Self-measurement and automatic measurement in ambulatory blood pressure monitoring

INTRODUCTION: There are strictly determined conditions under which blood pressure measurement should be done and diagnosis of hypertension made. The first BP measurement should be performed on both arms. If there is a difference, controls should be made on the side on which the pressure is higher. In older persons the Osler manoeuvre should be made in order to exclude pseudohypertension. One should be aware that in hospitalized patients the BP is lower due to the bed rest itself. SELF-MEASUREMENT OF BLOOD PRESSURE: It seems that erroneous interpretation of blood pressure fluctuation and the tendency for self-medication by patients are the most important shortcomings of blood pressure self-monitoring. According to the World Hypertension League instructions, the BP self-measurement is not recommended for patients obsessed by the disease, neurotic and anxious persons, old subjects and in those who are physically handicapped. Since the diagnosis of hypertension should be made by the physician in office conditions, in our opinion the evolution of the disease and effects of treatment should be estimated under the same conditions. BLOOD PRESSURE AMBULATORY MONITORING: Ambulatory 24-hour monitoring is of a considerable diagnostic, therapeutic and prognostic importance over the casual or self-measurement, but one should be familiar with some peculiarrities of this method. Due to the adaptation to the device, the values of BP on the first measurement, particularly during the first 5 hours are significantly higher than during the subsequent measurements. In some subjects the values during the night may be higher due to the sleeping disturbances caused by the procedure. Differentiation between dippers and non-dippers has some prognostic and therapeutic implications. White coat hypertension may be successfully established by the ambulatory measurement. There is also a correlation between the BP variations and the myocardial mass. The trough:peak ratio may contribute to the estimation of efficiency of a certain drug. There are particular indications for ambulatory BP monitoring: the differences between the office and home values of BP are considerable; borderline hypertension; hypertension without signs of the target-organ damage; transitory hypertension of hypotension; syncopal attacks; vague symptoms in hypertensive patients; atypical or nocturnal angina; evaluation of the efficiency and duration of drug action; for research purposes.     

White coat effect and reactivity to stress: cardiovascular and autonomic nervous system responses

The aim of this study was to elucidate further the precise nature of the so-called "white coat" (WC) effect. We enrolled 88 hypertensive (46 men, 42 women) and 18 normotensive (4 men, 14 women) subjects in whom beat-to-beat blood pressure (BP) and heart rate (HR) were measured with a Finapres device at rest (R period) and during conventional BP measurement (WC period). The WC effect was defined as WC period minus R period values of Finapres systolic BP. Using the same method, we also measured the BP and HR variations induced by mental stress (MS period) and by assuming the standing position (S period). Variability was estimated in the frequency domain for BP (BPV) and HR (HRV) and gave indices of the autonomic nervous system. Pulse wave velocity was taken as an index of arterial distensibility. In hypertensive subjects, the WC effect was significantly and positively correlated with the BP response to stress (0.51, P<.0001) and standing (0.63, P<.0001). An increased BPV was observed in the low-frequency band (0 to 0.150 Hz) during WC, MS, and S periods. In normotensive subjects, the WC effect was very slight and not correlated with the responses to stress and standing. In this group, the WC period was not accompanied with an increased BPV, unlike the stress and standing periods. HRV was similar in normotensives and in hypertensives: decreased, unchanged, and increased during MS, S, and WC periods, respectively. The PWV was significantly increased in the hypertensives relative to the normotensives, even in the quartile of those with the lowest BP (on average similar to that of the normotensives). This work shows that the WC effect is associated with an enhanced BP response to standing and mental stress; these three situations are characterized by an increased BPV in the low frequencies, suggesting a similar modification of the sympathovagal balance. The WC effect may entail an increased risk because it is associated with impaired arterial distensibility.     

Do geomagnetic disturbances of solar origin affect arterial blood pressure?

