Recommendations for Blood Pressure Measurement in Humans and Experimental Animals

A comparative study of an ambulatory blood pressure measuring device and a wrist blood pressure monitor with a position sensor versus a mercury sphygmomanometer

BACKGROUND

Self-measurements of blood pressure (BP) and 24-hour BP measurements are better predictors of cardiovascular mortality and morbidity than office BP measurements. The objective of this study was to compare the accuracy and precision of a wrist BP monitor with a position sensor (Omron 637IT) and of an ambulatory BP measuring monitor (ABPM; Nissei DS-250) with a mercury sphygmomanometer.

METHODS

A total of 139 patients (69 women and 70 men) were included in the study. The BP of each subject was first measured with a mercury device using the same (left) arm. After this, the wrist monitor was used for BP measurement. Upon completion of the BP readings, 24-hour BP monitoring was performed using Nissei DS-250 monitors. Mean and standard deviations were calculated for all devices. In order to assess the agreement between the measurement methods, the Bland-Altman method and graphics were utilized.

RESULTS

The mean systolic BP measured by the mercury device was 133.2+/-18.4 mmHg and the diastolic BP was 85.4+/-12.5 mmHg, whereas the digital device measured systolic BP as 135.7+/-17.2 mmHg and diastolic BP as 87.0+/-12.5 mmHg. The 24-hour BP measurement was 134.6+/-16.6 mmHg for systolic BP and 85.6+/-11.1 mmHg for diastolic BP. The difference with regard to systolic BP between the mercury and the Omron devices was -2.5+/-5.3 mmHg, which is within the AAMI standard. However, while the mean values of the differences between the mercury and ABPM devices remained under 5 mmHg, their standard deviation was above +/- 8 mmHg. For diastolic BP, the difference between all of the devices was below 5+/-8 mmHg.

CONCLUSIONS

The wrist BP monitor produced results consistent with those of the mercury sphygmomanometer when both were compared with the results of the ABPM. As BP measurement with these devices is a practical and repeatable method, they can be used instead of ABPM in the diagnosis and monitoring of hypertension. However, there is a need for further comparative studies.

Sons de Korotkoff: desenvolvimento da pesquisa em esfigmomanometria na Escola de Enfermagem da USP

Este artigo tem como objetivos reverenciar Sergei Nicolai Korotkoff por ocasião do centenário da descoberta do método auscultatório de medida da pressão arterial na Rússia, em 1905; relatar os fatos que culminaram no desenvolvimento da esfigmomanometria no Brasil; historiar a valiosa contribuição da Escola de Enfermagem da Universidade de São Paulo (EEUSP) no desenvolvimento da pesquisa, na área da medida da pressão e analisar o produto da linha de pesquisa "Influência da Largura do Manguito na Medida da Pressão Arterial", gerada na EEUSP a partir de 1974. O artigo relata a consolidação dos achados iniciais pelos estudos que permitiram a formação dos primeiros doutores na área, que sugere a confirmação de hipóteses em estudos longitudinais.

Analysis of renin-angiotensin-aldosterone system gene polymorphisms in resistant hypertension

Essential hypertension is a disease multifactorially triggered by genetic and environmental factors. The contribution of genetic polymorphisms of the renin-angiotensin-aldosterone system and clinical risk factors to the development of resistant hypertension was evaluated in 90 hypertensive patients and in 115 normotensive controls living in Southwestern Brazil. Genotyping for insertion/deletion of angiotensin-converting enzyme, angiotensinogen M235T, angiotensin II type 1 receptor A1166C, aldosterone synthase C344T, and mineralocorticoid receptor A4582C polymorphisms was performed by PCR, with further restriction analysis when required. The influence of genetic polymorphisms on blood pressure variation was assessed by analysis of the odds ratio, while clinical risk factors were evaluated by logistic regression. Our analysis indicated that individuals who carry alleles 235-T, 1166-A, 344-T, or 4582-C had a significant risk of developing resistant hypertension (P < 0.05). Surprisingly, when we tested individuals who carried the presumed risk genotypes A1166C, C344T, and A4582C we found that these genotypes were not associated with resistant hypertension. However, a gradual increase in the risk to develop resistant hypertension was detected when the 235-MT and TT genotypes were combined with one, two or three of the supposedly more vulnerable genotypes - A1166C (AC/AA), C344T (TC/TT) and A4582C (AC/CC). Analysis of clinical parameters indicated that age, body mass index and gender contribute to blood pressure increase (P < 0.05). These results suggest that unfavorable genetic renin-angiotensin-aldosterone system patterns and clinical risk variables may contribute to increasing the risk for the development of resistant hypertension in a sample of the Brazilian population.

Optimal timing for antihypertensive dosing: focus on valsartan

Some specific features of the 24 h blood pressure (BP) pattern are linked to the progressive injury of target tissues and the triggering of cardiac and cerebrovascular events. In particular, many studies show the extent of the nocturnal BP decline relative to the diurnal BP mean (the diurnal/nocturnal ratio, an index of BP dipping) is deterministic of cardiovascular injury and risk. Normalization of the circadian BP pattern is considered to be an important clinical goal of pharmacotherapy because it may slow the advance of renal injury and avert end-stage renal failure. The chronotherapy of hypertension takes into account the epidemiology of the BP pattern, plus potential administration-time determinants of the pharmacokinetics and dynamics of antihypertensive medications, as a means of enhancing beneficial outcomes and/or attenuating or averting adverse effects. Thus, bedtime dosing with nifedipine gastrointestinal therapeutic system (GITS) is more effective than morning dosing, while also reducing significantly secondary effects. The dose-response curve, therapeutic coverage, and efficacy of doxazosin GITS are all markedly dependent on the circadian time of drug administration. Moreover, valsartan administration at bedtime as opposed to upon wakening results in improved diurnal/nocturnal ratio, a significant increase in the percentage of patients with controlled BP after treatment, and significant reductions in urinary albumin excretion and plasma fibrinogen. Chronotherapy provides a means of individualizing treatment of hypertension according to the circadian BP profile of each patient, and constitutes a new option to optimize BP control and reduce risk.

