Differences in Blood Pressure Levels Obtained by Auscultatory and Oscillometric Methods

Levels of blood pressure measured by the conventional auscultatory method were compared with those measured by the Dinamap Monitor (Dinamap Monitor 1846 SX, Critikon Inc, Tampa, Fla), an oscillometric device. Triplicate measurements were obtained by the two methods 10 to 15 minutes apart in 381 seated fifth-grade children, ages 10 to 13 years. The width of the air bladder of the blood pressure cuff was selected to be 40% to 50% of the circumference of the upper arm. The mean systolic and diastolic pressures (at the fourth phase of Korotkoff sounds) by the auscultatory method were 6.4 mm Hg lower and 8.7 mm Hg higher than the oscillometric systolic and diastolic blood pressures, respectively. The findings of this study suggest that published normative levels of auscultatory blood pressure may be inappropriate as a standard when blood pressure measurement is obtained by the Dinamap Monitor. Until a new set of normative Dinamap blood pressure levels becomes available, one should use equations (A = 12.8 + 0.82D for systolic, and A = 34.3 + 0.54D for diastolic blood pressures at the fourth phase of Korotkoff sounds, where A is auscultatory blood pressure and D is Dinamap blood pressure) to predict auscultatory blood pressures before Dinamap blood pressures are compared with normative auscultatory blood pressure levels.