Validation of portable noninvasive blood pressure monitoring devices: comparisons with intra-arterial and sphygmomanometer measurements

Novel methods of testing and calibration of oscillometric blood pressure monitors

We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP simulator to determine the characteristic ratios used, and to explore differences between different devices. Assuming that classical auscultatory sphygmomanometry provides the best approximation to intra-arterial pressure, the results obtained from oscillometric measurements for a range of characteristic ratios are compared against a modified auscultatory method to determine an optimum characteristic ratio, Rs for systolic blood pressure (SBP), which was found to be 0.565. We demonstrate that whilst three Chinese manufactured NIBP monitors we tested used the conventional maximum amplitude algorithm (MAA) with characteristic ratios Rs = 0.4624±0.0303 (Mean±SD) and Rd = 0.6275±0.0222, another three devices manufactured in Germany and Japan either do not implement this standard protocol or used different characteristic ratios. Using a reference database of 304 records from 102 patients, containing both the Korotkoff sounds and the oscillometric waveforms, we showed that none of the devices tested used the optimal value of 0.565 for the characteristic ratio Rs, and as a result, three of the devices tested would underestimate systolic pressure by an average of 4.8mmHg, and three would overestimate the systolic pressure by an average of 6.2 mmHg.

Validation of a New Method of Detecting Peripheral Artery Disease by Determination of Ankle-Brachial Index Using an Automatic Blood Pressure Device

Peripheral artery disease (PAD) is a predictor of total and cardiovascular mortality; its most valuable simple index is the ankle-brachial index (ABI). The present study was designed to assess whether a commercially available automatic device could be used to determine ABI in comparison with the classical Doppler method. The ABI was defined as the ratio of systolic blood pressure at each ankle to the maximal brachial systolic pressure, a pathological index being defined for a ratio <0.90. The ABI were calculated in 219 consecutive patients (aged 55 ±19 years) with systolic blood pressure measured either by using a mercury sphygmo-manometer and a continuous-wave Doppler probe or an automatic manometer Omron M4. This device has been validated for measurements in upper limbs, and so the authors undertook validation in the lower limbs versus intraarterial measurements. There was an excellent correlation between intraarterial measurements and automatic readings in the range of 70-220 mm Hg, r =0.99, p<0.001. The systolic pressures measured in upper limbs correlated well in the right ( r =0.87, p<0.001) and the left ( r =0.89, p<0.001) upper limbs; and in the left ( r =0.72, p<0.001) and the right ( r =0.68, p<0.001) lower limbs. Correlations between ABI in both methods were good in the left ( r =0.66, p<0.001) and the right ( r =0.61, p<0.001) lower limbs. The sensitivity (76%), specificity (95%), positive predictive value (86%), negative predictive value (90%), and global accuracy (89%) of a pathological automatic index to predict an abnormal Doppler index were good. The use of a simple, automatic blood pressure device to determine ABI appears feasible, easy, and precise. It would provide a practical tool for physicians not trained in Doppler to detect PAD.

Comparative Effects of a New Cardioselective Beta-Blocker Nebivolol and Nifedipine Sustained-Release on 24-Hour Ambulatory Blood Pressure and Plasma Lipoproteins

This double-blind, parallel-group study compared the effects of nebivolol, a novel cardioselective beta-blocker, with those of nifedipine sustained-release on 24-hour ambulatory blood pressure and plasma lipoprotein levels. After a washout period of 8 weeks, 51 patients with mild to moderate essential hypertension were randomized to double-blind treatment with either nebivolol 5 mg once a day (n = 26) or nifedipine sustained-release 20 mg bid (n = 25) over a period of 12 weeks. Both treatments produced similar and significant (P = .0001) reduction in office blood pressure as well as in 24-hour, work, awake, and sleep ambulatory blood pressure. The clinical response (diastolic blood pressure less than 90 mmHg or decreased by greater than or equal to 10 mmHg) rate was 69% for nebivolol and 59% for nifedipine, respectively. Moreover, the nebivolol and nifedipine treatment-induced decreases in mean 24-hour ambulatory blood pressure were similar to the decreases in clinic blood pressure. Furthermore, the percentages of "blood pressure loads" (awake greater than 140/90 mmHg and asleep greater than 120/80 mmHg) were lowered significantly (P = .0001), from 60% to 29% with nebivolol and from 60% to 39% with nifedipine. Mean ambulatory heart rate was reduced (P = .0001) from 79 +/- 7 to 68 +/- 7 beats/minute during nebivolol therapy and from 80 +/- 9 to 79 +/- 7 (not significant) with nifedipine. Total plasma cholesterol and low-density lipoprotein levels decreased significantly (P less than .05) by 5 and 8%, respectively, after nebivolol treatment, and each decreased by 3% after nifedipine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Increasing the doses of both diuretics and angiotensin receptor blockers is beneficial in subjects with uncontrolled systolic hypertension

BACKGROUND

Blood pressure (BP) control is frequently difficult to achieve in patients with predominantly elevated systolic BP. Consequently, these patients frequently require combination therapy including a thiazide diuretic such as hydrochlorothiazide (HCTZ) and an agent blocking the renin-angiotensin-aldosterone system. Current clinical practice usually limits the daily dose of HCTZ to 25 mg. This often leads to the necessity of using additional antihypertensive agents to control BP in a high proportion of patients.

OBJECTIVES

To compare the efficacy of two doses of losartan (LOS)⁄HCTZ combinations in patients with uncontrolled ambulatory systolic hypertension after six weeks of treatment with LOS 100 mg⁄HCTZ 25 mg (LOS100⁄HCTZ25).

METHODS

Following a two- to four-week washout period, subjects with a mean clinic sitting systolic BP of 160 mmHg or higher and a mean ambulatory daytime systolic BP (MDSBP) of 135 mmHg or higher on LOS100⁄HCTZ25 (n=105; 33 women and 72 men) were randomly assigned to receive LOS 150 mg⁄HCTZ 25 mg (group 1; n=53) or LOS 150 mg⁄HCTZ 37.5 mg (LOS150⁄HCTZ37.5, group 2; n=52). The primary end point was the difference in MDSBP reductions.

RESULTS

At the end of the six-week treatment period, the respective additional decreases in MDSBP were 1.2 mmHg (P=0.335) on LOS 150 mg⁄HCTZ 25 mg and 5.6 mmHg (P<0.0001) on LOS150⁄HCTZ37.5 (difference of 4.4 mmHg; P=0.011). Daytime systolic ambulatory BP goal (lower than 130 mmHg) achievement tended to be higher (25% versus 17%; P=0.313) with LOS150⁄HCTZ37.5, while it was significantly higher (65% versus 43%; P=0.024) for mean daytime diastolic BP (lower than 80 mmHg). No deleterious metabolic changes were observed.

CONCLUSIONS

In patients with uncontrolled systolic ambulatory hypertension receiving LOS100⁄HCTZ25, increasing both HCTZ and LOS dosages simultaneously to LOS150⁄HCTZ37.5 may be an effective strategy that does not affect metabolic parameters.

