Showing papers in "Blood Pressure Monitoring in 1998"

Validation of the A&D TM-2430 device for ambulatory blood pressure monitoring and evaluation of performance according to subjects' characteristics.

Abstract: OBJECTIVE: To determine the accuracy of the TM-2430 blood pressure monitor, recently developed by the A&D company. DESIGN: Evaluation was performed using the 1990 and 1993 British Hypertension Society (BHS) protocols. Monitor's performance was assessed in relation to subjects' age, sex, level of blood pressure, and degree of adiposity. METHODS: Three TM-2430 recorders were assessed according to the various phases of the protocols. Simultaneous, same-arm readings were taken for the main validation test. Outcome was classified according to the criteria from the 1990 BHS recommendations, which are based on the cumulative percentage of readings differing from the mercury sphygmomanometer standard by 5, 10, and 15 mmHg or less, and using the criteria of the Association for the Advancement of Medical Instrumentation protocol, which considers a device accurate when the mean device-observer difference is within 5 mmHg and the related SD < 8 mmHg. RESULTS: During in-use assessment 2.3% of total measurements (N = 3744) were rejected automatically by the machine and another 5.5% werre discarded after visual inspection. The main validation test was performed with 98 subjects for a total of 595 blood pressure measurements. On the basis of the percentages of measurements differing from the mercury sphygmomanometer standard by

A comparison of the efficacies and duration of action of the angiotensin II receptor blockers telmisartan and amlodipine.

Abstract: OBJECTIVES: To compare the antihypertensive effects and duration of action of the angiotensin II receptor antagonist, telmisartan, amlodipine, and placebo in patients with mild-to-moderate hypertension using both conventional clinic blood pressures and ambulatory blood pressure monitoring (ABPM). METHODS: After a 4-week single-blind, placebo run-in period, qualifying patients were randomly allocated in double-blind manner to be administered 40 mg telmisartan (n = 73; increased to 80 and 120 mg as necessary for patients whose diastolic blood pressure (DBP) remained > 90 mmHg); 5 mg amlodipine (n = 78; titrated to 5 mg and titrated to 10 mg for patients whose DBP remained > 90 mmHg); or placebo (n = 81). ABPM was performed at the end of the baseline period and again at the end of 12 weeks of double-blind treatment. RESULTS: Telmisartan and amlodipine treatments significantly decreased trough supine systolic blood pressure and DBP (P < 0.001, measured conventionally) to a similar extent (by 13.1/7.1 and 14.0/7.1 mmHg, respectively, at the end of 12 weeks' treatment) compared with placebo. Both drugs also significantly reduced 24 h mean systolic blood pressures and DBP compared with placebo (P < 0.0001), measured using ABPM, maintaining control of blood pressure throughout the dosing period. Reductions in DBP with telmisartan were greater (P < 0.05) than those with amlodipine during the night-time interval and the last 4 h of the dosing period. Twenty-four-hour mean ABPM DBP < 85 mmHg were observed in 71% of telmisartan patients and in 55% of patients administered amlodipine. In addition, heart rates in patients treated with telmisartan were lower than heart rates in those treated with amlodipine during the final 4 h of the dosing period (P = 0.0003) and during the morning interval (P = 0.005). Generally, both telmisartan and amlodipine were well tolerated, however, drug-related edema occurred significantly more commonly (P < 0.05) among the patients administered amlodipine than it did among patients administered either telmisartan or placebo. CONCLUSIONS: Clinic blood pressure measurements detected no difference between the antihypertensive effects and durations of action of telmisartan and amlodipine, both agents producing statistically significant reductions compared with placebo. ABPM measurements, however, revealed differences between the efficacies at specific time points within the dosing periods. These findings highlight the potential importance of the use of ABPM for evaluating and comparing efficacies of antihypertensive agents.

Evaluation of the efficacy of the Omron HEM-737 IntelliSense device for use on adults according to the recommendations of the Association for the Advancement of Medical Instrumentation.

Abstract: BACKGROUND: Automatic noninvasive blood pressure measuring devices should be independently validated prior to marketing by using standard guidelines such as those published by the Association for the Advancement of Medical Instrumentation and British Hypertension Society. OBJECTIVE: To assess a new noninvasive oscillometric automatic home blood pressure (Omron HEM-737 IntelliSense; Omron Healthcare Inc., Vernon Hills, Illinois, USA). METHODS: We compared the device's measurements with mercury column measurements for 90 subjects (270 measurements). In addition to calculation of the limits of agreement for the device versus observers, we also dtermined the impacts of age, level of blood pressure, body mass, and arm size on the levels of agreement. RESULTS: Observers showed that close agreement was attained, with mean differences of 0.42 +/- 3.65 mmHg for systolic blood pressure and 0.37 +/- 3.59 mmHg for diastolic blood pressure. The proportions of values agreeing to within 5, 10, and 15 mmHg were 88, 99, and 100% for systolic and 86, 100, and 100% for diastolic blood pressure for the two obsevers. The observer-device disagreement was 0.76 +/- 6.55 mmHg for systolic and 1.0 +/- 5.5 mmHg for diastolic blood pressure. The proportions of values agreeing to within 5, 10, and 15 mmHg were 71, 93, and 97% for systolic and 77, 96, and 98% for diastolic blood pressure for the observers and device. CONCLUSIONS: The Omron HEM-737 IntelliSense satisfied the Association for the Advancement of Medical Instrumentation's criteria for a general adult population across large ranges of age, blood pressure, body mass, and arm circumference. These findings support the use of this recorder for out-of-office self-monitoring of blood pressure.

Accuracy of the SpaceLabs Medical 90217 ambulatory blood pressure monitor.