The occurrence of the alerting response is independent of the method of blood pressure measurement in hypertensive patients

OBJECTIVE

Current guidelines stress the need for more than one measurement of blood pressure in the hypertensive patient. The frequency with which the first blood pressure significantly exceeds subsequent blood pressures (alerting response) is unknown. Participants in a hypertension treatment trial before initiation of therapy were included in post-hoc analyses to investigate the alerting response separately for trained nurse blood pressure measurements with mercury sphygmomanometer and measurements taken by an Omron 705 CP automated device.

BASIC METHODS

A total of 313 participants were included. Each participant had three nurse blood pressure readings before a 24-h automated blood pressure monitoring device was attached, and three Omron measurements at the time the automated blood pressure monitoring device was removed. Alerting response was defined separately for systolic and diastolic measures as a decrease of > or =8 or > or =6 mmHg, respectively, from first measure to the average of the second and third measures.

MAIN RESULTS

An alerting response was observed in 20.4% of nurse-performed blood pressure measurements and 28.4% of Omron measurements. A large range of variation between first blood pressure and average second and third measures was observed, with changes of up to 30 mmHg systolic and 20 mmHg diastolic. The only demographic factor associated with the alerting response was body mass index, with obese patients more likely to exhibit an alerting response (P=0.004) in nurse-measured blood pressure.

CONCLUSIONS

We found the alerting response with both methods of blood pressure measurement; however, it was not consistently observed in the same individuals. This confirms that hypertensive patients require multiple blood pressure measurements.

Evaluation of pharmacy students' blood pressure and heart rate measurement skills after completion of a patient assessment course

OBJECTIVES

To evaluate pharmacy students' skills at measuring brachial artery blood pressure and radial heart rate at the completion of a patient assessment course in the second-professional year of a doctor of pharmacy (PharmD) program.

METHODS

Students enrolled in a required patient assessment laboratory course (n = 83) participated in this study. Each student was randomly matched with a classmate and manually measured the classmate's blood pressure by auscultation of the brachial artery and heart rate by palpation of the radial pulse.

RESULTS

The student-device absolute disagreement was 6.5 +/- 4.8 mmHg for systolic blood pressure (SBP), 6.2 +/- 4.5 mmHg for diastolic blood pressure (DBP), and 5.3 +/- 4.0 beats per minute (BPM) for heart rate. Student and machine measurements of SBP, DBP, and HR significantly correlated.

CONCLUSIONS

Pharmacy students in the second-professional year of a PharmD program demonstrated competence in but not mastery of manual blood pressure and heart rate measurement. These skills need further refinement during third- and fourth-professional year APPEs.

The effects of anatomical structures on adult forearm and upper arm noninvasive blood pressures

OBJECTIVE

The purpose of this study was to determine the effects of anatomical structures, specifically limb subcutaneous tissue and vessels on differences between forearm and upper arm oscillometric noninvasive blood pressure measurements.

METHODS

Nineteen volunteers with a mean age of 21.7+/-3.7 years and without peripheral vascular disease or coronary artery disease participated. Circumference and skinfolds were measured for the upper arm and forearm. Body mass indices were calculated. Ultrasound measured vessel depth and diameter in the upper arm and forearm. Dual energy X-ray absorptiometry determined percentage of subcutaneous tissue in the arm. With participants seated, American Heart Association guidelines were used to measure blood pressures, first by auscultatory method (upper arm only) and then by oscillometric method (upper arm and forearm) with a Dinamap 100 oscillometric blood pressure monitor.

RESULTS

Statistically significant differences were seen between upper arm auscultatory and oscillometric systolic blood pressures (t=-4.88; P=0.000) and mean arterial pressures (t=-3.07; P=0.007). Differences between oscillometric forearm and upper arm blood pressure readings were statistically significant for mean arterial pressures (t=-2.39; P=0.028). A regression model suggested that forearm and upper arm vessel depth, forearm vessel diameter, and upper arm circumference explained a statistically significant portion of the difference between forearm and upper arm blood pressures.

CONCLUSIONS

Differences between forearm and upper arm oscillometric blood pressures can be partially explained by vessel size, depth and upper arm circumference.

The value of home blood pressure monitoring

Home blood pressure (BP) monitoring has become popular and acceptable. The value of home BP monitoring has been recognized, because it has some potential advantages over office BP. Home BP monitoring is more accurate and reproducible, has a better prognostic value, and increases patients' compliance with treatment. Home BP monitoring should be performed with an adequate device, following a standardized procedure. The automated arm-cuff-oscillometric devices are recommended currently, and home BP should be measured at least twice daily, in the morning and in the evening. Home BP monitoring has revealed the phenomena of "white-coat hypertension," "masked hypertension," and "morning hypertension," and it is useful for their management. In the future, home BP monitoring will be an essential aspect of clinical practice.

