1911.] Ventilation of the Lung during Chloroform Narcosis. 357 



Experiment 6. — Example in which the respiration is comparatively slow 

 (40 in 30 sees.) and also shallow ; average depth, 47*88 c.c, and a low total 

 ventilation of 1915 c.c. per 30 sees. There is no trace of an initial danger- 

 point (fig. 6) : — 



Fig. 6. 



Depth of respiration, 1 division = 21'28 c.c. ; time intervals, 30 sees. ; |, chloroform on. 



Table VI. — Measurements of Tracing in Fig. 6. 



Intervals 

 in minutes. 



Antesthetic. 



respirations 

 per minute. 



Amplitude of 

 respiration. 



ventilation, 



0-5 





51 



54 -39 



2772 



0-5 





52 



48 -82 



2272 



0-5 





48 



28-41 



1364 



The cat continued to breathe for several minutes without any marked 

 alteration in the type of respiration, and the experiment was then stopped. 



It is clear, from the typical experiments quoted, that the initial effect of 

 chloroform is to produce a marked diminution in the average depth of 

 respiration. This occurs during the first few minutes of anaesthesia, but 

 subsequently the depth of respiration becomes constant at a lower level. 

 The rate is not affected to anything like the same extent. In the initial 

 stage a slight increase in the frequency, followed by a decrease, generally 

 occurs, but sometimes a slight decrease takes place at once. The cessation of 

 respiration, which is an initial danger-point in chloroform anaesthesia and 

 may result in death, is the direct effect of deep and rapid respiration prior 

 to the administration of the drug, and the higher the percentage of the 

 drug administered the more likely it is to occur. This can be rendered 

 negligible by a low percentage of chloroform. An examination of many 



