The measurement of blood pressure and its interpretation.

The auscultatory or indirect technique of measuring blood pressure has been proved reliable in multiple clinical settings and has received wide application. In clinical studies, special efforts are used to train observers in the measurement of blood pressure and to ensure properly functioning equipment. Similar diligence in providing quality control is necessary in everyday practice to guard against potential errors. With proper care it is possible to obtain readings that classify the pressure to the nearest 5 mm Hg. Table 1 lists some of the sources of error that are possible with the indirect technique and the magnitude of these errors. It should be emphasized that many factors affect blood pressure variation and that any single reading is of limited value. A number of specific sources of information are useful to the practicing physician and his staff for maintaining equipment and for standardizing technique and procedure. Application of these principles to primary care practice should improve the accuracy of health maintenance and allow proper clinical application of the results of the many clinical studies of mild hypertension that are presently being conducted around the world.