用动态血压监测探讨计算T/P比值的方法学研究

目的　用 30h动态血压 (ABPM)监测 ,探讨高血压病患者服长效降压药物后计算谷峰比值 (T/P)的方法学。方法　 10 8例轻中度高血压病患者 ,服用缓释吲哒帕胺 (N SR) 1 5mg 8周前、后测定 30hABPM。用个体与总体 2种方法计算T/P比值。剔除T、P为负数以及T/P >1者中的无效或短效患者后计算T/P比值并作比较。计算机随机抽样分别重复 2 0 0 0次 ,计算T/P比值的平均值和 95 %CI,估计测定T/P比值的最佳样本量。结果　 (1)高血压病患者服用N SR后 30h的血压显著平稳下降。 (2 )用个体方法计算 2 4h的T/P比值中位数 ,收缩压与舒张压分别为 0 4 1、0 36 ,离散度大 ;用总体方法计算的结果为 0 80 4、0 76 2 ,与 30hABPM结果大致符合。 (3)分析 10 8例资料 ,T/P比值为负数中有 6例 ,T/P >1中有 2例 ,其峰效应 <7/ 5mmHg(1mmHg =0 133pBa) ,定为无效病例。其余 10 0例峰效应 >7/ 5mmHg ,其中 2 6例为短效。 (4 )按T/P比值的 95 %CI为0 4 97～ 0 94 9,6 0例为本研究的最佳样本数。结论　计算T/P比值用总体方法优于个体。使用≥ 7/5mmHg作为峰效应的有效标准是可取的。N SR用ABPM计算T/P比值的最小样本量需约 6 0例。     

The trough: peak ratio and the normalization of blood pressure profiles

Experts from the Food and Drug Administration (FDA) of the USA have assumed that hypertensive patients are likely to achieve greatest benefit from therapy in which the antihypertensive effects do not vary excessively during the course of the day. They suggested that the ratio of the minimal (trough) effect to the maximal (peak) effect of the drug should be no lower than 0.5. The concept of the trough: peak ratio (TPR) raises many practical problems. Using actual data, the effect of a drug often shows erratic fluctuations with several local minima and maxima. Mean blood pressure levels for several hours have been used to estimate the trough and peak effects. Blood pressure averages over 4 h may e a good choice, because blood pressures measured 4 h apart are not correlated. The statistical distribution of the TPR is not Gaussian. Negative and very low or positive and very high individual ratios are frequently observed. Therefore, the individual TPR is of questionable clinical value, except when the ratio is applied for responders only. The TPR can be calculated for a sample. In that case, the bootstrap method can be used to estimate the error of the TPR. Most important is the question of why the TPR should be higher than 0.5. We introduced the concept of 'normalization of the blood pressure profile', namely 'reducing the blood pressure profiles in hypertensives to match those profiles in normotensives'. This concept leads very naturally to the TPR and justifies the lower limit of 0.5 for the TPR.     

Lisinopril and enalapril in hypertension: a comparative study using ambulatory monitoring

Detecting differences in the effect of two antihypertensive agents is bedevilled by the inherent variability of blood pressure itself. Using an ambulatory blood pressure monitoring technique, we compared, in a cross-over design study, the effects of four weeks' treatment with enalapril, 10 mg once daily, to lisinopril, 10 mg once daily, on the blood pressure of 19 patients with mild to moderate hypertension. A significant reduction in blood pressure was shown by both drugs. However, lisinopril produced a greater fall in mean 24 hour systolic pressure than did enalapril (difference; 5.94 (C.I. -0.77 to -11.1) mmHg, P = 0.027). The difference of 3.3 mmHg (C.I. +0.54 to -7.10) in diastolic pressure between the two agents, though in the same direction, was not significant. Plasma renin activity did not predict the responses to either agent. Studying the prevailing information for these two drugs one might expect there to be little difference between them when administered once daily in terms of antihypertensive effect. The explanation for the superiority of lisinopril may lie in the slightly longer pharmacokinetic half-life and possibly in differences in tissue distribution or persistence. The side effects of both drugs were mild and of similar frequency to those recorded during placebo treatment, illustrating the generally well tolerated nature of this class of antihypertensive therapy. The use of ambulatory blood pressure monitoring provides a method that can detect small, but possibly important differences between drugs. In the clinical setting it allows a more thorough assessment of a particular patient's response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Self monitoring versus ambulatory blood pressure monitoring]

