Ambulatory monitoring allows some normality with regard to daily activity. The device is worn for 24 h and programmed to take blood pressure measurements at a set time interval. Most devices will give some warning, e.g. a beeping sound, that the cuff is about to inflate. This is an indication to the patient to stop any activity and to keep their arm still. Home monitors are designed to be initiated manually.
Whether self-initiated blood pressures are different from those initiated by the clinician, is not known. It is, however, quite likely as even the gender of the investigator performing the measurement can influence the reading (Millar and Accioly, 1996).
In the non-pregnant population, ambulatory blood pressure measurements correlate better with target organ damage (Asmar et al., 1988; Bianchi et al., 1994; Devereux et al., 1983;
Table 18.4. Meta-analysis of 10 validation studies in pregnant women with and without pre-eclampsia
Pregnancy PET Pregnancy PET
Subjects (n) 597 176 8 30
Systolic* -1.13 (5.80) -4.60 (8.04) 4.11 (10.95) -17.76 (10.12)
Diastolic* -1.20 (6.03) -5.16 (7.19) 3.00 (8.00) -8.17 (6.59)
*Mean pressure difference and standard deviation (SD) mmHg.
Shimada et a/., 1992) and direct cardiovascular morbidity (Perloff et a/., 1983, 1989, 1991) than casual blood pressure measurements. Its use in a hypertensive adult population is quite extensive.
It was first used in pregnancy in the late 1980s (O'Brien et a/., 1991) and soon thereafter in hypertensive pregnancy (Rath et a/., 1990). Normal values of 24-h ambulatory blood pressure measurement have been determined (Contard et a/., 1993; Ferguson et a/., 1994; Halligan et a/., 1993) and it is known that women with pre-eclampsia have an attenuated nocturnal fall in blood pressure.
It was thought that ambulatory monitoring could have a predictive value related to the absence of a nocturnal fall (> 12 mmHg) in women destined to become pre-eclamptic (Halligan et a/., 1993; Moutquin et a/., 1992). Other studies have shown that significantly higher systolic and mean arterial pressures occur at 18 and 28 weeks gestation in those women who subsequently develop pre-eclampsia (Kyle et a/., 1993). The predictive capability of ambulatory monitoring is limited by the need to screen a large number of women with relatively intensive monitoring. It does, however, appear to be useful in evaluating hypertensive pregnancies. It is a better predictor of adverse obstetric outcome than conventional mercury sphygmomanometry (Peek et a/., 1996; Penny et a/., 1998) with regard to severe hypertension. Disappointingly, it remains a weak predictor of subsequent proteinurea, i.e. pre-eclampsia.
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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...