Blood Pressure Distribution Research Articles

Distribution of blood pressure and prevalence of hypertension in Tehran adult population: Tehran Lipid and Glucose Study (TLGS), 1999-2000.

The purpose of this study was to estimate the current prevalence and distribution of hypertension in an adult Tehranian population. Data were collected for 3343 men and 5148 women aged 20-69 years in the Tehran Lipid and Glucose Study (TLGS), which is a cross-sectional phase of a large epidemiologic study, first established in 1999. The study used the mean of two separate blood pressure (BP) measurements in each individual. Twenty-two percent (23% of women vs 20% of men, P = 0.01) had hypertension according to 'JNC-VI' and 'WHO-ISH' criteria. The average systolic BP (SBP), diastolic BP (DBP) and pulse pressure of hypertensive participants were 31, 16, and 15 mm Hg higher than the corresponding value for normotensives, respectively. Thirty-six percent of participants with JNCVI-based hypertension were using antihypertensive medication (23% of men and 43% of women). Of these, 40% (45% of men and 39% of women) had normal BP. Hypertension awareness was 50% in these participants (57% in men vs 37% in women, P < 0.001). Data for 3179 men and 4646 women aged 20-69 years with no antihypertensive treatment were used for analysis of BP measures. Of these, 15% (16% of men and 14% of women, P = 0.006) had high and 85% (84% of men and 86% of women) normal or high-normal BP levels according to JNC-VI. Prevalence of optimal BP was 49% (47% of men and 51% of women). Mean SBP was 117.8 +/- 16.6 and 116.4 +/- 16.4 mm Hg in men and women, respectively (P < 0.001). The equivalent values were 77.4 +/- 10.7 and 77.3 +/- 9.9 mm Hg for DBP (P = 0.5) and 40.4 +/- 12 and 39.1 +/- 11.7 mm Hg for pulse pressure (P < 0.001). A relatively high prevalence of JNC-VI/WHO-ISH defined hypertension was found in the TLGS adult population with 50% undiagnosed and 60% uncontrolled hypertension. These findings emphasise further considerations for detection and better management of hypertension in the urban population of Tehran.

The effect of differences in measurement procedure on the comparability of blood pressure estimates in multi-centre studies.

The procedures for obtaining blood pressure measurements, and their quality of performance, should be similar between epidemiological studies to allow a valid comparison of blood pressure distribution and prevalence of hypertension between study populations. However, considerable methodological variation currently exists as there are several international guidelines on blood pressure measurement and a standard method of measurement has not yet been agreed. This paper reviews the literature in order quantitatively to define systematic differences between blood pressure measurements resulting from differences in arm used, body position, number of measurements, verbal communication, cuff size applied and measuring device used. The results were applied to differences in procedure between European Prospective Investigation into Cancer and Nutrition (EPIC) study centres, showing that blood pressure measurements may systematically differ between centres by as much as 10 mmHg for procedural reasons alone. For most reviewed methodological differences, it was possible to at least estimate a range of systematic error. There are, however, additional possible causes of systematic variation, for example arm position, postprandial hypotension and diurnal blood pressure variation, that could not be taken into account. It may be possible to make only a partial correction for the systematic inter-centre variation of the EPIC blood pressure measurements. This study highlights the importance of standardized protocols for blood pressure measurements in epidemiological studies.

Hypertension as a complex genetic trait

Pickering first showed that blood pressure distribution is unimodal and that the diagnosis of essential (primary) hypertension is an arbitrary quantitative trait. His family studies suggested that not 1, but many, perhaps 30 or more, gene variations are responsible for raising blood pressure. Two approaches have been used to address the genetics of essential hypertension. Candidate genes have been selected by virtue of their physiologic function, and case-control association studies have been performed. Numerous candidates have been evaluated, genes of the renin-angiotensin-aldosterone system, genes coding for adrenergic receptors, genes coding for proteins regulating endothelial function, and genes involved in signaling have been studied. True to Pickering's prediction, each gene tested thus far seems to exert, at best, a small effect and contradictory studies are common. Linkage studies have been performed to map the loci of genes regulating blood pressure or inducing hypertension. Studies of dizygotic twins and their parents have permitted an identity-by-decent linkage analysis. Studies of affected sibling pairs involve subjects whose parents are generally already dead. Identity-by-state analysis requires a far greater number of pairs for results. Nevertheless, some large linkage studies have now been performed including subjects from Framingham. Log odds (LOD) scores are far removed from actually cloning genes responsible for hypertension. Single nucleotide polymorphisms (SNPs) permit linkage dysequilibrium mapping, which may enable cloning new genes. Thus far, very few new genes have been cloned for any complex genetic disease. The task is daunting but not impossible.

