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(Hypertension. 1998;32:430-436.)
© 1998 American Heart Association, Inc.

Scientific Contributions

Statistical Base Value of 24-Hour Blood Pressure Distribution in Patients With Essential Hypertension

Osamu Tochikubo; Satoshi Hishiki; Eiji Miyajima; ; Masao Ishii

From the Second Department of Internal Medicine, Urafune Hospital of Yokohama City University (O.T., S.H., E.M.), and the Second Department of Internal Medicine, School of Medicine, Yokohama City University (M.I.), Yokohama, Japan.

Correspondence to Osamu Tochikubo, MD, Second Department of Internal Medicine, Urafune Hospital of Yokohama City University, 3-46 Urafune-cho, Minami-ku, Yokohama 232, Japan.

Abstract—The purpose of this study was to calculate statistically the minimum (base) blood pressure (BP) of nighttime (sleep-time) BP values obtained by ambulatory BP monitoring (ABPM) and to investigate its clinical significance. Twenty-four-hour recording of ECG with ABPM was performed directly (n=89) or indirectly (n=117) in 206 patients with essential hypertension. A telemeter was used for the direct method and a multi-biomedical recorder (TM2425) was used for indirect measurement. First, minimum heart rate (HR₀=60/RR₀) was determined from sleep-time ECG. The mean product of sleep-time diastolic BP (DBP) and pulse interval (RR) was divided by RR₀ to obtain DBP₀ [DBP₀=(DBPxRR)s/RR₀]. The correlation between systolic BP (SBP) and DBP was used to determine SBP₀ corresponding to DBP₀. Statistical base mean BP (MBP₀) was calculated from these values, and its reproducibility and relation to hypertension severity were investigated. MBP₀ values were similar to true base values of sleep-time MBP obtained by the direct method (mean±SD difference, 2.0±4.2 mm Hg). Direct MBP₀ criteria predicted hypertension severity (mild, moderate, or severe target organ damage) more accurately (predictive accuracy, 89%) than daytime MBP criteria (53%, P<0.01). Almost the same results were obtained using indirect MBP₀ criteria. Day-to-day indirect MBP₀ variation (mean absolute difference) was smaller (2.4±1.8 mm Hg) than day-to-day daytime and nighttime MBP variation (6.3±5.3 and 5.4±3.4 mm Hg, respectively; n=61, P<0.01), and the correlation coefficient between day-to-day variations of daytime MBP and physical activity (measured by an acceleration sensor) was 0.38 (P<0.05). In conclusion, statistical base BP was almost equal to true base (minimum) BP of sleep-time BP distribution. It was closely related to the severity of hypertensive organ damage, was highly reproducible, and is considered likely to serve stochastically and physiologically as a representative BP value in an individual subject.

Key Words: blood pressure monitoring, ambulatory • sleep • hypertension, essential

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				O. Tochikubo, E. Miyajima, T. Shigemasa, and M. Ishii Relation Between Body Fat–Corrected ECG Voltage and Ambulatory Blood Pressure in Patients With Essential Hypertension Hypertension, May 1, 1999; 33(5): 1159 - 1163. [Abstract] [Full Text] [PDF]