Abstract: OBJECTIVE: To test the SpaceLabs Medical 90217 ambulatory blood pressure monitor for compliance with The Association for the Advancement of Medical Instrumentation's standard and a modification of the British Hypertension Society (BHS) protocol. METHODS: The study concerned 85 subjects aged 17-88 years with various arm circumferences and ranges of blood pressure. Resting casual blood pressure was 135 +/- 24/76 +/- 14 mmHg (mean +/- SD). For each subject nine readings of the 90217 device were compared with auscultatory reference readings of two independent observers who used a dual stethoscope. The measurements were performed with subjects standing, sitting and supine. The manual reference readings were alternated with the 90217 monitor's readings. RESULTS: Average differences between manual (average of recordings by two clinicians) and automated readings were -5 +/- 4.3/0.6 +/- 4.6 mmHg (seated), 0.0 +/- 6.0/-1.8 +/- 4.7 mmHg (standing) and -1.6 +/- 5.1/-0.7 +/- 5.1 mmHg (supine).CONCLUSIONS: The device meets the Association for the Advancement of Medical Instrumentation's standard. Comparing the results with the modified BHS protocol, it was found that the device earned the highest BHS grade of 'A' both for systolic and for diastolic blood pressures.

Evaluation of Meditech ABPM-04 ambulatory blood pressure measuring device according to the British Hypertension Society protocol.

Abstract: BACKGROUND The use of ambulatory blood pressure measuring devices has become widespread in the diagnosis of hypertension. The accuracy of the device is fundamental for the diagnosis and treatment of the disease. OBJECTIVE Internationally accepted validation of the newest ambulatory blood pressure measuring device, the ABPM-04 prototype, manufactured by Meditech Ltd. PATIENTS AND METHODS Validation was carried out by assessing 94 outpatients, according to the British Hypertension Society protocol. RESULTS The test device achieved grade B on the scale defined in the British Hypertension Society protocol, for both systolic and diastolic blood pressure. The mean and standard deviation of the difference between measurements of the test device and the mercury standard for both systolic and diastolic blood pressure were within the recommendations of the Association for the Advancement of Medical Instrumentation. CONCLUSION The present study demonstrates that the Meditech ABPM-04 ambulatory blood pressure measuring device complies with the above mentioned requirements, and thus can be recommended for clinical use.

Superiority of home blood pressure measurements over office measurements for testing antihypertensive drugs.

Abstract: OBJECTIVE: To compare the effects on office blood pressure and home blood pressure of placebo and active drug administration. DESIGN: After a 2-week wash-out period, patients with mild-to-moderate hypertension entered a 2-week single-blind placebo period and then a 4-week double-blind period. Patients were randomly assigned to be administered either 2 mg trandolapril once daily or its placebo in a 2:1 proportion. Office blood pressure was measured by a physician at the end of each period, using a mercury sphygmomanometer (mean of three consecutive measurements). Home blood pressure was measured during the last week of each period according to standard procedure carefully taught to each patient by the physician. Compliance was checked by using electronic pill boxes. RESULTS: Data for 34 of the 44 patients who entered the study were eligible for analysis. Baseline systolic blood pressure/diastolic blood pressure were significantly (P = 0.0001/P = 0.0001) higher for office blood pressure (161/101 mmHg) than they were for home blood pressure (145/93 mmHg). There was no statistically significant difference between the placebo and active-treatment groups at baseline. During the single-blind period, blood pressures measured at the office and at home did not change significantly. Office blood pressure decreased by 2.7 +/- 10 mmHg for systolic blood pressure and by 0.5 +/- 4 mmHg for diastolic blood pressure whereas home blood pressure increased by 0.8 +/- 6 mmHg for systolic blood pressure and by 0.7 +/- 4 mmHg for diastolic blood pressure. During the double-blind period, office blood pressure fell significantly with trandolapril treatment (systolic by 10.2 +/- 12 mmHg, diastolic by 8.3 +/- 6 mmHg; P = 0.0005/0.0001, versus single-blind placebo period) but this decrease was not significantly different (P = 0.45/0.92) from the fall in members of the placebo group (systolic by 6.9 +/- 9 mmHg, diastolic by 8.0 +/-6 mmHg; P = 0.04/0.002, versus single-blind placebo period). Thus, no antihypertensive effect of trandolapril was demonstrated. The fall lin home blood pressure with trandolapril treatment was significant (systolic by 10.7 +/- 8 mmHg, diastolic by 5.8 +/- 5 mmHg; both P = 0.0001, versus single-blind placebo period) and was significantly greater (P = 0.0004/0.004) than the minimal change observed with placebo (systolic fell by 0.2 +/- 5mmHg, diastolic fell by 0.6 +/- 4 mmHg; P = 0.90/0.62, respectively, versus single-blind placebo period). The evening decrease in home blood pressure was similar to the morning decrease in home blood pressure in members of the trandolapril-treated group. The resulting morning:evening decrease in blood pressure ratio was 0.83 for diastolic blood pressure and 0.95 for systolic blood pressure. For the subgroup of responders, mean of individual ratios was 0.77 +/- 0.43 for diastolic blood pressure and 0.70 +/- 0.39 for systolic blood pressure. CONCLUSION: The placebo effect observed with office blood pressure measurements does not occur with home blood pressure measurements. Expected treatment effect can alter a physician's blood pressure readings. The precision of measurements is greater with home blood pressure (there is a lower SD). Use of home blood pressure measurements increases the power of comparative trials, allowing one either to study fewer subjects or to detect a smaller difference in blood pressure.

Alteration of diurnal rhythms of blood pressure and heart rate to workers exposed to radiofrequency electromagnetic fields.

