Recommendations for Human Blood Pressure Determinations by Sphygmomanometers

IT SHOULD be clearly recognized that arte- rial pressures cannot be measured with precision by means of sphygmomanometers. Direct registration of pressures by cali- brated intra-arterial manometers has shown (1) that even during quiet breathing and slight sinus arrhythmia, systolic and diastolic pres- sures vary from beat to beat by several mm. Hg, and that these differences are greatly in- tensified during states of arrhythmia and deep breathing; (2) that auscultatory systolic read- ings from the brachial artery average 3 or 4 mm. Hg too low and show average scatter of ±8 mm. Hg; and (3) that auscultatory diastolic pressures taken at the point of dulling of the sounds average about 8 mm. Hg too high. The errors of clinical measurement of blood pres- sure can be summarized by saying that in normal persons a mean error of ±8 mm. Hg may be expected in individual readings of sys- tolic and diastolic pressures. Despite this, clin- ical blood pressure determinations have proved very serviceable for practising physicians, clin- icians, insurance carriers, and others concerned with physical examinations, diagnosis, prog- nosis, or therapy. It is important, however, that any basic deficiency of sphygmomanom- etry be not increased by additional errors due to apparatus or technic. The following recommendations have been drawn up with the idea of aiding examiners to avoid pitfalls and, as far as possible, to establish The authors constituted the Committee to Revise "Standardization of High Blood Pressure Readings. "This Committee, whose Chairman was Dr. Carl J. Wiggers, functioned under the auspices of the Council for High Blood Pressure Research of the Scientific Council of the American Heart Association. These recommendations are being presented simul_ taneously in Circulation and in the Journal of the American Medical Association. less. A length of bag sufficient to half-encircle