Blood-pressure Changes. 



109 



leaving both hands free, in place of the usual rubber bulb or 

 Politzer bag as the source of pressure. 



The greatest difficulty is the satisfactory palpation of the small 

 pulse in the foot. In certain dogs it is impossible, and animals 

 must be selected that possess a reasonably large and superficial 

 artery. It is impossible to appreciate the return of the pulse after 

 obliteration, but with practice, if the animal can be kept quiet, the 

 obliteration of the pulse can be appreciated within perhaps 10 or 

 15 mm. limits of error, always on the side of under-estimation. 

 When the foot is cold, it should be wrapped in warm cloths to 

 dilate the vessels, before taking readings. 



A number of experiments, in which I have followed the pres- 

 sure changes during an operation coincidently with a direct carotid 

 tracing, show that one can follow fairly rapid and marked fluctua- 

 tions of blood-pressure in this way, with reasonable certainty. The 

 results have no absolute, but, I am convinced, a real relative value. 

 For the solution of such problems as the one studied by Passler 

 and Heineke, and which Carrel and I are engaged in, I believe 

 that frequent approximate blood-pressure observations are of more 

 significance than a few isolated, though accurate, measurements. 



57 (395) 



Note on the blood-pressure changes following reduction of the 

 renal arterial circulation. 



By THEODORE C. JANEWAY. 



\F]'0]n the Rockefeller Institute for Medical Research^ 



Of the various workers who have studied the effects of reduc- 

 tion of kidney substance, only Passler and Heineke record system- 

 atic blood-pressure observations. They were able to make direct 

 measurements in the femoral on five dogs before and after operation, 

 and reported a rise in pressure in all, the smallest increase being 

 15 mm., the greatest 29 mm., and the average 21.5 mm. These 

 figures are based on the comparison of single readings before 

 operation with one or more after operation, and are open to the 

 objections I have previously urged. Because of the small number 

 of reported observations in this field, I hope to be pardoned for 

 presenting my still very incomplete studies at this time, in order 