The mean machine; accurate non-invasive blood pressure measurement in the critically ill patient

OBJECTIVE

Accurate indirect prehospital blood pressure measurement in the critically ill patient remains an important challenge to both patient management and prehospital research. Ambulatory blood pressure measuring devices have not been trialled for prehospital use in critically ill patients. Prior to prehospital validation where conditions are suboptimal, we aimed to test under favourable conditions in the Intensive Care Unit, a selection of ambulatory devices that may be suitable for use in the field.

METHODS

Systolic, diastolic and mean pressures of three ambulatory devices were compared to the average of 1 min of independently recorded, high fidelity intra-arterial reference pressures. Eighteen critically ill patients were recruited. Device performance was required to fulfil the Association for the Advancement of Medical Instrumentation (AAMI) protocol. Additionally, agreement between measurement methods was examined using Bland-Altman plots. Two-level linear mixed model analyses were under- taken.

RESULTS

For each device, 150 paired measurements (arterial reference and device) were analysed. According to the AAMI protocol, no device measured systolic pressures accurately. One device measured diastolic pressures accurately. Integrated mean pressures were accurately measured by all devices. Overall, SunTech Medical's Oscar 2 performed best with mean pressure error not exceeding 17 mmHg. For this device, Bland-Altman plots showed uniform agreement across a wide range of mean pressures. Two-level linear mixed effects analyses showed that Oscar 2 mean error reduced during vasopressor use by (-) 3.9 mmHg (95% CI -5.9, -1.9; P < 0.001), and clinically, performance was little affected during mechanical ventilation. For the Oscar 2, there was up to (-) 7.0 mmHg (95% CI -10.3, -3.5; P < 0.001) l ess mean error during hypotension compared to normo- tension.

CONCLUSIONS

In the Intensive Care Unit, the performance of one device, the Oscar 2, surpassed the others and fulfilled the AAMI protocol criteria for mean pressure measurement. This device is suitable for prehospital validation.

[Blood pressure. Regulation and epidemiology. Standard measures and values]

The use of mercury in the field of blood pressure measurement will decrease and even disappear by the xxist century. Concurrently, automatic devices outspread will significantly limit the observers' bias. In order to better define hypertension, not only does one have to use several measurement methods but also to consider blood pressure reference values for each of these methods. Moreover, analyzing the various peripheral pressures: systolic, diastolic and pulse pressures have to be completed with further specific parameters such as measurement of central BP and arterial stiffness, major determinants of blood pressure levels. This should lead to improve therapeutical approaches of cardiovascular diseases and consequently, to a better management of hypertensive patients.

Expedited blood pressure control with initial angiotensin II antagonist/diuretic therapy compared with stepped-care therapy in patients with ambulatory systolic hypertension

OBJECTIVES

The present study investigated whether initiating therapy with a combination of losartan (L) and hydrochlorothiazide (HCTZ) allows for faster blood pressure (BP) control and fewer medications than the usual stepped-care approach in patients with stage 2 or 3 hypertension and ambulatory systolic hypertension.

METHODS

Patients with a mean daytime systolic ambulatory BP (ABP) of 135 mmHg or higher were randomly assigned to receive L 50 mg plus HCTZ 12.5 mg titrated to L 100 mg plus HCTZ 25 mg versus HCTZ 12.5 mg plus atenolol 50 mg. Amlodipine 5 mg was then added, if needed, to achieve a BP goal of less than 130 mmHg. Treatment titration was based on ABP.

RESULTS

Significantly more patients randomly assigned to L/HCTZ (63.5%) than stepped-care (37.5%; P=0.008) achieved the primary end point (daytime systolic BP of less than 130 mmHg). Initial L/HCTZ induced significantly greater decreases in ABP during each 24 h period after six weeks of therapy. Although reductions in systolic and diastolic ABP were not statistically different at the end of the study, ABP reduction was significantly greater (P<0.001) with the L/HCTZ-based regimen. Twice as many patients in the L/HCTZ group achieved the goal ABP with no more than two drugs (30.0% versus 14.7%; P=0.03). Moreover, tolerability was significantly better (P=0.006) in the L/HCTZ group, with a 40.0% incidence of adverse events, versus 65.6% in the stepped-care group.

CONCLUSION

Initiating antihypertensive therapy with the combination of L/HCTZ in patients with stage 2 or 3 hypertension and ambulatory systolic hypertension reaches a target BP faster in a higher proportion of patients, with fewer adverse events and less need for a third drug regimen than the conventional stepped-care approach.

Blood pressure in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

BACKGROUND

In patients with congenital adrenal hyperplasia (CAH) recording of blood pressure (BP) must be included in monitoring treatment to detect hypertension.

AIM

To investigate the BP patterns in patients with CAH.

METHODS

Twenty-three children and adolescents (age 6-17 years) and 11 adult patients (age 18-26 years) were studied (21 females, 13 males; 28 salt-wasting patients). In the whole group BP in the outpatient clinic was compared with BP under hospitalisation and in 11 of the children and adolescents also with 24-hour ambulatory blood pressure monitoring (ABPM).

RESULTS

BP in the ward in children and adolescents but not in adults was significantly higher than BP in the outpatient clinic, where BP was in the upper normal range. There was also a significant difference between BP in the outpatient clinic and the lower ABPM in the 11 patients tested. Atrial natriuretic peptide (ANP) in blood serum showed normal values.

CONCLUSIONS

BP measured in outpatients in a relaxed and calm atmosphere meets the requirements for monitoring of treatment. Measurement of BP on the ward leads to falsely high results. ABPM is not necessary. Estimation of ANP provides no additional information.

Level of acculturation and hypertension among Dallas County Hispanics: findings from the Dallas Heart Study

PURPOSE

The purpose of this study is to examine whether the prevalence of hypertension differs by acculturation status among Hispanics in Dallas County, Texas. The authors test the hypothesis that compared with those of low acculturation, those of mid- and high-level acculturation will be at greater risk for having hypertension.

METHODS

Conducted from July 2000 through October 2002, the Dallas Heart Study (DHS) is a general population cross-sectional study of cardiovascular risk factors among Dallas County residents. These analyses focus on the 1163 DHS participants who self-reported Hispanic ethnicity, completed a household interview, and had blood pressures measured. Acculturation was assessed with a validated 12-item scale that measured the following dimensions of cultural adaptation: language; media preference; social interaction; and ease of relationships with those of other ethnicities.

RESULTS

The majority of participants were born in Mexico (57.5%) and ranged in age from 18 to 65 years (mean age 33 years). Women made up just under half of the sample (47.81%). The unadjusted prevalence of hypertension was 9.78%. When age-adjusted for the 2000 US Standard Population, the prevalence was 17.27%. The chi(2) analysis showed that those of low acculturation were significantly less likely to have hypertension (6.05%) than those of mid- and high-level acculturation (10.78% and 12.80%, respectively). After controlling for the effects of possible confounders (i.e., sociodemographic factors, health care access and utilization, health behaviors, and health status), logistic regression showed that when compared with Hispanics of low acculturation, those of middle and high acculturation were at greater risk of having hypertension (OR=3.04, 95% CI, 1.27, 7.29 and OR=2.62, 95% CI, 1.04, 6.59, respectively).