Blood pressure is a variable parameter for which the isolated determination cannot be considered as a characteristic of the subject. Therefore, the clinical measurement of blood pressure constitutes the method of reference but presents limits and causes of errors which pose a problem for its validity in evaluating the average blood pressure level in certain patients. In order to overcome the limits of occasional measurement, different methods of blood pressure measurement have been proposed. Among these methods, self monitoring of blood pressure by the patient and 24 hour ambulatory blood pressure monitoring (ABPM) are the most used. Each of these methods presents advantages and disadvantages, indications and limits of use. The information obtained by each of them is of a different nature: these methods are not substitutes but are complementary. Self monitoring and ABPM seem to evaluate the pressure load better than clinical monitoring and are better correlated to the organic effects of hypertension and thus the cardiovascular morbidity and mortality, ABPM in particular. However, it remains to be clarified whether the use of these methods in the evaluation of cardiovascular risk and the therapeutic management of the hypertensive can improve the long term cardiovascular prognosis.     

动态血压监测指导依那普利抗原发性高血压治疗临床观察

目的根据原发性高血压患者24h血压变化规律决定依那普利给药时间,观察降压疗效。方法对于临床确诊的1~2级原发性高血压患者,服用安慰剂2周后,根据24h动态血压监测夜间血压与白昼相比是否下降≥10%或10mmHg,分为勺型高血压及非勺型高血压,对勺型高血压者6:00及下午血压最高值前3h分别给予依那普利5mg,非勺型者6:00及18:00分别给予依那普利5mg,2周后,若患者坐位舒张压≥90mmHg,依那普利加量至10mg,每日2次。8周后复查24h动态血压。结果完成研究的80例原发性高血压患者中勺型58例,占72.5%,非勺型22例,占27.5%。依那普利对勺型组和非勺型组患者有效率分别为(52/58)89.7%,(19/22)86.4%,勺型组24h平均血压、白昼(6:00~22:00)血压、夜间(22:00~6:00)血压分别下降9.9/6.6mmHg,9.0/6.8mmHg,2.8/2.6mmHg,非勺型组分别下降13.9/7.6mmHg,11.9/6.6mmHg,13.8/10.4mmHg。两组白昼及夜间血压负荷均显著下降。勺型组收缩压与舒张压谷峰比值分别为66.6%,63.5%,非勺型组70.6%,66.5%。结论在时间治疗学理论指导下,依那普利每日给药两次能24h平稳降压,是一种价廉物美的降压药物,值得推广应用。     

Spectral analysis of 24 h blood pressure monitoring in the assessment of trough: peak ratio. A randomized, placebo-controlled, cross-over comparison of ramipril and enalapril

BACKGROUND: The ratio between the magnitude of blood pressure reduction during the steady-state dosage interval (trough) and the maximum blood pressure reduction (peak) is an integrated in-vivo index both of the pharmacokinetic properties and of pharmacodynamic activity of an antihypertensive drug. Angiotensin converting enzyme inhibitors are often characterized by a low (often lower than 50%) trough: peak ratio but no direct drug comparisons are available. OBJECTIVE: To compare the absolute blood pressure reduction and the trough: peak ratio of daily doses of two angiotensin converting enzyme inhibitors, 5 mg ramipril and 10 mg enalapril. METHOD: After a 1-month wash-out and a 2-week placebo run-in, 25 mild hypertensives aged 47 +/- 4 years (17 men and eight women) were randomly assigned to treatments separated by a 2-week interval. Ambulatory blood pressure monitoring was performed and trough: peak ratio was calculated by the fast Fourier transform analysis of placebo-effect-subtracted data. RESULTS: After 1 month of ramipril treatment, 24 h blood pressure decreased from 139 +/- 10 to 129 +/- 11 mmHg for systolic (P < 0.05) and from 89 +/- 8 to 81 +/- 5 mmHg for diastolic blood pressure (P < 0.01). Also enalapril treatment caused a significant 24 h reduction in blood pressure both for systolic (to 132 +/- 7 mmHg, P < 0.05) and for diastolic blood pressure (to 84 +/- 5 mmHg, P < 0.05). Placebo caused a 24 h reduction in blood pressure (to 136 +/- 8 mmHg for systolic and 87 +/- 5 mmHg for diastolic blood pressure, NS, versus wash-out period). The two drugs were equally effective in reducing ambulatory blood pressure, but ramipril produced a trough: peak ratio significantly higher than that with enalapril both for systolic (48 +/- 11%, range 34-74%, versus 38 +/- 11%, range 21-67%, P < 0.005)and for diastolic blood pressure (47 +/- 11%, range 30-79 %, versus 37 +/- 12%, range 21-68%, P < 0.05). CONCLUSION: The low trough : peak ratios could have been due to the daily pattern of blood pressure of mild hypertensives, many of whom are normotensives at night-time, so that the main antihypertensive effect is exerted during daytime rather than during the night or early morning.     