Distribution of blood pressure, body mass index and smoking habits in the urban population of Dar es Salaam, Tanzania, and associations with socioeconomic status.

To estimate the distribution of blood pressure (BP), body mass index (BMI), smoking habits and their associations with socioeconomic status (SES) in an urban population in early epidemiological transition. Cross-sectional survey of the entire population aged 25-64 years in five branches of Dar es Salaam (Tanzania) through visits to all homes in the study area. Blood pressure was based on the mean of the second and third readings with an automated device. Socioeconomic status was estimated with indicators of education, occupation and wealth. In all 9254 people were examined. Age-adjusted prevalence (%) among men/ women aged 35-64 years was 27.1/30.2 for BP > or = 140/90 mmHg or antihypertensive medication, 13.1/17.7 for BP > or = 160/95 mmHg or antihypertensive medication, 28.0/27.4 for BMI of 25.0-29.9 kg/m(2), 6.9/17.4 for BMI > or = 30 kg/m(2), and 22.0/2.6 for smoking (> or = 1 cigarette per day). Prevalence of categories of drinking frequency and history of diabetes are also reported. After adjustment for covariates, SES was associated inversely with BP and smoking and directly with BMI. Body mass index was associated positively with BP (1.01 and 0.91 mmHg systolic BP per 1 kg/m(2) BMI in men and women, respectively) and inversely with smoking (-1.14 kg/m(2) in male smokers versus non-smokers). Hypertension treatment rates were low, particularly in people of low SES. High prevalence of several cardiovascular risk factors in the urban population of a low-income country stresses the need for early public health interventions and adaptation of the health care infrastructure to meet the emerging challenge of cardiovascular disease. The direct SES-BMI association may drive increasing BMI and BP while the population becomes more affluent.

Blood pressure levels among cross-cultural populations of Visakhapatnam district, Andhra Pradesh, India

Background : Elevated blood pressure is a leading cause of morbidity and mortality throughout the world, as a major contributor to cardiovascular diseases. Blood pressure tends to vary cross-culturally and studies to address the influence of acculturization/modernization on blood pressure are limited from India, particularly from Andhra Pradesh. Aim : To provide information on blood pressure levels and variability across population groups from the State of Andhra Pradesh, India, and to examine the influence of acculturization/modernization on blood pressure levels. Subjects and methods : The blood pressure levels among 1316 individuals (646 men and 670 women) belonging to two tribal (Khondh and Valmiki) and two caste groups (Wadabalija and Settibalija) from rural and urban areas from Andhra Pradesh were collected. Analysis of covariance (ANCOVA) was used to examine the effect of age and sex, and population differences. Results : The distribution of blood pressure showed significant variability among these population groups. Higher levels of blood pressure were noticed in an acculturizing tribe, the Valmiki, than among the Khondh, a traditional tribal population. The results indicate that age had significant effect on both systolic and diastolic blood pressure levels. Also, the systolic blood pressure was relatively more sensitive than diastolic blood pressure to the effect of age. The sex did not contribute significantly to the variability of blood pressure. Conclusions : The study revealed significant population differences in the variability of blood pressure, with higher levels among acculturizing tribal population than the non-acculturizing group. But no significant variation was noticed between rural and urban slum dwellers. Age had a significant effect on blood pressure levels.

Left ventricular hypertrophy was infrequent in patients starting dialysis after undergoing a strict blood pressure control in the pre-dialytic period.

