Page 478 - My FlipBook

476 DENTAL MEDICINE.
According to the temperament, the stage of excitement is tran-
sient or prolonged •, in some cases there are strange illusions,
with a form of intoxication, which may be manifested by decla-
mation, singing, laughing or crying, or melancholy, with a dis-
position at times to assault all near. Such effects, if the admin-
istration is not interrupted, soon pass off. For surgical operations,
the gas is given with less admixture of air, and the inhalation
persisted in until the stage of excitement is overcome and insen-
sibility produced, when the face becomes exceedingly pale, the
respirations, at first shallow, become deep and stertorous, the jaw
fixed, the eyes protruding, and a bluish and purplish color about
the lips and face, the patient presenting a very alarming and
death-like appearance, a condition of which Bartholow says : " So
far as the exterior phenomena can afford any indication of the
nature of the action, is an asphyxiated state. The blood ceases
to be oxygenated, carbonic acid accumulates, and the centres of
conscious impressions are rendered inactive in consequence of the
deficient supply of oxygen and the excess of carbonic acid. The
rational indications of the nature of the narcosis produced by
nitrous oxide are confirmed by physiological experiment. It has
been found that the exhalation of carbonic acid is decidedly di-
minished by the inhalation of nitrous oxide, and that animals live
no longer in an atmosphere of this gas than in an atmosphere of
hydrogen." The same author speaks of the fatal cases that have
occurred, as being with propriety attributable to the lethal action
of this gas, and refers to various cases under his own observation
in which nervousness, vague mental symptoms and headache
at the same time he
have been experienced after the inhalations ;
pronounces nitrous oxide to be almost free from danger. Prof.
H. C. Wood believes that nitrous oxide acts as an anaesthetic by
shutting off oxygen. There is no doubt but that the prompt ac-
tion of nitrous oxide gas, and the rapid subsidence of the nar-
cosis, have much to do with its safety, and account for the im-
punity with which it is used. According to recent investigations,
^nitrous oxide gas has no direct effect upon the heart and vaso-
motor system, but indirectly causes a rise of arterial pressure by
the slight asphyxia it produces. Although the anaesthesia may