Page 711 - My FlipBook

SHOCK. 721

tlie heart. The effect of the blow seemed to have paralyzed those
nerve-centres which control the tension of the vascular system, causing
sucli a dilatation of the vessels of the abdomen particularly that the
blood did not fill them, and the heart was unable to proceed normally
for Avant of the usual stimulus of a proper blood-supply. When the
animal was laid down, so that gravitation would bring the blood to the
heart, the normal pulsations were resumed. It is clear that the animal
could not have recovered had it remained suspended, for without the
circulation, which under the circumstances could not be resumed, the
nerve-centres could not recover their vigor. But with this the tension
was soon restored. This experiment shows that an animal—and prob-
ably a man as well—may bleed to death without the loss of a drop of
blood, simply by the dilatation of the vessels to such an extent that they
shall not be filled with blood. It is probable that the great vessels of
the abdomen when utterly relaxed will contain the whole blood of the
vascular system, and in this condition it will for the time be as com-
pletely lost to the system as though it had been poured out. This seems
to indicate the exact manner of death in some of the cases of shock
already alluded to. Savory states that instant death may occur from
a blow on the epigastrium which, though severe, leaves no detectable
lesion ; and Mansel-Moullin relates a case of sudden death from shock
caused by the introduction of a trocar into a cyst of the liver, in which
the tissue injury was so trifling that death could not be explained except
on a supposition of a paralysis of the vaso-motor centres.
These facts seem to show plainly the nature of the condition which is
known as shock or collapse. The vaso-motor nerves are for the time
rendered inoperative, and in this way the circulation is so enfeebled,
when not cut off entirely, that its functions are imperfectly performed,
and the whole svstem suffers in consequence. There seems to be a pos-
itive enfeeblement of the heart as well, probably from the same cause,
for in those cases of the lesser degrees of shock the effect on the heart
seems to be the prominent factor, at least the most marked symptom. Yet
in all cases the character of tlie pulse, which is very short and compres-
sible, speaks plainly of lack of arterial tension. The heart is so far
independent of other innervation than that contained within its own
walls that it is capable of continuing its regular rhythmical actions when
all other sources of nerve-supply are cut off. The great nerve-centres
may be removed one after another until the last one is severed, and yet
the nerves contained in its own walls will serve the purpose of continuing
its motions. At the same time, it is so connected with these great nerve-
centres that the irritation of one of its connecting branches may bring it
to an immediate stop. Not only this, but irritation applied to a per-
ipheral nerve may produce the same effect through reflex action. We^
have also learned through direct experiment, some of which was detailed
while treating of hyperemia, that the blood-vessels, veins as well as
arteries, are under a control of the same nature and are affected in
the same way by similar causes. While all of this is true, and the
heart may be stopped by these reflex impulses, and the tone of the
arteries may be relaxed, the local nerves of the heart will, after a time,
set up these actions anew independently of other nerve-influence. It is
Vol. I.—46