BACKGROUND: Although body position is known to be an important factor influencing the results of ambulatory blood pressure monitoring (ABPM), even very recent studies assessing postprandial blood pressure (BP) have not taken into account the possibility that the examined subjects were lying down after a meal. We addressed this issue by analysing diurnal BP profiles together with subject's reports on supine rest periods and meal consumption during ABPM. MATERIAL/METHODS: The ABPM results of 109 non-medicated subjects were analysed (age 40+/-12 years, daytime BP 132/84+/-15/11 mmHg). BP and heart rate (HR) changes were assessed on the basis of 2-hour means. RESULTS: Subjects who lay down within 2 hours after a meal showed significantly greater decreases in systolic and diastolic BP and HR than individuals who did not: -10+/-10 vs. 1+/-10 mmHg, -11+/-10 vs. -3+/-7 mmHg, and -7+/-9 vs. 0+/-11 beats/min, respectively. The BP decrease was greater when the duration of supine rest was longer. There were no significant differences between BP/HR changes during those periods when the subjects lay down within 2 hours after the meal and BP/HR changes during those periods when supine rest was not preceded by a meal. The mean changes for the latter group were -9+/-10 mmHg, -11+/-8 mmHg, and -9+/-9 beats/min. for SBP, DBP, and HR, respectively. CONCLUSIONS: Our results indicate that supine body position is an important factor, which may influence postprandial BP investigated by ABPM. Body position should always be taken into consideration when ABPM results are analysed.

Keywords: Blood Pressure Determination, Blood Pressure Monitoring, Ambulatory - methods, Diastole, Postprandial Period, Supine Position, Systole, Time Factors