The dilemma of nocturnal blood pressure

Automatic data extraction from 24 hour blood pressure measurement reports of a large multicenter clinical trial

BACKGROUND AND OBJECTIVES

Ambulatory blood pressure monitoring (ABPM) is usually reported in descriptive values such as circadian averages and standard deviations. Making use of the original, individual blood pressure measurements may be advantageous, particularly for research purposes, as this increases the flexibility of the analytical process, enables alternative statistical analyses and provide novel insights. Here we describe the development of a new multistep, hierarchical data extraction algorithm to collect raw data from .pdf reports and text files as part of a large multi-center clinical study.

METHODS

Original reports were saved in a nested file system, from which they were automatically extracted, read and saved into databases with custom made programs written in Python 3. Data were further processed, cleaned and relevant descriptive statistics such as averages and standard deviations calculated according to a variety of definitions of day- and night-time. Additionally, data control mechanisms for manual review of the data and programmatic auto-detection of extraction errors was implemented as part of the project.

RESULTS

The developed algorithm extracted 97% of the data automatically, the missing data consisted mostly of reports that were saved incorrectly or not formatted in the specified way. Manual checks comparing samples of the extracted data to original reports indicated a high level of accuracy of the extracted data, no errors introduced due to flaws in the extraction software were detected in the extracted dataset.

CONCLUSIONS

The developed multistep, hierarchical data extraction algorithm facilitated collection from different file formats and paired with database cleaning and data processing steps led to an effective and accurate assembly of raw ABPM data for further and adjustable analyses. Manual work was minimized while data quality was ensured with standardized, reproducible procedures.

The Role of Nocturnal Blood Pressure and Sleep Quality in Hypertension Management

The accurate measurement, prediction and treatment of high blood pressure (BP) are essential to the management of hypertension and the prevention of its associated cardiovascular (CV) risks. However, even if BP is optimally controlled during the day, nocturnal high blood pressure may still increase the risk of CV events. The pattern of circadian rhythm of BP can be evaluated by ambulatory BP monitoring (ABPM). Night-time ABPM is more closely associated with fatal and nonfatal CV events than daytime ambulatory BP. However, the use of ABPM is limited by low availability and the fact that it can cause sleep disturbance, therefore may not provide realistic nocturnal measurements. Home blood pressure monitoring (HBPM) offers an inexpensive alternative to ABPM, is preferred by patients and provides a more realistic assessment of BP during an individual’s daily life. However, until recently, HBPM did not offer the possibility to measure nocturnal (sleep time) BP. The development and validation of new BP devices, such as the NightView (OMRON Healthcare, HEM9601T-E3) HBPM device, could overcome these limitations, offering the possibility of daytime and night-time BP measurements with minimal sleep disturbance.

Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association

The accurate measurement of blood pressure (BP) is essential for the diagnosis and management of hypertension. This article provides an updated American Heart Association scientific statement on BP measurement in humans. In the office setting, many oscillometric devices have been validated that allow accurate BP measurement while reducing human errors associated with the auscultatory approach. Fully automated oscillometric devices capable of taking multiple readings even without an observer being present may provide a more accurate measurement of BP than auscultation. Studies have shown substantial differences in BP when measured outside versus in the office setting. Ambulatory BP monitoring is considered the reference standard for out-of-office BP assessment, with home BP monitoring being an alternative when ambulatory BP monitoring is not available or tolerated. Compared with their counterparts with sustained normotension (ie, nonhypertensive BP levels in and outside the office setting), it is unclear whether adults with white-coat hypertension (ie, hypertensive BP levels in the office but not outside the office) have increased cardiovascular disease risk, whereas those with masked hypertension (ie, hypertensive BP levels outside the office but not in the office) are at substantially increased risk. In addition, high nighttime BP on ambulatory BP monitoring is associated with increased cardiovascular disease risk. Both oscillometric and auscultatory methods are considered acceptable for measuring BP in children and adolescents. Regardless of the method used to measure BP, initial and ongoing training of technicians and healthcare providers and the use of validated and calibrated devices are critical for obtaining accurate BP measurements.

