Comparison of Dinamap PRO-100 and Mercury Sphygmomanometer Blood Pressure Measurements in a Population-Based Study

The accuracy of automated oscillometric devices has been questioned. In addition the acceptability of these devices for research under the field conditions is unclear. 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. 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 ≥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. 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.