Reliability of ambulatory blood pressure monitoring

Ambulatory Blood Pressure Monitoring: Our Experience in Routine Clinical Practice

Objective: To evaluate feasibility and usefulness of ambulatory blood pressure monitoring (ABPM) in outpatient setting.

Material and methods: In this prospective study, data of 58 patients who were evaluated with ABPM for diagnosis or therapeutic efficacy purpose were collected from their records. Demographic details of these were recorded. Patients were categorized into different categories based on 24 hours BP pattern. Dipping pattern was compared based on the gender, age, and presence of diabetes or hypertension. Number of patients diagnosed as hypertensive with ABPM reports was compared with office and home BP measurement.

Results: Fifty-eight patients (mean age 57.8 years; 70.69% males) were included of whom 22 (37.93%) underwent ABPM for diagnostic purposes. There was gender-wise significant difference in terms of purpose of performing ABPM (p=0.040). Diabetes was present in 22 (37.93%) patients. Out of 36 known hypertensive patients, 17 (47.22%) patients were receiving dual therapy. Out of 45 patients whose records for active BP variability were available, 26 (57.78%) had high variability. The number and percentage of dippers, extreme dippers and reverse dippers as 23 (42.79%), three (5.56%), and six (11.11%), respectively. Depending on the age, there was significant difference in the dipping pattern (p=0.013). On office blood pressure measurement, 35 (64.81%) patients were found to have hypertension. ABPM revealed hypertension in 32 (59.26%). Masked hypertension and white-coat hypertension was observed in nine (16.17%) and 12 (22.22%) patients, respectively.

Conclusion: ABPM is feasible and useful in routine outpatient clinical practice for diagnosis of essential hypertension, pattern of dipping, masked hypertension, and white-coat hypertension and also for the therapeutic evaluation of patients in clinical practice.

Feasibility of 24-h blood pressure telemonitoring in community pharmacies: the TEMPLAR project

OBJECTIVES

Low-quality ambulatory blood pressure monitoring (ABPM) due to recurring artifacts may limit its clinical value. We evaluated the features and impact on BP control and patient management of ABPMs performed in Italian community pharmacies, according to their quality.

METHODS

Twenty-four-hour ABPMs were obtained by a clinically validated, automated upper arm device and uploaded on a certified web-based telemedicine platform (www.tholomeus.net). The system automatically evaluated the quality of the recording according to current guidelines. In case of poor ABPM quality, the pharmacist was prompted to repeat the test. All the ABPMs were labeled as valid or invalid. Demographic and clinical characteristics of the patients and BP control were compared between the two groups.

RESULTS

A total of 45 232 ABPMs were obtained in as many patients through 812 pharmacies (87.7% recordings were valid). Factors significantly associated with a better ABPM quality were younger age, use of antihypertensive medications, presence of at least one cardiovascular risk factor, concomitant disease or treatment, a test performed in the coldest months, and residence in the cooler northern regions of the country. The 24-h and daytime ambulatory BP level and the prevalence of ambulatory hypertension and white-coat hypertension were higher, and the prevalence of masked hypertension lower in patients with valid recordings. High odds of obtaining a valid recording were observed in patients repeating the ABPM.

CONCLUSION

Ambulatory BP telemonitoring is feasible in community pharmacies as long as potential predictors of unsuccessful outcomes are taken into account and adequately managed.

Effects of fractionized and continuous exercise on 24-h ambulatory blood pressure

PURPOSE

The objective of this study is to compare the effects of fractionized aerobic exercise (three 10-min exercise sessions) and continuous exercise (one 30-min exercise session) on 24-h ambulatory blood pressure (ABP).

METHODS

Eleven healthy prehypertensive subjects (28.3 ± 8.0 (SD) yr) completed three randomly assigned conditions: 1) three 10-min sessions of aerobic exercise (3 × 10 min), 2) one continuous 30-min session of aerobic exercise (1 × 30 min), and 3) a nonexercise control trial (control). The mode of exercise was walking on a motor-driven treadmill at 75%-79% of maximum heart rate (HRmax) (60%-65% V˙O2peak). Twenty-four-hour ABP was monitored with an automated ABP device (Oscar 2™; SunTech Medical, Morrisville, NC). Linear mixed models were used to compare 24-h ABP responses between trials.

