Clinical validation of the accutracker, a novel ambulatory blood pressure monitor using R-wave gating for Korotkoff sounds.

We compared simultaneous, same-arm blood pressure (BPs) obtained with the Accutracker, an ambulatory blood pressure (BP) monitor, which uses R-wave gating for Korotkoff sounds to those of both a blinded, skilled clinician using a mercury column and a three-channel graphic display of cuff pressure tracings, Korotkoff sounds, and ECG tracing. Eighteen subjects, with a wide variety of BPs, heart rates, and ages, participated in the study. The systolic BP obtained by the ambulatory recorder, clinician, and the three-channel strip chart recorder were 132 +/- 23 mmHg, 132 +/- 24 mmHg, and 133 +/- 25 mmHg, (all NS), respectively. Accutracker recorder-determined systolic BP correlated highly both with the clinician and strip chart readings (r = 0.98 and 0.97, respectively; p less than 0.0001 for both). The diastolic BP obtained by the Accutracker recorder was slightly, but significantly, lower than the clinician's readings (76 +/- 12 mmHg vs. 81 +/- 13 mmHg; p less than 0.005) and similar to the strip chart recorder readings (76 +/- 12 mmHg vs. 77 +/- 12 mmHg; NS). In 32 young, healthy subjects with no activity restrictions, 91% of the raw BP data from 24-hour ambulatory recordings was acceptable using strict deletion criteria. These data demonstrate that the Accutracker is highly accurate compared with clinician-determined blood pressures. The lower diastolic BP readings may stem from the ability of this device to detect softer Korotkoff sounds than can be detected by the clinician. These findings should be taken into consideration when using ambulatory BP monitoring in clinical trials of antihypertensive drugs.