Effect of pre-measurement relaxation time on manual blood pressure measurement

In clinical practice, blood pressures (BPs) are often measured without relaxation before the measurement is taken, allowing little time for BP to stabilise. However, there is little evidence on the effect of pre-measurement relaxation time on manual BP measurement. This study aimed to provide these data. Twenty subjects were studied. Manual systolic and diastolic BPs (SBP and DBP) were obtained by a trained observer. There were two sessions for each subject with two pre-measurement relaxation times (none and 10 min). Within the first session, the subjects were asked to sit relaxed at the reception for a 10 min before entering the measurement room. Three sequential BP measurements were then taken at 0, 10, and 20 min. For the second session, the subjects were asked to walk around for 800 m at their normal walking speed before a similar series of BP measurements were taken. The measured BPs were then compared between the two pre-measurement relaxation times. ANOVA analysis showed there was no significant sequential changes in BPs (P>0.15), and there was no effect of pre-measurement relaxation time on SBP. However, the effect of the two relaxation times (none and 10 min) on DBP was significant (P<;0.05). On average, the DBP measured with no relaxation was 1. 7 mmHg higher than with 10 min relaxation. In conclusion, this study quantified the effect of relaxation period on manual BP measurement.