OBJECTIVE: Episodic reports suggest that geomagnetic disturbances of solar origin are associated with biological and clinical events, including increased arterial blood pressure (BP). We reassessed this aspect by relating solar activity levels to ambulatory BP measured in our out-patient population. PATIENTS AND METHODS: The ambulatory BP measurements of 447 consecutive untreated patients attending a hypertension out-patient clinic who did a monitoring for diagnostic purposes over 5 years were retrieved. The mean daytime, night-time and 24-h BP and heart rate values were related to the temporally corresponding geomagnetic index k-sum obtained by the nearest observatory. K-sum is a local measurement of the irregular disturbances of the geomagnetic field caused by solar particle radiation. RESULTS: Significant to highly significant positive correlations were observed for k-sum with systolic (daytime and 24 h) and diastolic BP (daytime, night-time and 24 h), but not with heart rate. No correlations were found with the k-sum of 1 or 2 days before the monitorings. Multiple correlations which also included other potential confounding factors (date, age) confirmed a significant effect of k-sum on BP. Comparison made in season-matched subgroups of quiet and disturbed days (using three different criteria of definition), always showed significantly higher values in the disturbed days for all BP parameters except systolic night-time pressure. The difference between the quietest and the most disturbed days was of about 6 to 8 mm Hg for 24-h systolic and diastolic BP. CONCLUSION: These results are unlikely to be due to unrelated secular trends, but seem to reflect a real relation between magnetic field disturbances and BP.     

The impact of physician vs automated blood pressure readings on office-induced hypertension

Blood pressure (BP) readings in the doctor's office are frequently higher than home or ambulatory values. This study examines the role of the physician in the aetiology of the 'white coat' effect, by comparing standard readings taken by the family physician of 27 treated hypertensive patients with readings taken by an automated BP recording device, with the patient alone in the examining room during the same office visit. The physician and automated readings were each compared to the mean awake ambulatory BP. Mean (+/-s.e.m.) routine office BP (mm Hg) recorded by the patient's physician (155+/-4/80+/-2) was similar to the mean value obtained using the automated BP recording device (157+/-3/83+/-2). The mean awake ambulatory BP was 145+/-3/78+/-2 with the systolic value lower (P < 0.05) than either the physician or automated reading. Self-measurement of BP by the patient in the office setting does not reduce the magnitude of the white coat effect.     

Knowledge of blood pressure measurement among a teaching hospital staff in a developing nation

Hypertension is a common and potentially serious disease and accurate measurement of blood pressure (BP) is important for its diagnosis and management. The aim of this study was to assess the knowledge of hospital staff on the basic principles of BP measurement. Consultants, junior doctors and nurses in a large teaching hospital in southern Saudi Arabia were requested to answer a questionnaire about the most important aspects pertaining to BP measurement. The overall response rate was about 70%. There was a wide diversity of responses reflecting a poor knowledge of some of the basic techniques of BP measurement. This included inconsistencies regarding the knowledge of cuff size, recording of diastolic BP, position of the arm and rate for deflating the cuff. Overall, 60% of the respondents had insufficient knowledge. Inaccurate BP measurement can seriously affect the diagnosis and management of the patient with this common disease. Hospital staff need to improve their knowledge about BP measurement, and teaching programmes about BP measurement should be developed as part of continuing education.     

Conserved themes but novel activities in recombinases and topoisomerases

OBJECTIVE: Hypertension is thought to play an important role in the pathogenesis of acromegalic cardiomyopathy. So far, hypertension has been defined by clinical measurement, with considerable variations reported concerning its prevalence in acromegalics. DESIGN: To determine the mean blood pressure (BP) values and the prevalence of hypertension in patients with active acromegaly according to non-invasive 24-hour ambulatory BP monitoring (ABPM) and to compare the data obtained with those provided by clinical measurement. PATIENTS: Forty patients with active acromegaly (22 women, 18 men, mean age 48.6 +/- 12.5 years) were included. Patients were in wash-out for antihypertensive treatment and none had been using any medical treatment for acromegaly for at least 3 months before the study. All were studied as outpatients. MEASUREMENTS: Clinical BP values were calculated as the mean of BP values obtained by standard sphygmomanometric measurement in three separate occasions. Mean 24-hour, daytime and night-time BP values were obtained by ABPM. RESULTS: The mean 24-hour BP values were lower than clinical BP values, the difference being significant for both systolic BP (SBP: 131.1 +/- 21.5 versus 136.1 +/- 16.3 mmHg, P < 0.02) and for diastolic BP (DBP: 74.6 +/- 10.6 versus 88.8 +/- 9.1 mmHg, P < 0.0001). ABPM values recorded during the daytime were 137.8 +/- 20.9 mmHg for SBP and 78.6 +/- 11.5 mmHg for DBP, the latter being significantly lower than the corresponding clinical BP values (P < 0.0001). About 60% of the patients considered hypertensive by clinical measurement were found to be normotensive by ABPM, thereby decreasing the prevalence of hypertension in this series from 42.5% to 17.5% according to ABPM (P < 0.02). In contrast, all patients defined as normotensive by clinical measurement were also normotensive by ABPM. CONCLUSIONS: Ambulatory blood-pressure monitoring indicated a lower prevalence of hypertension in acromegalic patients then usually reported, suggesting that the role of hypertension in the pathogenesis of acromegalic cardiomyopathy is commonly overestimated. We propose that ambulatory blood-pressure monitoring should be routinely proposed in acromegalics with high or borderline clinical blood pressure values although it is not useful in patients defined normotensive according to repeated clinical measurement.     