Dietary calcium intake and renin angiotensin system polymorphisms alter the blood pressure response to aerobic exercise: a randomized control design

Background

Dietary calcium intake and the renin angiotensin system (RAS) regulate blood pressure (BP) by modulating calcium homeostasis. Despite similar BP regulatory effects, the influence of dietary calcium intake alone and combined with RAS polymorphisms on the BP response following acute aerobic exercise (i.e., postexercise hypotension) has not been studied. Thus, we examined the effect of dietary calcium intake and selected RAS polymorphisms on postexercise hypotension.

Methods

Subjects were men (n = 50, 43.8 ± 1.3 yr) with high BP (145.3 ± 1.5/85.9 ± 1.1 mm Hg). They completed three experiments: non-exercise control and two cycle bouts at 40% and 60% of maximal oxygen consumption (VO₂max). Subjects provided 3 d food records on five protocol-specific occasions. Dietary calcium intake was averaged and categorized as low (<880 mg/d = LowCa) or high (≥ 880 mg/d = HighCa). RAS polymorphisms (angiotensin converting enzyme insertion/deletion, ACE I/D; angiotensin II type 1 receptor, AT₁R A/C) were analyzed with molecular methods. Genotypes were reduced from three to two: ACE II/ID and ACE DD; or AT₁R AA and AT₁R CC/AC. Repeated measure ANCOVA tested if BP differed among experiments, dietary calcium intake level and RAS polymorphisms.

Results

Systolic BP (SBP) decreased 6 mm Hg after 40% and 60% VO₂max compared to non-exercise control for 10 h with LowCa (p < 0.01), but not with HighCa (p ≥ 0.05). Under these conditions, diastolic BP (DBP) did not differ between dietary calcium intake levels (p ≥ 0.05). With LowCa, SBP decreased after 60% VO₂max versus non-exercise control for 10 h among ACE II/ID (6 mm Hg) and AT₁R AA (8 mm Hg); and by 8 mm Hg after 40% VO₂max among ACE DD and AT₁R CC/CA (p < 0.01). With HighCa, SBP (8 mm Hg) and DBP (4 mm Hg) decreased after 60% VO₂max compared to non-exercise control for 10 h (p < 0.05), but not after 40% VO₂max (p ≥ 0.05).

Conclusion

SBP decreased after exercise compared to non-exercise control among men with low but not high dietary calcium intake. Dietary calcium intake interacted with the ACE I/D and AT₁R A/C polymorphisms to further modulate postexercise hypotension. Interactions among dietary calcium intake, exercise intensity and RAS polymorphisms account for some of the variability in the BP response to exercise.

Effectiveness of Blood Pressure Control Outside the Medical Setting

We studied the effectiveness of blood pressure (BP) control outside the clinic by using ambulatory BP monitoring (ABPM) among a large number of hypertensive subjects treated in primary care centers across Spain. The sample consisted of 12 897 treated hypertensive subjects who had indications for ABPM. Office-based BP was calculated as the average of 2 readings. Twenty-four–hour ABPM was then performed using a SpaceLabs 90207 monitor under standardized conditions. A total of 3047 patients (23.6%) had their office BP controlled, and 6657 (51.6%) were controlled according to daytime ABPM. The proportion of office resistance or underestimation of patients’ BP control by physicians in the office (office BP ≥140/90 mm Hg and average daytime ambulatory BP <135/85 mm Hg) was 33.4%, and the proportion of isolated office control or overestimation of control (office BP <140/90 mm Hg and average daytime ambulatory BP ≥135/85 mm Hg) was 5.4%. BP control was more frequently underestimated in patients who were older, female, obese, or with morning BP determination than in their counterparts. BP control was more frequently overestimated in those who were younger, male, nonobese, smokers, or with evening BP determination. Ambulatory-based hypertension control was far better than office-based hypertension control. This conveys an encouraging message to clinicians, namely that they are actually doing better than is evidenced by office-based data. However, the burden of underestimation and overestimation of BP control at the office is still remarkable. Physicians should be aware that the likelihood of misestimating BP control is higher in some hypertensive subjects.

Blood pressure recordings within and outside the clinic and cardiovascular events in chronic kidney disease

BACKGROUND

Blood pressure (BP) measured outside the clinic correlates better with cardiovascular outcomes in patients with essential hypertension. To assess the role of out-of-clinic BP recordings in predicting cardiovascular events in patients with chronic kidney disease (CKD), a prospective cohort study was conducted in 217 veterans with CKD.

METHODS

BP was measured outside the clinic at home and by 24-hour ambulatory recordings, and in the clinic by 'routine' and standardized methods. Patients were followed over a median of 3.4 years to assess the combined end-point of total mortality, myocardial infarction or stroke.

RESULTS

Average (+/-SD) home BP was 147.0 +/- 21.4/78.3 +/- 11.6 mm Hg, 24-hour ambulatory BP 133.5 +/- 16.6/73.1 +/- 11.1 mm Hg and in-clinic BPs were 155.2 +/- 25.6/84.7 +/- 14.2 mm Hg by the standardized method, and 144.5 +/- 24.2/75.4 +/- 14.7 mm Hg by the 'routine' method. A 1 SD increase in systolic BP increased the hazard ratio (HR) of the composite end-point by 1.16 (95% CI 0.89-1.50) for routine BP, 1.57 (95% CI 1.19-2.09) for standardized BP, 1.66 (95% CI 1.27-2.17) for home BP, and 1.42 (95% CI 1.10-1.84) for 24-hour ambulatory BP recording. The HR of the composite end-point was only significant for hypertension defined by 24-hour ambulatory BP monitoring (HR 2.22 (95% CI 1.23-4.01)). Adjusted for the propensity scores, BP measured by the ambulatory technique was not an independent predictor of cardiovascular events. Non-dipping was associated with increased cardiovascular risk, but not when adjusted for other risk factors.

