Note on the regulation of the pressure on the artery in the application of the sphygmograph / by Bathazar W. Foster, M.D.

  • Foster, Balthazar Walter, 1840-1913.
Date:
[1867], [©1867]
Catalogue details

Licence: Public Domain Mark

Credit: Note on the regulation of the pressure on the artery in the application of the sphygmograph / by Bathazar W. Foster, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    4/8 (page 2)
    back^ an addition to the screw, which I have since had applied and used with advantage. A, Index. £, Pressure-screw. Screw seen from above. C, The spring. The woodcuts represent two views of the pressure screw (b), as placed in Marey^s sphygmograph, and show also the additions I have made. These consist in connecting an index (a) with the screw, around which a circle has been described and graduated. The index moves along with the screw, and indicates on the circle the pressure equivalent in any observation. By this simple arrangement, without any alteration in its form, the sphygmograph may be made much more reliable in the hands of beginners, for each one will be able to record at the side of the pulse trace, the pressure exercised upon the artery beyond that necessitated by the application of the instrument. Moreover, in making a series of observations^ in the same or even in different cases, the spring can be fixed at that point which allows it to follow most accurately the movements of the vessel, and the conditions in all being thus rendered practically the same, the conclusions based upon a comparison of the traces become much more trustworthy. In cases of aortic aneurism, there can be no doubt that the most valuable assistance in diagnosis may be occasionally obtained from a careful com- ^ Physiological section, British Association Meeting, Nottingham, 1866. 2 Mr. Meyer, of Great Portland Street, made the above-described alterations for me, and calculated the equivalents of pressure to be as follows: When the index points to 5, the extra pressure equals 20 grammes in weight. 7 „ 31 , 10 12 15 18 20 25 30 40 52 64 79 93 123 160 A scale increasing more gradually would no doubt be preferable. This could be easily arranged, as every instrument would have to be graduated according to the elasticity of its spring. I have remarked in several sphygmographs which I have examined a wide difterence in this respect. Wolff also particularly mentions this in his ' Charakteristik des Arterien Pulses.* Leipzig, 1865.