Abstract: BACKGROUND In previous studies we found measurable effects on variability of heart rate and on blood-pressure parameters of workers exposed to radiofrequency electromagnetic fields (EMF)compared with a control population, but none of the effects could be assigned clinical significance. In general, the obtained results strongly suggested that dysregulation of the autonomic control of the circulatory system was occurring. Therefore, it seemed logical that analysis of diurnal rhythms of blood pressure and heart rate, on the basis of data from 24 h recordings, might further support the above hypothesis. OBJECTIVE The aim of this study was to determine the course of diurnal rhythms of blood pressure and heart rate in a group of workers exposed to various intensities of radiofrequency electromagnetic fields. METHODS In the study we used 61 healthy workers (aged 30-50 years) who had been exposed to radiofrequency EMF of 0.738-1.503 Mhz and 42 healthy workers at radio-line stations (aged 28-49 years), who had not been exposed to EMF occupationally. The work patterns of these two groups were identical (12 h day working shift, 24 h interval, 12 h night shift and then 48 h rest). During the second day of the rest period 24 h ambulatory blood pressure (ABP) was recorded. For analysis of diurnal rhythms the group of exposed workers was divided into two subgroups: group A of 38 subjects exposed to low intensities of radiofrequency EMF (20-180 V/m) and group B of 23 subjects exposed to high intensities of radiofrequency EMF (200-550 V/m). Parameters of diurnal rhythms of blood pressure and heart rate (acrophase, amplitude and mean) were calculated by performing a least-square fit of a 24 h cosinor (single cosinor analysis) at P < 0.05. RESULTS Healthy men aged 28-49 years, working on a pattern of 12-24-12-48 h, exhibited typical, well-preserved diurnal rhythms of blood pressure and heart rate with two maxima (at about 1400 and 1700-1800 h) and one minimum (at about 0200-0400 h). For workers exposed to radiofrequency EMF we noted a significant lowering of the amplitudes of rhythms of blood pressure and heart rate (P < 0.01) and a shift of the acrophase to an earlier time (1100-1200 h; P < 0.05). These changes were more pronounced among workers exposed to high intensities of radiofrequency EMF. CONCLUSIONS Occupational exposure to radiofrequency EMF can result in changes of the diurnal rhythms of blood pressure and heart rate with lowering of their amplitudes and a shift of the acrophase. The clinical relevance of the present finding needs to be investigated in further studies.

White-coat hypertension: not guilty when correctly defined.

Abstract: The coexistence of persistently high office blood pressure with normal blood pressujre outside the medical setting is often referred to as 'white-coat', 'office' or 'isolated clinic' hypertension. The definition of normal blood pressure outside the medical setting is controversial. In our experience, not only the prevalence of white-coat hypertension, but also left ventricular mass measured echocardiographically and the prevalence of left ventricular hypertrophy in this condition markedly vary on going from more restrictive (lower) to more liberal (higher) limits of ambulatory blood pressure normalcy over quite a narrow range. In a prospective study, cardiovascular morbidities of healthy normotensive controls and subjects with white-coat hypertension did not differ. A more recent analysis of our database supports the use of qujite a restrictive definition of white-coat hypertension (average daytime blood pressure < 130/80 mmHg) in order to identify the minority of subjects who have a low risk of cardiovascular morbid events during the subsequent years. A recent document published by the American Society of Hypertension suggests that slightly higher upper limits of ambulatory blood pressure normalcy (i.e. average daytime blood pressure < 135 mmHg systolic and 85 mmHg diastolic) should be used. In a follow-up study by our group, 37% of subjects with white-coat hypertension spontaneously evolved into cases of ambulatory hypertension, with accompanying increases in left ventricular mass. In that study, the probability of a subject developing ambulatory hypertension increased with the baseline values of ambulatory blood pressure and it was quite low (20%) for those with daytime blood pressures below 130/80 mmHg. In two recent controlled studies, the rate of development of ambulatory hypertension over time for untreated subjects did not differ between the normotensive control group and the group with white-coat hypertension. A final answer regarding the clinical significance of white-coat hypertension will come from very large surveys of the natural history of this condition in the long term. For now, we suggest a verdict of innocence for white-coat hypertension when low values of daytime ambulatory blood pressure (i.e. < 130/80 mmHg) and absence of organ lesions and other risk factors coexist.

Morning versus evening amlodipine treatment: effect on circadian blood pressure profile in essential hypertensive patients.

Abstract: OBJECTIVE: To determine the antihypertensive efficacy and the potential impact on circadian blood pressure pattern of morning versus evening administration of amlodipine to essential hypertensive patients. METHODS: Twelve mild-to-moderate essential hypertensives were investigated in this open, randomized cross-over study. Blood pressure and heart rate were measured by use of ambulatory blood pressure monitoring after a wash-out period of 1 week and after treatment schedules with 5 mg amlodipine once a day either at 0800 h or at 2000 h for 3 weeks. Effects were evaluated by linear and rhythm analysis using the ABPM-FIT program. RESULTS: Both morning and evening administrations of amlodipine significantly (P < 0.01) reduced the elevated systolic and diastolic blood pressures during daytime. However, due to baseline values being lower during night-time, a significant (P < 0.05) reduction was observed only in systolic, not in diastolic, blood pressure. Maximal blood pressure values were significantly (P

Automated blood pressure measurement: state of the market in 1998 and the need for an international validation protocol for blood pressure measuring devices

Abstract: The market for blood pressure measuring devices is increasing rapidly. A vast market for self-measuring devices has existed for many years and this continues to grow. There is also a large market for autoated devices in specialized hospital areas, such as operating theatres and intensive care units. Since the introduction of ambulatory blood pressure monitoring into clinical practice, a growing market for devices to measure blood pressure over time has been created. The states of these three markets are reviewed in this paper. With the likely banning of mercury from clinical use, the traditional sphygmomanometer will disappear and it is inevitable that a new and large market will be created by the demand for an automated alternative to the mercury sphygmomanometer in hospitals and in general practice. It is mandatory that such automated devices are validated independently for accuracy and performance. At present two validation protocols are widely used to test the accuracy of blood pressure measuring devices - the British Hypertension Society and the Association for the Advancement of Medical Instrumentation protocols. These protocols have a common purpose and many similarities. It is proposed that a common protocol should be devised for international use. Experience with these protocols allows one to make suggestions concerning how such an international protocol might be simplified and improved.