High-temperature dilatometer for measuring shrinkage during sintering

Summary The laboratory device for studying the dilatometric effect, made of high-temperature graphite, is reliable in operation and makes possible the measurement of temperatures up to 2500°C with a sufficiently high accuracy (an error of only 2.6%).     

The role of glutamate in the pathophysiology of Parkinson''s disease

In 137 healthy volunteers between 18 and 85 years of age, blood pressure (BP) and heart rate (HR) were measured continuously with the Finapres device during active change of posture (ACP), i.e. standing upright, passive tilt (PT, i.e. head-up tilt), Valsalva manoeuvre (VM), deep breathing (DB), isometric muscle exercise (IME) and a mental arithmetic task (MA). Mean HR activation was attenuated with increasing age in all manoeuvres, but was unrelated to sex. In non-orthostatic challenge procedures like MA and IME mean BP increases were independent of age and sex, despite lower increases in HR in the elderly. This points to a preserved sympathetic efferent activity. Following a forced fall in BP during ACP, PT and VM, the initial responses and maintenance values of BP showed a significant age-related decrease. This finding was strongly related to lower BP values in males compared with females, which became more pronounced with increasing age. Further studies to investigate age-related changes in the activation of the various components of the cardiovascular regulation need to consider the mode of activation of the autonomic nervous system and sex as factors of influence. Normal ranges, and also some new points in time not previously measurable, were calculated for all standard autonomic tests based on the continuous measurement of BP and HR. The minimum length of time necessary to assess the cardiovascular responses during ACP and PT was found to be 60 s. The upper time limits for reaching maximum activation during IME and MA were 3.5 min and 1 min, respectively. Age had a relevant influence on the lower limits of normal of all HR parameters and of some BP measurements during PT, ACP and VM. Sex was found to have no relevant impact on normal ranges. Over 65 years of age the normal values for HR activation during VM and DB hardly exceeded baseline values. The possibility of increasing the sensitivity of detection of autonomic dysfunction by measuring BP continuously must be approached with caution, as sufficient sensitivity was only reached at the lower limits of normal during late phase II of the VM. The initial increase of HR after ACP and the BP values after 60 s standing time proved to be the parameters with the best sensitivity for detecting an affection of the regulation of HR and BP over the whole range of age.     

Steady-state bioavailability and day-to-day variability of a multiple-unit (CR/ZOK) and a single-unit (OROS) delivery system of metoprolol after once-daily dosing

Home blood pressure (BP) monitoring is useful in the clinical management of patients with hypertension and the identification of those with "white-coat" hypertension; i.e. high readings in the clinic but normal BP at home. In the process of evaluating this technique, we compared self-measured home BP with intra-arterial BP. Healthy white men (n = 40) of 20-40 years of age and body weight below 95 kg were recruited by advertising in the local newspaper. Following a standardized procedure, performed within 2-4 weeks of a response to the advertisement, BP was measured by a physician at a clinic screening, by the subject at home (14 readings in 7 days) and finally in the clinic concomitantly intra-arterially and oscillometrically. The correlation coefficient for mean (M) home BP (r = 0.73) and oscillometric BP (r = 0.74) against intra-arterial BP were slightly higher than for screening BP (r = 0.65). However, in plots of the differences for individual MBP between the methods against the average of the methods, it appears that at levels of average MBP above 100 mmHg, screening BP overestimates the BP level, while this was not the case for home BP or oscillometric BP. Thus, by using intra-arterial measurement as standard of comparison, subject self-measured home BP is a reliable method of estimating blood pressure level in young men. Home BP measured shortly after screening and recruitment provides useful information of resting BP in subjects who potentially may have initial anxiety about BP measurement.     

