When using HBPM to obtain a BP average either for confirming a diagnosis or assessing HTN control, patients should be instructed to record their BP measurements twice in the morning and twice at night for a minimum of 3 days (ie, 12 readings).26,27 For each monitoring period, both SBP and DBP readings should be recorded, although protocols differ as to whether to discard the initial reading of each day, or the entire first day of readings.26-29 Consecutive days of monitoring are preferred, although nonconsecutive days also are likely to provide valid data. Once BP stabilizes, monitoring 1 to 3 days a week is likely sufficient.
Most guidelines cite a mean BP of ≥ 135/85 mm Hg as the indication of high BP on HBPM.1,28,29 This value corresponds to an office BP average of 140/90 mm Hg. TABLE 21 shows the comparison of home, ambulatory, and office BP thresholds.
Device selection and validation
As with any BP device, validation and proper technique are important. Recommend only upper-arm cuff devices that have passed validation protocols.30 To eliminate the burden on patients to accurately record and store their BP readings, and to eliminate this step as a source of bias, additionally recommend devices with built-in memory. Although easy-to-use wrist and finger monitors have become popular, there are important limitations in terms of accurate positioning and a lack of validated protocols.31,32
The brachial artery is still the recommended measurement location, unless otherwise precluded due to arm size (the largest size for most validated upper-arm cuffs is 42 cm), patient discomfort, medical contraindication (eg, lymphedema), or immobility (eg, due to injury). Arm size limitation is particularly important as obesity rates continue to rise. Data from the National Health and Nutrition Examination Survey indicate that 52% of men and 38% of women with HTN need a different cuff size than the US standard.33 If the brachial artery is not an option, there are no definitive data to recommend finger over wrist devices, as both are limited by lack of validated protocols.
The website www.stridebp.org maintains a current list of validated and preferred BP devices, and is supported by the European Society of Hypertension, the International Society of Hypertension, and the World Hypertension League. There are more than 4000 devices on the global market, but only 8% have been validated according to StrideBP.
Advances in HBPM that offset previous limitations
The usefulness of HBPM depends on patient factors such as a commitment to monitoring, applying standardized technique, and accurately recording measurements. Discuss these matters with patients before recommending HBPM. Until recently, HBPM devices could not measure BP during sleep. However, a device that assesses BP during sleep has now come on the US market, with preliminary data suggesting the BP measurements are similar to those obtained with ABPM.34 Advances in device memory and data storage and increased availability of electronic health record connection continue to improve the standardization and reliability of HBPM. In fact, there is a growing list of electronic health portals that can be synced with apps for direct transfer of HBPM data.
Ambulatory blood pressure monitoring
ABPM involves wearing a small device connected to an arm BP cuff that measures BP at pre-programmed intervals over a 24-hour period, during sleep and wakefulness. ABPM is the standard against which HBPM and office BP are compared.1-3
