Comparison of Dinamap PRO-100 and mercury sphygmomanometer blood pressure measurements in a population-based study.

BACKGROUND: The accuracy of automated oscillometric devices has been questioned. In addition the acceptability of these devices for research under the field conditions is unclear.
METHODS: We compared blood pressure (BP) readings obtained using the Dinamap PRO-100 with readings obtained using a standard mercury sphygmomanometer in 305 participants aged 48 to 86 years who were enrolled in the ongoing Multi-Ethnic Study of Atherosclerosis. The BP was measured three times by each device in random order in each participant.
RESULTS: Approximately one half of the participants were male and 46.6% had hypertension. The Dinamap and mercury measurements were well correlated (r = 0.89 for systolic BP and r = 0.81 for diastolic BP). Overall the Dinamap underestimated BP: the mean difference (Dinamap - mercury sphygmomanometer) was -0.5 mm Hg (P = .36, SD = 9.8 mm Hg) for systolic BP and -2.9 mm Hg (P < .001, SD = 6.6 mm Hg) for diastolic BP. However, the Dinamap device tended to overestimate systolic BP in participants who were 75 to 86 years of age, who had a pulse pressure >or=60 mm Hg, or who had stages I to III hypertension. On the other hand, the Dinamap underestimated diastolic BP among these same subgroups but with a smaller underestimate than for the rest of the study sample.
CONCLUSIONS: Although the BP measurements obtained by the Dinamap PRO-100 tend on average to be slightly lower than those obtained by the standard mercury sphygmomanometer in middle-aged and older persons, the discrepancies may vary with age, pulse pressure, and BP. Health care providers and researchers should know of this variation and should interpret Dinamap-measured BP with caution.