CONCLUSION

These findings demonstrate that acculturation is significantly associated with hypertensive status.

Comparison of ankle-brachial pressure index measurements using an automated oscillometric device with the standard Doppler ultrasound technique

BACKGROUND

The aim of the present study was to assess the accuracy of an automated oscillometric device (DINAMAP) in measuring ankle-brachial pressure index (ABPI) in the clinical setting. Results were then compared to those obtained using the standard Doppler technique.

METHODS

A prospective comparative study of 50 healthy volunteers was carried out using a standard ward DINAMAP machine, hand-held Doppler and a 14 cm sphygmomanometer cuff. Three consecutive pressure readings were taken from all four limbs of the volunteers using both Doppler and DINAMAP techniques. The two techniques were carried out by different investigators who were blind to the findings of the other. The ABPI was calculated for each technique and the two techniques were compared.

RESULTS

There was no significant agreement between the ABPI readings obtained by DINAMAP and those obtained by the standard Doppler technique. There was also a substantial variation in pressure readings produced by the DINAMAP for a given limb as measured by intraclass correlation of the three readings taken.

CONCLUSIONS

There is no role for standard automated oscillometric devices in the calculation of ABPI in the vascular clinic.

Twenty-four-Hour blood pressure variability after acute ischemic stroke

In people who are healthy, circadian rhythm in blood pressure is well established, with a 10% to 20% decrease in systolic and diastolic blood pressure during nighttime. Deviations correlate with target organ disease such as left ventricular hypertrophy, retinopathy, renal disease, and stroke. Little is known about blood pressure and circadian patterns in stroke patients. This study examined 13 patients hospitalized after ischemic stroke and monitored 24-hour blood pressure with ambulatory blood pressure monitors programmed tocollect readings every 30 minutes. All subjects had an abnormal pattern in blood pressure that did not dip during nighttime. Blood pressure load, a reported indicator of risk for target organ damage, was exceeded in all subjects during daytime and nighttime. Thus stroke patients are at high risk for target organ disease including recurrent stroke. Hypertensive management of stroke patients requires further investigation.

ACE-inhibitor therapy with spirapril increases nocturnal hypotensive episodes in elderly hypertensive patients

The purpose of this double-blind, randomised trial with a 4-week placebo run-in period followed by an active treatment period using either spirapril 3 mg or 6 mg once a day was to clarify the existence of hypotensive episodes in elderly hypertensive patients treated by an ACE-inhibitor. Forty hypertensive patients aged 60-76 years underwent 24-h ABPM at the end of the run-in (week 4) and active treatment (week 9) periods. The mean 24-h systolic blood pressure (SBP) decreased from 161.9 (26.7) mm Hg to 150.6 (29.9) mm Hg (P < 0.001) and diastolic blood pressure (DBP) from 91.70 (14.7) mm Hg to 84.2 (17.3) mm Hg (P < 0.001). No episodes of mean arterial pressure (MAP) <50 mm Hg were seen during the placebo period. Instead 11 episodes were observed during the antihypertensive treatment (one in the 3 mg group and 10 in the 6 mg group, P < 0.01 between the two treatment groups). Fifty-four episodes of MAP <70 mm Hg were observed during the placebo period and 117 during the treatment period (P < 0.001). During the placebo period low MAPs were observed only during night time. During the treatment period they were seen also from 11 am to 4 pm. In conclusion, ACE-inhibitor therapy with spirapril significantly increased hypotensive episodes in elderly hypertensive patients which may worsen their cerebral and myocardial circulation.

Prognostic significance of blood pressure measured on rising

Previous works using ambulatory blood pressure (BP) monitoring demonstrated that independently of the mean level of BP, the variability in BP, or the day-night range, could have prognostic significance. We have also found that the value of BP on rising in the morning is strongly correlated with left ventricular mass of hypertensive individuals independently of the 24-h value. In the present study, we sought its predictive value for cardiovascular complications in a cohort of hypertensive patients. The population studied belongs to a cohort of initially untreated hypertensive patients recruited since 1983 and followed for more than 5 years. Patients were then treated and followed by their family doctor. At entry, all patients were equipped with a device to measure ambulatory BP. They were requested to trigger a measurement manually on rising in the morning (arising BP). The data on their outcome were collected by a physician unaware of the initial state of the patients. A total of 256 patients have been followed up for 5 years or more, 19 were lost to follow-up. The mean follow-up period was 84 +/- 29 months. Cardiovascular complications were recorded in 23 individuals. The arising systolic BP (SBP) was significantly higher in the group who presented a complication. In a stepwise discriminant analysis including age, office, fitting, arising and 24-h average SBPs only age and arising SBP entered the equation. In conclusion, the single BP value measured by an ambulatory device on rising in the morning seems more discriminant of future cardiovascular events than the value of BP measured on fitting the device or the average of three measurements taken under standardised conditions in the hospital or office.

Relationship between circadian blood pressure patterns and progression of early carotid atherosclerosis: A 3-year follow-up study

BACKGROUND

Arterial hypertension is a major risk factor for cardiovascular damage. The results of several studies suggest that target organ damage is greater in hypertensive persons with high blood pressure variability.

METHODS AND RESULTS

During 3.3 years of follow-up, we studied the relationship between circadian blood pressure changes and the progression of early carotid atherosclerosis in 286 patients aged >55 years. Blood pressure patterns were evaluated with a long-term blood pressure monitor, and the extent of atherosclerosis was measured as the intima-media wall thickness (IMT) of the common carotid artery. Patients were subdivided according to blood pressure variability. The progression of IMT was significantly greater in the patients with increased systolic blood pressure variability (0.11 mm/y [95% CI 0.09 to 0.14] versus 0.05 mm/y [0.03 to 0.08]; P:<0.005) even after adjustment for other risk factors. Multivariate regression analysis revealed the daytime systolic blood pressure variability to be the best predictor for the progression of IMT. Raised daytime systolic blood pressure variability (>15 mm Hg) is associated with an increased relative risk of the development of early atherosclerosis (3.9 [1.4 to 11.1]; P:<0.01) and of cardiovascular events (1.87 [1.08 to 3.20]; P:<0.01).

CONCLUSIONS

The daytime systolic blood pressure variability is a strong predictor of early carotid atherosclerosis progression and is useful to define the risk-benefit ratio of therapeutic approaches.

Long-term comparison of losartan and enalapril on kidney function in hypertensive type 2 diabetics with early nephropathy

BACKGROUND

The objectives of this study were to compare the effects of the angiotensin II receptor blocker, losartan, to those of the angiotensin-converting enzyme inhibitor, enalapril, on albuminuria and renal function in relationship to clinic and ambulatory blood pressure (ABP) in hypertensive type 2 diabetic subjects with early nephropathy. The tolerability of these agents and their effect on the metabolic profile were also evaluated.