阿罗洛尔、咪唑普利和依那普利治疗原发性高血压疗效观察(附24小时动态血压结果分析)

目的 评价阿罗洛尔、咪唑普利、依那普利对24 h血压的降压效果。方法 轻、中度原发性高血压患者60例,采用随机区组法分为三组,每组20例,使用24 h动态血压监测方法对阿罗洛尔(20-30mg/d)、咪唑普利(5-10mg/d)及依那普利(5-1Omg/d)降压疗效进行为期六周的对比现察。结果 三种药物对诊室血压均有明显降压效果(P<0.001),组间无明显差别(P>0.05)。动态血压结果显示三种药物均有明显降低动态血压的效果(P<0.05),阿罗洛尔组降低24 h平均血压及白天平均血压幅度比其它两组大(P<0.05)。三种药物的谷/峰比值均大于50%。治疗前后的血压曲线,阿罗洛尔组呈完全分离状态,咪唑普利组、依那普利组均有交叉重叠现象,依那普利组重叠点较多。结论 阿罗洛尔对控制白天血压较为理想,长效制剂咪唑普利能平稳地控制24 h血压。     

Multiple clinic and home blood pressure measurements versus ambulatory blood pressure monitoring.

To compare multiple clinic and home blood pressure (BP) measurements and ambulatory BP monitoring in the clinical evaluation of hypertension, we studied 239 middle-aged pharmacologically untreated hypertensive men and women who were referred to the study from the primary healthcare provider. Ambulatory BP monitoring was successfully completed for 233 patients. Clinic BP was measured by a trained nurse with a mercury sphygmomanometer and averaged over 4 duplicate measures. Self-recorded home BP was measured with a semiautomatic oscillometric device twice every morning and twice every evening on 7 consecutive days. Ambulatory BP was recorded with an auscultatory device. Two-dimensionally controlled M-mode echocardiography was successfully performed on 232 patients. Twenty-four-hour urinary albumin was determined by nephelometry. Clinic BP was 144.5+/-12.6/94.5+/-7.4 mm Hg, home BP (the mean of 14 self-recorded measures) was 138.9+/-13.1/92.9+/-8.6 mm Hg, home morning BP (the mean of the first 4 duplicate morning measures) was 137.1+/-13.7/92.4+/-9.2 mm Hg, daytime ambulatory BP was 148.3+/-13. 9/91.9+/-7.8 mm Hg, nighttime ambulatory BP was 125.5+/-16.4/75. 6+/-8.9 mm Hg, and 24-hour ambulatory BP was 141.7+/-14.0/87.2+/-7.6 mm Hg. Pearson correlation coefficients of clinic, home, home morning, and daytime ambulatory BPs to albuminuria and to the characteristics of the left ventricle were nearly equal. In multivariate regression analyses, 36% (P<0.0001) of the cross-sectional variation in left ventricular mass index was attributed to gender and home morning systolic BP in models that originally included age, gender, and clinic, self-measured home morning, and ambulatory daytime, nighttime, and 24-hour systolic and diastolic BPs. We concluded that carefully controlled nonphysician-measured clinic and self-measured home BPs, when averaged over 4 duplicate measurements, are as reliable as ambulatory BP monitoring in the clinical evaluation of untreated hypertension.     

