An evaluation of the A&D UA-751 semi-automated cuff-oscillometric sphygmomanometer

Sources of inaccuracy in the measurement of adult patients' resting blood pressure in clinical settings: a systematic review

BACKGROUND

To interpret blood pressure (BP) data appropriately, healthcare providers need to be knowledgeable of the factors that can potentially impact the accuracy of BP measurement and contribute to variability between measurements.

METHODS

A systematic review of studies quantifying BP measurement inaccuracy. Medline and CINAHL databases were searched for empirical articles and systematic reviews published up to June 2015. Empirical articles were included if they reported a study that was relevant to the measurement of adult patients' resting BP at the upper arm in a clinical setting (e.g. ward or office); identified a specific source of inaccuracy; and quantified its effect. Reference lists and reviews were searched for additional articles.

RESULTS

A total of 328 empirical studies were included. They investigated 29 potential sources of inaccuracy, categorized as relating to the patient, device, procedure or observer. Significant directional effects were found for 27; however, for some, the effects were inconsistent in direction. Compared with true resting BP, significant effects of individual sources ranged from -23.6 to +33 mmHg SBP and -14 to +23 mmHg DBP.

CONCLUSION

A single BP value outside the expected range should be interpreted with caution and not taken as a definitive indicator of clinical deterioration. Where a measurement is abnormally high or low, further measurements should be taken and averaged. Wherever possible, BP values should be recorded graphically within ranges. This may reduce the impact of sources of inaccuracy and reduce the scope for misinterpretations based on small, likely erroneous or misleading, changes.

Clinical efficacy of percutaneous renal revascularization with stent placement in hypertension among patients with atherosclerotic renovascular diseases

AIM

The aim was to assess the effect of renal angioplasty with stent on systolic, diastolic, and mean arterial blood pressure (MAP) in awake and sleep time with ambulatory blood pressure (ABP) monitoring (Holter monitoring).

MATERIALS AND METHODS

Patients with angiographically proven atherosclerotic renal artery stenosis (RAS) were referred to the Angiography Department of Imam Hospital for intervention during a 1-year period from June 2008 to December 2009. Primary stent placement was attempted by a single operator in 27 severe RAS cases although 1 case was omitted from the study because of technical failure. Pre- and postprocedure creatinine levels, ejection fraction (EF), history of diabetes mellitus (DM), and ABP were obtained. Twenty-six (17 men, 9 women; average age, 62.6 years; age range, 90-21 years) consecutive patients participated in the study.

RESULTS

All patients had severe hypertension resistant to multiple medications; 10 patients had impaired renal function (serum creatinine level greater than 130 µmol/L). A total of 3 (11.5%) patients had congestive heart failure, and 10 (37.7%) were diabetic. Hypertension was cured in 1 (4%) patient, had improved in 23 (88.4%) patients, and had failed to respond to treatment in 2 (7.6%). Serum creatinine decreased significantly from 1.46 ± 0.89 to 1.35 ± 0.61 mg/dL (P<0.05).

CONCLUSION

Percutaneous transluminal angioplasty for atheromatous RAS rarely cures hypertension, but improved blood pressure control is often achieved.

Simple, shared guidelines raise the quality of antihypertensive treatment in routine care

AIMS

To assess the impact of simple, collectively produced, evidence-based guidelines on optimizing the choice of antihypertensive drugs in routine care.

METHODS AND RESULTS

Forty-eight physicians agreed to produce and test these guidelines for 1 year in their daily practice on a random sample of 1049 treated hypertensive patients (intervention group). A control group of 42 general practitioners recruited and followed up for 1 year a parallel nonintervention cohort of 722 treated hypertensive patients. After 1 year of follow-up, the patients in the nonintervention group had no changes in any of the predefined end points. In the intervention group, the use of diuretics and beta-blockers--drugs with documented preventive efficacy--increased, respectively, from 48.3% to 57.6% and from 22.0% to 29.7%; and the proportion of hypertensive patients receiving indicated drugs (with no contraindications) rose from 66.1% to 73.0%. The prescription of poorly tolerated drugs decreased from 12.4% to 7.2%, and noncompliance with the antihypertensive therapy decreased from 5.2% to 3.8%. In the intervention group, both systolic and diastolic blood pressure control improved (systolic pressure <140 mm Hg, from 23.3% to 39.5%; diastolic pressure <90 mm Hg, from 65.4% to 87.4%).

CONCLUSIONS

An intervention strategy based on the collaborative production of simple evidence-based guidelines appears to be effective in raising the quality of antihypertensive therapy in routine care.

Comparison of agreement between different measures of blood pressure in primary care and daytime ambulatory blood pressure

OBJECTIVE

To assess alternatives to measuring ambulatory pressure, which best predicts response to treatment and adverse outcome.

SETTING

Three general practices in England.

