STAGES OF AN.KSTHESIA. 



33 



Another modification, suitable for hospitals or infirmaries 

 where operations are constantly being performed, consists in an 

 arrangement whereby all pumping by means of the bellows is 

 done away with, a cylinder of compressed air with a regulating 

 valve being attached to the bottle in such a way that the current 

 (when turned on) passes either over or through the chloroform, 

 and so forces the mixed vapour onwards into the mask (Fig. 17). 



Whichever inhaler is used, care must be taken to produce 

 anaisthesia slowly, and to administer the vapour as regularly 

 and steadily as possible. The average length of time required 



Fig. 10. 

 Diagram of author's second design of inlialer. 



in which to produce the safe stage of unconsciousness for a cat 

 or small dog is from one to two minutes ; for a dog the size of 

 a terrier, about three or four minutes ; and for the larger breeds, 

 six or eight minutes. 



Stages of Anaesthesia. — During the process of complete an- 

 aesthetisation an animal passes through four stages. The first 

 one is a stage of surprise and alarm, during which the patient 

 sometimes holds its breath as if unwilling to receive the strong- 

 vapour. This is especially noticeable in cats and rabbits, and 



care must be taken to allow the respirations to become regular 



C 