We retrospectively investigated the factors influencing the left ventricular hypertrophy (LVH) occurrence in patients with chronic renal failure (CRF). Blood pressure and echocardiographyically determined LVH were assessed in 110 patients on the basis of availability of monthly follow-up data obtained during the period of 2 years before the start of dialysis. When the patients showed the left ventricular mass index of not less than 125 g/m2, they were diagnosed as having LVH. Mean casual blood pressure distribution was classified into 5 groups: Group 1; <93 mmHg, Group 2; 93-100 mmHg, Group 3; 100-106 mmHg, Group 4; 106-114 mmHg and Group 5; >114 mmHg. LVH frequencies were 31.8, 72.7, 72.7, 81.8 and 95.5 (%) in Groups 1-5, respectively. Logistic regression showed that the factors influencing the progression of LVH were the duration of hypertension (per 1 year relative risk) (RR) 1.13, 95% confidential interval (CI) (1.01-1.26), treatment with angiotensin-converting enzyme inhibitors (ACE-1) (RR: 0.20, 95%CI: 0.04-0.99), pulse pressure (RR: 1.06, 95%CI: 1.00-1.11) and mean blood pressure (MBP). The RR of developing LVH increased progressively as MBP increased: Compared with LVH frequency in Group 1, RR of Group 2 was 4.38 (95%CI: 1.05-18.19), that of Group 3 was 5.50 (95%CI: 1.08-28.02), that of Group 4 was 5.66 (95%CI: 1.22-26.15), and that of Group 5 was 19.13 (95%CI: 1.75-209.4). Strict blood pressure control and ACE-I treatment could prevent LVH in patients with CRF.

Distribution of blood pressure and hypertension in Canada and the United States

Background:Two North American population based surveys, the Third National Health and Nutrition Examination Survey (NHANES III) and the Canadian Heart Health Surveys (CHHS) have similar time frames and methods that allow comparisons between these countries in terms of the distribution of systolic (SBP) and diastolic (DBP) blood pressure and the levels of hypertension awareness, treatment, and control. Methods:Cross-sectional population surveys using similar methods conducted home interviews and clinic visits (CHHS), and medical examinations (NHANES III). The CHHS included the ten Canadian provinces (1986–1992) and NHANES III, a representative sample of the United States population (1988–1994). Blood pressure measurements were available for 23,111 Canadians (age 18–74 years), and restricted to the 15,326 US participants in the same age range (age 18–74 years) with both systolic and diastolic mean values. Standardized techniques were used for BP measurements. Mean of all available measurements was used from four measurements for the CHHS and six measurements for NHANES III. A mean SBP/DBP of 140/90 mm Hg or treated with medication defined hypertension. All measures were weighted to represent population values. Results:Both surveys showed similar trends in mean BP by age, with slightly higher levels in the CHHS. Hypertension prevalence using the same definitions and the same age range (18–74 years) was NHANES III: 20.1%, CHHS: 21.1%. Although the prevalence of isolated systolic hypertension (ISH) was similar in both studies, around 8% to 9%, the CHHS had higher ISH prevalence than NHANES III in the younger age groups and lower prevalence in the older age groups. Elevated SBP dominated the prevalence figures after the 1950s in both studies. Compared to NHANES III, the CHHS showed a lower proportion (43% v 50%) of individuals with optimal BP (<120/80 mm Hg) and a very low proportion of hypertensives under control (13% v 25%). About half of diabetic participants were hypertensive (using 140/90 mm Hg) in both countries with a very low level of control in Canada (9%) v the US (36%) for ages 18 to 74 years. Conclusions:The results of these two surveys highlight the importance of SBP, in the later decades of life, an overall low control of hypertension in both countries, and a better overall awareness, treatment, and control of hypertension in the US than in Canada for that period. Dissemination of hypertension guidelines and a more aggressive focus on SBP are urgently needed in Canada, with special attention to diabetics.

Blood pressure and body water distribution in chronic renal failure patients.

Evidence exists of the important role of sodium balance and extracellular fluid volume in the genesis of hypertension in chronic renal failure (CRF). Several studies have shown that patients with advanced CRF have an increased, interstitial and intravascular, extracellular water volume (ECW). The relationship between the increase in ECW and high blood pressure has also been reported. Using electric bioimpedance, body water distribution was studied in 32 patients from our dialysis unit. Twelve of these patients were hypertensive and 20 had normal blood pressure. Hypertensive patients had a significantly greater total body water volume and ECW than the normotensive patients. Given the importance of ECW in controlling blood pressure, one of the main aims of haemodialysis is a suitable extraction of sodium and water during the treatment. Despite technological advances in dialysis therapy, cardiovascular instability during treatment is still a clinical problem. In recent years, new strategies to control ECW, with good haemodynamic tolerance, have been developed. These strategies include haemofiltration, haemodiafiltration and sodium and ultrafiltration profiles.

