Blood Pressure Measurement under Within-Visit Conditions in Normotensive Volunteers

The dynamics of mean values and blood pressure (BP) variability were studied under within-visit conditions in normotensive subjects. The study involved 104 volunteers aged 20 to 65 years (46 men and 58 women) without the history of hypertension. Nine repeated BP measurements were performed within 35 min in a summer period to determine the final time for the BP decrease, i.e., for the “stabilization” of BP within one visit, and the within-visit BP variability (WVV) expressed as the standard deviation (SD) and the coefficient of variation (CV). The tenth measurement of BP was conducted to assess the effect of physical activity after a 5-min walk followed by a 5-min seated position. In order to study the effect of seasons on the BP variation, 32 volunteers were examined in winter (January–February) and in summer (June–July) of the same year. The within-visit BP in normotensive subjects was characterized by two aspects. The first one associated with a decrease in systolic BP (SBP) and diastolic BP (DBP), on average, by 7 mmHg and up to 2 mmHg, respectively, ended by the 25th minute and was followed by the period of conventional stabilization in mean values. The following two periods were observed in the SBP decrease: a 5-min rapid decrease (1 mmHg/min) and a 20-min slow decrease (0.1 mmHg/min). The dynamics of mean SBP values depended on gender and age. The second aspect is the individual SBP variability, which continued against the stabilization of mean values. The CV of 35-min SBP reached, on average, 4% and was higher in women compared with men. SD was higher in the older age group. The maximum variability was observed within the first 5 min under the investigation. Then, in the periods of slow decrease and stabilization, the variability did not change significantly (not exceeding 3%, on average), despite a significant decrease in the mean SBP values. During a rapid SBP decrease neither of variability indices depended on gender or age. The SD of SBP during the slow decrease and stabilization was higher in the older female group than in the young women, not differing in men of both age categories. After 5 min of rest in a seated position, the consequences of walking for BP were insignificant in normotensive subjects. The dynamics of SBP did not differ in summer and winter of the same year.