LOCAL ANASTHESIA., 43 
later by intermittent arterial systole. As soon as the pulse is irreg- 
ular and the visible mucous membranes are becoming pale, cardiac 
syncope is imminent; inhalations must be suspended at once, the 
head inclined, the respiration kept up, and thythmic traction upon 
the tongue performed. : 
In small animals, during the anesthetic sleep, it may happen that 
the tongue, retracted in the mouth, presses with its root against the 
epiglottis and closes the larynx. Respiration becomes embarrassed, 
and then its sounds suddenly cease. If this accident occur, tractions 
upon the tongue must be immediately applied to relieve the larynx. 
At the beginning of anesthesia, in the stage of excitement, alarm- 
ing symptoms may be manifested (general stiffness, staring eyes, 
cyanosed membranes, and arrest of respiration), due to the closing of 
the glottis by spasms of the laryngeal muscles. If these symptoms 
appear, anesthesia must be at once stopped, applications of cold’ 
water must be made upon the head and the face or chest slapped 
with a cloth dipped in cold water. 
Intoxication by the inhalation of too great a quantity of ether or chlo- 
roform is not to be feared unless anesthesia has been bad y. applied 
4, 
or carried too far. & 
> 
i : 
LOCAL ANESTHESIA. 
The dangers of general anesthesia have suggested the idea of find- 
ing means by which only the region to be operated upon should be 
anesthetized. Continued pressure over the tissues and the mediate 
compression on the nerves being very imperfect in their result, ice 
freezing mixtures or nebulization of ether have been successfully em- 
ployed. Then came cocaine, the use of which has now become 
general. 
. ANAESTHESIA BY CoLD.—1. Freezing Mixtures.—The continued ap- 
plication of cold upon superficial tissues produces in them modifica- 
tions, which bring on ischemia, numbness, a diminution, and 
even an abolition, of sensibility. 
During this century cold has been resorted to for the purpose of 
performing some short operations upon the skin and the first sub- 
cutaneous layers, where refrigeration might, without inconvenience, 
be rapidly realized. 
In veterinary surgery it has been resorted to for operations on the 
lower parts of the extremities. Ice and common kitchen salt are 
mixed in equal parts or in the proportion of two to one. This mix- 
ture is placed in a bag or wrapped in a cloth and applied upon the 
parts to be operated upon. In a few minutes this becomes cold, 