High-normal albuminuria and cardio-vascular risk factors in normo-albuminuric essential hypertensive men

Microalbuminuria, usually defined as an urinary albumin excretion(UAE)≥15μg/min,is associated with cardiovascular risk factors and predicts morbid events in non proteinuric essential hypertensive patients (EH). Much less known is the distribution of cardiovascular risk factors in presence of UAE values below the microalbuminuric threshold of 15μg/min. To address that point, we studied 141 never treated, glucose-tolerant male EH with UAE <15 μg/min (the median of three overnight collections). Data were analyzed by evaluating the distribution of 24-hr blood pressure (BP), cardiac structure and geometry (by echocardiography), BMI, common carotid artery intima thickness (IMT, high-sensitivity ultrasonography), insulin sensitivity (as approximated through the HOMA index: fasing insulin (μU/ml)/[22.5 X E-LN(GLUCOSE [MMOL/L])]) (tertile cut-off points: 4.6 and 7.8 μg/min, n=46, 47 and 48 respectively) across UAE tertiles. As compared with the intermediate and bottom thirds, patients in the top tertile showed higher 24-hr BP (143±19/93±12 vs 133±13/86±8 and 135±11/88±10 mmHg, p<0.01), thicker interventricular septum thickness (1.19±0.14 vs 1.1±0.13 and 1.04±0.1 cm, p<0.001), increased relative wall thickness (RWT, IVST+PWT/EDD) (0.47±0.06 vs 0.44±0.06 and 0.44±0.05, p<0.01), heavier body size(26.8±3.1 vs 25.2±2.4 and 25.9±2.2 Kg/m2, p<0.02). Left ventricular mass index (LVMI, 54±14 vs 51±12 and 52±12 g/m2.7) did not differ significantly, but the percentage of patients with a concentric hypertrophic pattern (LVMI> 51g/m2.7 & RWT>0.45) was more frequent in the top tertile (48 vs 18 and 11%, p<0.001). Lipids, carotid thickness (0.73±0.3 vs 0.77±0.2 and 0.75±0.2 mm), HOMA index (2.6±3.8 vs 2.5±1.2 and 2.4±1.1) did not differ. Some cardiovascular and metabolic parameters predictive of risk are linearly associated with UAE values below the conventional microalbuminuric thresholds. Normoalbuminuric EH with high-normal albuminuria are characterized by an adverse risk profile with potentially important negative prognostic consequences. These data might suggest to shift downwards the limits for diagnosing microalbuminuria in essential hypertension, a possibility to be tested in future studies.

Ambulatory blood pressure of adults in Novosibirsk, Russia: interim report on a population study

Objective To describe the distributions of the ambulatory blood pressure in a sample drawn from the Siberian population. Methods In the European Project On Genes in Hypertension (EPOGH), a random population sample of 162 persons (72 men and 90 women) was investigated in Novosibirsk, Russia. Mean age (± SD) was 40.6 ± 15.3 years. Validated oscillometric 90207 SpaceLabs monitors were programmed to obtain ambulatory blood pressure readings at intervals of 15 min from 0800 h to 2200 h and at 30 min intervals from 2200 h to 0800 h. Daytime and nighttime were defined using short fixed-clock time intervals, which ranged from 1000 h to 2000 h and from midnight to 0600 h, respectively. Results In the 162 participants, of whom 54 were hypertensive, 24-h clocktime day and clocktime night blood pressures averaged 120/73, 126/79 and 110/60 mmHg, respectively. Compared with daytime values, blood pressures at the clinic were 5.7/1.1 mmHg lower in 108 normotensive people, but 17.0/13.1 mmHg higher in 54 hypertensive patients. In the normotensive subgroup, the 95th percentiles of the 24-h clocktime day and clocktime night blood pressures were 128/81, 136/86 and 118/72 mmHg, respectively. Conclusion In comparison with other population surveys, the present interim report on the EPOGH study produced consistent results with respect to the distributions of the ambulatory measurements both in normotensive subjects and in the overall study population.

