RESPIRATION 235 



primary failure of the respiratory centre followed by failure of 

 the heart, or from primary paralysis of the heart or of the whole 

 vascular mechanism (including the muscular tissue of the heart 

 and bloodvessels and the vaso-motor centre) , followed by paralysis 

 of the respiratory centre. Sometimes the respiratory failure and 

 the vascular paralysis may be simultaneous ; often one* may 

 follow so hard on the heels of the other that it is difficult to 

 decide which is primary and which secondary. Much depends 

 upon the concentration of the chloroform vapour. Where it 

 is dilute (at any rate, up to 5 per cent, of the inspired air 

 in cats), and is administered by means of an apparatus which 

 insures a definite and uniform concentration, the respiration 

 invariably stops before the heart. The chloroform is mainly 

 taken up by the coloured corpuscles. The percentage of the drug 

 in the blood increases very rapidly in the first minutes of ad- 

 ministration, and then rapidly declines, to increase again to a 

 maximum, which is now maintained during the remainder of the 

 anaesthesia. In those first few minutes occurs a definite danger 

 point as regards the respiratory centre (Buckmaster). The 

 stronger the chloroform mixture inhaled the greater is the 

 damage to the vascular mechanism relative to that inflicted 

 upon the respiratory apparatus, and the more rapidly does it 

 become irreparable. It has been shown that the concentra- 

 tion of chloroform necessary to produce serious effects upon the 

 isolated mammalian heart when added to the liquid used for 

 perfusion is practically identical with that found in the blood of 

 animals fully narcotized with the drug by inhalation. In ether 

 narcosis the quantity of the anaesthetic in the blood is not suffi- 

 cient to seriously affect the heart, and this is the reason why 

 ether is so much safer than chloroform. The practical lesson is 

 that in administering chloroform both the respiration and the 

 pulse must be watched. The drug should be given by a method 

 which allows exact control of its concentration in the air. The 

 primitive drop-bottle and towel method should be abandoned. 

 In addition to the dangers connected with the direct action of 

 chloroform on bulbar centres, the possibility of untoward reflex 

 effects must be borne in mind. At a certain stage in chloroform 

 anaesthesia, before it has become very deep, comparatively trifling 

 causes may bring about great and sudden changes in the pulse- 

 rate, owing to the abnormal mobility ol the vagus centre (Mac- 

 William). It is further of interest in connection with the causa- 

 tion of death during the administration of anaesthetics that the 

 afferent nerves of the alveoli can be chemically stimulated when 

 irritant vapours, such as chloroform, hydrochloric acid, am- 

 monia, bromine, or formaldehyde are inhaled through a tracheal 

 cannula, causing reflex arrest of the heart and of the respiratory 



