Comparison of three devices for measuring blood pressure

Blood pressure measurement with two automatic devices, Dinamap 845 and Sentry, was compared with the standard mercury sphygmomanometer, by means of a 3-period crossover experiment. Both automatic devices read diastolic pressure considerably lower than the mercury sphygmomanometer (about 7 mmHg on average); agreement was better for systolic pressure. Device differences in individual patients were often much higher. To assess the patient's emotional pressor response during manual measurement, Dinamap was used to monitor blood pressure before, during and after measurement with the mercury sphygmomanometer. No rise in pressure was found. It is concluded that the three devices can often give different values, and that the physician's involvement cannot explain these differences.