The values of certain haemodynamic parameters, membrane structure and activity Ca2+ -dependent K+ -chanels in F2 SHRxWKY hybrids are predictable by ID-repeat polymorphism

Spontaneously hypertensive rats (SHR, Okamoto-Aoki strain) have been employed as a model of human primary essential hypertension (EH). EH is inherited in non-mendelian manner, being characterized by very high incidence in population and smooth transition in the arterial blood pressure distribution from norm to pathology. We have suggested that genetic determination of primary hypertension is represented by genomic rearrangements caused by reorganisation of clusters of repetitive sequences. The present study evaluated the role of moderate ID-repeats in the inheritance of spontaneous hypertension in rats. A DNA of 98 F2(SHR X WKY) hybrids were studied by method based on the PCR technique with random primers (SCAN). It was found 35 polymorphous electrophoretic bands in genome of F2 (SHRxWKY) hybrids. It was shown that systolic and diastolic blood pressure, heart rate, activity of erythrocyte Ca2+-dependent K+-channels and contents of the erythrocyte plasma membrane proteins may be predicted by electrophoretic spectra of PCR fragments with statistical methods of piecewise and multiple linear regressions. From 2 to 4 electrophoretic bands were chosen for the prediction of each haemodynamic characteristics. A method of the genomic DNA moderate repeats fingerprinting allows to predict the value of all phenotyping characteristics in F2(SHRxWKY) hybrids.

CFD ANALYSIS OF HEARTQUESTTM LVAD

The purpose of this study is to present some of the design aspects used to develop the clinical version of the HeartQuestTM LVAD, a magnetically-levitated centrifugal blood pump. A 3-dimensional computational fluid dynamic (CFD) model of the HeartQuestTM LVAD including inlet and outlet was developed using Tascflow software (AEA Technology.) Detailed flow characteristics throughout the pump were simulated, providing blood velocity, pressure distribution, and shear stresses at several operating conditions. Initial results revealed a leading edge vortex within the inlet of the pump, extending into the leading edge of the impeller. Calculation of shear stress indicated regions of the flow, particularly along the blade tips, which may be susceptible to blood damage. These results were used to modify the flow path design. Additional simulation within the magnetic clearance regions were performed to assure shear stress and exposure were within satisfactory limits. Modifications to the dimensions were made to satisfy these requirements while minimizing loss of volumetric efficiency. Calculation of the fluid dynamic forces on the impeller provided essential data for the design of the magnetic levitation system. In summary, the CFD model has proved invaluable for designing both the blood flow paths and the magnetic suspension system.

Genetic Factors in Hypertension – What is Known and What Does It Mean?

The cause of primary hypertension is unknown but the normal distribution of blood pressure in the population, of which hypertension represents the upper tail, suggests a multifactorial aetiology. Approximately 30%–60% of the blood pressure variation in the population is accounted for by genetic factors whereas environmental exposure explain the remaining part [1, 2]. Primary hypertension is likely to be the result of the net effect of various environmental factors and number of common variants in different genes, each of which will have a moderate effect on blood pressure [3]. Thus hypertension susceptibility genes will occur also in the normotensive segment of the population, although less frequently than in hypertensive patients. The exact genetic defects of a number of rare salt sensitive monogenic forms of hypertension have been described [4–6]. The causative mutations all lead to increased reabsorption of sodium in the renal tubules. These discoveries have highlighted the clinical relevance of searching for hypertension genes as they have allowed for early diagnosis, prevention with salt restriction and specific and effective pharmacological treatment of these monogenic forms of hypertension. The genetic background of primary hypertension is more complex and considerably harder to dissect as the number of genes and environmental factors involved are greater, resulting in a "non-Mendelian" inheritance pattern. However, thanks to the recent enormous development of molecular genetics [7], genetic statistics [8, 9] as well as of advances in clinical hypertension research, identification of primary hypertension susceptibility genes now seems feasible. This article reviews the strategies that can be used for hypertension susceptibility gene identification and gives an overview of the as yet most important findings in the field of genetics of hypertension. Finally, views on what we can expect from this research field in the future and what impact it will have on clinical medicine are put forward.

