EFFECTS OF NONINVASIVE AMBULATORY BLOOD-PRESSURE MEASURING DEVICES ON BLOOD-PRESSURE

It is well recognized that the act of blood pressure (BP) measurement may influence the level of BP.1 This "cuff response" is attributed to an alerting reaction; it does not decrease with repeated measurement, and is worse in the presence of a doctor than in the presence of a nurse.2 This suggests that the major component of the reaction is not discomfort from inflation of the cuff, and this is supported by the fact that BP usually increases before the cuff is applied. These observations have led to the assumption that ambulatory cuff BP devices do not provoke such effects. This is implicit in the high reproducibility of measurements in groups of subjects that has been observed with some modern machines,3 although this could simply reflect the reproducibility of the alerting response. This issue has only been addressed in subjects confined to bed for relatively brief periods.4 No account has been taken of the possibility of effects on patients trying to sleep at night, or of the overall impact of wearing such devices. Ambulatory BP monitors are coming into wide use for the assessment of hypertensive subjects before and after treatment. This follows observations that ambulatory measurements are better prognostic indicators than casual readings.5 This study tests the hypothesis that wearing an ambulatory cuff BP monitor might, in itself, alter BP by increasing discomfort, influencing activity or sleep patterns, or by promoting an alerting response. © 1990.