(A) 
Physiology. — “A new method of determining the arterial blood- 
pressure in man; at the same time an attempt at estimating 
the influence of the arterial wall on it’. By Dr. D. pr Vrins 
Rerinen. (Communicated by Prof. WeNCKrBACH). 
(Communicated in the meeting of March 25, 1911). 
I]. A SHORT SURVEY OF THE USUAL METHODS. 
The arterial blood-pressure in man was in the beginning determined 
according to the older methods of von Bascu, von Frny, Poraiy, and 
others. By these methods, as the newer methods of investigation 
teach us, only an approximate estimation was obtained. 
A great improvement in the solution of the problem was obtained 
by the invention of Riva-Rocct and Hirn and Barnarp i.e. by the 
method of the circular compression of the arm by a hollow rubber 
armlet in which the pressure could be increased and diminished. 
Originally only a narrow armlet was used, but von RECKLINGHAUSEN 
showed that the influence of the surrounding tissues of the arm was 
considerably less, if an armlet of at least 13 ¢.m. broad was used. 
Since that time this broad armlet is almost universally used. LrONARD 
Hint even makes the determinations of the blood-pressure with an 
armiet of 20 em. broad. 
Now the blood-pressure is usually measured according to two 
different principles, according to which it is customary to distinguish 
the oscillatory and the palpatory method. 
A. Oscillatory method. 
A hollow armlet is applied to the upper-arm of the person that 
is to be examined, whilst the pressure of air in the interior of the 
armlet is constantly increased. Then there occur in the armlet 
pulsations, the intensity of which can be determined in some way 
or other: either by registering them graphically on a revolving drum 
or by reading them from a mercury- or water-column or any other 
index connected with the armlet. 
The peculiarity of these pulsations is that they increase in the 
same measure as the pressure in the armlet increases, till they have 
reached a certain maximum, and that afterwards, when the pressure 
in the armlet augments, they decrease and disappear at last almost 
entirely. 
Originally it was admitted, that the diastolic or minimal blood- 
pressure (mp) in the armlet was reached when it showed the 
greatest pulsations. It was supposed that just then the artery during 