CONCLUSION

Risk factors that differentiate hypertension or non-dipping appear to confer a cardiovascular risk in CKD.

Systems for care of hypertension in the United States

Control of hypertension in recent clinical trials varies from 48% to 65%. However, in community care of hypertension in the United States, estimates of control of hypertension are far lower. The United States has no single system of care; however, several care systems can be identified for comparison, such as the Department of Veterans Affairs, managed care organizations, and the Indian Health Service. This review compares control of hypertension in certain centers in these systems with that achieved in clinical trials and in the community at large. Certain components of care systems are assessed for their contribution to the control of hypertension. The author concludes that for community control of hypertension to approach that achieved in clinical trials, the use of physician extenders, together with reduced or minimal cost of medication, improved education of providers with feedback, and computerization of management systems will be needed. In addition, specific interventions targeted to medically underserved groups will be required.

Impact of blood pressure vs. glycemic factors on target organ damage in patients with type 2 diabetes mellitus

The hypothesis that three measures of target organ damage in type 2 diabetics would be more closely related to blood pressure (BP) than to glycemic factors was tested by recording 24-hour ambulatory BP and glycosylated hemoglobin. The prevalence of silent cerebral infarcts with brain magnetic resonance imaging, left ventricular mass index with cardiac ultrasonography, and albuminuria in 244 asymptomatic diabetics (mean age, 65.4+/-9 years; 122 men and 122 women; hypertension, 73%) were evaluated. Multivariate analysis showed that age (standard partial regression coefficient: b=0.299; p<0.001), duration of hypertension (b=0.176; p=0.007), and 24-hour systolic BP (b=0.195; p=0.004) were significantly associated with the number of silent cerebral infarcts, but glycosylated hemoglobin (b=0.104; p=0.109) and duration of diabetes were not. Left ventricular mass index was associated with 24-hour systolic BP (b=0.377; p<0.001) and male sex (b=0.172; p=0.019). Presence of albuminuria was significantly associated with 24-hour systolic BP (b=0.209; p=0.003), duration of diabetes (b=0.154; p=0.022), cholesterol (b=0.132; p=0.042), and insulin use (b=0.150; p=0.026). In conclusion, all three measures of target organ damage were related to 24-hour BP, but only albuminuria was related to glycosylated hemoglobin in type 2 diabetics. BP may be more important than glycemic factors for predicting future cardiovascular complications.

Gender differences in ambulatory blood pressure monitoring profile in obese, overweight and normal subjects

The incidence of obesity has increased enormously in the past several decades, and has been described as a modern epidemic. Obesity is a major factor contributing to hypertension. To the best of our knowledge, no study of ambulatory blood pressure monitoring (ABPM) comparing men with women in relation to body mass indexes (BMI) has been performed. From December 2002 to May 2006, we performed 24-h ABPM in 5950 subjects (3102 men and 2848 women), with a wide range of BMI (range 15.9-53.2 kg/m(2)). We defined obese subjects as those with BMI> or =30.0 kg/m(2), overweight subjects as those with BMI>25.0 and <30.0 kg/m(2), and normal subjects as those with BMI< or =25.0 kg/m(2). Data on 989 subjects (501 men and 488 women) aged from > or =18 to < or =69 years without antihypertensive treatment, atrial fibrillation or diabetes were included for analysis. We consistently found that obese men had the expected increased heart rate compared to normal and overweight men, whereas women (normal, overweight and obese) had similar HRs. In addition, normal and obese women had similar diastolic blood pressures (BP), as opposed to obese men, who had raised diastolic BP. These results may indicate that different pathogenetic mechanisms may be involved in the relationship between obesity and hypertension in men and women.

The problem of artifacts in patient monitor data during surgery: a clinical and methodological review

Artifacts are a significant problem affecting the accurate display of information during surgery. They are also a source of false alarms. A secondary problem is the inadvertent recording of artifactual and inaccurate information in automated record keeping systems. Though most of the currently available patient monitors use techniques to minimize the effect of artifacts, their success is limited. We reviewed the problem of artifacts affecting patient monitor data during surgical cases. Methods adopted by currently marketed patient monitors to eliminate and minimize artifacts due to technical and environmental factors are reviewed and discussed. Also discussed are promising artifact detection and correction methods that are being investigated. These might be used to detect and eliminate artifacts with improved accuracy and specificity.

Utility of ambulatory blood pressure monitoring in children and adolescents

Diagnosis of hypertension is critically dependent on accurate blood pressure measurement. "Accurate" refers to carefully following the guidelines for blood pressure measurement laid out for children and adults to minimize observer and subject errors that commonly occur in clinical blood pressure measurement. Accurate blood pressure measurement is more important in children and adolescents as the misdiagnosis of hypertension may have a life-long adverse impact on insurability and employment. Automated blood pressure measurement offers multiple advantages in achieving high-quality blood pressure determinations by reducing observer errors. The most commonly used form of automated blood pressure measurement is 24-h ambulatory blood pressure measurement (ABPM). Information on ABPM in children has grown exponentially over the last decade. Normative data exists for diagnosis of hypertension in children using ABPM including a novel method for determining normal values with the LMS method. There is further information about the utility of different determinants of 24-h blood pressure such as dipping status, morning surge and blood pressure load. ABPM has been able to detect significant differences in blood pressure in many disease states in children including chronic renal failure, polycystic kidney disease, solitary functioning kidney, and after renal transplantation. Increasingly nonambulatory automated blood pressure determinations have been used in management of hypertension in children. Although nonambulatory automated readings lack information about nocturnal blood pressure or blood pressure during daily activity, studies have suggested that home automated blood pressure measurements are a helpful adjunct to the usual office blood pressure reading.