Relationship between activity levels and circadian blood pressure variations

In 17 healthy Japanese students (14 males and 3 females) an ambulatory activity level monitoring instrument (Actigraph) was attached to the wrist for 48-hour measurement of wrist movement (with 0.01G or higher acceleration). At the same time, an ambulatory blood pressure monitoring apparatus was attached to these subjects to monitor blood pressure (BP) and heart rate (HR) every 30 minutes. Sleeping hours were calculated from the activity levels. The sleeping hours obtained by the Actigraph correlated with those judged from the diary. The correlation was better for the go-to-sleep time than for the awakening time. Activity level, HR and BP showed a similar circadian variation. Activity level differed significantly between the active daytime (4500 counts/hour) and during sleep at night (720 counts/hour). The acrophase of activity level, obtained by the cosinor method, was 235 degrees which did not significantly differ from that of BP and HR. Hourly activity levels correlated with HR and BP at corresponding hours. These results suggest that BP is affected by activity levels even if this rhythm continues to recur in bedrest.     

Effects of suprachiasmatic lesions on circadian rhythms of blood pressure, heart rate and locomotor activity in the rat

To determine whether the circadian rhythms in blood pressure (BP), heart rate (HR) and locomotor activity are controlled by an internal biological clock located in the suprachiasmatic nucleus (SCN), we continuously measured these parameters in SCN-lesioned rats using a newly developed implantable radiotelemetry device and a computerized data collecting system. Although SCN-lesioned rats showed a weak but significant 24-h periodicity in BP and HR under light-dark (LD) cycles, BP, HR and locomotor activity became completely aperiodic under constant dark (DD) conditions. The amount of locomotor activity was significantly reduced in SCN-lesioned rats compared to that in intact rats. BP tended to be higher in SCN-lesioned rats, but the differences were significant only in the comparison of systolic blood pressure (SBP) under LD and DD (p < 0.05) and of mean blood pressure (MBP) under LD (p < 0.05). HR in SCN-lesioned rats was significantly lower under LD (p < 0.05), but not under DD. The standard deviation and the variation coefficient of MBP, as indices of short-term variability of this parameter, were significantly larger in SCN-lesioned rats than in intact rats, while those of HR and locomotor activity did not differ significantly between SCN-lesioned and intact rats. These results indicate that the SCN is important not only for generating circadian rhythms of BP, HR and locomotor activity, but also for buffering the short-term variability of BP in rats.     

热轧厂35kV右母线滤波装置优化

热轧厂在轧制难度大的产品时，引进的３５ｋＶ右母线滤波装置经常过流跳闸，并影响主变压器跳闸。通过现场测试，对过流跳闸原因进行综合分析，确定了设备优化改造对策。经１年多时间的实践考核证明改造是成功的。     

动态铁水轨道衡的改造

针对动态铁水专用轨道衡使用过程中存在的台面震动、计量误差大等问题，从机械、电器、软件等方面对系统进行改进。通过加固道床、增加台面有效计量长度，减少了车列对台面的冲击；更换传感器消除了昼夜温差带来的计量误差；系统软件增加温漂修正功能和零漂自动补偿功能，使系统的综合计量误差率由2％降为0．34％。     

Antihypertensive effects, determined by a telemetry method, of trichloromethiazide and 7-O-ethylfangchinoline, a derivative of tetrandrine, in spontaneously hypertensive rats

1. The antihypertensive effects of 10 mg/kg trichloromethiazide (TCM), 10 mg/kg 7-O-ethylfangchinoline (7-O-EFC) and the combination of these drugs given orally once daily for 2 weeks were investigated by measuring the blood pressure (BP), heart rate (HR) and activity in conscious, freely moving spontaneously hypertensive rats (SHR) fitted with a telemetry device. 2. Clear diurnal rhythms of the HR and activity in synchrony with the light/dark cycle were observed during therapy, whereas the BP rhythm was obscure. 3. Alone, TCM and 7-O-EFC produced slight and insignificant reductions of 24h mean BP, whereas in combination they produced an additive and significant BP reduction, compared with the vehicle-treated controls, from the third day of therapy. The BP reduction induced by the combination of these drugs during the dark phase was more marked than that during the light phase. 4. None of the drug therapies affected the HR and activity diurnal rhythms. 5. The results of the present study demonstrate that the telemetry method is useful for monitoring the antihypertensive effects of drugs in SHR under physiological conditions with minimal stress.     

Adrenal function and the hypothalamo-pituitary adrenal axis in immunodeficiency virus-associated tuberculosis

A force measurement device has been designed to monitor the mechanical properties of fracture site with external fixation. Forces are measured through electric resistance strain gauges mounted on fixation framework and the measurement results are displayed on an LCD screen. The device features a force range of 0-10 kg with linearity and repeatability less than 1% and accuracy less than 0.1 kg.     