RESULTS

The mean ± SD 24-h systolic blood pressure (SBP) was significantly lower during the 3 × 10-min trial (127 ± 15 mm Hg) compared with control (130 ± 15 mm Hg) (P < 0.001). Although both 3 × 10-min and 1 × 30-min trials reduced SBP compared with control during daytime/evening (1300-2300 h), only the 3 × 10-min trial reduced SBP during nighttime (2300-0800 h, 118 ± 16 vs 122 ± 14 mm Hg, P = 0.024) and the following morning (0800-1200 h, 127 ± 15 vs 131 ± 15 mm Hg, P = 0.016). For 24 h, 26.7% of SBP values during 3 × 10 min were normal (i.e., <120 mm Hg) compared with 18.3% for 1 × 30 min and 19.4% for control (P < 0.001).

CONCLUSIONS

In prehypertensive individuals, fractionized exercise (e.g., three 10-min aerobic exercise sessions spread and effective exercise alternative to continuous exercise for cardiovascular risk reduction in this population.

Masked hypertension and prehypertension: diagnostic overlap and interrelationships with left ventricular mass: the Masked Hypertension Study

BACKGROUND

Masked hypertension (MHT) and prehypertension (PHT) are both associated with an increase in cardiovascular disease (CVD) risk, relative to sustained normotension. This study examined the diagnostic overlap between MHT and PHT, and their interrelationships with left ventricular (LV) mass index (LVMI), a marker of cardiovascular end-organ damage.

METHODS

A research nurse performed three manual clinic blood pressure (CBP) measurements on three occasions over a 3-week period (total of nine readings, which were averaged) in 813 participants without treated hypertension from the Masked Hypertension Study, an ongoing worksite-based, population study. Twenty-four-hour ambulatory blood pressure (ABP) was assessed by using a SpaceLabs 90207 monitor. LVMI was determined by echocardiography in 784 (96.4%) participants.

RESULTS

Of the 813 participants, 769 (94.6%) had normal CBP levels (<140/90 mm Hg). One hundred and seventeen (15.2%) participants with normal CBP had MHT (normal CBP and mean awake ABP ≥135/85 mm Hg) and 287 (37.3%) had PHT (mean CBP 120-139/80-89 mm Hg). 83.8% of MHT participants had PHT and 34.1% of PHT participants had MHT. MHT was infrequent (3.9%) when CBP was optimal (<120/80 mm Hg). After adjusting for age, gender, body mass index (BMI), race/ethnicity, history of high cholesterol, history of diabetes, current smoking, family history of hypertension, and physical activity, compared with optimal CBP with MHT participants, LVMI was significantly greater in PHT without MHT participants and in PHT with MHT participants.

CONCLUSIONS

In this community sample, there was substantial diagnostic overlap between MHT and PHT. The diagnosis of MHT using an ABP monitor may not be warranted for individuals with optimal CBP.

Techniques for self-measurement of blood pressure: limitations and needs for future research

Self blood pressure measurement (SBPM) improves the overall management of hypertension provided it is implemented with methodologic care. This concerns especially the accuracy and technical requirements of blood pressure (BP) measuring devices that should be validated according to internationally accepted protocols. The use of memory-equipped automatic home monitors is strongly recommended because they reduce observer bias, avoid patients' misreporting, and allow fully automatic analysis by software. For current use, simple software should be worked out that allow for analysis of readings in an objective manner. Miscuffing is also a frequent source of measurement error in obese arms when oscillometric devices are used. Modern automatic devices can overcome this problem because of special software algorithms that can provide accurate measurements over a wide range of arm circumferences when coupled with a single cuff of standard dimensions. Tronco-conical-shaped cuffs are a key component of this instrumentation because they better fit on large conical arms frequently present in obese individuals. Semi-rigid cuffs should be increasingly used because they ensure that the proper amount of tension is applied without the intervention of the user. Continuous technology improvement of instrumentation for SBPM can be achieved through close cooperation between manufacturers and validation centers.

Should pulse pressure and day/night variations in blood pressure be seen as independent risk factors requiring correction or simply as markers to be taken into account when evaluating overall vascular risk?