Systemic Bevacizumab (Avastin) Therapy for Neovascular Age-Related Macular Degeneration

PURPOSE

To evaluate the safety, efficacy, and durability of bevacizumab for the treatment of subfoveal choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (AMD).

DESIGN

Open-label, single-center, uncontrolled clinical study.

PARTICIPANTS

Age-related macular degeneration patients with subfoveal CNV (n = 18) and best-corrected visual acuity (VA) letter scores of 70 to 20 (approximate Snellen equivalent, 20/40-20/400).

METHODS

Patients were treated at baseline with an intravenous infusion of bevacizumab (5 mg/kg) followed by 1 or 2 additional doses given at 2-week intervals. Safety assessments were performed at all visits. Ophthalmologic evaluations included protocol VA measurements, ocular examinations, and optical coherence tomography (OCT) imaging at each visit. Retreatment with bevacizumab was performed if there was evidence of recurrent CNV.

MAIN OUTCOME MEASURES

Assessments of safety and changes from baseline in VA scores and OCT measurements were performed through 24 weeks.

RESULTS

No serious ocular or systemic adverse events were identified through 24 weeks. The only adverse event identified was a mild elevation of mean systolic and diastolic blood pressure measurements (+11 mmHg, P = 0.004; +8 mmHg, P<0.001) evident by 3 weeks and easily controlled with antihypertensive medications. By 24 weeks, the systolic and diastolic mean blood pressures were at or below baseline measurements. Visual acuity in the study eyes improved within the first 2 weeks, and by 24 weeks, the mean VA letter score increased by 14 letters in the study eyes (P<0.001), and the mean OCT central retinal thickness measurement decreased by 112 microm (P<0.001). By 24 weeks, retreatment was needed for only 6 of the 18 study eyes, and after retreatment, the recurrent leakage was eliminated, with restoration of any lost VA.

CONCLUSIONS

Systemic bevacizumab therapy for neovascular AMD was well tolerated and effective for all 18 patients through 24 weeks. By 6 months, most patients did not require any additional treatment beyond the initial 2 or 3 infusions. Despite these impressive results, it is unlikely that systemic bevacizumab will be studied in a large clinical trial because of the potential risks associated with systemic anti-VEGF therapy and the perception that intravitreal therapy is safer.

Medium-Term Variability of Blood Pressure and Potential Underdiagnosis of Hypertension in Patients With Previous Transient Ischemic Attack or Minor Stroke

Background and Purpose— Blood pressure (BP) is a major risk factor for stroke. However, the variability of systolic and diastolic BP (SBP and DBP) means that single measurements do not provide a reliable measure of usual BP. Although 24-hour ambulatory BP monitoring can correct for the effects of short-term variation, there is also important medium-term variability. The extent of medium-term variability in BP is most marked in patients with a previous transient ischemic attack (TIA) or stroke. We studied the potential impact of this variability on the likely recognition of hypertension.

Methods— We analyzed multiple repeated measurements of BP in 3 large cohorts with a TIA or minor stroke: the UK-TIA trial (n=2098), the Dutch TIA trial (n=2953), and the European Carotid Surgery Trial (ECST; n=2646). Regression dilution ratios and coefficients of variation were calculated for SBP and DBP from baseline and repeated measurements during the subsequent 12 months. Categorization based on single baseline measurements was also compared with categorization based on the subsequent “usual” BP.

Results— The correlation between measurements of BP at baseline and 3 to 5 months later was poor ( R 2 from 0.17 to 0.31 for SBP and from 0.10 to 0.20 for DBP). Categorization of patients by baseline values resulted in substantial misclassification in relation to usual BP. For example, of patients with an SBP <140 mm Hg at baseline, the percentage with a usual SBP ≥140 mm Hg was 31.6% in the UK-TIA trial, 48.2% in the Dutch TIA trial, and 57.7% in the ECST. At least 3 consecutive measurements of SBP <120 mm Hg were required to be >90% certain that subsequent usual SBP would not be ≥140 mm Hg.

Conclusions— Given the greater medium-term variability of BP in patients with a previous TIA or stroke than in the general population, single measurements of “normal” or “low” BP will substantially underestimate the true prevalence of hypertension.

Cronoterapia con torasemida en pacientes hipertensos: aumento de la duración y la eficacia terapéuticas con su administración a la hora de acostarse

BACKGROUND AND OBJECTIVE

Torasemide is a high ceiling loop diuretic frequently used for treatment of heart failure, renal failure and hypertension, according to results mainly based on clinic blood pressure measurements, without proper evaluation of the 24-hour efficacy of the drug. Accordingly, we investigated the time-dependent antihypertensive efficacy of torasemide in hypertensive patients.

PATIENTS AND METHOD

We studied 58 patients with grade 1-2 essential hypertension (25 men and 33 women), 48.7 (11.9) years of age, randomly assigned to receive torasemide (5 mg/day) either upon awakening or at bedtime. Blood pressure was measured by ambulatory monitoring for 48 consecutive hours before and after 6 weeks of therapy.

