摘要:

BackgroundThe pressor response to examination in the clinic setting is called the 'white coat effect' (WCE). This response may be a confounder when investigators use clinic blood pressure as a measure of response to antihypertensive therapy.ObjectiveTo study the effect of the pressor response by evaluating the sex-specific effect of treatment with calcium antagonism on blood pressure measured in the clinic and by ambulatory blood pressure monitoring (ABPM).MethodsUntreated hypertensive subjects (n = 39) with seated clinic diastolic blood pressures (DBP) ≤ 100 and ≥ 130 mmHg were studied. Same-day clinic systolic blood pressure (SBP) and ambulatory SBP were obtained after 1 week of placebo, and after 1 month of treatment with either nifedipine or verapamil in a randomized, blinded, parallel trial.Results With placebo, women's average SBP was 18 ± 4 mmHg lower than clinic SBP. By contrast, men's average SBP with placebo was 4 ± 15 mmHg lower than clinic SBP. There was a significantly greater reduction in clinic SBP for women than there was for men after 1 month of treatment (by 33 ± 13 versus 18 ± 18mmHg,P<0.005). However, reduction in ambulatory SBP after 1 month was the same for both sexes (20 ± 11 versus 19 ± 12 mmHg).ConclusionsIn this study of moderate-to-severe hypertensives, the large WCE measured for women, which markedly diminished with treatment, accounts for the observed sex difference in response of clinic SBP to calcium antagonism. By contrast, with ABPM there was an equivalent response to treatment for both sexes. Use of ABPM could be a valuable means of eliminating the WCE as a confounder in clinical research.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundAmbulatory blood pressure monitoring (ABPM) has been shown to be more representative of blood pressure levels in adult patients than are casual measurements of blood pressure.ObjectiveTo evaluate, by means of ABPM, the behavior of blood pressure in children with chronic renal failure submitted to continuous ambulatory peritoneal dialysis and compare the results with casual blood pressure monitoring measurements.DesignEvaluation of blood pressures in chronically dialyzed pediatric patients by ABPM.MethodsTen pediatric patients, treated by continuous ambulatory peritoneal dialysis were evaluated by ABPM using the oscillometric SpaceLabs 90207 monitor, every 10min during the day and every 15 min during the night, for 24 h.ResultsSix of 10 patients were found normotensive by office measurement of blood pressure; four of 10 patients were found hypertensive by casual measurements of blood pressure. With ABPM we obtained a mean success rate of 92.5%, confirmed hypertension in all the patients classified hypertensive in terms of office readings and reclassified six of six patients from normotensive to hypertensive. The mean systolic and diastolic physiologic falls in blood pressure at night were respectively by 10 and 15%. At the time of the ABPM study end-organ damage was present in two patients judged to be normotensive in terms of office blood pressures.ConclusionCasual recordings of blood pressure are not representative of average blood pressure in dialyzed pediatric patients. ABPM seems to be a useful diagnostic aid for assessing treatment of hypertension in children with end-stage renal disease.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundAmbulatory blood pressure monitoring (ABPM) has been used increasingly in assessing dialysis patients. However, devices have not been validated formally for this population. Formal device validation is important in order to guarantee adequate performance for populations with special characteristics, such as patients undergoing hemodialysis.ObjectiveTo achieve formal validation of the SpaceLabs 90207 ambulatory blood pressure device (SLD) using a modified British Hypertension Society protocol.MethodsEighty-five hemodialysis patients were studied, generating 255 readings. Readings were obtained with patients supine (in a dialysis chair) over 5–10min during hemodialysis. Simultaneous, same-arm readings were obtained through the use of a T connector to a calibrated mercury manometer. The mean differences between readings obtained by observers and those obtained by the device were calculated. Limits of agreement between observers and SLD were determined and plotted according to the method of Bland and Altman. For grading of performance, we determined the number of readings for which the readings obtained by the device were within 5, 10, and 15mmHg of manometer readings. Final gradings were ascribed according to British Hypertension Society criteria.ResultsThe mean blood pressure (±SD) was 141/76± 31/15mmHg (observers) and 141/77 ± 27/15 mmHg (SLD), and the mean (±SD) difference between observers and device (observer-device) was −0.5± 7.5mmHg for systolic blood pressure (SBP) and −0.2± 5.2 mmHg for diastolic blood pressure (DBP). The device was less accurate in extreme ranges of SBP. In fact, there was a positive correlation between average [(observer+ device)/2] and difference (observer - device) for SBP (r= 0.54,P<0.0001), showing that underestimation in higher ranges, and overestimation in lower ranges of blood pressure occurred for SBP. For SBP, 53% of readings were within 5 mmHg of those obtained by the observers, 85% were within 10 mmHg, and 97% within 15 mmHg. For DBP, 78% were within 5 mmHg, 96% within 10 mmHg, and 98% within 15 mmHg. These observations conferred on the device grade C for SBP and grade B for DBP. The type of vascular access and the presence of non-functioning arteriovenous grafts and fistulas in the ipsilateral arm did not alter these results significantly.ConclusionsThese data validate the use of this device for hemodialysis patients. However, caution should be exercised in the evaluation of upper and lower ranges of SBP.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Blood pressure fluctuates during daytime hours in response to changes in activities and to daily life stressors. Lifestyle factors may influence changes in blood pressure through a modulation of the sympathetic nervous system's activity, which is often elevated in subjects with borderline hypertension. In the HARVEST smoking, consumption of coffee, intake of alcohol, physical activity habits, and use of oral contraceptives influenced daytime blood pressure to a greater extent than did office blood pressure and had an effect on sympathetic tone (determined by measuring levels of urinary catecholamines). Subjects with borderline hypertension have a greater than normal risk of cardiovascular morbidity and mortality, but few data on the relation between ambulatory blood pressure and hypertensive complications during the early stage of hypertension are available. In the HARVEST the impact of ambulatory blood pressure on the walls of the left ventricle and on left ventricular mass in women was remarkable, whereas it was weak for men. The assessment of left ventricular systolic function confirmed that ejective performance in many young borderline hypertensive subjects is greater than normal. However, in 9.2% of the HARVEST participants left ventricular contractility evaluated by midwall measurement was found to be depressed. Although the prevalence of microalbuminuria (rate of excretion of urinary albumin >30mg/24h) appeared to be low (6.1%), rate of excretion of albumin was highly statistically significantly correlated to 24 h blood pressure. Ambulatory blood pressure monitoring is useful for identifying those borderline hypertensive subjects for whom antihypertensive treatment should be started.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

