October 25, 1906] 



NA TURE 



639 



veins being comparatively low; in the large veins- 

 opening into the right heart it may, indeed, be 

 minus, owing to the suction action of the thorax, and 

 hence when these veins are cut air may actually be 

 sucked into the blood-stream. 



The vascular blood-pressure is subject to consider- 

 able variation both in health and disease, and it will 

 readily be seen that its accurate estimation is of great 

 clinical value. To take an illustrative case. In 

 certain poisoned states of the blood the small arteries 

 undergo considerable contraction ; in consequence of 



.—Dr. George Oli 

 coloured spiril-ind 

 the rubber lube cc 

 the b!oocl-i 



r"s Hx'tnomanometer (redi 

 i, represented by the dart 

 imunicating with the envt 

 i being taken. 



this the blood caimot pass into the capillaries and 

 veins with its wonted facility, and tends to be dammed 

 back upon the large arteries and heart ; in other 

 words, the blood-pressure rises in the left ventricle 

 and in the whole arterial tree proximal to the ron- 

 tracted area, and this heightened pressure is further 

 augmented by an increase in the force of the heart- 

 beat, called forth by the necessity to overcome the 

 increased resistance. .Vn increased strain is thus put 

 upon the heart and arteries, and this, if long con- 

 tinued, may lead to disease in them ; and in this wav 

 such serious affections as aneurism, heart-disease, 

 and apople.\y may be brought about. The importance 

 of early detecting such cases of augmented pressure 

 is apparent, in that it enables steps to be taken to 

 correct the underlying faulty condition 

 of blood, and thus to ward off grave 

 consequences. 



Until recently the physician had to 

 be content to rely upon his sense of 

 touch in estimating blood-pressure. 

 and thus it was that the older phv- 

 sicians spoke of a " hard " and a 

 " soft " pulse, the former indicating a 

 high and the latter a low blood- 

 pressure. More modern physicians de- 

 scribe the pulse as " compressible " or 

 " incompressible," or the vessel as 

 being in a state of high or low " ten- 

 sion," according to the readiness with 

 which it yields to the pressure of the 

 finger. This tactile method is, how- 

 ever, far from trustworthy. Not onlv 

 is long experience needed to acquire 

 even moderate efficiency in it, but from 

 a variety of causes the most skilful are 

 liable to make false estimates by its 

 means ; nor do the findings admit of 

 accurate record. In short, though useful as a rough- 

 and-ready method, it lacks the precision needful for 

 scientific observation. 



The earliest method of estimating the arterial 

 blood-pressure consisted in cutting the artery of an 

 animal and observing the height to which the blood 

 was forced out. Later the more delicate plan was 

 adopted of connecting the interior of the vessel with 

 a mercurial manometer, by means of an elastic tubing 

 filled with saline solution. Clearly neither of these 



NO. 1930. VOL. 74] 



methods is available for clinical purposes. Recently, 

 however, a method has been devised in which the 

 employment of the knife can be dispensed with, and 

 one, moreover, yielding results quite as accurate as 

 those just referred to. It consists in enveloping some 

 part of the upper extremity — arm, forearm, or finger — 

 in a gutta-percha bag, and connecting the latter, by 

 means of a tubing, with a manometer. The bag is 

 blown up until the pulse on the distal side of it is 

 obliterated, the pressure then registered by the mano- 

 meter representing the "systolic," or " obliterative " 

 pressure. The 



" diastolic " prcs- 

 sure, or that 

 obtaining between 

 the heart beats, 

 is measured by 

 noting the excur- 

 sions of the mano- 

 metric index pro- 

 duced by the pul- 

 sations of the 



ced to half size), a is the graduated glass tube along which moves the „^,.„_,. . jf :„ UplH 

 curved line at the right-hand bend ; B is the open end on lo which fits artery , It 1S_ nelO 

 loping b.ag. or armlet ; c is kept closed by means of an air-block, while that the maximum 



movements occur 

 when the pressure 

 on the artery is just sufficient to balance the diastolic 

 pressure. 



Hitherto the manometer most frequently used in 

 these observations has been the ordinary mercurial 

 one; but Dr. George Oliver, of Harrogate, has 

 recently devised an instrument which is not only more 

 handy, but would appear to give more accurate read- 

 ings than the mercurial manometer. It consists of 

 a fine bored glass tube (Figs, i and 2) which during 

 use is kept closed at one end, and connected at the 



ing the armlet with the glass tube ; 

 provided with a screw (covered by the 

 d tubing may bi gradually deflated. 



Other with the enveloping bag by means of elastic 

 tubing. .\ minute drop of coloured spirit introduced 

 into the glass tube serves as the index. .\t the com- 

 mencement of an observation the index is at zero, 

 which is situated at the open end of the tube. .As the 

 bag is blown up the index is driven onwards, com- 

 pressing the air in front of it, and advancing with 

 every increment of pressure. The instrument is 

 readily graduated by means of a mercurial mano- 

 meter. It will be seen from this description that the 