RESULTS

Efficacy of torasemide was significantly higher with bedtime dosing (11.2 and 8.0 mmHg reduction in the 24-hour mean of systolic and diastolic blood pressure, respectively) as compared to the administration of the drug on awakening (6.2 and 3.7 mmHg reduction in systolic and diastolic blood pressure). The percentage of patients with controlled ambulatory blood pressure after treatment was also higher after bedtime treatment (54% versus 27%). The time-response curves indicate a full 24-hour therapeutic duration only when torasemide was administered before bedtime. With regard to the safety profile, 2 patients presented secondary effects (abdominal pain, diarrhea) in morning dose, and 4 patients taking the drug at bedtime reported nicturia.

CONCLUSIONS

A dose of 5 mg/day torasemide is effective for blood pressure reduction after bedtime administration. The differences in efficacy and therapeutic duration as a function of the circadian time of treatment with torasemide here documented should be taken into account when prescribing this loop diuretic for treatment of patients with essential hypertension.

Paradoxical effects of social support on blood pressure reactivity among defensive individuals

BACKGROUND

Social support can reduce cardiovascular responses to an acute stressor. However, prior clinical research suggests that defensive individuals may react negatively to social support.

PURPOSE

This experiment examined whether emotional support provided during a speech stressor would escalate rather than decrease blood pressure (BP) reactivity among defensive individuals.

METHODS

After completing personality measures, 176 female undergraduates were randomly assigned to give a speech in 1 of 3 social conditions: alone, or with a neutral or supportive confederate present. Mean arterial BP was assessed at baseline, immediately before, and during and after the stressor.

RESULTS

In the supportive condition, defensiveness predicted higher BP reactivity during anticipation (beta = .35, p = .04) and delivery of the speech (beta = .32, p = .03), and longer recovery to baseline BP levels (beta = .35, p = .01). In the absence of support (i.e., alone and neutral conditions), defensiveness was not associated with BP reactivity. Defensiveness also predicted greater dissociation between subjective stress and BP responses (beta = .35, p = .05), but only in the supportive condition.

CONCLUSIONS

According to results, the provision of social support during stressors does not benefit defensive individuals' BP reactivity but has the opposite effect.

Methods for assessing body composition, cardiovascular and metabolic function in children and adolescents: implications for exercise studies

PURPOSE OF REVIEW

To critically evaluate the most recent literature on the methods used to assess body composition, cardiovascular and metabolic function in children and adolescents.

RECENT FINDINGS

Although regional body composition can be fairly accurately calculated by dual-energy X-ray absorptiometry, the accuracy of noninvasive estimations of visceral adipose tissue is questionable. Regarding the cardiovascular and metabolic adaptations, there is no doubt that direct and invasive methods provide high accuracy and reproducibility. For instance, exercise until exhaustion, direct Fick equation, nuclear magnetic resonance and magnetic resonance imaging are valid methods to determine maximum oxygen uptake, cardiac output and tissue substrate metabolism, respectively. Except for the direct Fick equation, all have been successfully used in pediatric studies. Relatively new techniques for the assessment of exercise training-induced adaptations in youths include the thoracic bioimpedance and the Modelflow method for cardiac output determination, and magnetic resonance spectroscopy for intramuscular and intrahepatic lipid content. Additional validation and reliability studies in pediatric populations are needed for some of these techniques (e.g. the Modelflow method).

SUMMARY

Most of the techniques used in adults appear not directly applicable to youths. A combination of techniques and/or the application of new, promising and easy to use ones, such as near-infrared spectroscopy and Laser Doppler flowmetry, may advance our knowledge in pediatric exercise science.

Aferição da pressão arterial: experiência de treinamento de pessoal e controle de qualidade no Estudo Pró-Saúde

A adequação das condutas terapêuticas e a validade das inferências epidemiológicas sobre a hipertensão arterial dependem crucialmente da acurácia dos procedimentos para sua aferição. Este artigo relata a experiência dos procedimentos adotados para o treinamento e controle de qualidade da aferição da pressão arterial na Fase 2 do Estudo Pró-Saúde, conduzido entre 3.574 funcionários de uma universidade no Rio de Janeiro, Brasil, em 2001. Foram utilizados aparelhos de coluna de mercúrios e técnicas padronizadas de aferição, baseada em protocolos internacionais. Foram monitoradas a adesão dos aferidores às técnicas preconizadas, a preferência por dígitos terminais, a diferença entre aferições consecutivas e a proporção de dados faltantes. O conjunto de procedimentos utilizados contribuiu para minimizar possíveis erros sistemáticos associados à técnica auscultatória de aferição da pressão arterial, possibilitando análises válidas acerca de fatores associados à ocorrência da hipertensão arterial.

Management of hypertension in hemodialysis patients

The relationship of hypertension with adverse outcomes is uncertain in the hemodialysis population. If hypertension is an etiologically significant cardiovascular risk factor in hemodialysis patients, the first step would be to assess the level of BP accurately. BP obtained at home over a week and averaged using a validated oscillometric automatic device can prove valuable. To the extent BP lowering influences cardiovascular outcomes, home BP of 150/90 mm Hg would warrant therapy, since it correlates with target organ damage and hypertension diagnosed by ambulatory BP monitoring. To manage hypertension, limiting dietary sodium intake and individualizing dialysate sodium delivery would be first steps. The magnitude of reduction in BP with dietary sodium restriction and the whether dialysate sodium can be safely limited in those who are hypotension-prone is unclear. Antihypertensive drug therapies can effectively reduce BP and are needed by the vast majority of hemodialysis patients. Whether control of hypertension translates into better outcomes is not known, but collective evidence suggests that hypertension should be controlled in hemodialysis patients.