Target-organ damage and cardiovascular risk profile in resistant hypertension. Influence of the white-coat effect.

Abstract: Background It is difficult to draw definite conclusions about the prevalence and clinical characteristics of patients with resistant hypertension because of the heterogeneity of study designs described in published studies. Objectives To estimate the prevalence of resistant hypertension, the associated cardiovascular risk factors and the degree of target-organ damage, and to analyze the differences between true resistant hypertension (TRH) and white-coat resistant hypertension (WCRH). Design Cross-sectional study. Methods Patients who visited the Hypertension Clinic with resistant hypertension were sequentially included. Resistant hypertension was defined as an average of three measurements of systolic blood pressure, >/= 160 mmHg or a diastolic blood pressure >/= 95 mmHg, or both, in patients treated with a triple-drug regimen, over at least 2 months. Twenty-four-hour ambulatory blood pressure monitoring and M-mode bi-dimensional echocardiography were performed. WCRH was defined as a mean daytime ambulatory blood pressure Results Of 1200 hypertensive subjects who visited the clinic, 60 patients with resistant hypertension were included [mean age 59+/-8 years; 38 women (63%)]. Office blood pressure was 173+/-14/100+/- 8 mmHg. Of 36 patients with a good quality echocardiograph, 18 had left ventricular hypertrophy. Twenty cardiovascular events were recorded in 16 patients. Obesity was present in 43% of patients, diabetes in 28%, and hypercholesterolemia in 47%. Hypoalphalipoproteinemia was detected in 18%of the patients, all of whom had TRH (P = 0.01). Nineteen subjects (32%) had WCRH. The subjects with TRH had a higher office systolic blood pressure, greater frequency of hypoalphalipoproteinemia than those who had WCRH and a greater proportion of clinical target-organ damage. Conclusions Resistant hypertension is uncommon in clinical practice. Resistant hypertension is associated with multiple cardiovascular risk factors, including left ventricular hypertrophy. A third of patients with resistant hypertension achieve adequate control of their blood pressure outside the physician's office. The proportion of patients with clinical target-organ damage is greater in subjects with TRH than in those with WCRH.

Nocturnal blood pressure epidemiology, determinants, and effects of antihypertensive therapy.

Abstract: It has been established that blood pressure and heart rate have a reproducible circadian pattern characterized by a low period during sleep; an early morning, post-awakening rise; and a high plateau period while a subject is awake. This rhythm is influenced by extrinsic (lpar;environmental) and intrinsic (physiologic and pathophysiologic) factors. When hypertensive patients have the typical circadian pattern of blood pressure described above, they are referred to as 'dippers', whereas, when the normal nocturnal fall of blood pressure is diminished or blunted,s the term 'nondipper' is applied. Cross-sectional and prospective data have shown that nondippers have more target-organ damage than have dippers. Therefore, the prognostic implications of the nondipper status may be important since the overall 24 h blood pressure load is elevated in these individuals. Assessing the effects of antihypertensive therapy on 24 h blood pressure and heart rate using ambulatory monitoring has become routine in clinical trials. However, the methods of analysis and tyipes of trial design may significantly affect evaluation of therapeutic effects on nocturnal blood pressure. This article describes the influence of analysis on 24 h blood pressure measurement especially insofar as it pertains to nocturnal (or sleep) blood pressure values.

Cardiovascular triggers and morning events.

Abstract: Sudden cardiac death, myocardial infarction, unstable angina, ventricular tachyarrhythmias, fatal pulmonary thromboembolism, rupture of thoracic aorta, and ischemic and hemorrhagic cerebrovascular accidents exhibit a prominent circadian pattern with events more frequently during the morning (0600-1200 h)after awakening. Hematologic processes (e.g. increases in secretion and aggregability of platelets, changes in blood clotting, and fibronolysis), vascular processes (e.g. increase in vascular tone), and hemodynamic processes (e.g. morning surge of blood pressure, secretion of catecholamines, and shear forces) have been implicated in onset of disease. The primary significance of the recognition of circadian variation in the onset of myocardial infarction at any time of the day. Several triggers of the onset of cardiovascular disease have been identified. These include the start of activity in the morning, sexual activity, anger, and heavy physical exertion. However, increasing levels of habitual physical activity have been associated with progressively lower relative risks for cardiovascular events. Through further epidemiologic, clinical, and basic scientific research, we may achieve a better understanding of the mechanisms s that provoke the onset of acute cardiovascular disease. This knowledge will help investigators to devise effective preventive treatments for acute cardiovascular disorders.

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

Abstract: 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.

Accuracy and 'range of uncertainty' of oscillometric blood pressure monitors around the upper arm and the wrist.