METHODS

The study was a one-year prospective, double-blind trial with losartan and enalapril administered alone or in combination with hydrochlorothiazide and other antihypertensive agents. ABP and renal and biochemical parameters were measured at baseline and after 12, 28, and 52 weeks of active treatment. Ninety-two hypertensive type 2 diabetics with early nephropathy completed the study.

RESULTS

Both losartan and enalapril administered alone or in combination with other agents induced significant reductions in sitting clinic (P < 0.05) and ABP (P < 0.002) without a statistical difference between groups. Geometric means for urinary albumin excretion (UAE) decreased significantly (P < 0.001) in patients treated with losartan from 64. 1 to 41.5 microg/min and in those treated with enalapril from 73.9 to 33.5 microg/min after 52 weeks of therapy. A significant relationship (P < 0.05) between changes in systolic and diastolic ABP and the decrease in UAE at 52 weeks was seen in both groups. The decline in glomerular filtration rate (GFR) was stabilized at the end of therapy and was identical in both treatment groups. Treatment with enalapril was associated with a significantly higher incidence of cough (P = 0.006) and a rise in serum uric acid (P = 0.002) compared with losartan.

CONCLUSIONS

Our results indicate that a one-year course of antihypertensive therapy with either losartan or enalapril significantly reduces UAE in hypertensive type 2 diabetic patients with early nephropathy. The reduction in UAE with each treatment is similarly related to decrements in ABP. In addition, the rate of decline in GFR is similar in both treatment groups.

Means for load variation during echocardiographic assessment of the Frank-Starling relationship

Because minimally invasive methods of preload variation are not validated for load-insensitive indexes of cardiac performance, intravenous nitroglycerin (NTG), phenylephrine, and saline solution (VOL) boluses were used in blocked and intact autonomic states to alter load and were compared with vena caval occlusion in the assessment of preload recruitable stroke work relationships between stroke work and left ventricular end-diastolic volume in dogs. In both autonomic states NTG and VOL produced comparable linear relationships. NTG and saline solution were combined with noninvasive measurements of left ventricular pressure and volume to construct echocardiographic relationships between stroke work and left ventricular end-diastolic cross-sectional area; NTG produced linear relationships similar to vena caval occlusion. Therefore NTG and VOL reliably alter load in constructing preload recruitable stroke work relationships, and NTG may be used with noninvasive measurements to provide load-insensitive estimates of cardiac function in a minimally invasive manner.

Effect of red ginseng on blood pressure in patients with essential hypertension and white coat hypertension

The objective of this study is to evaluate the changes of diurnal blood pressure pattern after 8 weeks of red ginseng medication (4.5 g/day) by 24 hour ambulatory blood pressure monitoring. In 26 subjects with essential hypertension, 24 hour mean systolic blood pressure decreased significantly (p = 0.03) while diastolic blood pressure only showed a tendency of decline (p = 0.17). The decrease in pressures were observed at daytime (8 A.M.-6 P.M.) and dawn (5 A.M.-7 A.M.). In 8 subjects with white coat hypertension, no significant blood pressure change was observed. We suggest that red ginseng might be useful as a relatively safe medication adjuvant to current antihypertensive medications.

Influence of arrhythmias on accuracy of non-invasive blood pressure monitors

PURPOSE

To compare the accuracy of non-invasive blood pressure (NIBP) monitors in response to common cardiac arrhythmias.

METHODS

Simulated signals of normal sinus rhythm (NSR), premature ventricular contractions (PVCs), atrial fibrillation (AF) and missed beats (MB) were generated from a Cufflink (Dynatech Nevada) NIBP simulator. Using these signals, the Critikon 1846SX (C1846), Critikon 845xt (C845). Critikon Vital Signs (CVIT), and Hewlett Packard M1008a (HP1008) were studied at a standard dynamic blood pressure of 120/90/80 mmHg, in order to compare monitor accuracy and signal response times.

RESULTS

The C845 monitors most closely estimated a simulated SBP of 120 mmHg, although SBP was greater during PVCs and AF than NSR (P < 0.05). The Critikon 1846, Critikon Vital Signs, and Hewlett Packard systematically underestimated SBP during these arrhythmias, but variability was modest, as reflected by small coefficients of variation (< 2% for SBP) with all monitor types. In general, MAP and DBP were less sensitive to the effects of these arrhythmias. Finally, missed beats prolonged signal response times with all four monitor types (P < 0.05), whereas PVCs and AF did not alter this parameter.

CONCLUSIONS

This study demonstrates the extent to which the accuracy of NIBP monitors is altered by common cardiac arrhythmias. Differences in the electromechanical characteristics of these devices may help to explain the observed similarities and discrepancies.

Cardiovascular reactivity to a naturally occurring stressor: development and psychometric evaluation of a psychophysiological assessment procedure

Three studies were conducted to examine the feasibility, reactive effects of assessment, stability, sampling parameters, and sensitivity of an assessment procedure designed to measure cardiovascular responses to a discrete, naturally occurring, and replicatable stressor--university course examinations. Undergraduate students monitored their blood pressure and heart rate several times during one or two classroom examinations and for several class sessions preceding each examination. Classroom examinations were generally associated with significant increases in subjective measures of distress and cardiovascular measures. Reactive effects of assessment and other sources of error were minimized and responses were reasonably stable over time. These results support the potential utility, validity, and cost-efficiency of this methodology for assessing cardiovascular reactivity to naturally occurring stressors.

Novel delivery system for verapamil designed to achieve maximal blood pressure control during the early morning

Because the risk of cardiovascular events appears to be greatest in the early morning, this period is a time during which adequate blood pressure (BP) control appears to be most desirable. In this study, a controlled-onset extended-release system (COER-24) that delivers verapamil in a manner designed to achieve maximal levels of drug during the early morning surge in BP was compared with placebo. Ninety-five patients with mild to moderate hypertension were studied. Of this group, 49 patients (mean age 57.6 +/- 1.4 years; 35 men and 14 women) were randomized to take verapamil COER-24 240 mg at 10 PM, and 46 subjects (mean age 55.8 +/- 1.5 years; 29 men and 17 women) were randomized to take placebo. Ambulatory BP monitoring was performed after a 4-week initial placebo period and was repeated after 4 weeks of treatment with verapamil or placebo. Verapamil COER-24 resulted in significant (p < 0.001) decreases in mean whole-day systolic and diastolic BP (-8.2/-6.3 mm Hg; baseline 152/93.0 mm Hg) when compared with placebo (+0.3/-0.9 mm Hg; baseline 150.3/93.2 mm Hg). From 6 AM to noon, verapamil COER-24 resulted in a change in systolic and diastolic BP of -11.6/-9.0 mm Hg, which was significantly (p < 0.001) greater than the change that occurred with placebo (-0.5/-1.0 mm Hg) during the same period. In the last 4 hours of the dosing interval (6 PM to 10 PM), verapamil COER-24 caused significantly greater (p < 0.001) decreases in BP (-7.4/-4.8 mm Hg) than did placebo (+2.7/+1.0 mm Hg). These data demonstrate that the COER-24 system, when administered in the late evening, achieves maximal BP reduction during the early morning hours. Moreover, BP reductions were sustained throughout the 24-hour period.