Importance of quantitative genetic variations in the etiology of hypertension

Recent progress has been remarkable in identifying mutations which cause diseases (mostly uncommon) that are inherited simply. Unfortunately, the common diseases of humankind with a strong genetic component, such as those affecting cardiovascular function, have proved less tractable. Their etiology is complex with substantial environmental components and strong indications that multiple genes are implicated. In this article, we consider the genetic etiology of essential hypertension. After presenting the distribution of blood pressures in the population, we propose the hypothesis that essential hypertension is the consequence of different combinations of genetic variations that are individually of little consequence. The candidate gene approach to finding relevant genes is exemplified by studies that identified potentially causative variations associated with quantitative differences in the expression of the angiotensinogen gene (AGT). Experiments to test causation directly are possible in mice, and we describe their use to establish that blood pressures are indeed altered by genetic changes in AGT expression. Tests of differences in expression of the genes coding for the angiotensin-converting enzyme (ACE) and for the natriuretic peptide receptor A are also considered, and we provide a tabulation of all comparable experiments in mice. Computer simulations are presented that resolve the paradoxical finding that while ACE inhibitors are effective, genetic variations in the expression of the ACE gene do not affect blood pressure. We emphasize the usefulness of studying animals heterozygous for an inactivating mutation and a wild-type allele, and briefly discuss a way of establishing causative links between complex phenotypes and single nucleotide polymorphisms.

Association of the human Y chromosome with high blood pressure in the general population.

Genetic variation in the Y chromosome has significant effects on male blood pressure in experimental animals, but the effects in humans are unknown. We examined the relationship between blood pressure and a polymorphic HINdIII restriction site in the nonrecombining region of the Y chromosome in 409 randomly selected men from the general population. Carefully standardized measures of systolic and diastolic blood pressures were made. The HINdIII restriction site was significantly more common (43.2%) in men in the lowest decile of the diastolic blood pressure distribution than men in the highest decile (15.9%, P=0.007). No significant difference in genotype frequency was observed between the lowest and highest deciles for systolic pressure (32.4% versus 27.8%, P=0.66). In the entire group, men with the HIN:dIII restriction site had significantly lower diastolic blood pressures (81.2 mm Hg, SD:8.3, versus 83.2 mm Hg, SD:8.7, P=0.03). No significant differences in systolic blood pressure (130.6 mm Hg, SD:14.7, versus 128.3 mm Hg, SD:13.6) were observed in relation to genotypes. Our results indicate that genetic variation in the human Y chromosome is associated with high blood pressure and contributes significantly to the quantitative variation of male diastolic blood pressure in the general population.

Plasma leptin concentrations and obesity in relation to insulin resistance syndrome components among school children in Taiwan--The Taipei Children Heart Study.

Leptin, an adipose tissue-derived product of the obesity (OB) gene, is an important regulator of energy metabolism and may be associated with the occurrence of insulin resistance and diabetes in humans. The purpose of this study was to evaluate the association of plasma leptin concentration with obesity and the components of insulin resistance syndrome (IRS) among school children in Taiwan. After multistage sampling of 85 junior high schools in Taipei, we randomly selected 1,264 children (617 boys and 647 girls) aged 12-16y. Obesity measurements included body mass index (BMI) and waist-to-hip circumference ratio (WHR). We calculated an IRS summary score for each individual by adding the quartile ranks from the distribution of systolic blood pressure (BP), serum triglyceride (TG), HDL-cholesterol (inverse), and insulin levels. Boys had a higher BMI and WHR, BP and IRS score and lower leptin, insulin, TG and HDL-C levels than girls. BMI, WHR and plasma leptin levels were significantly associated with the IRS summary score and each of its components in both genders. Children with higher plasma leptin levels (> 75th percentiles) have significantly higher BP, TG, insulin levels and IRS score than children with low leptin levels. The associations between plasma leptin level and the IRS components and score were still significant after adjusting for BMI in boys, but less so in girls. In both genders, after adjusting for WHR, plasma leptin levels were still significantly associated with the IRS components and summary score (P< 0.001). The final model that included the standard covariates, BMI and leptin, but not WHR, was the most predictive of the IRS summary score among school children. Insulin resistance syndrome in childhood, characterized by high blood pressure, dyslipidemia, and hyperinsulinemia, may be an early marker of cardiovascular risk. From the present BMI and leptin in combination are the most predictive markers of insulin resistance syndrome among school children in Taiwan.

Ambulatory blood pressure of adults in Novosibirsk, Russia: interim report on a population study.

