270 REPORTS ON THE STATE OF SCIENCE. 



APPENDIX I. 



On the Principles of Ancesthesia by Ether Vapour. 

 By Dr. A. D. Waller. 



During recent years, in consequence of serious misgivings relating to 

 the safety of chloroform as ordinarily administered, and of the good results 

 of ether reported from the United States, many anaesthetists in this 

 country and on the Continent have been led to adopt anaesthesia by ether, 

 administered by what is termed the open method. ' Open ether ' was an 

 expression frequently employed in this connection at the recent dis- 

 cussion on anaesthetics that took place at the last meeting of the British 

 Medical Association, and it is necessary in the first instance to under- 

 above the face, and brought gradually quite close. But it can also be 

 ' Open ether ' implies, I understand, any method by which the patient is 

 not made to breathe and re-breathe the same mixture of air, ether, and 

 accumulating carbon dioxide. It may be effected, as is the Boston prac- 

 tice, by means of a mask saturated with liquid ether, held at a distance 

 above the face, and brought gradually quite close. But it can also be 

 effected by a closed face-piece through which an ether-air mixture of 

 required strength is supplied on the plenum system. In this case the 

 fit of the face-piece is of set purpose incomplete, there being on the 

 plenum system an excess of mixture supplied, which carries away with 

 its overflow the products of expiration. The imperfection of closure 

 can, if preferred, be secured by an actual orifice guarded by an expiration 

 valve. 



The factor of primary importance in anaesthesia by ether, as in 

 anaesthesia by chloroform, is quantity — i.e., the percentage of ether in 

 the cther-and-air mixture offered to inspiration. I find as the general 

 result of prolonged trials, conducted in various ways — (1) that the 

 physiological power of chloroform is six to eight times that of ether, 

 or, as I expressed it for the sake of clearness some years ago, that — 



Chloroform _ 7 . 

 Ether 1 S 



(2) that whereas chloroform-and-air should be maintained at between 

 1 and 2 per 100, ether-and-air is required at between 8 and 16 per 100 

 for the production and maintenance of satisfactory anaesthesia. 



Chloroform is par excellence the powerful anaesthetic. It is easy 

 to deliver chloroform-and-air continuously at 1 and 2 per 100 or more. 

 And by reason of this facility chloroform anaesthesia, unless great care 

 be observed, is dangerous to life. 



Ether is par excellence the safe anaesthetic. It is comparatively 

 difficult to deliver ether-and-air continuously at 8 to 16 per 100; and by 

 reason of this difficulty ether anaesthesia is more troublesome, the 

 trouble being to give enough ether. 



A fortiori it is difficult to give too much ether, while it is only too 

 easy to give too much chloroform. 



' Open ether,' in any strict sense of the term, is all but an impos- 

 sibility with the usual methods of administration by cone or mask, 