Patients with a blunted fall in nocturnal BP (known as non-dippers) have a high risk of micro- and macrovascular complications, particularly if they have hypertension, but also in normotensive patients with diabetes. A blunted fall in nocturnal BP reflects the high level of CV risk in these patients. ABPM data indicating an altered circadian BP rhythm reverse circadian BP profile should alert the physician to the potential risk of complications and should lead to efforts to treat hypertension effectively, especially at night, and to check for sleep apnoea syndrome, particularly in cases of resistant hypertension, or autonomic neuropathy (postural hypotension), a well known risk factor for cardiovascular (CV) events. Patients should be carefully screened for nephropathy. However, the definitions of "non-dipper" vary widely. Suitable treatments are poorly defined, but angiotensin-converting enzyme inhibitors (ACEi), diuretics, salt restriction and the maintenance of continuous positive airway pressure (CPAP) can be used as non-specific treatments. The efficacy of taking blood pressure-lowering drugs at bedtime rather than in the morning is still debated but deserves attention. In the diabetic population, brachial pulse pressure (PP) is an independent predictor of cardiovascular mortality, but not of all-cause mortality. It is also associated with complications of both type 2 and type 1 diabetes, this effect being stronger for nocturnal than for diurnal PP, and is strongly predictive of coronary heart disease in patients with type 2 diabetes. The stronger association between PP and age in diabetic than in non-diabetic populations suggests that diabetes accelerates vascular ageing. In patients with incipient nephropathy or overt renal failure, PP increases CV risk. However, misinterpretation could be related to confusion between brachial PP and central PP. The therapeutic implications of PP measurement remain poorly documented in diabetes.

Prognostic Significance for Stroke of a Morning Pressor Surge and a Nocturnal Blood Pressure Decline

There is continuing controversy over whether the pattern of circadian blood pressure (BP) variation that includes a nocturnal decline in BP and a morning pressor surge has prognostic significance for stroke risk. In this study, we followed the incidence of stroke in 1430 subjects aged > or =40 years in Ohasama, Japan, for an average of 10.4 years. The association between stroke risk and the pattern of circadian BP variation was analyzed with a Cox proportional hazards model after adjustment for possible confounding factors. There was no significant association between total stroke risk and the nocturnal decline in BP (percentage decline from diurnal level) or between total stroke risk and the morning pressor surge. The cerebral infarction risk was significantly higher in subjects with a <10% nocturnal decline in BP as compared with subjects who had a > or =10% nocturnal decline in BP (P=0.04). The morning pressor surge was not associated with a risk of cerebral infarction. On the other hand, an increased risk of cerebral hemorrhage was observed in subjects with a large morning pressor surge (> or =25 mm Hg; P=0.04). Intracerebral hemorrhage was also observed more frequently in extreme dippers (those with a > or =20% nocturnal decline in BP) than dippers (those with a 10% to 19% decline; P=0.02). A disturbed nocturnal decline in BP is associated with cerebral infarction, whereas a large morning pressor surge and a large nocturnal decline in BP, which are analogous to a large diurnal increase in BP, are both associated with cerebral hemorrhage.

Too much of a good thing? A critique of overemphasis on the use of ambulatory blood pressure monitoring in clinical practice

Ambulatory blood pressure monitoring (ABPM) can be considered a major achievement in clinical medicine. However, its superiority over traditional clinical measurement has often been overemphasized in the literature. In both cross-sectional and longitudinal studies, ABPM has been compared with clinical blood pressure calculated from only a few readings taken over a short period of time. For reasons of costs and practicality, ABPM should not be considered as a routine test in the assessment of the hypertensive patient. Most patients with borderline hypertension or isolated clinical hypertension can be profitably assessed with multiple clinical readings and self-blood pressure monitoring. Patients with large short-term or long-term blood pressure oscillations appear as optimal candidates to ABPM. The many methodological problems associated with the use of this technique suggest that ABPM is performed only by experienced doctors.

Task Force I: methodological aspects of blood pressure measurement

OBJECTIVE

To reach a consensus on important methodological aspects of blood pressure measurement.

METHODS

A Task Force on the methodological aspects of blood pressure measurement wrote this review after the Eighth International Consensus Conference on Blood Pressure Monitoring, in Sendai, Japan (28-31 October 2001). This consensus paper is based on the papers presented by Task Force I and on the discussion sessions, and is therefore representative of a broad spectrum of expert opinion.

POINTS OF CONSENSUS

Consensus was reached on the following five issues: (1) there is an urgent need for a simplified protocol for the validation of blood pressure measuring devices; (2) there is a need for a means of updating the "state of the market" for validated devices so that users can have easy access to this information; (3) new devices must be validated independently, and existing devices that have not been validated must be reappraised; (4) manufacturers should confirm when new models use algorithms which have been validated previously; (5) the Food and Drug Administration now accepts that when ambulatory blood pressure measurement is used in clinical short-term trials in which side-effects are not being assessed, a placebo arm is not required.