The trough:peak ratio and the smoothness index in the evaluation of control of 24 h blood pressure by treatment in hypertension

The duration and homogeneity of the antihypertensive effect of a drug are commonly quantified by computation of the trough:peak ratio (T/P) from 24 h ambulatory blood pressure recordings [i.e. the ratio of the reduction in blood pressure at the end of the interval between doses (trough) and the reduction in blood pressure at the time of the maximal effect of a drug (peak)]. Although it is widely employed, this index has a lot of limitations: it makes use of only a small portion of a 24 h blood pressure recording; individual T/P values do not have a normal distribution, unless responders at peak are selected; it bears no relation to 24 h blood pressure variability; peak changes in blood pressure are affected by a placebo effect and thus T/P needs correction for effects of placebo; peak and trough changes in blood pressure are reproducible over time but T/P is not; and, finally, it was shown in the SAMPLE study that T/P is not correlated to changes in left ventricular mass induced by treatment, and thus has a limited clinical value.     

Comparison of labetalol versus enalapril as monotherapy in elderly patients with hypertension: results of 24-hour ambulatory blood pressure monitoring

PURPOSE: This study compared the safety and efficacy of labetalol and enalapril as antihypertensive therapy for elderly patients. PATIENTS AND METHODS: A randomized, open-label, parallel controlled trial was conducted. After completing a 4-week placebo phase, 79 elderly (65 years or older) patients with an average standing diastolic blood pressure (BP) 95 mm Hg or above and 114 mm Hg or less were randomized to receive a 12-week course of either labetalol or enalapril in an open-label design. The patients' BP and heart rate were evaluated biweekly by trained observers unaware of the treatment status, and drug dosage was titrated (up to 400 mg twice a day of labetalol or 40 mg daily of enalapril) to achieve a standing diastolic BP of less than 90 mm Hg and a decrease of 10 mm Hg from baseline. Patients underwent 24-hour ambulatory BP monitoring (ABPM) at the end of the placebo phase and again after 8 weeks of active treatment. RESULTS: The treatment groups were comparable in their reduction of supine diastolic BP, with no significant differences between the two treatments. Labetalol demonstrated a significantly greater reduction (p less than 0.05) in standing diastolic BP at the end of the titration period compared to enalapril, but this difference was not significant by the end of the study period. Based on 24-hour ABPM readings, labetalol reduced mean 24-hour diastolic BP (p less than 0.05) and mean heart rate (p less than 0.05) more than enalapril. The labetalol-treated patients were significantly less often above their diastolic BP goal throughout the 24-hour ABPM period (p less than 0.01). The two treatments were equally well tolerated. CONCLUSIONS: The results indicate that labetalol and enalapril are equally effective in lowering supine diastolic BP in the elderly, but labetalol is more effective in lowering ambulatory BP and heart rate throughout the day.     

The effects of missing a dose of enalapril versus amlodipine on ambulatory blood pressure

OBJECTIVE: To compare the antihypertensive actions of amlodipine and enalapril in a double-blind, randomized, parallel-group study during treatment and when missing a dose. METHOD: After a single-blind run-in 4-week placebo period, patients were randomly allocated to receive enalapril (15 patients) or amlodipine (15 patients). Patients received active treatment for 4 weeks (20 mg enalapril or 5 mg amlodipine). For those with sitting diastolic office pressure not below 90 mmHg the dosage was doubled and continued up to week 12. Ambulatory blood pressure monitoring was performed at the end of the placebo run-in period for 24 h and at the end of week 12 for 48 h; in this case, patients took the active tablet at 0700 h of the first day and a placebo tablet on the next day to stimulate a missing dose in a single-blind manner. RESULTS: Of the patients, 60% had office blood pressure controlled by enalapril therapy and 80% had amlodipine therapy. The average dosage was 30.7 mg a day for enalapril and 7.3 mg a day for amlodipine. Reductions in blood pressures were higher for the amlodipine group. Ambulatory blood pressure measurement shows a reduction in systolic and in diastolic blood pressure during the 24 h when patients from both groups were receiving their medication with respect to placebo values. During the second day of ambulatory blood pressure recording, when the patient had taken a placebo tablet instead of an active one, the antihypertensive effect was progressively lost with enalapril, but not with amlodipine. CONCLUSION: Enalapril and amlodipine reduced ambulatory systolic and diastolic blood pressure during treatment; however, when patients missed an enalapril dose, control of blood pressure was progressively lost, whereas patients receiving amlodipine maintained their blood pressure under control up to 48 h after the last dose.     

Clinical value of ambulatory blood pressure monitoring.

