120 



Scientific Proceedings (66). 



subject in a horizontal position and taking the systolic pressure 

 in the brachial artery. The subject is then required to stand, and 

 without removing the cuff, blood pressure is taken in a vertical 

 position. In a perfectly strong and vigorous subject the splanch- 

 nic vaso-tone will increase and the blood pressure will be found 

 raised about 10 millimeters of mercury. In an individual weak- 

 ened by dissipation, overwork, lack of sleep, or by the incidence 

 of disease, the blood pressure will tend not to rise but to fall. 

 Under conditions which may still be classed as normal, this fall 

 of pressure may amount to ten millimeters. These facts have 

 been verified by repeated tests upon those known to be in good 

 and in bad condition, in subjects well rested, and others thoroughly 

 wearied. It appeared, therefore, at this point in the investigation, 

 that we have arrived at a test of an important function and that 

 the test could be expressed numerically on a scale ranging from 

 plus ten to minus ten. A further factor of importance was, 

 however, present. It was found in the vigorous subjects that the 

 heart rate did not increase on standing, and in the wearied subjects 

 it increases as much as forty-four beats per minute. It was 

 further found that this difference varied with the blood pressure 

 differences and in some cases took the place of the blood pressure 

 variation. In other words, the same subject under the same 

 conditions would show a weakness sometimes by a decrease in 

 blood pressure, and at other times by an increase in heart rate, 

 and vice versa. After further observation, it was determined 

 that a decrease of one millimeter of mercury had a value of an 

 increase in heart rate of approximately two. It was obviously 

 necessary to consider both elements and to adjust the heart-rate 

 changes with the corresponding blood-pressure changes. To do 

 this, it was assumed that the total observed ranges in heart rate 

 and blood pressure were equal in total value, and equal in each 

 step in the scale in a proportion to approximately two to one. A 

 table which balanced these two elements was constructed as 

 shown on page 121. 



The ioo per cent, rating indicates a rise of ten in pressure with 

 practically no increase in the heart rate. Throughout the table, 

 an inefficiency exhibited either in blood pressure or in heart rate is 

 given a corresponding lower rating until zero is reached. The 