Evidence-based out-of-hours hospital medicine

Out-of-hours (OOH) hospital ward cover is generally provided by junior doctors and is typified by heavy workloads, reduced staff numbers and various non-urgent nurse-initiated requests. The present inefficiencies and management problems with the OOH service are reflected by the high number of quality improvement projects recently published. In this narrative review, five common situations peculiar to the OOH general ward setting are discussed with reference to potential areas of inefficiency and unnecessary management steps: (1) prescription of hypnotics and sedatives; (2) overnight fluid therapy; (3) fever; (4) overnight hypotension and (5) chasing outstanding routine diagnostic tests. It is evident that research and consensus guidelines for many clinical situations in the OOH setting are a neglected arena. Many recommendations made herein are based on expert opinion or first principles. In contrast, the management of significant abnormalities in outstanding blood results is based on well-established guidelines using high-quality systematic reviews.

Effect of the physical activity program on the treatment of resistant hypertension in primary care

BACKGROUND

Regular physical activity is widely recommended for patients with arterial hypertension as an essential component of lifestyle modification. Much less is known about the impact of physical exercise on the management of treatment of resistant hypertension (RH). The aim was to assess the effect of physical activity program intensified by mobile phone text reminders on blood pressure control in subjects with RH managed in the primary care.

METHODS

In total, 53 patients with primary hypertension were qualified, including 27 who met the criteria for RH and 26 with well-controlled hypertension (WCH). Ambulatory 24-h blood pressure was monitored and body composition evaluated with bioimpedance and habitual physical activity profile was determined continuously over 72 h with accelerometer. All measurements were performed at baseline and after three and six months. The patients were asked to modify their lifestyle according to American Heart Association Guidelines that included regular aerobic physical activity tailored to individual needs.FindingsPhysical activity in RH increased significantly after six months compared with control subjects (P=0.001). Office systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the RH group decreased significantly after three months but after six months only office DBP remained significantly lower. After three months 24-h SBP decreased by 3.1±11 mmHg (P=0.08) and DBP by 2.0±6 mmHg (P=0.17) in RH, whereas in WCH respective changes were +1.2±10 and -0.3±6 mmHg. After six months 24-h BP changes were similar.

CONCLUSION

Individualized structured physical activity program increases physical activity in the treatment of resistant hypertensives in primary care but the effect on 24-h blood pressure is only transient.

Differences in night-time and daytime ambulatory blood pressure when diurnal periods are defined by self-report, fixed-times, and actigraphy: Improving the Detection of Hypertension study

OBJECTIVES

To determine whether defining diurnal periods by self-report, fixed-time, or actigraphy produce different estimates of night-time and daytime ambulatory blood pressure (ABP).

METHODS

Over a median of 28 days, 330 participants completed two 24-h ABP and actigraphy monitoring periods with sleep diaries. Fixed night-time and daytime periods were defined as 0000-0600 h and 1000-2000 h, respectively. Using the first ABP period, within-individual differences for mean night-time and daytime ABP and kappa statistics for night-time and daytime hypertension (systolic/diastolic ABP≥120/70 mmHg and ≥135/85 mmHg, respectively) were estimated comparing self-report, fixed-time, or actigraphy for defining diurnal periods. Reproducibility of ABP was also estimated.

RESULTS

Within-individual mean differences in night-time systolic ABP were small, suggesting little bias, when comparing the three approaches used to define diurnal periods. The distribution of differences, represented by 95% confidence intervals (CI), in night-time systolic and diastolic ABP and daytime systolic and diastolic ABP was narrowest for self-report versus actigraphy. For example, mean differences (95% CI) in night-time systolic ABP for self-report versus fixed-time was -0.53 (-6.61, +5.56) mmHg, self-report versus actigraphy was 0.91 (-3.61, +5.43) mmHg, and fixed-time versus actigraphy was 1.43 (-5.59, +8.46) mmHg. Agreement for night-time and daytime hypertension was highest for self-report versus actigraphy: kappa statistic (95% CI) = 0.91 (0.86,0.96) and 1.00 (0.98,1.00), respectively. The reproducibility of mean ABP and hypertension categories was similar using each approach.