Ambulatory blood pressure monitoring (ABPM) has now become an established clinical tool. It is appropriate to take stock and assess the situation of this technique. UPDATE ON EQUIPMENT: Important improvements in equipment have occurred, with reductions in weight, in awkwardness and in noisiness of the machines, better acceptability and tolerance by the patients, and better reliability. Validation programmes have been proposed and should be referred to. Limitations of the technique persist with intermittent recording in current practice. The reproducibility is limited in the short-term while recording over 24 h is acceptable. DIAGNOSIS AND PROGNOSIS: White-coat effect (WCE) is manifested as a transient elevation in blood pressure during the medical visit The frequency of this phenomenon, the size of the effect, age, sex and level of blood pressure (BP) or the situation of occurrence (general practitioner, specialist or nurse) have been interpreted differently. It does not seem that WCE predicts cardiovascular morbidity or mortality. White-coat hypertension (WCH) is diagnosed on the evidence of abnormal clinical measures of BP and normal ABPM. The latest upper limits of normality by ABPM recommended by the JNCVI are < 135/85 mmHg while patients are awake and < 120/75 mmHg while patients are asleep. If we accept these upper limits of normality in ABPM, WCH does not appear to be a real problem as regards risk factors or end-organ effects. In terms of prognosis, data are limited. Cardiovascular morbidity seems low in WCH but identical to that of hypertensive subjects in these studies. However, further studies are needed to confirm these results. WCH does not appear to benefit from anti-hypertensive treatment. It is obvious that the lower the BP regarded as the limit of normality, the less likely the occurrence of secondary effects of metabolism, or end-organ effects or complications in those classified as hypertensive. 24 HOUR CYCLE: One of the most specific characteristics of ABPM is the possibility of being able to discover modification or alteration of the 24 h cycle of BP. Non-dippers are classically defined as those who show a reduction in BP of less than 10/5 mmHg or 10% between the day (06.00-22.00 h) and the night, or an elevation in BP. In contrast, extreme dippers are those in whom the BP reduction is greater than 20%. CARDIOVASCULAR SYSTEM: The data remain inconclusive with regard to the existence of a consistent relationship between the lack of a nocturnal dip in blood pressure and target organ damage. As regards prognosis, it seems that an inversion of the day-night cycle is of pejorative significance. CEREBROVASCULAR SYSTEM: Almost all studies have shown that non-dippers had a significantly higher frequency of stroke than dippers. In contrast, too great a fall in nocturnal BP may be responsible for more marked cerebral ischaemia. RENAL SYSTEM: Non-dippers have a significantly elevated median urinary excretion of albumin. There is a significant correlation between the systolic BP and nocturnal diastolic BP, and urinary excretion of albumin. Various studies have confirmed the increased frequency of change in the 24 h cycle in hypertensive subjects at the stage of renal failure. DIABETES: BP abnormalities should be considered as markers of an elevated risk in diabetic subjects but cannot be considered at present as predictive of the appearance of micro-albuminuria or other abnormalities. ABPM is thus of interest in type I or type II diabetes both in the initial assessment and in the follow-up and adaptation of treatment. PHARMACO-THERAPEUTIC USES: The introduction of ABPM has truly changed the means and possibilities of approach to the study of the effects of anti-hypertensive medications, with new possibilities of analysis such as trough-peak ratio smoothness index, etc.     

Reproducibility of ambulatory blood pressure monitoring

OBJECTIVE: To investigate whether blood pressure monitoring is reproducible. DESIGN: Reproducibility of ambulatory blood pressure monitoring data was assessed by means of traditional and relatively new statistical methods, namely correlation coefficients, regression analysis and agreement analysis. METHODS: Ninety-one normotensive and hypertensive, uncomplicated outpatients underwent monitoring twice (mean interval 241 days). Data were analysed for reproducibility, correlation, difference and adaptation. Analyses were performed to verify the reproducibilities of the diagnosis of hypertension and of the treatment assessment. RESULTS: Ambulatory blood pressure monitoring is highly reproducible in terms of traditional statistics, but not in terms of the agreement analysis (error as high as 18 mmHg), although it performs better than does office sphygmomanometry (error as high as 38 mmHg). Reproducibility is acceptable in normotensive subjects and in patients who respond to treatment, but untreated hypertensives and those who do not respond to treatment show a worse ratio. CONCLUSION: The reproducibility of ambulatory blood pressure monitoring requires improvement. We do not know how many repeated measurements we need before diagnosing hypertension. Spontaneous variability of blood pressure interferes with blood pressure reproducibility. Diagnosis and treatment assessment in hypertension must take into account poor reproducibility.     