Abstract: Background Although they have been marketed widely, few data about the diagnostic accuracy of blood pressure monitors are available. Methods Repeated measurements of blood pressures in 85 patients were performed in random sequence with two oscillometric blood pressure monitors around the upper arm (Visomat OZ2) and the wrist (Omron R3( and with a standard sphygmomanometer. The oscillometric blood pressure monitors were validated according to protocols of the British Hypertension Society (BHS) and the American Association for the Advancement of Medical Instrumentation (AAMI). Subsequently, sensitivity and specificity of these monitors for the diagnosis of hypertension or exclusion of the possibility of its presence in a general medical outpatient population were calculated. Results Sphygmomanometric readings exceeded oscillometric blood pressure measurements by 3.7+/-7.5/4.8+/-5.6 mmHg (systolic/diastolic) for the upper arm and 5.7+/-6.2/6.8+/-6.8 mmHg for the wrist. Deviations occurred in both directions and were higher for blood pressures in the hypertensive range. Oscillometric blood pressure measurements at the upper arm, but not at the wrist, satisfied validation criteria of BHS and AAMI protocols. Optimal sensitivity and specificity for the diagnosis of hypertension, defined as blood pressure > 140/90 mmHg with a standard sphygmomanometer, was achieved with blood pressure limits of 133/82 mmHg for the Visomat OZ and 131/80 mmHg for the Omron R3. Conclusions Average sphygmomanometer values exceed oscillometrically measured blood pressure values but individual disagreements cannot be predicted. Measurements at the upper arm are more accurate than are those at the wrist according to the validation protocols of the BHS and AAMI. Additional appraisal of sensitivities and specificities and of a 'range of uncertainty' for the diagnosis of hypertension may allow better judgement of accuracy of individual oscillometric blood pressure measurements.

Validation of pulse dynamic blood pressure measurement by auscultation.

Abstract: BACKGROUND: The accurate measurement of arterial blood pressure is essential for the diagnosis and treatment of hypertension. The development of new automated methods of measurement that provide reliable determinations of blood pressure should be valuable in the assessment of hypertension not only in the clinic or hospital but also, in the home for self-monitoring. DESIGN: We evaluated a noninvasive method for the measurement of systolic and diastolic blood pressures in 132 subjects. METHODS: Measurements obtained using the pulse dynamic method of blood pressure determination were validated with simultaneous manual measurements. Two qualified nurses used Korotkoff sounds to determine systolic (phase I) and diastolic (phase IV) blood pressures according to the Association for the Advancement of Medical Instrumentation 1987 guidelines. RESULTS: Inter-nurse variability was 2.7 +/- 4.1 mmHg (mean +/- SD) for systolic blood pressure and 4.0 +/- 3.7 mmHg for diastolic blood pressure and correlations were r = 0.98 and 0.94, respectively. We observed excellent agreement between auscultatory and pulse dynamic methods for systolic (127 +/- 21 versus 132 +/- 20 mmHg; r = 0.97) and diastolic (72 +/- 10 versus 71 +/- 10 mmHg; r = 0.89) blood pressures. Bland-Altman analysis demonstrated that there was a mean difference (reference-device) between the two methods of - mmHg (pulse dynamic value higher) and SD of 5 mmHg for systolic blood pressure and a mean difference of 1 mmHg (pulse dynamic value lower) and SD of 5 mmHg for diastolic blood pressure. CONCLUSION: The results of this study demonstrate that this noninvasive method of measurement of blood pressure is accurate and reliable and should therefore be appropriate for the evaluation of hypertension both in the home and in clinical settings.

Conventional and ambulatory measurements of blood pressure in old patients with isolated systolic hypertension: baseline observations in the Syst-Eur trial.

Abstract: OBJECTIVES: To compare clinic and am measurements of blood pressure in old patients with isolated systolic hypertension and their reproducibilities. PATIENTS: In total 610 patients aged >/= 60 years with isolated systolic hypertension detected by clinic measurement were monitored during the placebo run-in phase of the Syst-Eur trial. METHODS: The time-weighted 24 h blood pressure, clock-time day and night blood pressures, the cumulative-sum-derived crest and trough blood pressures and the high and low blood pressure levels according to the square-wave model were computed. The daily alteration between the high and low spans of blood pressure was quantified using the day-night difference, the cumulative-sum-derived magnitude of circadian alteration, the Fourier amplitude and the difference between the high and low blood pressure levels of the square-wave model. RESULTS: The daytime am systolic blood pressure was, on average, 21 mmHg lower than the clinic systolic blood pressure, whereas diastolic pressure was, on average, similar with both techniques of measurement. Clinic levels of blood pressure in the 141 patients who underwent repeat measurements and the parameters describing the difference between the daily high and low spans of blood pressure were equally reproducible. However, both were less reproducible than the ambulatory blood pressure levels. The reproducibility coefficients, expressed as percentages of near maximum variation, were 49 and 50% for the clinic systolic and diastolic blood pressures, 30 and 32% for the mean 24 h systolic and diastolic blood pressures and 45-55% for the parameters describing the daily alteration between the high and low spans of blood pressure. CONCLUSION: Values of blood pressure in old patients with isolated systolic hypertension were more reproducible for ambulatory than they were for clinic measurements. Levels in patients selected because they have a high clinic blood pressure may be substantially higher with conventional than they are with daytime ambulatory measurement. The prognostic significance of this difference for the present patients is currently under investigation.

Variability of blood pressure.

Abstract: INTRODUCTION: The justification for ambulatory blood pressure monitoring is that blood pressure varies, and a better understanding of the causes of such vqariability will greatly improve our knowledge of its consequences. Although it is generally assumed that the average or true level of blood pressure is the main culprit causing vascular damage, it would be surprising if the variability did not also contribute. Variability of blood pressure is a compoex issue, and is the result of internal and external influences acting in various combinations.

Circadian variation in cardiovascular events.