Ambulatory blood pressure reproducibility and application of the method in a healthy Finnish cohort

The aim of the present study has been to study the reproducibility, validity and normal values of ambulatory blood pressure measurement in a healthy Finnish cohort. The reproducibility of ambulatory blood pressure monitoring was examined in healthy volunteers and normal values were determined in a Finnish cohort of males and women of different ages. In the reproducibility study the recording was repeated at 2-week intervals. In the validity study simultaneous measurements were done manually with a mercury sphygmomanometer and compared with the measurement by the ambulatory blood pressure recording unit, both connected with the cuff by a T-tube; this study included 100 consecutive measurements in a patient group. A relatively small cohort was taken from the normal value study group. In addition to ambulatory blood pressure their left ventricle mass was also determined by echocardiography. The correlation between manual blood pressure measurement and simultaneous measurement by the ambulatory blood pressure unit was 0.98. In the reproducibility study the correlations between the two 24-h measurements 2 weeks apart were also good. Depending on the parameter (daytime, nighttime or 24-h blood pressure mean, systolic or diastolic values) the correlation coefficient varied between 0.81 and 0.91. Thus both systolic and diastolic blood pressures, whether expressed as 24-h averages and daytime or nighttime averages, correlated well between these two recording sessions. The data obtained in the present Finnish cohort were well within the published reference value limits, showing only fairly modest age-dependence appearing at quite an old age. There was no significant correlation between the left ventricle mass and ambulatory blood pressure values in a population having normal blood pressure. The results suggest good intra-individual correlation and reproducibility in ambulatory blood pressure monitoring, suggesting this method to be useful in the monitoring of individual blood pressure levels. The validity of the method is good and the published reference values can be applied with reasonable reliability in different populations. In an adult population with normal blood pressure, no correlation between left ventricle mass and blood pressure values can be found, suggesting this correlation may first appear in cohorts including persons with elevated blood pressure values.

Assessment of the Frank-Starling relationship by two-dimensional echocardiography

The Frank-Starling relationship between left ventricular stroke work and end-diastolic minor-axis cross-sectional area was evaluated as a load-insensitive measure of inotropic state by two-dimensional echocardiography in 10 conscious dogs. Stroke work was calculated as the product of systolic change in cross-sectional area and either (1) beat-to-beat mean arterial pressure or (2) initial systolic blood pressure. Both Frank-Starling relationships were highly linear during preload variation (mean r = 0.96), sensitive to the inotropic state (slope increase with calcium 51% +/- 43% and 62% +/- 53%, respectively), and insensitive to afterload (r < 0.4, slope or x intercept versus afterload). Thus the Frank-Starling relationships derived from two-dimensional echocardiographic images and peripheral arterial pressure may be a useful and practical means of assessing inotropic state with minimally invasive measurements.

Coronary haemodynamics in left ventricular hypertrophy

BACKGROUND

Left ventricular hypertrophy is associated with an increased risk of cardiovascular morbidity and mortality. Previous studies have shown that patients with left ventricular hypertrophy develop electrocardiographic changes and left ventricular dysfunction during acute hypotension, and suggest that the lower end of autoregulation may be shifted upwards.

AIM

To measure coronary blood flow (velocity) and flow reserve during acute hypotension in patients with left ventricular hypertrophy.

PATIENTS

Eight patients with atypical chest pain and seven with hypertensive left ventricular hypertrophy; all with angiographically normal epicardial vessels.

SETTING

Tertiary referral centre.

METHODS

The physiological range of blood pressure was determined by previous ambulatory monitoring. Left ventricular mass was determined by echocardiography. At cardiac catheterisation, left coronary blood flow velocity was measured using a Judkins style Doppler tipped catheter. During acute hypotension with sodium nitroprusside, coronary blood flow velocity was recorded at rest and during maximal hyperaemia induced by intracoronary injection of adenosine. Quantitative coronary angiography was performed manually.

RESULTS

For both groups coronary blood flow velocity remained relatively constant over a range of physiological diastolic blood pressures and showed a steep relation with diastolic blood pressure during maximal hyperaemia with intracoronary adenosine. Absolute coronary blood flow (calculated from quantitative angiographic data), standardised for left ventricular mass, showed reduced flow in the hypertensive group at rest and during maximal vasodilatation.

CONCLUSION

The results are consistent with an inadequate blood supply to the hypertrophied heart, but no upward shift of the lower end of the autoregulatory range was observed.

Ambulatory blood pressure monitoring in healthy schoolchildren

Ambulatory blood pressure monitoring (ABPM) was performed in 564 healthy schoolchildren during normal circadian activities. The data of two cohorts (155 boys and 139 girls aged 9-13 years and 184 boys and 168 girls with a body height between 120 and 155 cm) are presented. From the age of 9 to 13 years the mean 24-h systolic/diastolic blood pressure (SBP/DBP) increases from 107 +/- 9/66 +/- 7 mmHg to 115 +/- 13/68 +/- 9 mmHg in boys and from 104 +/- 5/64 +/- 6 mmHg to 109 +/- 8/65 +/- 9 mmHg in girls. When related to body height the values rise from 105 +/- 6/64 +/- 6 mmHg at 120 cm to 113 +/- 8/67 +/- 7 mmHg at 155 cm in boys and from 100 +/- 7/65 +/- 7 mmHg to 112 +/- 9/66 +/- 9 mmHg in girls. In comparison with the causal blood pressure data obtained from European studies, the presented ABPM values (daytime BP) are higher throughout, which may be explained by the increased activity during daytime with ABPM. There is a mean difference of 4.4 mmHg in boys and of 3.0 mmHg in girls for SBP and of 10.8 mmHg in boys and of 9.0 mmHg in girls for DBP when related to age. In relation to body height, there is a mean difference of 4.4 mmHg in boys and of 3.5 mmHg in girls for SBP and of 10.9 mmHg in boys and of 10.5 mmHg in girls for DBP. We conclude that standards derived from causal blood pressure measurements should not be used for the evaluation of ABPM data.

Changes of circadian blood pressure patterns and cardiovascular parameters indicate lateralization of sympathetic activation following hemispheric brain infarction

The effects of left- and right-sided hemispheric brain infarction on variability in circadian blood pressure and cardiovascular measures were investigated in 35 patients to test for asymmetry of the sympathetic consequences of stroke. No significant differences regarding age, size of infarction or extent and frequency of damage to the insular cortex could be detected between the two groups. Patients with right-sided infarction showed a significantly reduced circadian blood pressure variability [diastolic: -1% (95% CI -4 to 1) vs -6% (-9 to -2); P < 0.05] and a higher frequency of nocturnal blood pressure increase (47% vs 35%; P < 0.05) as compared with patients with left-sided infarction. Right-sided infarction was also associated with higher serum noradrenaline concentrations [546 pg/ml (95% CI 415-677) vs 405 pg/ml (266-544); P < 0.05], and ECG more frequently showed QT prolongation (53% vs 35%; P < 0.05) and cardiac arrhythmias (67% vs 20%; P < 0.005). However, irrespective of the hemisphere damaged, patients with insular infarction showed the most pronounced changes of these parameters. In addition, two patients with right-sided strokes (13%) involving the insula, but none with a left-sided infarction, developed myocardial infarction. These findings suggest lateralization of sympathetic activation with right-sided dominance for sympathetic effects following hemispheric stroke.