Reproducibility of ambulatory blood pressure monitoring

Short-term blood pressure variability has been studied extensively with monitoring techniques. To assess whether or not and to what extent average 24-hour blood pressure varies when repeatedly recorded, 12 mild to moderate hypertensive subjects underwent 3 non-invasive blood pressure monitorings at monthly intervals. When the average 24-hour blood pressure of the whole group was evaluated no substantial differences were found between the 3 recordings, even though slightly lower blood pressure values were recorded at the first monitoring. However, when the within-period comparison was studied in the single patients, remarkable discrepancies of up to 20.9/15.8 mmHg were detected. Systolic and diastolic blood pressure variations greater than or equal to 5 mmHg were recorded in 58% of the subjects. These differences were unrelated to the number of faulty readings. Casual blood pressure varied even to a greater extent between the first and the subsequent visits; no correlation was found between casual and 24-hour blood pressure variations. The results of the present study indicate that ambulatory blood pressure may vary even to a great extent when repeatedly recorded. This finding entails important clinical implications, as the evaluation of the hypertensive patient is usually made with a single blood pressure monitoring.     

Diagnosis of white coat hypertension by ambulatory blood pressure monitoring.

White coat hypertension (WCH) is common in referred hypertensive patients. Ambulatory blood pressure monitoring (ABPM) is not free from the white coat syndrome. We examined the use of the elevation of the first and last measurements of ABPM for diagnosis of WCH in a hypertensive population that had been referred to a hospital-based hypertension unit. Data were obtained on 1350 patients for clinic and ABPM parameters. WCH, as diagnosed by conventional clinic blood pressure (BP) measurement, was compared with a variety of alternative methods determined from ABPM. In all cases, mean daytime pressure was <135 mm Hg/85 mm Hg with an elevation of clinic BP >/=140 mm Hg systolic or 90 mm Hg diastolic. The definitions tested for this elevation were first hour mean pressure, first reading, maximum reading in first hour, last hour mean pressure, last reading, maximum reading in the last hour and maximum reading in first or last hour. Elevation of the maximum pressure in the first hour or last hour above 140 mm Hg systolic or 90 mm Hg diastolic showed a high level of agreement (kappa=0.91) with classical WCH for diagnosis of the white coat syndrome. Termed ambulatory white coat hypertension, patients with this finding were older than classic white coat patients and had higher daytime (127+/-6/78+/-5 mm Hg versus 121+/-5.5/74+/-6 mm Hg, P<0.005 for systolic and diastolic) and nighttime (114+/-11/67+/-8 mm Hg versus 106+/-9/61+/-6 mm Hg, P<0.005 for systolic and diastolic) pressures. They also had a significantly greater Sokolow-Lyon index (leads V(1)+V(5), 21+/-7 mV versus 18+/-6 mV). Elevation of BP above 140 mm Hg systolic or 90 mm Hg diastolic in the first or last hour of monitoring diagnoses patients with a white coat response in whom there is a higher BP profile than in patients with classic white coat response alone. We suggest, therefore, that this is a better measure of the white coat phenomenon.     

Prediction of stroke by ambulatory blood pressure monitoring versus screening blood pressure measurements in a general population: the Ohasama study

OBJECTIVE: To investigate the association between 24 h, daytime and night-time ambulatory blood pressures and first symptomatic stroke, to compare their predictive powers for stroke with that of casual (screening) blood pressure, and to compare the predictive power for stroke between daytime and night-time blood pressures, in a general population in Ohasama, Japan. DESIGN: A prospective cohort study. SUBJECTS AND METHODS: We obtained ambulatory blood pressure on 1,464 subjects aged > or = 40 years without history of symptomatic stroke, then followed-up their stroke-free survival. There were 74 first symptomatic stroke during the follow-up period (mean = 6.4 years). The prognostic significance of blood pressure for stroke risk was examined by a Cox proportional hazards regression model adjusted for possible confounding factors. RESULTS: The non-parametric and parametric analysis indicated that 24-h, daytime and night-time ambulatory blood pressures were linearly related with stroke risk. The likelihood ratio analysis demonstrated that these ambulatory blood pressures were significantly better related to stroke risk than did screening blood pressure, and that daytime blood pressure better predicted stroke risk than did night-time blood pressure. CONCLUSIONS: The present study which prospectively investigated the relation between ambulatory blood pressure and first symptomatic stroke risk in a general population demonstrated that (i) ambulatory blood pressure values were linearly related to stroke risk; (ii) ambulatory blood pressures had the stronger predictive power for stroke risk than did screening blood pressure; and (iii) daytime blood pressure better related to stroke risk than did night-time blood pressure.     

