A comparison of blood pressure measurements obtained with the Dinamap 845XT, the standard mercury sphygmomanometer and the London School of Hygiene device.

Blood pressure measurements obtained with the Dinamap 845XT Vital Signs monitor were compared with measurements obtained with a standard mercury sphygmomanometer and a London School of Hygiene mercury sphygmomanometer in a group of 31 normotensive and hypertensive subjects. The experimental design allowed reading to be taken with all 3 devices at approximately the same time. 12 sets of readings were obtained with each device in each subject. Although inter-device differences estimated from analysis of variance were small (less than 2 mmHg after allowing for calibration differences) differences between measurements taken simultaneously with the 3 devices were often substantial. Agreement between the two mercury sphygmomanometers was better than that between either sphygmomanometer and the Dinamap. This may be a reflection of fundamental differences between auscultatory and oscillometric measurements. Differences between devices were unrelated to blood pressure level. The observed variability within subjects was similar with each device.