Page 628 - My FlipBook

626 EXTRACTION OF TEETH.

diictioii of nitrons ox id uiu'stlu'sia. It is also justly considcrccl to be
siihjccting- a patient to an unwarrantahlc (lant;vr to permit the asphyxia]
oH'cct to manifest itself to a profound degree, as in many eases it is
a menace to life and liealtli, and might have a fatal effect. The object
of Dr. Hewitt's method is t(j control or eliminate the asphyxial clement
by administering a requisite amount of oxygen.

Fig. 569.

Showing arrangement of the mixing-chamber, with dial and valve for controlling the
relative proportions of the gases.

No fixed rule can be laid down for the quantity of oxygen to be
added, as each case will require a different amount and this amount
varies during the several stages of the anesthetic procedure. The
operator is guided entirely by the symjitoms of the patient during the
administration, his object being to avoid on the one hand the tendency
toward asphyxia indicated by cyanosis of the lips, and return of con-
sciousness and sensation on the other hand, which is easily produced
by an excess of oxygen. By the admixture of oxygen, as in Dr.
Hewitt's method, the anesthesia is somewhat prolonged over the ordinary
nitrous oxid method and is slower of induction, but there is entire
absence of cyanosis, stertorous breathing, jactitation, or any of the
symptoms of asphyxia. The modification of the Hewitt apparatus
that has been lately introduced embodies certain features that make it
an improvement on the original apparatus. The arrangement of the
mixing-chamber in reference to the bags containing the gases is such as
to enable the operator to more accurately control the mixture that is