Ambulatory blood pressure monitoring in paediatric patients treated by regular haemodialysis and peritoneal dialysis

Ambulatory blood pressure monitoring (ABPM) has been shown to be more representative of blood pressure (BP) levels than casual BP measurements in adult patients treated by haemodialysis (HD). In this study we compared ABPM using the oscillometric SpaceLabs 90207 monitor with casual BP measurements in 35 paediatric patients [17 treated by peritoneal dialysis (PD) and 18 by HD]. Heart rate and plasma concentrations of atrial natriuretic peptide were also measured. No correlations were found between ABPM and causal BP measurements, except for systolic day-time BP in PD patients (r = 0.63). Seventy percent of PD and 33% of HD patients were regarded as hypertensive when evaluated by ABPM, while casual BP measurements demonstrated hypertension in 47% (P < 0.05) of PD patients and in 44% (NS) of HD patients. One-third of patients were reclassified by ABPM either from normotensive to hypertensive (7/19) or from hypertensive to normotensive (5/16). BP assessed by ABPM was higher in PD than in HD patients. The physiological decline of BP at night was significant and more pronounced in PD than in HD patients. In HD patients day-time BP did not differ between the 1st and the 2nd interdialytic day, but increased in the night hours before the following dialysis session. A positive correlation was found between day-time BP and pre-dialysis plasma atrial natriuretic peptide in both treatment groups. In conclusion this study demonstrates that casual BP recordings are not representative of average BP in dialysed paediatric patients. ABPM is useful in the diagnosis and treatment of hypertension in children with end-stage renal disease.

Mathematical modeling of noninvasive blood pressure estimation techniques--Part I: Pressure transmission across the arm tissue

A mathematical model of the arm tissue mechanical behavior under the effect of external pressure loads is presented. The model has been used to study stress and strain distribution across the tissue, and pressure transmission to the brachial artery, when the arm is compressed by two adjacent cuffs independently inflated. Using this configuration, the tissue elastic parameters (Young modulus and Poisson ratio) can be individually identified using a simple and noninvasive experimental procedure. Model validation has been achieved by comparing its results with data obtained experimentally on 10 subjects. These comparisons demonstrate that the proposed model may constitute a simple but valid new tool able to describe tissue behavior, subjected to external pressures, with sufficient accuracy. Joined with a model of brachial hemodynamics, it might contribute to improve our understanding of noninvasive blood pressure estimation techniques.

Treatment of mild hypertension with low once-daily doses of a sustained-release capsule formulation of verapamil

The efficacy and safety of a low dose (120 mg) of a sustained-release capsule formulation of verapamil administered once daily in the treatment of 42 patients with mild hypertension were assessed in this clinical trial. After a 4-week placebo washout period (baseline), patients with diastolic clinic blood pressures of 91 to 100 mm Hg inclusive were treated for 4 weeks with once-daily verapamil sustained-release 120 mg capsules. Clinic blood pressure was measured and 24-hour ambulatory blood pressure monitoring was performed at the end of both the baseline and the 4-week treatment periods. Twenty-four hour, day, and night systolic and diastolic ambulatory blood pressure were significantly (P < 0.01) reduced in the entire study population (24-hour, -5/-4 mm Hg; day, -6/-4 mm Hg; night, -4/-3 mm Hg). On the basis of mean daytime (6 AM to 6 PM) ambulatory diastolic blood pressure, patients were stratified into subgroups of patients with confirmed (> 85 mm Hg) and unconfirmed mild hypertension (< or = 85 mm Hg). The magnitude of the mean change in systolic and diastolic blood pressure was greater in the group of patients with confirmed mild hypertension than the group with unconfirmed hypertension. The incidence of adverse experiences was low in frequency and events were of mild severity; quality of life scores improved (P = 0.02). Low daily doses (120 mg) of verapamil sustained-release capsules provide a well-tolerated and sustained antihypertensive effect over 24 hours in patients with mild hypertension.

Measuring hypertensive cardiovascular risk: the vascular overload concept

Hypertensive cardiovascular risk may be related primarily to vascular overload, the sum of three vascular abnormalities: increased arteriolar resistance, increased large-artery stiffness, and the effect of increased early pulse-wave reflection. A method for quantifying vascular overload as an index can be derived from measurements of mean arterial pressure and pulse pressure. Several lines of evidence support the hypothesis that abnormal artery stiffness and early pulse-wave reflection become larger components of vascular overload as the duration and severity of hypertension increase. Moreover, these studies suggest that vascular overload is a true indicator of hypertensive cardiovascular risk. Increased systolic blood pressure is a surrogate for vascular overload in young and middle-aged hypertensive subjects. Increased pulse pressure and decreased diastolic pressure are superior to increased systolic pressure as surrogates for vascular overload in geriatric isolated systolic hypertension. By itself, diastolic blood pressure is difficult to interpret and may be an epiphenomenon. Therefore new therapeutic goals, are control of systolic pressure in the young and of pulse pressure in the elderly.

Changes of circadian blood pressure patterns after hemodynamic and thromboembolic brain infarction

BACKGROUND AND PURPOSE

We investigated the changes of circadian blood pressure patterns after thromboembolic and hemodynamic brain infarction and evaluated the relation between circadian blood pressure variation, infarct location, and activation of the autonomic nervous system after thromboembolic stroke.

METHODS

Repeated 24-hour blood pressure measurements were performed in 45 patients with proven first-ever brain infarctions of different origins. Evaluation of serum norepinephrine concentration, prolongation of the QT interval, and degree of cardiac arrhythmias were used to determine the extent of sympathetic activation after thromboembolic stroke.

RESULTS

Whereas circadian blood pressure variation was significantly increased after hemodynamic infarction compared with a control group (diastolic, -25.2 +/- 4.5% versus -13.8 +/- 6.5%; p < .005), a clearly reduced variation was observed after thromboembolic infarction (diastolic, -5.2 +/- 6.9%). Blood pressure variation was positively related to serum norepinephrine concentration (r = .79; P < .01) after thromboembolic infarction. Patients with involvement of the insular cortex showed a nocturnal rise of blood pressure significantly more frequently (66.7% versus 11.8%; P < .005) and had higher norepinephrine levels (66.7 +/- 110 pg/mL versus 290 +/- 178 pg/mL; P < .01) than patients without insular cortex infarction, indicating increased sympathetic activity. This was associated with a significantly more frequent occurrence of QT prolongation and cardiac arrhythmias.