Reliability of ambulatory blood pressure monitoring

OBJECTIVE: To focus on the reliability of ambulatory blood pressure monitoring and on its limitations in clinical practice, and to construct adequate strategies to improve ambulatory monitoring performance. METHODS: The literature was reviewed, and personal data were used. DISCUSSION: Since the beginning of non-invasive ambulatory blood pressure monitoring, it appeared that some subjects had a high proportion of outlying readings that were unlikely to be accurate. Although ambulatory blood pressure is more reproducible than clinic blood pressure, large day-to-day differences have also been reported in reproducibility studies for average 24 h blood pressure. It has been shown that, for day-to-day 24 h blood pressure differences greater than 4/3 mmHg, ambulatory blood pressure is poorly predictive of the degree of target organ damage. The variability of average 24 h blood pressure may arise from several causes, including true biological variability, a lack of standardization of activities and measurement errors. Artefactual readings can easily occur if patients are not properly instructed. Although editing procedures can eliminate outliers, it is often impossible to identify inaccurate readings included within the patient's trend. To optimize ambulatory blood pressure monitoring, health-care providers should be instructed adequately on how to perform this technique. Appropriate patient selection, a proper application of instrumentation and the checking of its performance, careful instructions to patients, the immediate evaluation of the patient's diary and 24 h tracing after completion of the recording should improve the results of ambulatory monitoring. CONCLUSIONS: A checklist of criteria that should be used for optimizing ambulatory monitoring in clinical practice should be proposed by the Consensus Conference on ambulatory blood pressure monitoring. To improve doctors' proficiency, strategies including educational protocols and training programmes should be implemented.     

Epidemiology of ambulatory blood pressure monitoring

An operational threshold for making clinical decisions on the basis of ambulatory blood pressure monitoring must be defined [1-3]. This requires that the relationship between the ambulatory blood pressure and the incidence of cardiovascular complications be clarified beyond present understanding [4-7]. In addition, the distribution of the ambulatory blood pressure must be characterized better under various conditions and for various populations and compared with the centrality and spread of the conventional blood pressure under similar circumstances.     

Benazepril versus felodipine as supplement to bendroflumethiazide: evaluation by office and ambulatory blood pressure

OBJECTIVE: To compare a combination of a thiazide diuretic and an angiotensin converting enzyme inhibitor with a thiazide diuretic and a calcium antagonist. DESIGN: A double-blind randomized trial with subjects in two parallel groups administered either 10-20 mg benazepril once daily or 5-10 mg extended-release felodipine once daily, both titrated according to diastolic office blood pressure. During run-in and all 12 weeks of the study members of both groups were administered 2.5 mg bendroflumethiazide once daily. We measured 24 h ambulatory blood pressure with thiazide alone and after 12 weeks of combination therapy. SETTING: General practices. PATIENTS: We studied 96 hypertensive patients (50 women and 46 men), aged 25-75 years, whose blood pressures were insufficiently regulated (i.e. office diastolic blood pressure >/= 95 mmHg) despite treatment with a thiazide diuretic for at least 3 months. RESULTS: The responses of office blood pressure after 12 weeks of treatment did not differ between the groups and neither did the proportions of responders. The ambulatory recordings revealed, after 12 weeks of treatment, a fall in daytime blood pressure of 16.3/10.3 mmHg in members of the benazepril group compared with a fall of 8.5/5.2 mmHg in members of the felodipine group (P < 0.001/<0.001). Analysis of variance showed that the systolic but not the diastolic office blood pressure in members of the benazepril group was significantly lower during the 12-week study period. When evaluating rising single quote, left (low)white-coat-positive' patients separately, there was a tendency for there to be a more pronounced reduction of their (normal) blood pressure with benazepril therapy. There was a significant reduction in weight of patients in the benazepril group (by 0.9 kg), but not of patients in the felodipine group. We observed no difference in side effects between the two treatment groups.CONCLUSION: Add-on therapies both with benazepril and with felodipine are effective and both drug regimens are well tolerated, but ambulatory blood pressure monitoring yielded differing results.