DESIGN

Validation study.

PARTICIPANTS

Patients with newly diagnosed high or borderline high blood pressure; patients receiving treatment for hypertension but with poor control.

MAIN OUTCOME MEASURES

Overall agreement with ambulatory pressure; prediction of high ambulatory pressure (>135/85 mm Hg) and treatment thresholds.

RESULTS

Readings made by doctors were much higher than ambulatory systolic pressure (difference 18.9 mm Hg, 95% confidence interval 16.1 to 21.7), as were recent readings made in the clinic outside research settings (19.9 mm Hg,17.6 to 22.1). This applied equally to treated patients with poor control (doctor v ambulatory 21.4 mm Hg, 17.3 to 25.4). Doctors' and recent clinic readings ranked systolic pressure poorly compared with ambulatory pressure and other measurements (doctor r=0.46; clinic 0.47; repeated readings by nurse 0.60; repeated self measurement 0.73; home readings 0.75) and were not specific at predicting high blood pressure (doctor 26%; recent clinic 15%; nurse 72%; patient in surgery 81%; home 60%), with poor likelihood ratios for a positive test (doctor 1.2; clinic 1.1; nurse 2.1, patient in surgery 4.7; home 2.2). Nor were doctor or recent clinic measures specific in predicting treatment thresholds.

CONCLUSION

The "white coat" effect is important in diagnosing and assessing control of hypertension in primary care and is not a research artefact. If ambulatory or home measurements are not available, repeated measurements by the nurse or patient should result in considerably less unnecessary monitoring, initiation, or changing of treatment. It is time to stop using high blood pressure readings documented by general practitioners to make treatment decisions.

The effect of differences in measurement procedure on the comparability of blood pressure estimates in multi-centre studies

The procedures for obtaining blood pressure measurements, and their quality of performance, should be similar between epidemiological studies to allow a valid comparison of blood pressure distribution and prevalence of hypertension between study populations. However, considerable methodological variation currently exists as there are several international guidelines on blood pressure measurement and a standard method of measurement has not yet been agreed. This paper reviews the literature in order quantitatively to define systematic differences between blood pressure measurements resulting from differences in arm used, body position, number of measurements, verbal communication, cuff size applied and measuring device used. The results were applied to differences in procedure between European Prospective Investigation into Cancer and Nutrition (EPIC) study centres, showing that blood pressure measurements may systematically differ between centres by as much as 10 mmHg for procedural reasons alone. For most reviewed methodological differences, it was possible to at least estimate a range of systematic error. There are, however, additional possible causes of systematic variation, for example arm position, postprandial hypotension and diurnal blood pressure variation, that could not be taken into account. It may be possible to make only a partial correction for the systematic inter-centre variation of the EPIC blood pressure measurements. This study highlights the importance of standardized protocols for blood pressure measurements in epidemiological studies.

Evidence for persistence of upper airway narrowing during sleep, 12 years after adenotonsillectomy

AIMS

To establish whether subjects with previous evidence of sleep apnoea prior to adenotonsillectomy continue to have evidence of narrower upper airways during sleep, 12 years later.

METHODS

Twenty subjects (median age 16 years) underwent repeat sleep studies at home, 12 years after such studies had shown significant sleep apnoea in many of them prior to an adenotonsillectomy. Twenty control subjects, also studied 12 years ago, underwent repeat home sleep studies as well. The sleep studies provided information on snoring, hypoxia, and inspiratory effort (from measures of pulse transit time). A questionnaire was also administered, the subjects were weighed, and their heights measured.

RESULTS

There was more reported snoring in the previous adenotonsillectomy group (50% versus 20%) and also during the sleep study (80 versus 31 snores per hour). The measure of inspiratory effort overnight was higher in the previous adenotonsillectomy group (15.6 versus 12.3 ms). Allowance for potentially confounding variables (obesity and nasal congestion) partially reduced the statistical significance of the difference in snoring, but not that of the measure of inspiratory effort.

CONCLUSION

Results suggest that a narrower upper airway during sleep, to the point of snoring, persists 12 years after adenotonsillectomy, and may partly account for the occurrence earlier of preoperative sleep apnoea while adenotonsillar hypertrophy was present. It is not known if this narrowing is one of the risk factors for later development of adult sleep apnoea.

Evaluation of two automatic sphygmomanometers in Hong Kong: implications for the future development of automated blood pressure monitors in clinical practice

The application of automated devices in measuring patients' blood pressure has been widely adopted in nursing practice. This study compared blood pressure recordings of two automated blood pressure monitors which were commonly used in clinical settings in Hong Kong. Single-arm recordings were obtained from 31 subjects with both devices. Ten blood pressure recordings were obtained for each subject, with half of the subjects taking five measurements from one device first and five measurements from the other device second, and vice versa. A total of 155 sets of measurements were available for analysis. The results indicated that there was no significant difference in the variation of systolic, diastolic, mean arterial pressure and heart rate between these two devices. Implications for future research and development of an improved automated blood pressure device are made.