To describe the distributions of the ambulatory blood pressure in a sample drawn from the Siberian population. In the European Project On Genes in Hypertension (EPOGH), a random population sample of 162 persons (72 men and 90 women) was investigated in Novosibirsk, Russia. Mean age (+/-SD) was 40.6+/-15.3 years. Validated oscillometric 90207 SpaceLabs monitors were programmed to obtain ambulatory blood pressure readings at intervals of 15min from 0800h to 2200h and at 30min intervals from 2200h to 0800h. Daytime and nighttime were defined using short fixed-clock time intervals, which ranged from 1000h to 2000h and from midnight to 0600h, respectively. In the 162 participants, of whom 54 were hypertensive, 24-h clocktime day and clocktime night blood pressures averaged 120/73, 126/79 and 110/60mmHg, respectively. Compared with daytime values, blood pressures at the clinic were 5.7/1.1mmHg lower in 108 normotensive people, but 17.0/13.1mmHg higher in 54 hypertensive patients. In the normotensive subgroup, the 95th percentiles of the 24-h clocktime day and clocktime night blood pressures were 128/81, 136/86 and 118/72mmHg, respectively. In comparison with other population surveys, the present interim report on the EPOGH study produced consistent results with respect to the distributions of the ambulatory measurements both in normotensive subjects and in the overall study population.

Evidence for a vestibulo-cardiac reflex in man

Changes in posture demand rapid cardiovascular adjustments to maintain blood pressure and volume distribution. We demonstrated a vestibulo-cardiac reflex in supine individuals by measuring electrocardiogram and arterial blood pressure after small backwards drops of the head triggered at varying intervals after the R-spike. In normal volunteers heart rate was accelerated by drops occurring within 500-600 ms of a beat, but no rapid effect was noted in patients with a vestibular defect. The speed at which the vestibular signal of head drop accelerated heart rate implies a direct reflex. Impairment of the vestibulo-cardiac reflex would help to explain the vaso-vagal consequences of labyrinthitis.

Normal values of blood pressure self-measurement in view of the 1999 World Health Organization-International Society of Hypertension guidelines

New guidelines for the management of hypertension have been published in 1999 by the World Health Organization (WHO) and the International Society of Hypertension (ISH). The WHO/ISH Committee has adopted in principle the definition and classification of hypertension provided by the JNC VI (1997). The new classification defines a blood pressure of 120/80 mm Hg as optimal and of 130/85 mm Hg as the limit between normal and high-normal blood pressure. It is unclear which self-measured home blood pressure values correspond to these office blood pressure limits. In this study we reevaluated data from our Dübendorf study to determine self-measured blood pressure values corresponding to optimal and normal office blood pressure using the percentiles of the (office and home) blood pressure distributions of 503 individuals (age, 20 to 90 years; mean age, 46.5 years; 265 men, 238 women). Self-measured blood pressure values corresponding to office values of 130/85 mm Hg and 120/80 mm Hg were 124.1/79.9 mm Hg and 114.3/75.1 mm Hg. Thus, we propose 125/80 mm Hg as a home blood pressure corresponding to an office blood pressure of 130/85 mm Hg (WHO 1999: normal) and 115/75 mm Hg corresponding to 120/80 mm Hg (optimal).

Electrical Stimulation for Pressure Sore Prevention and Wound Healing

This paper reviews applications of therapeutic electrical stimulation (ES) specific to wound healing and pressure sore prevention. The application of ES for wound healing has been found to increase the rate of healing by more than 50%. Furthermore, the total number of wounds healed is also increased. However, optimal delivery techniques for ES therapy have not been established to date. A study of stimulation current effects on wound healing in a pig model has shown that direct current (DC) stimulation is most effective in wound area reduction and alternating current (AC) stimulation for wound volume reduction at current densities of 127 μA./cm2 and 1,125 μA/cm2, respectively. Preliminary studies have been carried out at two research centers to assess the role of ES in pressure sore prevention. Surface stimulation studies have shown that ES can produce positive short-term changes in tissue health variables such as regional blood flow and pressure distribution. The use of an implanted stimulation system consisting of intramuscular electrodes with percutaneous leads has been found to produce additional long-term changes. Specifically, gluteal muscle thickness increased by 50% with regular long-term ES application concurrent with a 20% decrease in regional interface pressures and increased tissue oxygen levels. These findings indicate that an implantable ES system may have great potential for pressure sore prevention, particularly for individuals who lack sensation or who are physically unable to perform regular independent pressure relief.