Accurate nighttime blood pressure monitoring with less sleep disturbance

Abstract

Nocturnal hypertension has been reported to be a strong risk factor for cardiovascular events [1–4], and the importance of nighttime blood pressure (BP) control for hypertension management has been recognized. Ambulatory BP monitoring (ABPM), which typically measures BP every 15–30 min throughout the day and night, has been considered the gold standard for measuring nighttime BP during sleep. Although considerable evidence has been accumulated from ABPM, its use is not widespread, partly due to the discomfort and disturbance of daily activities and sleep. Recently, home BP monitoring (HBPM) devices equipped with timer functions allowing automatic measurement during sleep have been developed. However, with either method, some individuals feel discomfort and experience sleep disturbance resulting from the frequent brachial cuff inflation of BP measurement during sleep. Sleep disturbance caused by nighttime BP measurement can lead to the following problems: (1) inaccurate BP assessment due to arousal or sleep deprivation (higher than usual nighttime BP value); and (2) reduced adherence of patients to repeat nighttime BP monitoring (i.e., failure to follow hypertension treatment or to monitor nighttime BP over multiple nights). In terms of the former problem, a study by Verdecchia et al. assessing perceived sleep quality during overnight ABPM monitoring in 2934 untreated hypertensive subjects found that nighttime BP increased and its prognostic significance decreased in subjects with ≥2 h sleep deprivation induced by cuff inflation [5]. These findings indicate that sleep disturbance and lower than usual sleep quality may lead to underestimation of cardiovascular risk, or perhaps, overdiagnosis. In addition, the Japan Morning Surge-Home Blood Pressure (J-HOP) nocturnal BP study showed the importance of considering both sleep duration and nighttime BP in cardiovascular risk assessment; that is, sleep hygiene is important for implementing cardiovascular disease prevention strategies in patients with hypertension [6]. Related to the latter problem, some previous studies revealed that most subjects who underwent nighttime BP monitoring complained of sleep disturbance [7]. Individuals who experienced reduced sleep quality during nighttime BP measurement may be reluctant to repeat nighttime BP measurements. Therefore, reducing sleep disturbance caused by nighttime BP measurement is indispensable for hypertension management throughout the day and night. One simple approach to reduce sleep disturbance is to reduce the frequency of BP measurements with cuff inflation per night; however, this will naturally lead to a decrease in the accuracy of nocturnal hypertension diagnoses. Yang et al. investigated the number of BP measurements required to obtain an estimate of mean BP during sleep similar to that obtained by a full night of ABPM in 4277 participants from the International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes (IDACO) study [8]. They found that 3–4 BP readings during sleep are the minimum requirement to estimate the mean BP from fullnight readings. Moreover, a recent study by Jaeger et al. examined the timing of a limited number of BP measurements to obtain an accurate estimate of mean BP from a full night of ABPM using data from 621 participants of the Jackson Heart study (mean age: 58.8 ± 10.5 years, mean asleep SBP: 120 ± 14.7 mmHg) and 458 participants of the Coronary Artery Risk Development in Young Adults study (mean age: 54.7 ± 3.7 years, mean asleep SBP: 111 ± 15.1 mmHg), who slept >5 h and recorded >1 valid asleep BP measurement every 30 min between midnight and 5:00 AM during their ABPM assessment [9]. They sampled 2–4 BP measurements at specific times from a full night of ABPM readings, and a total of 74 sampling approaches were evaluated for diagnostic accuracy of nocturnal hypertension (defined by a mean nighttime SBP ≥ 120mmHg or mean * Naoko Tomitani [email protected]