CONCLUSIONS

The observed differences in circadian blood pressure patterns may (1) help to distinguish the pathophysiological basis of the stroke, (2) help to explain worsening in some cases of hemodynamic stroke, (3) confirm the importance of the insular cortex for sympathetic activation, and (4) identify subgroups of patients with increased risk of myocardial infarction and arrhythmia.

Changes in circadian rhythm of blood pressure in on-call pediatric residents

To provide an objective measure of the effects of on-call stress on the blood pressure (BP) of a group of pediatric residents, we used a SpaceLabs Ambulatory Blood Pressure Monitor (ABPM) to compare 37 pediatric residents' on- and off-call BPs. Residents wore the ABPM for 24 h (once on call and again off call) to assess systolic and diastolic BPs every 30 min during the day and hourly overnight. We found significantly higher MESOR (an acronym for midline estimating statistic of rhythm, which yields a mean value more representative of the true mean than an average of a series of measurements) BPs and BP loads (%BP readings > 135 mm Hg for systolic and/or 85 mm Hg diastolic) during the on-call period. Some residents became hypertensive on call, and the normal 24-h pattern of lower nighttime blood pressures was altered during this period. ABPM monitoring may prove useful in evaluating the effectiveness of interventions to reduce the stress of residency training.

Evaluation of blood pressure measuring devices

Validation of blood pressure measuring devices is a relatively new field of research. There are two national protocols for validating blood pressure measuring devices: the protocol of the American Association for the Advancement of Medical Instrumentation (AAMI) and the protocol of the British Hypertension Society (BHS), each of which has recently been revised. 19 blood pressure measuring devices have been validated according to one or both of these protocols. These protocols have been beneficial in drawing attention to the potential inaccuracy of blood pressure measuring systems, they permit comparison between devices and they have brought manufacturers of blood pressure measuring devices into closer contact with the profession. There are some inherent weaknesses in both protocols which include the fallibility of the 'gold standard', the lack of provision for validation in special circumstances and in special groups, such as the elderly and pregnant women, and failure to allow for deteriorating accuracy with higher pressure levels. The revised BHS protocol attempts to redress these deficiencies.

Bias and variability in blood pressure measurement with ambulatory recorders

This study sought to determine whether patient characteristics such as age, sex, blood pressure, and pulse pressure differently affect the accuracy of an oscillometric (SpaceLabs 90207) and a microphonic (TM2420 version 7) blood pressure monitor. Blood pressure recorded by two oscillometric and two microphonic ambulatory monitors was compared with simultaneous readings by two pairs of trained, blinded observers using random-zero sphygmomanometry. One hundred and eighteen subjects (53 men and 65 women, aged 17 to 94 years; systolic pressure, 89 to 211 mm Hg; diastolic, 44 to 116 mm Hg) were studied. There were no significant differences within each observer pair or between the two observer pairs as well as no correlation between interobserver differences and patient characteristics. The differences between the monitor and trained observers' readings were 2.8 +/- 9.9 mm Hg systolic and 3.9 +/- 6.8 mm Hg diastolic for the SpaceLabs and 5.0 +/- 5.2 mm Hg systolic and 3.4 +/- 6.1 mm Hg diastolic for the TM2420. Patient characteristics that predicted measurement error were defined by multiple regression. For oscillometry, systolic measurement error was highly correlated with systolic pressure, pulse pressure, and subject age. The diastolic error was significantly correlated with pulse pressure, diastolic pressure, and subject sex. For the oscillometric monitor, patient characteristics accounted for 36.6% of the variation of the systolic error and 34.7% of the variation of the diastolic error. For the microphonic monitor, only age correlated with diastolic error, and no significant correlations were seen with systolic error. Patient characteristics accounted for only 1.2% of the systolic and 8.9% of the diastolic error.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic characteristics of hypertension: importance of positive family history

This study was performed to compare metabolic and endocrine characteristics of untreated hypertensive patients and normal controls. Measurements were made in age-matched, body mass index (BMI) matched, normotensive patients with (n = 40; age = 53; BMI = 28) and without (n = 39; age = 54; BMI = 27) a family history of hypertension and hypertensive patients with (n = 38; age = 53; BMI = 28) and without (n = 25; age = 54; BMI = 29) a family history of hypertension. Norepinephrine, renin activity, and total cholesterol blood concentrations were similar in normotensive patients with a positive family history of hypertension and in hypertensive patients with or without a family history. Similarly, there were no differences in plasma insulin concentrations or insulin/glucose ratios between the normotensive patients with a family history of hypertension and hypertensive patients with or without a family history. But in all three groups the values were significantly greater (at least p < 0.05 for each) than in the normotensive patients without a family history. Increases in systolic blood pressure during treadmill testing were 51 +/- 4 mm Hg in the normotensive patients with a family history, 50 +/- 3 mm Hg in hypertensives with a family history, and 45 +/- 5 mm Hg in hypertensives without a family history; these changes were all less (p < 0.05 for each) than in normotensives without a family history (65 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

A clinical trial evaluating the 24-hour effects of bisoprolol/hydrochlorothiazide 5 mg/6.25 mg combination in patients with mild to moderate hypertension

This study used 24-h ambulatory blood pressure (BP) monitoring to investigate the effectiveness of a novel low-dose combination of bisoprolol/hydrochlorothiazide in adult patients with mild to moderate essential hypertension. Thirty-six patients with stable mild to moderate hypertension (sitting diastolic BP 95-114 mmHg) after a placebo run-in phase received oral bisoprolol/hydrochlorothiazide 5 mg/6.25 mg once daily for 4 weeks in a single-blind regimen. At office visits, BP and pulse were measured with statistically significant reductions (p < 0.01) recorded after 2 and 4 weeks of treatment. Twenty-four-h ambulatory BP monitoring at the completion of therapy revealed significant reductions (p < 0.01) in both systolic and diastolic 24-h, daytime, and nighttime BP, compared with the end of the placebo treatment phase. Systolic and diastolic load were also reduced (p < 0.01). The combination was well tolerated, and overall quality-of-life questionnaire scores indicated an improvement after bisoprolol/hydrochlorothiazide therapy (p = 0.02). No clinically significant changes from baseline in laboratory parameters were observed; in particular, serum potassium was unchanged. This is the first study to demonstrate the 24-h effectiveness of the bisoprolol/hydrochlorothiazide 5 mg/6.25 mg combination, using 24-h ambulatory BP monitoring. In addition, antihypertensive therapy with low doses of bisoprolol/hydrochlorothiazide in combination may improve tolerability.

Circadian blood pressure patterns in four cases with hemodynamic brain infarction and prolonged blood-brain barrier disturbance

We report on four patients with hemodynamic brain infarction and pathological circadian blood pressure patterns with nocturnal hypotension which gave rise to a prolonged disturbance of the blood-brain barrier. Besides at least one severe stenosis of the internal carotid artery, there was an untreated chronic arterial hypertension and a pathologically reduced vasomotor reactivity after CO2 stimulation in all patients. The 24-h blood pressure monitoring then carried out showed a distinctly pathological circadian profile with hypertensive day values and nocturnal hypotension with minimum values of 95/50 mm Hg. The range of variation between day and night values was significantly raised (systolic: 20% +/- 2.15%; diastolic: 22.9% +/- 2.58%) compared to patients with essential hypertension as well as normotensive subjects (P < 0.01), and was in excess of 40% in the individual case. There was a slow recovery of the blood-brain barrier after drug-induced normalization of the pathological circadian blood pressure profile. We conclude that the registration of circadian blood pressure patterns may be of prognostic and therapeutic relevance. It may also contribute to further clarification of the pathophysiological significance of blood pressure variability for the development of brain infarction.

