Repeated measurements of ambulatory blood pressure

Automated non-invasive recorders allow repeated measurement of blood pressure, 24 h a day; the question of how often to sample blood pressure remains unanswered. Interrupting the patients for a reading more often than necessary may elevate blood pressure or compromise patient cooperation. Thirty-two normotensive subjects were each monitored for 24 h at two measurement rates, one and four readings per h, on 2 work days, to determine whether the rates affected blood pressure and behaviour. The blood pressure level at home and at work and most behaviours were indistinguishable on the 2 monitoring days. The heart rate was slightly higher and subjects reported greater disruption of their daily routine on the four/h monitoring day. The results suggest that blood pressure can be read as often as four times an hour without falsely elevating blood pressure, inducing emotional distress or impairing cooperation with the monitoring procedure.