In-field validation of automatic blood pressure measuring devices

The method for rapid evaluation of automatic blood pressure (BP) measurement devices (READ) is based on numerous BP measurements at rest and during a standardised postural challenge in a small number of subjects with a wide range of BPs. The present study proposes additional parameters of the READ for in-field validation of automatic BP measurement devices. BP measurements were done in supine position for 10 min followed by head-up tilt for 30 min and again supine for 10 min. BPs were determined simultaneously by automatic (AU) and mercury sphygmomanometric (MS) measurements on the same arm. The BP differences Delta BP:AU-MS were calculated. Three units of the Colin BP-8800 and the Datex-Engstrom Cardiocap(TM) II were evaluated. Based on Delta BP(AU-MS), the grade of accuracy, aberration patterns and correlates of accuracy were assessed for each unit. Per unit, an average of 121 measurements were done, every BP category being met in greater than or equal to 20 MS measurements. In general, the AU systolic BP values were higher than MS systolic BP values (mean systolic Delta BP = 1.26 +/- 17.1 mm Hg) and AU diastolic BP values were lower than MS diastolic BP values (mean diastolic Delta BP = -12.31 +/- 7.8 mm Hg). All units classified into category D of the British Hypertension Society grading system and exhibited inconsistent aberration patterns, making design of correction formulas impractical. Inaccuracy of the instruments was independent on mode of measurement, posture, magnitude of the BP and heart rate, early or late measurements from beginning of the head-up tilt test, and prolonged use of the unit. The READ permitted to identify rapidly the degree of accuracy of automatic BP measuring devices. Identification of the aberration pattern of an instrument could be the basis for calculating equations for correction of the measured BP. Further studies will show which parameters of the READ may expose specific defects of the instruments.