other veins, must be allowed; and that the symptoms of obstructed
venous circulation arising from this cause, will exactly resemble those
of phlegmasia dolens, will scarcely be denied.
"Besides depositions of pus in certain portions of the frame," observes
Dr. Ferguson, "I have seen two other states of the limb, which are
connected with and traceable to the cause originating puerperal fever.
In one of these the malady looks like erysipelas...; in the other, the
leg is attacked with a disease so exactly resembling phlegmasia dolens,
as to leave no doubt in my mind that they are one and the same malady.
In this, as in other forms of the disease, there may be a tendency to
gangrene of the skin."
The period of the occurrence of what has been described under the name
of uterine phlebitis is marked with much precision, and the affection
of the system is often general and sudden. It may be stated as the
result of all the observations hitherto made, that it occurs most
frequently from the 10th to the 20th day after parturition.[23] If
the inflammation in such cases were propagated along the vessel only,
it would be difficult to account for such an apparently capricious
selection of time for its development. This difficulty, however,
disappears when the period is observed to be so strictly in accordance
with the time at which the same symptoms occur after other local
complaints, and to be, moreover, the time at which the coagula formed
in the veins, may naturally be expected to shrink.
[23] DR. LEE. Medico-Chirurgical Transactions.
It has been observed, that inflammation after child-birth usually
attacks the spermatic veins alone, and for the most part the one only
on that side of the uterus to which the placenta has been attached. The
hypogastric veins are comparatively rarely affected. The appearances
observed upon dissection in the spermatic vein, usually terminate
abruptly at its opening into the vena cava on the right side, or into
the renal on the left. This fact is in perfect accordance with that
observed by Mr. Arnott, that the coagulum in veins extends usually
only to the nearest collateral branch; the explanation appears to
be the same in both cases, as illustrated by Experiment VI. If the
coagulating blood be left undisturbed, it will form adhesions to the
sides of the vessel and produce increased action in its coats; but
if mechanically disturbed, it will be carried forward before the
process of coagulation is completed, and leave the vein in its natural
condition. When any portion of a vein is obstructed, the blood is
kept at rest between the obstruction and the next collateral branch;
and, if disposed to coagulate, there is nothing to interfere with
such an action. But the case is different, as soon as one vein opens
into another. A fresh current of blood is then continually sweeping
the orifice of the obstructed vessel; and, even although the blood
at this point should have a tendency to coagulate, it is carried on
in the course of the circulation, before it can adhere to the sides
of the unobstructed vein. The sudden termination of the diseased
appearances in these cases, affords an additional proof that the blood
is the medium by means of which this affection is transmitted. It is
true, in such instances the diseased fluid cannot be always, or even
generally, traced in the veins, and very many cases occur where a
retained and putrid placenta, or decomposing coagula, remain in contact
with the mouths of the uterine veins, without any of the symptoms of
local phlebitis being produced; but this is only in accordance with
what is observed in cases where purulent or other fluids have been
directly injected into the blood. The examination of the blood, or of
the vessels, in such cases, will by no means invariably indicate the
presence of foreign matter after it has once become thoroughly mixed
with the blood, nor will inflammation of the vein through which the
fluid passes, be by any means invariably produced.
When a foreign substance is introduced into an artery, any immediate
effects upon the blood may naturally be looked for in the system
of capillaries which it supplies. If the blood then coagulates,
local symptoms alone, will, in the first instance, be produced, and
the constitution will remain unaffected. M. Magendie,[24] indeed,
asserts that fluids injected into the arteries of animals, return
quickly through the corresponding veins, and that this takes place
even more rapidly in the living than in the dead body. If this were
universally true, it would matter little whether foreign matter were
introduced into the arterial or venous system. The effect upon the
constitution would be the same in either case. But if, as is now
maintained, extraneous matter introduced into the blood may, under
certain circumstances, produce its coagulation, then the effects
will be confined, more or less completely, to the first system of
capillaries which the blood meets with in the natural course of its
circulation, and the constitution will be affected only in consequence
of the changes which then take place. M. Gaspard has shown that greasy
fluids, and such as contain sediments, do not find their way readily
from the small arteries into the veins. They become entangled in the
intermediate capillaries, and there produce, first patches of local
congestion, and subsequently serous effusion and abscesses. Some clear
fluids, on the other hand, such as solutions of tartar emetic, of
opium, and of nux vomica, when introduced into an artery, pass readily
in the course of the circulation, and produce their full effect upon
the constitution; and in such cases no irritation is manifested in
the capillaries through which they pass. The first of these poisons
produces vomiting and purging, the second stupor, and the third tetanic
rigidity, exactly in the same manner as if they had been introduced
into the stomach, or injected into a vein.
[24] Précis Elémentaire de Physiologie, t. ii, p. 389.
There are yet another class of substances differing in their effects
from both of the former; and under this head are classed infusion of
tobacco, solution of acetate of lead, putrid fluids, etc. These are
distinguished from the first class above mentioned, as not offering in
themselves any mechanical impediment to the circulation of the blood,
and from the second, as not producing the same constitutional symptoms
when injected into an artery as when thrown into a vein. M. Gaspard
found that, when introduced into an artery, the infusion of tobacco
neither produced vomiting nor stupor, the solution of acetate of lead
did not act upon the intestines, and the putrid fluids did not produce
the evacuations usually observed after their introduction into the
system by other means. All these substances, however, were found to
produce violent local irritation in the parts to which the branches of
the injected artery were distributed, and the constitutional symptoms
were those produced in consequence of the local irritation, and not
those which would arise directly from the action of those poisons upon
the system.
In Experiment XX, seven or eight cubic inches of common air were
gradually injected into the carotid artery of a dog, and half an hour
afterwards an ounce of water, to which seventy drops of medicinal
prussic acid had been added, was thrown into the same vessel; none of
the peculiar effects of the poison followed this operation. At the
expiration of another quarter of an hour, an ounce of a saturated
solution of nux vomica was likewise injected, still without producing
any constitutional symptoms. It is very remarkable in this experiment,
that M. Gaspard[25] should have considered that the elasticity of the
air contained in the vessels was sufficient to counteract the impetus
of the blood, and thus to prevent the progress of the poison along the
vessels, especially when we find him stating that, on a post-mortem
examination, the smaller vessels appeared to have been _obstructed by
very hard clots of blood_.
[25] Journal de Physiologie, t. v, p. 328 and 336.