Heart rate and blood pressure variabilities in mild to moderate hypertensive patients with or without left ventricular hypertrophy

AIM OF THE STUDY: To compare heart rate (HR) and blood pressure (BP) variability in hypertensives with or without left ventricular hypertrophy (LVH). METHODS: Thirty-three mild to moderate hypertensive patients, mean age 45 +/- 15 years, underwent an echocardiogram, a 24 hr ambulatory BP monitoring (ABPM), a 24 hr ECG monitoring and a continuous BP recording over 15 minutes both in supine and standing positions, by using digital plethysmography (Finapres device). Statistical analysis: non parametric tests. RESULTS: [table: see text] CONCLUSION: LVH is associated with a reduction in the markers of sympathetic activity and a decreased baroreflex sensitivity.     

一种新型高炉风口中套压紧装置的设计与应用

针对天钢3 200 m~3高炉风口大套前端锥面与风口中套上端锥面之间煤气泄漏的问题,通过对风口装置进行结构分析和现场跟踪实测,在风口中套的另一端设计安装了一套中套压紧装置。该新型压紧装置投入使用后,保证了高炉风口装置的安全稳定运行,减少了设备损失,创造了较高的经济效益。     

Effects of amlodipine on 24-hour ambulatory blood pressure profiles, electrocardiographic monitoring, and left ventricular mass and function in black patients with very severe hypertension

In a 3-month, open-label study, 54 consecutive black patients with very severe hypertension were treated with amlodipine. Very severe hypertension was defined as an average sitting diastolic blood pressure (BP) > or = 115 mmHg and < or = 140 mmHg as a mean of 10 readings over a 30-minute period using an automatic BP measuring device and a mean 24-hour diastolic ambulatory blood pressure (ABP) > or = 110 mmHg and < or = 140 mmHg). Serial changes in 24-hour ABP and electrocardiographic monitoring, left ventricular (LV) mass index, and LV systolic function were evaluated. Mean 24-hour ABP was reduced from 181 +/- 14/119 +/- 6 to 140 +/- 15/92 +/- 9 mmHg at 3 months (P < 0.0001). Target BP (mean 24-hour diastolic ABP < 90 mmHg) was achieved in 35% of the patients. The reduction in BP was sustained for 24 hours after drug administration. Simultaneous BP measurements using the automatic BP measuring device were significantly different from the ABP measurements before and after treatment, suggesting a marked "white coat" pressor effect. At baseline, frequent or complex ventricular arrhythmias (> 30 ventricular extrasystoles per hour, ventricular couplets) were present in 2 (4%) patients, with no significant change after treatment. Left ventricular mass index regressed from 140 +/- 50 to 111 +/- 30 g/m2 at 3 months (P < 0.03); LV performance was not adversely affected. Adverse effects were few and tended to disappear during the treatment period. All of the clinical laboratory parameters tested remained unchanged. In this group of patients, treatment with amlodipine showed a marked and sustained antihypertensive action as demonstrated by 24-hour ABP monitoring, and was well tolerated and associated with LV mass regression without adverse effect on systolic cardiac function. Further, a low rate of complex ventricular arrhythmias was documented.     

室温磁热效应直接测量仪的误差分析

简单介绍了室温磁热效应测量仪的组成、工作原理及其优点;用金属G d作为标准样品,用两个不同尺寸的温度传感器,测量了两个大小不同的样品。结果表明,相同条件下测量的数据重复性很好,而不同条件下测量的数据有一些差别,对此进行了分析,发现测量样品时特别是样品较小时,温度传感器的热容以及绝热条件等因素是引起误差的主要原因。     

Conditional Assessment of Flow Measurement Accuracy

A study conducted by the Utah Water Research Laboratory assessed the accuracies of a wide variety of flow measurement devices currently in service. During the study, a wide variety of flow measurement devices, including flumes, weirs, and rated sections in open channel systems, were evaluated; magnetic and ultrasonic meters in closed-conduit systems were also tested. The specified design accuracies for each device are presented. Actual flow measurements were determined at 70 sites and were compared with the theoretical discharges of each device. Comparison of actual and theoretical flow indicates that only 33% of the measurement devices tested currently measure flow within manufacturer-designed specifications. Field data is presented, and possible reasons for the flow measurement errors and their corrections are discussed.