Sustained-release nicardipine in mild-to-moderate hypertension

STUDY OBJECTIVE

To evaluate the antihypertensive effects and tolerability of a sustained release preparation of nicardipine (NIC SR), a dihydropyridine calcium channel antagonist.

DESIGN AND INTERVENTIONS

After at least 1 week without receiving antihypertensive medications and 2 weeks of single-blind placebo treatment, the patients were randomized to receive in a double-blind fashion, either placebo or NIC SR 30, 45, or 60 mg twice daily at 12-h intervals for 12 weeks. Supine and standing blood pressure were measured in all patients and 24-h ambulatory blood pressure monitoring was performed in a subset of 75 patients at baseline during treatment with single-blind placebo and during the double-blind treatment period.

SETTING

Academic and private hypertension research clinics.

PATIENTS

Two hundred sixty-four patients with supine diastolic blood pressures of 95 to 114 mm Hg, ranging in age from 22 to 75 years and in weight from 50 to 137 kg, approximately evenly divided by gender; one third were black.

RESULTS

In comparison with placebo, all doses of NIC SR significantly reduced systolic and diastolic blood pressures, with a trend toward greater effects from 45 to 60 mg twice daily than with 30 mg twice daily. At all doses, reduction of blood pressure from baseline levels was fully apparent within the first 2 weeks of therapy and was maintained throughout the remaining 10 weeks of the trial. Ambulatory blood pressure monitoring demonstrated that the antihypertensive effect was maintained throughout the dosing interval. Adverse effects were primarily extensions of pharmacologic activity (eg, pedal edema, flushing). Six percent of the placebo group and 10 percent of the combined NIC SR groups experienced at least one adverse event that was judged to be probably related to therapy. Withdrawals due to unacceptably high blood pressure totaled 5 percent of the combined NIC SR groups and 25 percent of the placebo group.

CONCLUSIONS

Sustained-release nicardipine at a dose of 30 to 60 mg every 12 h provided effective and generally well-tolerated antihypertensive control throughout the day in most patients with mild-to-moderate essential hypertension.

Comparison of bisoprolol with atenolol for systemic hypertension in four population groups (young, old, black and nonblack) using ambulatory blood pressure monitoring. Bisoprolol Investigators Group

The antihypertensive effects of drugs are partly determined by characteristics of the patients treated. A randomized, double-blind study used 24-hour ambulatory blood pressure (BP) monitoring to compare the effects of 2 beta blockers, bisoprolol (10 to 20 mg; n = 107) and atenolol (50 to 100 mg; n = 96), administered once daily in 4 population groups. After a 4-week placebo period, patients with an office diastolic BP between 95 and 114 mm Hg were stratified according to race and age, and were randomly assigned to treatment with bisoprolol or atenolol for 8 weeks. BP averages measured by automated monitoring for the 24-hour periods were compared between groups. In elderly patients, the reductions in both average 24-hour systolic and diastolic BP were greater with bisoprolol than with atenolol (13 +/- 3/13 +/- 1 mm Hg [n = 23] vs 4 +/- 2/6 +/- 1 mm Hg [n = 30]; p < 0.01). Similarly, bisoprolol produced greater reductions in average 24-hour diastolic BP than did atenolol in nonblack patients (16 +/- 2/12 +/- 1 mm Hg [n = 85] vs 12 +/- 2/9 +/- 1 mm Hg [n = 83]; p = 0.02). Bisoprolol and atenolol were similar in the black (10 +/- 5/9 +/- 3 mm Hg [n = 22] and 10 +/- 6/6 +/- 3 mm Hg [n = 13], respectively) and young (15 +/- 1/11 +/- 1 mm Hg [n = 84] and 16 +/- 2/10 +/- 1 mm Hg [n = 66], respectively) groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-four hour blood pressure monitoring in healthy children

Blood pressure and heart rate were measured every 20 min during the day and every 30 min during the night in 105 children (51 girls and 54 boys, aged 6-10 years) with a portable automated blood pressure monitor using an oscillometric principle of measurement. The monitor was well accepted by most of the children and the rate of invalid measurements was only 13%. Mean systolic and diastolic blood pressure was 114 +/- 7/72 +/- 5 by day and 99 +/- 7/56 +/- 6 by night. The corresponding heart rates were 93 +/- 8 and 72 +/- 9 beats/min. No significant differences were found between boys and girls. At night, systolic blood pressure dropped by 13% +/- 4%, the diastolic value by 22% +/- 7% and heart rate fell by 22% +/- 6%. Mean systolic and diastolic blood pressure measurements correlated positively with the subject's height, whereas no correlation was found with age.

Ambulatory blood pressure: a predictor of left ventricular mass and future blood pressure in subjects predisposed for hypertension

Twenty-four-hour ambulatory blood pressure (SpaceLab 5200) and a single laboratory blood pressure were measured in a population-derived sample of normotensive men (mean age 36 years) with (n = 13) or without (n = 16) a positive family history of hypertension. The aim was to determine whether ambulatory monitoring was a better predictor than clinical measurements for echocardiographic derived indices of left ventricular mass and for future blood pressure. At the initial examination ambulatory blood pressure could discriminate between the groups, showing significant differences that were not evident from the clinical blood pressure measurement. After 5 years the blood pressure had increased in the group with a family predisposition for hypertension but only one subject had overt hypertension. The correlation between the average day-time blood pressure and the clinical blood pressure at follow-up was only marginally better than the correlation for the initial clinical blood pressure. In contrast to the clinical blood pressure, both day-time and night-time blood pressure averages were significantly correlated to left ventricular mass at the initial examination. It is concluded that in still normotensive subjects, ambulatory monitoring is a better predictor than clinical measurements for left ventricular mass but not for future blood pressure.

Office and ambulatory blood pressure in patients with craniomandibular disorders

To assess the physiologic response to daily life stress in patients with craniomandibular disorders (CMD), office and ambulatory blood pressure and heart rate were studied in 25 female patients and 25 controls. Significant differences (p < 0.05) were found between the groups for heart rate before the clinical examination and that in the patient group when compared before and after the clinical examination. Higher values were found for mean daytime systolic and diastolic blood pressure in the control group compared with the patient group (p < 0.05). The mean number of systolic blood pressure > or = 140 mmHg during 24 h and daytime was significantly higher (p < 0.05) in the control group than in the patient group. In this study the CMD patients with muscular diagnosis were not more stressed than healthy subjects in the daily activities as evaluated by ambulatory blood pressure measurements.