Effect of respiration, talking and small body movements on blood pressure measurement

It is accepted that accuracy of auscultatory blood pressure (BP) measurement is influenced by measurement conditions. However, there is little comparative quantitative clinical data. The aim of this study was to provide these data. Auscultatory systolic and diastolic BPs (SBPs and DBPs) were measured in 111 healthy subjects under five different conditions (resting, deeper breathing, talking, head and arm movement). The measurement sequence was randomized, and repeated three times. BPs and their within-subject variabilities were compared with resting values. SBP and DBP changed significantly in comparison with the resting condition: decreasing by 4.4 and 4.8 mm Hg, respectively, with deeper breathing (both P<0.001), increasing by 3.7 and 5.0 mm Hg with opposite arm movement, and increasing by 5.3 and 6.2 mm Hg with talking (all P<0.001). The mean differences between deeper breathing and talking were 9.7 and 11.0 mm Hg for SBP and DBP. The within-subject variability for repeat measurement of SBP and DBP under resting condition were 3.7 and 3.2 mm Hg and increased for non-resting conditions (all P<0.05, except for DBP while talking). We have shown that measurement conditions significantly influence manual auscultatory BPs and their measurement variabilities, and we provide quantitative data to allow comparison of the effects.