General Surgery 13 



narcotize a dog, but twenty grams killed it. The range is twelve 

 grams. 



Ether has the same power in proportion, but is infinitely less 

 dangerous, since between active and lethal dose there is a range of 

 nearly forty grams. According to Embley, the chief factor in the 

 causation of sudden death under chloroform is vagus inhibition. 

 Chloroform vapor not stronger than one and one-half per cent in 

 air after a period of mild excitation, slowly depresses vagus ex- 

 citability, and if administered in strength of over two per cent may 

 cause dangerous or persistent inhibition. This action is all the 

 more intense and fatal from being exercised upon an organ whose 

 spontaneous excitability is diminished by the paralytic effect of the 

 drug upon the heart muscle itself. The failure of respiration is due 

 to fall of blood-pressure, and takes place invariably long before the 

 heart stops. Hence respiration should be watched as an index to the 

 circulatory condition. 



If atropine is administered prior to the chloroform the vagus 

 is never inhibited and cardiac arrest does not follow. Rudolf and 

 others have made similar observations. Hence, we have in atropine, 

 administered hypodermically previous to chloroformization a very 

 convenient antidote, one which reduces all risk of vagus inhibition 

 to a minimum. If a little morphine is combined with the atropine 

 the primary excitant period attending the chloroform administra- 

 tion is suppressed, but the atropine should be in amount somewhat 

 in excess of what would be given alone, to provide for the mutual 

 neutralization of the two alkaloids. A suitable mixture for this 

 purpose is made in the following proportions: Morphine sulphate 

 three-quarters of a grain, atropine sulphate one-twentieth of a 

 grain, distilled water one drachm. Of this, small dogs take five 

 to ten minims, medium sized dogs ten to twenty minims, and large 

 dogs twenty to thirty minims, h3rpodermically. Some twenty min- 

 utes later the chloroform should be administered. In this manner 

 very little of the latter drug suffices to induce a profound and safe 

 narcosis of considerable duration. 



During administration the action of the iris should be closely 

 observed. It is an almost infallible guide in the estimation of 

 the blood-pressure. Insensibility of the conjunctiva is often re- 

 garded as an indication of insensibility of the higher centers ; but as 

 a matter of fact, the former is established before the latter, conse- 