Prognostic importance of ambulatory blood pressure recordings in patients with chronic kidney disease

Ambulatory systolic blood pressure (BP) correlates better with risk factors for progression of chronic kidney disease (CKD) compared to clinic measured BP, but its role in predicting end-stage renal disease (ESRD) and death in patients with CKD is unknown. In a cohort study of 217 Veterans with CKD BP was measured by ambulatory monitoring and in the clinic. Twenty-four hour ambulatory BP was 133.5 +/- 16.6/73.1 +/- 11.1 mm Hg and clinic BP was 155.2 +/- 25.6/84.7 +/- 14.2 mm Hg. The composite renal end point of ESRD or death over a median follow-up of 3.5 years occurred in 75 patients (34.5%), death occurred in 52 patients (24.0%), and ESRD in 36/178 patients (20.2%). Thirty-nine patients died before reaching ESRD. One standard deviation (s.d.) increase in systolic BP increased the risk of composite outcome to 1.69 (95% confidence interval (CI) 1.32-2.17) for standard clinic measurement and to 1.88 (95% CI 1.48-2.39) for 24 h ambulatory BP recording. One s.d. increase in 24 h ambulatory systolic BP increased the risk of ESRD to 3.04 (95% CI 2.13-4.35) and to 2.20 (95% CI 1.43-3.39) when adjusted for standard clinic systolic BP. Non-dipping was associated with increased risk of total mortality and composite end point. In patients with CKD, BPs obtained by ambulatory monitoring are a stronger predictor of ESRD or death compared to BPs obtained in the clinic. Systolic ambulatory BP and nondipping are independent predictors for ESRD after adjusting for clinic BP. However, adjustment for other risk factors for CKD progression removes the independent prognostic value of ambulatory BP.

Influence of nighttime bathing on evening home blood pressure measurements: how long should the interval be after bathing?

The Japanese Society of Hypertension has recommended that evening home blood pressure measurement be taken just before bedtime. In this study, to elucidate the influence of nighttime bathing on evening home blood pressure and heart rate, measurements were performed for 7 days using volunteers who were employees of a single company and who had no alcohol intake during the study period. We used data obtained from 158 subjects (78 males and 80 females; mean age, 41.6 years) whose evening data consisted of a combination of pre-bathing and post-bathing measurements. We divided the subjects into four groups according to the time interval from bathing: blood pressure was measured at 30 min after bathing in group I (n=40), at 31-60 min after bathing in group II (n=89), at 61-120 min after bathing in group III (n=74) and at more than 121 min after bathing in group IV (n=53). We evaluated the changes after bathing in each group. For all subjects combined, the evening home blood pressure measured after bathing (114.0+/-17.1/69.4+/-10.9 mmHg) was significantly lower than the value before bathing (116.3+/-17.1/70.7+/-11.2 mmHg). However, there was no difference in heart rate. Both systolic and diastolic blood pressure after bathing in group I (109.1+/-15.2/66.3+/-10.8 mmHg) and II (112.0+/-15.2/66.5+/-10.1 mmHg) were significantly lower than those before bathing (group I: 113.2+/-15.8/70.2+/-10.6 mmHg; group II: 115.2+/-15.8/69.3+/-10.3 mmHg), but these differences disappeared in group III and IV. On the other hand, there was no difference in heart rate after bathing in group I, II, or III, but group IV showed a slight but significant decrease after bathing (67.7+/-10.0 --> 65.8+/-10.7 beats/min). In conclusion, if evening home blood pressure is to be measured after bathing, subjects should be instructed to wait more than 60 min after bathing before performing the measurement in order to eliminate the depressor effect of bathing.

Difference in Blood Pressure Readings with Mercury and Automated Devices: Impact on Hypertension Prevalence Estimates in Dar es Salaam, Tanzania

OBJECTIVES

(1) To compare blood pressure (BP) readings with an automated arm cuff oscillometric device (AutoBP) to readings with a mercury sphygmomanometer (HgBP) and (2) to evaluate the impact on the prevalence of hypertension (HBP) in a population-based survey.

METHODS

(1) In a convenience sample ("Comparison Study"), we measured BP with both AutoBP (Visomat OZ2) and HgBP and we modeled BP difference (DeltaBP = HgBP-AutoBP) with multiple regression analysis. (2) Using DeltaBP, we calculated HgBP in a survey previously conducted in Dar es Salaam ("Population Survey") in which BP was measured with the automatic device Visomat OZ2 and we compared the prevalence of HBP (> or =140/90 mmHg or treatment).

RESULTS

In the Comparison Study (404 subjects aged 25-64), systolic/diastolic BP was higher by 4.4/4.7 mmHg (SE: 0.4/0.3) with HgBP than AutoBP. The prevalence of HBP was 42% with HgBP and 36% with AutoBP (relative difference of 14%). DeltaBP was associated with age, BP and arm circumference. In the Population Survey (9.254 subjects aged 25-64), the prevalence of HBP was 17% with calculated HgBP and 14% with AutoBP (relative difference of 20%).

CONCLUSION

A small systematic bias in BP readings between two different devices had large impact on hypertension prevalence estimates. This suggests that automated devices used in epidemiological studies should be validated with particular care.

