I goo- 1. 



Observations on Blood Pressure. 



231 



minutes in one experiment and 7^ in another 

 — the respiration stops, and two or three 

 minutes later, the pressure being nearly at 

 zero, the pulse ceases. 



In Tracing 47, the animal having been 

 previously placed under atropine, chloroform 

 was pushed at 6. No morphia had been 

 given. A good deal of struggling occurred, 

 followed by a rapid fall in blood pressure. 

 Chloroform was removed, and the animal 

 quickly recovered. It is interesting to note 

 that although the pressure fell so low the 

 respiration did not stop as would almost 

 certainly have been the case if atropine had 

 not been given. This tracing shows inci- 

 dentally that the fall in blood pressure in 

 chloroform poisoning is not dependent upon 

 slowing of the heart's action. 



The action of atropine as an antidote to 

 chloroform poisoning does not seem to have 

 attracted much attention. Dr. H. C. Wood^ 

 found that in a dog in which the respiration 

 had stopped from chloroform poisoning "a 

 hypodermic injection of 10 c.cs. of a two per 

 cent, solution of atropine altered the rate of 

 the pulse but had no apparent effect on the 

 pressure and respiration, and in no wise 

 prevented the final cardiac arrest." 10 c.cs., 

 however, was such an enormous dose, repre- 

 senting as it does about three grains of 

 atropine, that he might well have got such a 

 result when a more moderate quantity might 

 have saved the animal. This quickening of 

 the pulse which Dr. Wood refers to is 

 shown in Tracing 48. In this case the 

 animal had been atropinized and then chloro- 

 form had been pushed until the respiration 

 stopped at 18. After that the pressure rose 

 gradually and then as gradually sank again 

 with hastening of the pulse. After the pulse 



I British Medical Journal, Aug. i6th, 1890. 