CONCLUSION

Given the high agreement with actigraphy, these data support using self-report to define diurnal periods on ABP monitoring. Further, the use of fixed-time periods may be a reasonable alternative approach.

Hypertension: is it time to replace drugs with nutrition and nutraceuticals?

Many hypertension patients want to learn about ways to reduce reliance on pharmaceuticals, says functional medicine practitioner Mark Houston, who believes it is often possible to reduce or eliminate reliance on drugs using nutrition and nutraceuticals.

Estimate of nocturnal blood pressure and detection of non-dippers based on clinical or ambulatory monitoring in the inpatient setting

BACKGROUND

Ambulatory blood pressure monitoring is regarded as the gold standard for monitoring nocturnal blood pressure (NBP) and is usually performed out of office. Currently, a novel method for monitoring NBP is indispensible in the inpatient setting. The widely used manual BP monitoring procedure has the potential to monitor NBP in the hospital setting. The feasibility and accuracy of manual sphygmomanometer to monitor NBP has not been explored widely.

METHODS

A cross-sectional study was conducted at the cardiology department of a university-affiliated hospital to study patients with mild-to-moderate essential hypertension. One hundred and fifty-five patients were recruited to compare BP derived from a manual device and ambulatory BP monitoring (ABPM). The manual BP measurement was performed six times at 22:00, 02:00, 06:00, 10:00, 14:00 and 18:00 h. The measurements at 22:00, 02:00 and 06:00 h were defined as night-time and the others as daytime. ABPM was programmed to measure at 30-min intervals between measurements.

RESULTS

All-day, daytime and night-time BP did not differ significantly from 24-h ambulatory systolic BP [all-day mean difference -0.52±4.67 mmHg, 95% confidence interval (CI) -1.26 to 0.22, P=0.168; daytime mean difference 0.24±5.45 mmHg, 95% CI -0.62 to 1.11, P=0.580; night-time mean difference 0.30±7.22 mmHg, 95% CI -0.84 to 1.45, P=0.601) rather than diastolic BP. There was a strong correlation between clinical and ambulatory BP for both systolic and diastolic BP. On the basis of ABPM, 101 (65%) patients were classified as non-dippers, compared with 106 (68%) by manual sphygmomanometer (P<0.001).

CONCLUSIONS

Traditional manual sphygmomanometer provides similar daytime and night-time systolic BP measurements in hospital. Moreover, the detection of non-dippers by manual methods is in good agreement with 24-h ABPM. Further studies are required to confirm the clinical relevance of these findings by comparing the association of NBP in the hospital ward assessed by manual monitoring with preclinical organ damage and cardiovascular and cerebrovascular outcomes.

Antihypertensive therapy: nocturnal dippers and nondippers. Do we treat them differently?

Hypertension is a major independent risk factor for cardiovascular diseases. Management of hypertension is generally based on office blood pressure since it is easy to determine. Since casual blood pressure readings in the office are influenced by various factors, they do not represent basal blood pressure. Dipping of the blood pressure in the night is a normal physiological change that can be blunted by cardiovascular risk factors and the severity of hypertension. Nondipping pattern is associated with disease severity, left ventricular hypertrophy, increased proteinuria, secondary forms of hypertension, increased insulin resistance, and increased fibrinogen level. Long-term observational studies have documented increased cardiovascular events in patients with nondipping patterns. Nocturnal dipping can be improved by administering the antihypertensive medications in the night. Long-term clinical trials have shown that cardiovascular events can be reduced by achieving better dipping patterns by administering medications during the night. Identifying the dipping pattern is useful for decisions to investigate for secondary causes, initiating treatment, necessity of chronotherapy, withdrawal or reduction of unnecessary medications, and monitoring after treatment initiation. Use of this concept at the primary care level has been limited because 24-hour ambulatory blood pressure monitoring has been the only method for documenting dipping/nondipping status so far. This monitoring technique is expensive and inconvenient for routine usage. Simpler methods using home blood pressure monitoring systems are evolving to document basal blood pressure in the night, which would help in greater acceptance and use of the concept of dipper/nondipper in managing hypertension at the primary care level.