THE CONCLUSIONS WHICH HAVE BEEN REACHED BY THE SERIES OF EXPERIMENTS RECORDED IN THE PRESENT MEMOIR ARE: First. Lowered arterial pressure has a comparatively feeble effect upon the respiration, but when the pressure falls sufficiently,
respiratory depression does occur. Second. Even excessive lowering of blood pressure primarily stimulates the vaso-motor centre, the sensibility of the centre being evidently necessary to the automatic regulation of the circulation. Third. The circulation recovers itself more slowly after profound etherization than after a like
chloroform narcosis. Fourth. It is possible for
ether as well as
chloroform to produce death some hours after the cessation of its administration, at a time when the cerebrum has long freed itself from distinct evidences of the
narcotic, so that consciousness and intellectual action have been restored. In applying these conclusions to the subject of practical anaesthesia it is evident that the depression of the circulation produced by
chloroform has effect upon the respiratory centres only when the pressure has fallen very low, and whilst it may be
a factor in the production of
respiratory failure during chloroformization, the failure must be chiefly due to the direct influence exercised by the
drug upon the respiratory centres. Clinical experience shows that
nausea and general depression are more pronounced after the use of
ether than after the use of
chloroform, a difference which is strongly insisted upon by the advocates of
chloroform as an important agent in favor of that anaesthetic. Our research confirms clinical observation, and experimentally shows that the depression of the circulation produced by
ether is more permanent than that caused by
chloroform; the reason probably being the large amount of
ether which is necessary to produce profound
narcosis, with lowering of the arterial pressure; an amount so large that it can neither be burned up in the system nor yet eliminated in the time which would be necessary for the much smaller amount of
chloroform to be gotten rid of after chloroformization.