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At times sudden exaggeration of the respiration and a rise of blood-pressure may result
from a temporary obstruction of the breathing. And in some instances it is possible that exag-
gerated respiration may be due to a directly stimulating effect of chloroform on the respiratory
centre, but in this case it would probably not be so sudden in its development.
Influence of certain Changes in the Action of the Heart and in the Blood-pressure upon
the Effects of Chloroform Inhalation .—I have seen no grounds for believing that changes in the
action of the heart alone (for example, changes in rate) can influence the results of chloroform
administration, except in so far as such changes affect the blood-pressure. A great increase in
the rapidity of the heart's action may be attended by little or no rise in the blood-pressure.
I have frequently seen a great and sudden acceleration of the heart without any important
change of pressure; and, conversely, a marked of the cardiac rhythm may be accom
- p a n i e d b y n o f a l l o f p r e s s u r e . I t i s r e a l l y t h e a l t e r a t i o n b r o u g h t a b o u t i n t h e b l o o d - p r e s s u r e
that is directly productive of marked effects in regard to the influence of chloroform. Changes
in blood-pressure do undoubtedly modify in every important degree the results of chloroform
or ether inhalation. The great resistance towards both chloroform and ether during certain
conditions of low arterial tension (for example, from vagus stimulation or section of splanchnics)
has been already referred to, and is quite in accordance with the observations of the
Hy d e r a b a d C o mmi s s i o n o n t h e s a me p o i n t . An a mo u n t o f c h l o r o f o r m wh i c h ma y b e g i v e n
during a state of low arterial tension. (depending on causes other than the anæsthetic) without
marked effect. may lead to grave results if the pressure be suddenly raised by artificial means,
for example, by compression of the abdominal aorta. The dose of chloroform then reaching
the vital organs is largely increased on account of the great augmentation of the blood stream
in the head and upper part of the body. In this way a sudden change of pressure may be
productive of dangerous effects.
During a condition of logy arterial pressure the occurrence of an asphyxial condition may
cause a great rise in the pressure, and thus lead to considerable variations in the amount of
chloroform reaching the vital tissues, especially if the elevation of pressure be followed by the
occurrence of exaggerated respiratory efforts, as may readily happen on the removal of a
mechanical obstruction to breathin
g .
When a low arterial tension is dependent on the depressing influence of chloroform
there is little or no chance of any important of pressure being brought about by irritation
of sensory nerves; the anæsthetic prevents the occurrence of such a vascular constriction from
sensory excitation
.
But during imperject anæsthesia a moderate pressure may suddenly be converted into a
high pressure by strong irritation of sensory nerves, causing stimulation of the vaso motor
-centre and increased vascular tone. when such an elevated pressure is combined with violent
respiratory efforts, there is danger of an overdose of chl
oroform being taken in unless great
care be exercised.
The danger involved in the abrupt change from a low pressure to a high pressure is due
t o t h e f a c t t h a t w h e n t h e p r e s s u r e i s l o w c h l o r o f o r m m a y b e g i v e n i n c o m p a r a t i v e l y l a r g e