An operational threshold for making clinical decision on the basis of ambulatory blood pressure monitoring must be defined. This requires that the relationship between the ambulatory pressure and the incidence of cardiovascular complications be clarified beyond present understanding. Preliminary cut-off points for ambulatory monitoring were derived by averaging the 95th percentiles of the ambulatory blood pressure measurements for the normotensive subjects enrolled in various large-scale studies. According to this approach, the upper limits of normotension, calculated by rounding downwards, would be 130/80 mmHg for the 24 h blood pressure and 135/85 and 120/70 mmHg for the daytime and night-time blood pressures. Abnormality, obtained by rounding upwards, would be blood pressure levels exceeding 135/85, 140/90 and 125/75 mmHg, respectively.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Measurements of ambulatory blood pressure as an adjunct to casual/clinic blood pressure measurements are currently widely used for the diagnosis and treatment of hypertension. There have been many recent reports on the clinical significance of ambulatory blood pressure. The relationship between ambulatory blood pressure level and target-organ damage uniformly demonstrated on a cross-sectional basis that average ambulatory blood pressure is correlated to target-organ damage. The main limitation of cross sectional- studies, however, is the difficulty of drawing inferences about causality from them. We have been monitoring the prognosis of the Ohasama population and reported that ambulatory blood pressure is superior to casual blood pressure for the prediction of mortality. We also observed that the daytime ambulatory blood pressure is a better predictor for cardiovascular mortality in the general population than is the night-time ambulatory blood pressure. It is widely recognized that casual/clinic blood pressure is less representative of the true blood pressure level than is average ambulatory blood pressure. One reason that clinic blood pressure is a poor predictor of prognosis is that clinic blood pressure includes several biases, including the white-coat effect. For determining white-coat hypertension, measurement of blood pressure in a non-medical setting such as ambulatory blood pressure monitoring is indispensable. We examined the prognostic significance for mortality of white-coat hypertension and reversed white-coat hypertension (clinic blood pressure <ambulatory blood pressure). The relative hazard (RH) for the overall mortality for patients with white-coat hypertension was significantly lower than that for true hypertension. Short-term variability of blood pressure has recently attracted attention as a cause of target-organ damage and cardiovascular complications. The findings in cross-sectional studies on the effect of short-term variability of blood pressure are controversial. We observed that short-term variability of blood pressure (variability of blood pressure every 30 min) was independently associated with cardiovascular morbidity. Circadian variation of blood pressure is characterized by a diurnal elevation and a nocturnal decline in blood pressure. In several pathophysiological conditions, however, this nocturnal decline is diminished (non-dipping) and sometimes inverts to nocturnal elevation (inverted dipping). We compared morbidities from strokes for dippers and non-dippers in Ohasama. The incidence of strokes increased with increasing duration of observation for dippers with antihypertensive medication but not in non-dippers with antihypertensive medication. On the other hand, the RH for mortality from cardiovascular diseases increased for non-dippers and inverted dippers. The results suggest that there is a cause-and-effect relationship for dippers and non-dippers.This review demonstrates the independent association between the prognosis of hypertension and each component of ambulatory blood pressure, indicating the prognostic significance of ambulatory blood pressure monitoring.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

