AND BLOOD PRESSURE 



123 





was placed round the neck of a dog, the maximal pulsation corre- 

 sponded to about the mean pressure as indicated by a mercurial 

 manometer connected with the femoral artery, and C. J. Martin 

 supported this finding. If the pressure just exceeds diastolic 

 pressure the artery should fill in systole and be emptied in diastole. 

 It takes time to do this, and when the pulse is frequent and the 

 pressure oscillations are large, not only is a very rapidly acting 

 instrument required to follow accurately the pulses, but there may 

 not be time for the full swing of the 

 artery to be carried out. Thus in 

 aortic regurgitation the maximal pul- 

 sation extends over a wide area of 

 pressure. It is owing to this that 

 divergence of opinion arises as to 

 what the maximal pulsation indicates. 

 The obliteration pressure, on the other 

 hand, unquestionably indicates the 

 maximal or systolic pressure, and the 

 only error which can arise is that due 

 to rigidity of arterial wall, if the 

 instrument be properly used. v. Basch 

 and C. J. Martin found that a 

 sclerosed radial artery is collapsed 

 by a few millimetres of mercury. 

 The writer found the carotid of a 

 child collapsed by 2 mm. Hg. 



Herringham and Womack, inves- 

 tigating a number of arteries taken 

 from the post-mortem room, found 4 

 to 18 mm. and in two cases 30 to 

 34 mm. The pressure required bore 

 no relation to the age of the men 

 from whom the arteries were taken ; 

 the varying amounts were probably due to post-mortem contrac- 

 tion, a conclusion which is confirmed by the fact that the two 

 brachials in one case differed as much as 10 mm. Hg. 



W. Russell and G. Oliver disbelieve the readings of the armlet 

 method in the case of contracted and sclerosed arteries. Russell 

 says he has felt arteries in life almost as brittle as glass, in other 

 cases rigidly contracted. He thinks it impossible that the high 



Fl. 15. The 

 Leonard Hill 

 sphygmometer. 