Abstract: Prospective studies have shown not only that there is a greater incidence of acute myocardial infarction during the morning waking hours but also that transient myocardial ischemia, unstable angina, sudden cardiac death, complex ventricular arrhythmieas, and strokes have a greater incidence at a similar time. Studies of the physiologic responses that occur throughout the day have shed much light on why such a pattern in the timing of cardiovascular events is seen. It has been shown, for example, that blood pressure and heart rate surge on waking and at the start of daily activities, as does release of catecholamine. It appears that delaying the time of arising and of commencing activities simply shifts the risk of cardiovascular events rather than negating it. The most important clinical message obtained from the study of circadian variation in cardiovascular disease is that protection should be offered to cover the morning waking hours in addition to other times of the day. This need is being addressed with the increasing use of long-acting therapeutic agents.

Seasonal variations in office and home blood pressures in hypertensive patients treated with antihypertensive drugs.

Abstract: OBJECTIVE: To analyze various factors influencing season variations in blood pressure under ordinary circumstances. METHODS: We examined home and office blood pressures in 315 outpatients with essential hypertension. The majority (88%) were being administered antihypertensived drugs. Their office and home blood pressures were recorded in 1993. The patients were 156 men and 159 women, aged 60.8 +/- 0.6 years (mean +/- SEM). The office blood pressure was measured monthly by the same physicians. The home blood pressure was measured every day by the patients, in the morning and evening. RESULTS: The home blood pressures both in men and in women exhibited significant seasonal variations, to a similar extent. The winter-summer difference in home blood pressure was 3.9 +/- 0.5 mmHg systolic and 1.7 +/- 0.3 mmHg diastolic for the men and 4.6 +/-0.5 mmHg systolic and 2.4 +/- 0.3 mmHg diastolic for the women. The office blood pressure of the men also exhibited significant seasonal variation. There was no seasonal variation in office systolic blood pressure in the women. The levels of home blood pressure in the men and women were similar during each season, whereas the office systolic blood pressure of the women was significantly higher than that of men throughout the year. For the total group of patients, the winter-summer differences in home systolic blood pressure was positively correlated to age. The seasonal variations in blood pressure were not affected by body mass index, smoking status, and administration of antihypertensive medication.CONCLUSIONS: Seasonal variations in blood pressure existed both for male and for female hypertensive patients and occurred even for subjects being treated with antihypertensive drugs. However, there was no seasonal variation in the office systolic blood pressure of women, suggesting that the differences between the office and home blood pressures and between thermoregulatory mechanisms for the sexes may have obscured it.

The (dP/dt)max derived from arterial pulse waveforms during 24 h blood pressure oscillometric recording.

Abstract: BACKGROUND: The modern developments in engineering allow one to record the speed at which the blood pressure rises on the advancing pulse wave front. It was possible to obtain this through the conversion of a conventional pulse from a single suprasystolic oscillation to the oscillometric envelope into its first derivative with respect to time. OBJECTIVE: The aim of this study was to report a preliminary comparison between healthy subjects and patients with heart failure as a first step towards the clinical ujse of this first derivative of a time-dependent function (dP/dt).METHODS: For 10 normal healthy subjects (aged 37 +/- 5 yhears) and five subjects with ischaemic cardiomyopathy (aged 41 +/- 7 years), whose ejection fractions (invasively assessed) wee < 40%, we evaluated six sequential oscillometric measurements of blood pressure obtain by using a Dynapulse Ps5000 (Pulse Metric, San Diego, California, USA) device, which simultaneously records blood pressure and analyses every arterial waveform. The mean and SD of (dP/dt)max for each subject were calculated, together with the relative mean distribution and the significance of the differences. RESULTS: The data show that (dP/dt)max of subjects with an impairment of cardiac function is less than normal. The mean (dP/dt)max of normalk subjects was significantly different (P < 0.05) from that of patients with ischaemic cardiomyopathy and lower than normalk ejection fractions. CONCLUSION: These preliminary results allowed us to raise the hypothesis that this parameter, being representative of the cardiac function, because many data are obtained, is extremely useful for monitoring changes during daily activities or to outline the nycthoemeral rhythm. We have to test the hypotheses that the analyses of the correlations between (dP/dt)max and other haemodynamic parameters may be used in the pathphysiological study of cardiomyopathies and that the comparison of differences in (dP/dt)max can be used in the evaluation of the effects of the treatment.

Sleep disturbance during ambulatory blood pressure monitoring of hypertensive patients.

Abstract: BACKGROUND: Hypertensive patients who fail to exhibit a normal fall in blood pressure at night may have a greater risk of target-organ damage. Sleep, with associated cessation of physical activity, is the principal determinant of nocturnal blood pressure 'dip'. OBJECTIVE: To ascertain whether hypertensive patients, who experience the discomfort of higher cuff-inflation pressures during ambulatory blood pressure monitoring, experience more interference with sleep, manifested by greater nocturnal physical activity. DESIGN: A retrospective case- control study. METHODS: Subjects were selected from a database of 475 patients who had undergone simultaneous 24 h ambulatory blood pressure monitoring and monitoring of physical activity with a wrist-mounted piezoelectric accelerometer. Sixty-one hypertensives (average daytime systolic blood pressure >/= 150 mmHg) were age matched to 61 subjects with average daytime systolic blood pressures

What are the normal levels for ambulatory blood pressure measurement

Abstract: With acceptance of ambulatory blood pressure measurement as a useful technique in the management of hypertension, the question of what constitutes the upper limit of normality for 24 h blood pressures has been the subject of a number of reviews [1,2]. In fact, there has been remarkable similarity in a number of large population studies [3-10]. For example, taking the 95th percentile as the upper limit of the distribution of daytime blood pressure in various studies in different countries (Internation Database 141/88 mmHg [3,4], Ireland 138/89 mmHg [5], Belgium 137/88 mmHg [6], Japan 138/83 mmHg [7], Denmark 139/88 mmHg [8] and Italy 134/88 mmHg [9,10] gave variations of less than 7/6 mmHg for systolic and diastolic blood pressures, respectively, the average for all studies being 138/87 mmHg (for review, [6]). A review of the literature carried out independently by the American Society of Hypertension [11] and our group [1,2,6] produced an identical recommendation for the levels of daytime blood pressure that may be regarded as normal and abnormal, namely, that blood pressures above 140/90 mmHg are probably abnormal and that blood pressures below 135/85 mmHg are probably normal. Moreover, the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure in its recent communication takes blood pressures of awake subjects below 135/85 mmHg to be normal [12].

