1911.] Ventilation of the Lung during Chloroform Narcosis. 371 



be saturated to the extent of 19 c.c. per 100 c.c. of blood, the oxygen tension 

 being equal to 99 - 49 mm. But during narcosis the haemoglobin is in the 

 same state of partial saturation that it would be with a carbon dioxide 

 tension of 40 mm. and an oxygen tension of only 45 - 5 mm. The 

 diminution of oxygen in the blood during chloroform narcosis seems too 

 great to be accounted for by the lowered level of respiration, particularly 

 in the initial stages, judging by the figures obtained by Loewy and Zuntz 

 and others.* 



The diminution of oxygen might, however, be to some extent accounted for 

 by a piling up of carbon dioxide in the blood during narcosis, a condition 

 which, as is well known, favours the dissociation of oxy haemoglobin. 



In order to test whether a lowered level of respiration, such as one finds 

 in chloroform narcosis, does result in a marked diminution of oxygen due 

 to the diminished respiration alone, we made the following experiment with 

 a low percentage air-ether mixture, ether being selected as it has a less 

 marked poisonous effect than chloroform : — 



A cat was anaesthetised with ether, the necessary operations performed, 

 and placed in the plethysmograph. It was then allowed to recover, and was 

 anaesthetised with 6 per cent, ether-air. Samples of the blood were 

 taken at two stages at which the number of respirations per minute was 

 the same, but the average depth of respiration much less in one than the 

 other. • 



The following was the breathing during the three minutes before Sample I 

 was taken : — 





No. of respirations. 



Average depth, 

 in c.c. 



Total ventilation, 



1st min. 



27 



39 -45 



1065 



2nd „ 



27 



38-00 



1026 



3rd „ 



29 



37 -28 



1084 



and before Sample II — 



1st min. 



27 



25 -22 



681 



2nd „ 



26 



25 -38 



657 



3rd „ 



28 



25 -20 



706 



4th „ 



22 



26 -60 



585 



The following results were obtained : — 

 Sample I. — Volume of blood = 10"3 c.c. 



Pressure of gas at 13'8° C. and constant volume (48'65 c.c.) = 8'2 cm. ; after addition 



* ' Archiv f. Anat. u. Physiol.,' 1904, p. 166. 



