Evaluation of a New Ambulatory Blood Pressure Monitor (Accutracker 102): Laboratory Comparisons With Direct Arterial Pressure, Stethoscopic Auscultatory Pressure, and Readings From a Similar Monitor (Spacelabs Model 5200)

Systolic (SBP) and diastolic (DBP) blood pressure levels generated by a new noninvasive ambulatory monitor, the Accutracker 102, were compared in the laboratory with intra‐arterial pressure levels in 12 normotensive men, and with stethoscopic auscultatory determinations in 27 normotensive and hypertensive men and women over a wide range of within‐subject pressure variations. In 11 subjects, its performance was also compared with another ambulatory monitor, the Spacelabs Model 5200. Highly positive correlations with both the intra‐arterial (median r =+.90 for SBP, +.92 for DBP) and the stethoscopic standards (median r =+.93 for SBP, +.88 for DBP) were obtained using Accutracker's automatic readings (digital readout), while slightly higher correlations were obtained with hand‐scoring of recorded data. The Spacelabs BP monitor also yielded readings that were highly correlated with stethoscopic readings (median r =+.83 for SBP, +.77 for DBP), although in 3 of the 11 subjects the Accutracker correlations were substantially higher than the Spacelabs correlations. Despite their generally good tracking of changes in pressure, both ambulatory monitors yielded absolute values in many subjects that differed by 5 mmHg or more from stethoscopic levels. The Accutracker's SBP levels were consistently too high and its DBP levels were occasionally too low, while Spacelabs' SBP and DBP values were too high and too low with equal frequency. However, mean deviation scores for each patient calculated from 5 concurrent ambulatory monitor and stethoscopic readings were shown to yield relatively stable correction factors for use when comparison with clinical standards is desired.