Algorithms for converting random-zero to automated oscillometric blood pressure values, and vice versa

Many surveys and cohort studies have used a random-zero sphygmomanometer blood pressure device (RZS) to measure subjects' blood pressure and to assess the value of blood pressure in predicting cardiovascular events. Recent studies used automated oscillometric blood pressure devices (AODs) that systematically measure higher blood pressure values than RZSs do, hampering comparability of values between these studies. In 2000-2003, the authors randomly used both an RZS and an AOD in an ongoing cohort study in Germany. This analysis aimed to compare blood pressure values by device and to develop an algorithm to convert estimates of blood pressure values from one device to the other. In a randomized subset of 2,365 subjects aged 45-75 years, each subject was measured three times with each device in a randomized order. The mean difference (AOD-RZS) between the devices was 3.9 mmHg for systolic blood pressure and 2.6 mmHg for diastolic blood pressure. The authors found that linear regression models including age, sex, and blood pressure level can be used to convert RZS blood pressure values to AOD blood pressure values, and vice versa. Results may help to better compare blood pressure values in epidemiologic studies that used different blood pressure devices.

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect

OBJECTIVES

BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse.

METHODS

Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices.

RESULTS

Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol.

CONCLUSIONS

Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.

Hypertension: trends in prevalence, incidence, and control

Hypertension is the leading cause of cardiovascular disease worldwide. Prior to 1990, population data suggest that hypertension prevalence was decreasing; however, recent data suggest that it is again on the rise. In 1999-2002, 28.6% of the U.S. population had hypertension. Hypertension prevalence has also been increasing in other countries, and an estimated 972 million people in the world are suffering from this problem. Incidence rates of hypertension range between 3% and 18%, depending on the age, gender, ethnicity, and body size of the population studied. Despite advances in hypertension treatment, control rates continue to be suboptimal. Only about one third of all hypertensives are controlled in the United States. Programs that improve hypertension control rates and prevent hypertension are urgently needed.

The trained observer better predicts daytime ABPM diastolic blood pressure in hypertensive patients than does an automated (Omron) device

OBJECTIVES

Accurate blood pressure measurement is critical to successful clinical trials. Concerns about observer errors have led to the use of automated oscillometric devices without evidence that their performance is similar to that of trained observers. This study compares blood pressures obtained by trained observers and with an oscillometric device (Omron 705CP) to 24-h ambulatory blood pressure monitoring.

METHODS

We performed a post-hoc analysis of 313 untreated hypertensive patients at the end of the washout phase of a Novartis hypertension trial. Patients had three seated trained observer mercury auscultatory blood pressure measurements followed by 24-h ambulatory blood pressure monitoring. The next day, the ambulatory blood pressure monitoring was removed and three seated readings were obtained with an Omron 705CP. Correlations for systolic blood pressure and diastolic blood pressure were obtained between daytime ambulatory blood pressure monitoring (0900 and 2100) and the two office methods. In addition, we investigated the degree of difference of trained observer and Omron measurements from ambulatory blood pressure monitoring.

RESULTS

For systolic blood pressure, the correlation with ambulatory blood pressure monitoring of the trained observer was significantly better than with that of the Omron 705CP (0.641 vs. 0.555, P=0.01). For diastolic blood pressure values, even greater disparity between the two office method correlations with ambulatory blood pressure monitoring was observed (trained observer=0.593 vs. Omron=0.319, P<0.0001). Both trained observer and Omron readings were consistently higher than ambulatory blood pressure monitoring for systolic blood pressure (P<0.0001) and diastolic blood pressure (P<0.0001). Omron measurements, however, deviated from ambulatory blood pressure monitoring more than those of the trained observer (P<0.0001 for systolic blood pressure and diastolic blood pressure).

CONCLUSIONS

For clinical trials using diastolic blood pressure targets, the Omron 705CP cannot replace the auscultatory blood pressure measurements of a trained observer. For systolic blood pressure, the Omron device and the trained observer had similar correlations with ambulatory blood pressure monitoring; however, both methods gave consistently higher systolic blood pressure values. Further study of oscillometric devices should be conducted before universally replacing auscultatory blood pressure determinations by trained observers in clinical trials.

Metoprolol succinate, a selective beta-adrenergic blocker, has no effect on insulin sensitivity

Insulin resistance is a risk factor for cardiovascular disease. Therapies to lower blood pressure should not decrease insulin sensitivity. Some b-adrenergic blocking agents can have an adverse effect on insulin sensitivity. This study examined the effect of extended-release metoprolol succinate on insulin sensitivity. Nondiabetics with hypertension (N=30) were started on (or changed to) hydrochlorothiazide (HCTZ) 12.5 mg daily for 14 days. Patients with blood pressure>140/90 mm Hg while taking HCTZ alone underwent an insulin clamp procedure to quantify insulin sensitivity. Metoprolol succinate treatment was begun at 50 mg daily and titrated to a dose that lowered blood pressure to <140/90 mm Hg. Following 12 weeks of metoprolol succinate plus HCTZ therapy, the insulin clamp procedure was repeated. On metoprolol succinate plus HCTZ treatment, there were no significant changes in insulin clamp measures of insulin sensitivity. Plasma cholesterol and low-density lipoprotein cholesterol decreased significantly on metoprolol succinate plus HCTZ. When b-blocker therapy is considered, metoprolol succinate can be used to treat hypertension without adverse metabolic effects.