Should one use electrocardiographic or Finapres-derived pulse intervals for calculation of cardiac baroreceptor sensitivity?

Abstract: BACKGROUND: Cardiac baroreceptor sensitivity (BRS) can now be calculated non-invasively with the advent of new beat-to-beat blood pressure monitors and simulatneous surface electrocardiographic recording. However, it is not known whether BRS values calculated using a pulse interval obtained from the pulse wave are different from those using the electrocardiographic trace. This is important with the advent of new portable monitors (e.g. Portapres), which do not record a simultaneous electrocardiographic trace. OBJECTIVE: To determine whether pulse interval derivations from pulse wave data and electrocardiographic data are comparable.METHODS: Twenty healthy volunteers (10 men) aged 48 +/- 17 years with mean blood pressure 134 +/- 13/77 +/- 7 mmHg were examined. Supine beat-to-beat arterial blood pressure (measured using a Finapres 2300 device from Ohmeda) and surface electrocardiographic readings were recorded and spectral analysis, using fast Fourier transformation (FFT), and sequence analysis used to calculate BRS. Pulse interval was marked using both electrocardiographic and blood pressure traces and we compared the resulting variability of pulse interval and BRS values obtained using the two methodologies. RESULTS: There was good agreement between the two methods for pulse interval power in the low-frequency bandwidth and for BRS sequence analysis, especially for 'down' sequences, (limits of agreement -26.3 to 77.1 ms2 and -1.6 to 2.7 ms/mmHg, respectively). However, in the high frequency bandwidth (0.15-0.35 Hz) and for the combined BRS, the agreement was less good (-69 to 153.8 ms2 and -0.3 to 1.5 ms/mmHg). Overall differences between methods were smaller for BRS calculated in the low frequency rather than high-frequency band, but only in the low-frequency band was the difference positively correlated to mean BRS values. CONCLUSION: Cardiac BRS values calculated using pulse intervals derived from the pulse wave are different from those on the surface electrocardiographic trace, the greatest differences occurring in BRS derived from the high-frequency bandwidth. However, these differences are small, especially in the low-frequency band at lower mean BRS values, and should not discourage use of these newer methods of BRS measurement that do not involve an electrocardiographic recording.

Age-based differences between mercury sphygmomanometer and pulse dynamic blood pressure measurements.

Abstract: BACKGROUND: Both the mercury sphygmomanometer and oscillometric measurement methods are widely in use for pediatric, adult, and geriatric patients. However, inherent differences between the methods of measurement may create varying degrees of sensitivity to age and potentially result in differences between measurements for these two techniques. DESIGN: Measurements of systolic and diastolic blood pressures in 154 subjects were obtained using the mercury sphygmomanometer and pulse dynamic oscillometric methods in accordance with the 1987 Association for the Advancement of Medical Instrumentation guidelines. Subjects were separated into three age groups and their data analyzed for differences between measurements for these two techniques. METHODS: Two qualified nurses derived systolic and diastolic blood pressures using phase I and phase IV Korotkoff sounds, respectively, during simultaneous monitoring with the pulse dynamic oscillometric method. RESULTS: Inter-nurse variabilities for measurement derived by mercury sphygmomanometer were 1.8 +/- 4.1 for systolic and 0.9 +/- 3.9for diastolic blood pressure. Mean differences (reference-device) of -5 +/- 5 mmHg (pulse dynamic value higher) for systolic and 1 +/- 5 mmHg (pulse dynamic value lower) for diastolic blood pressure between pulse dynamic and mercury sphygmomanometer values were found for all subjects. However, pulse dynamic systolic blood pressure was significantly higher than mercury sphygmomanometer systolic blood pressure for group 1 (n = 51, aged 11-22 years, mean difference -5.6 mmHg, P = 0.03). A similar trend was observed with group 2 (n = 51, aged 23-54 years, mean difference -4.3 mmHg, P = 0.06). We observedf no significant difference for systolic blood pressure with group 3 (n = 52, aged 55-85 years, mean difference -3.8 mmHg, P > 0.1). For all three groups we found no significant difference for diastolic blood pressure. CONCLUSION: The variation in the agreement of systolic blood pressure measurements can be attributed to the differing effects of age-dependent arterial changes on the measurement methods. The findings indicate that, although the pulse dynamic oscillometric method and mercury sphygmomanometer correlate well when patients of all ages were evaluated as a group, agreement between measurements of systolic blood pressure is dependent on age and the method of measurement employed.

Ambulatory blood pressure monitoring: test reproducibility and its implications.