There is a convincing volume of evidence to support the contention that optimal control of blood pressure should be based upon therapeutic strategies that consistently reduce blood pressure in a smooth and consistent fashion. Attention has, therefore, been focused on calculation of trough:peak ratios and, alternatively, the smoothing index as methodologies for defining the duration of action of an antihypertensive drug and for discriminating among alternative treatments.Acceptable accuracy and reproducibility for trough:peak ratio have been demonstrated in the controlled environment of a research unit. In contrast, trough: peak ratios from ambulatory blood pressure recordings exhibit wide inter-patient variability. With respect to clinical validity, unlike trough:peak ratio, the smoothing index has been shown to be correlated to the regression of left ventricular hypertrophy induced by treatment. Overall, neither index has been proven to offer definitive superiority and hence it is reasonable to suggest that the two are complementary.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Non-invasive ambulatory blood pressure monitoring (ABPM) is particularly useful for assessing the efficacy of antihypertensive drugs. It provides a large number of blood pressure readings during daytime as well as night-time, which results in a more precise assessment of prevailing blood pressure than can be obtained from sporadic measurements taken by a doctor. Because of this greater precision ABPM reduces the number of patents required in clinical trials to demonstrate differences. It also allows one to define precisely the profile of the blood-pressure-lowering effect of a given drug. Placebo has little effect on ABPM. Thus, a placebo phase is not absolutely necessary. ABPM makes it possible to evaluate the efficacy of an antihypertensive medication by analysing data for patients with a placebo effect separately from data for true responders to the medication. In everyday practice ABPM helps one to detect among patients with hypertension refractory to treatment those who exhibit controlled blood pressures outside the medical environment, thus permitting one to avoid an unnecessary step-up of treatment. In addition ABPM can also help one to identify symptoms occurring during antihypertensive treatment that are related to excessive drug-induced changes in blood pressure.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

During the last few years there has been a renewal of interest in blood-pressure-induced kidney damage due to a progressive increase in the incidence and prevalence of hypertension and vascular diseases as a cause of end-stage renal disease (ESRD). The need to prevent ESRD demands a continuation of effort to make the early identification of hypertensives who are at risk possible and to provide them with effective antihypertensive therapy-Since-ambulatory blood pressure monitoring has been used successfully to assess blood pressure and identify risk markers for cardiovascular diseases, a logical approach would be to use it also to identify the risk markers for ESRD. Higher than normal percentages of non-dippers have been found among subjects with renal failure, during dialysis (haemofiltration, peritoneal dialysis and continuous ambulatory peritoneal dialysis), among cases of renovascular hypertension or cystic kidney disease and among cases of renal transplantation. Although this non-dipping pattern might be related to the presence of severe hypertension in some patients, such as those who have renovascular hypertension, in other cases the abnormal circadian variability is present with milder forms of hypertension or even in the absence of hypertension. Monitoring ambulatory blood pressure could offer advantages for protection of renal function during antihypertensive treatment of subjects with mild renal insufficiency. Furthermore, ambulatory blood pressure monitoring seems to have been prognostic for the development of proteinuria in a group of refractory hypertensives. Whether higher than normal nocturnal blood pressures and the non-dipping pattern are causes or consequences of renal disease should be addressed in prospective studies. The above notwithstanding, assessment of nocturnal blood pressure seems to be an important aid in the management of patients with hypertension-related renal disease and of patients who are susceptible to developing it.

ISSN:1359-5237    

出版商:OVID    

年代:1999

数据来源: OVID