Abstract: The use of data from ambulatory blood pressure monitoring has the potential to shift how we think about assessing the cardiovascular risk factor of blood pressure. Group mean 24 h, 12 h, 8 h, and hourly blood pressures for two recordings are highly reproducible. A single 24 h ambulatory blood pressure data set correlates better to echocardiographic left ventricular wall thickness than does the average blood pressure of multiple office measurements and than does a single-office visit measurement. Both blunted and excessive nocturnal declines in blood pressure have been associated with more target-organ damage than that with a normal nocturnal decline in blood pressure. Ambulatory blood pressure monitoring has proven to be an indispensable tool in development of drugs. Unfortunately, movement, environmental noise, and excessive vibration interfere with measurement of ambulatory blood pressure. The devices are less accurate for patients with dysrhythmias. False data resulting in incorrect medical decisions might be the most important problem with ambulatory blood pressure monitoring. Reproducibility of individual ambulatory blood pressure data sets is poor. For an individual patient, it might be difficult to detect white-coat hypertension, determine dipping status, and assess a drug's effect. The use of a single ambulatory monitoring record can be inadequate for diagnosing a patient as hypertensive or normotensive. Portable noninvasive ABPM devices would provide more interpretable information if they included an activity detector, a body-position detector, and facilities for performing continuous electrocardiography and measurements of blood pressure. Devices should perform accurately when someone is engaged in vigorous activity. Perhaps detection of sleep and emotional arousal would complete the requirements for an ideal monitor.

The placebo effect in ambulatory blood pressure monitoring.

Abstract: The reduction of clinic blood pressure by placebo tablets in clinical trials of antihypertensive drugs is well established and health authorities require a placebo arm in these trials in order to know how much of the total reduction of blood pressure is attributable to the drug. Most authors now favor the hypothesis that, in contrast to clinic blood pressure measurements, ambulatory blood pressure monitoring (ABPM) is not subject to a placebo effect. Scientific evidence so far shows that ABPM recordings are affected by a negligible and clinically irrelevant placebo effect in short-term trials. Nevertheless, the results of the SYST-EUR study suggest that placebo treatment induces a reduction of blood pressure in old patients with isolated systolic hypertension even when blood pressure is measured by 24 h ABPM, and raise the question of whether a placebo arm is required in clinical trials when ABPM is used to measure changes in blood pressure. In this article, the evidence supporting and contradicting the hypothesis that placebo exerts an effect on ABPM and the possible explanations for the discrepancy are reviewed. My position is that clinical trials on antihypertensive drugs using ABPM should be designed with the same standards as those using clinic blood pressure measurements; that is, randomized, double-blind, placebo-controlled studies. This should be an absolute requirement in long-term trials. Short-term trials lasting no more than 12 weeks, particularly those focused on examining average changes in 24 h diastolic blood pressure, may be designed without a placebo arm.

Ambulatory blood pressure and the kidney.

Abstract: During the last few years there has been a renewed interest in blood-pressure-induced kidney damage, due to a progressive increase in the incidence and prevalence of hyipertension and vascular diseases as a cause of end-stage renal disease (ESRD). The need to prevent ESRD demands continued efforts to achieve the early identification of persons with hypertension who are at risk and to provide them with effective antihypertensive therapy. Ambulatory blood pressure monitoring (ABPM) has been used successfully to assess blood pressure values and identify risk markers for cardiovascular diseases. A logical approach would be to use it also to identify those for ESRD. For hypertensive and type 1 diabetics ABPM data usually have a stronger correlation to the presence and magnitude of microalbuminuria than do routine office blood pressure measurements. The best Pearson correlation coefficients for relationship between ambulatory blood pressure values and urinary excretion of albumin were obtained with nocturnal blood pressure regardless of whether systolic, diastolic or mean blood pressure were considered. Moreover, high percentages of non-dippers have been found among subjects with renal failure, subjects undergoing dialysis (haemofiltration, peritoneal dialysis, continuous ambulatory peritoneal dialysis (CAPD), subjects with renovascular hypertension and with cystic kidney disease, subjects who have had a kidney transplant and subjects with cyclosporine-induced hypertension. Finally, ABPM seems to be prognostic for development of proteinuria in some refractory hypertensives. Whether higher nocturnal blood pressure values and the non-dipping pattern constitute a cause or are consequences of renal disease should be addressed in prospective studies. Assessment of nocturnal blood pressure seems to be an important tool in the management of patients with hypertensive-related renal disease and of patients who are susceptible to developing it.

Office versus Ambulatory (OvA) recording of blood pressure, a European multicenter study: inclusion and early follow-up characteristics.

Abstract: Only a few large prospective trials intended to address the question of whether management of hypertensive patients should be guided by office (OBP) or ambulatory blood pressure (ABP) and whether fatal and nonfatal cardiovascular events are better predicted by ABP than they are by OBP are going on. Office versus Ambulatory (OvA) recording of blood pressure, a European multicenter study, is a multicenter prospective, 10 000 patient-years follow-up study of treated essential hypertension designed to correlate blood pressure to prognosis, blood pressure being defined either by ABP or OBP. Early in 1997, inclusion was stopped (n = 2224 inclusions, 48.3% women, aged 56.8 +/- 13.1 years) because the required number had been exceeded. Inclusion data reveal that OBP (152.9 +/-21.2/92.7 +/- 10.9 mmHg) of a large portion of patients remains high, although patients had been treated for at least 3 months with antihypertensive drugs. Mean 24 h ABP averaged 133.3 +/-15.9/84.0 +/-11.0 mmHg and 24 h blood pressure and heart rate profiles, large differences in drug treatment, apparatus, type of patients, and patients' activities notwithstanding, were like those expected from well-controlled studies. Risk profile was not particularly high. Evolution of OBP, ABP and electrocardiographic and echocardiographic indices of left ventricular hypertrophy indicate that reeductions of the OBP, ABP, and electrocardiographic indices of left ventricular hypertrophy had occurred after 12 months, after 24 months follow-up there was no longer any further change for most parameters. In conclusion, analysis of inclusion and preliminary follow-up data indicates that the OvA study is running well and that it is likely that final analysis of the data and events from the OvA study will lead to an answer to the study question of whether ABP monitoring is better suited than is OBP to deal with management of the treated hypertensive patient.