Evaluation of a modified cognitive-behavioural programme for weight management

OBJECTIVE

To evaluate a modified cognitive-behavioural treatment (M-CBT) for weight management which addresses both the psychosocial costs and the physiological health risks of obesity, without a focus on weight loss.

DESIGN

Randomized controlled trial comparing M-CBT with standard cognitive-behavioural therapy (S-CBT).

SUBJECTS

Sixty-three overweight women with body mass index (BMI) > or = 28 kg/m2, mean age = 47.5 and mean BMI = 35.4.

MEASURES

Weight, waist and hip circumference, blood lipids, blood glucose, blood pressure, psychological well-being, depression, self esteem, stress, binge eating, eating style, body image, nutrient intake, aerobic fitness, activity levels, patient satisfaction with treatment.

RESULTS

Both M-CBT and S-CBT achieved improvements in a broad range of physical, psychological and behavioural variables. Weight loss in the S-CBT group was greater than in the M-CBT group immediately after treatment, but both groups lost weight. Participants in the M-CBT group continued to lose weight up to the 1 y follow-up. M-CBT was evaluated positively by participants.

CONCLUSIONS

Both M-CBT and S-CBT programmes were successful at inducing modest weight loss, as well as improving emotional well-being, reducing distress, increasing activity and fitness, improving dietary quality and reducing cardio-vascular disease risk factors. The improvements were maintained or continued at 1 y follow-up. These results suggest that treatment based on the new weight-control paradigm which emphasizes sustained lifestyle change without emphasis on dieting, can produce modest benefits to health and well-being.

Effects of low-dose aspirin on clinic and ambulatory blood pressure in treated hypertensive patients. Collaborative Group of the Primary Prevention Project (PPP)--Hypertension study

Nonsteroidal antiinflammatory drugs may affect blood pressure (BP) control in hypertensive patients receiving drug treatment, but data on the effects of low-dose aspirin are scanty. This study assessed the effects of chronic treatment with low doses of aspirin (100 mg/day) on clinic and ambulatory systolic (SBP) and diastolic (DBP) BP in hypertensives on chronic, stable antihypertensive therapy. The study was conducted in the framework of the Primary Prevention Project (PPP), a randomized, controlled factorial trial on the preventive effect of aspirin or vitamin E in people with one or more cardiovascular risk factors. Fifteen Italian hypertension units studied 142 hypertensive patients (76 men, 66 women; mean age 59 +/- 5.9 years) treated with different antihypertensive drugs: 71 patients were randomized to aspirin and 71 served as controls. All patients underwent a clinic BP evaluation with an automatic sphygmomanometer and a 24-h ambulatory BP monitoring, at baseline and after 3 months of aspirin treatment. At the end of the study the changes in clinic SBP and DBP were not statistically different in treated and untreated subjects. Ambulatory SBP and DBP after 3 months of aspirin treatment were similar to baseline: deltaSBP -0.5 mmHg (95% confidence intervals [CI] from -1.9 to +2.9 mm Hg) and deltaDBP -1.1 mm Hg (95% CI from -2.5 to +0.3 mm Hg). The pattern was similar in the control group. No interaction was found between aspirin and the most used antihypertensive drug classes (angiotensin converting enzyme inhibitors and calcium antagonists). Despite the relatively small sample size our results seem to exclude any significant influence of low-dose aspirin on BP control in hypertensives under treatment.

Comparison of three blood pressure measurement methods for the evaluation of two antihypertensive drugs: feasibility, agreement, and reproducibility of blood pressure response

Our objective was to compare three different methods of blood pressure measurement through the results of a controlled study aimed at comparing the antihypertensive effects of trandolapril and losartan. Two hundred and twenty-nine hypertensive patients were randomized in a double-blind parallel group study. After a 3-week placebo period, they received either 2 mg trandolapril or 50 mg losartan once daily for 6 weeks. At the end of both placebo and active treatment periods, three methods of blood pressure measurement were used: a) office blood pressure (three consecutive measurements); b) home self blood pressure measurements (SBPM), consisting of three consecutive measurements performed at home in the morning and in the evening for 7 consecutive days; and c) ambulatory blood pressure measurements (ABPM), 24-h BP recordings with three measurements per hour. Of the 229 patients, 199 (87%) performed at least 12 valid SBPM measurements during both placebo and treatment periods, whereas only 160 (70%) performed good quality 24-h ABPM recordings during both periods (P < .0001). One hundred-forty patients performed the three methods of measurement well. At baseline and with treatment, agreement between office measurements and ABPM or SBPM was weak. Conversely, there was a good agreement between ABPM and SBPM. The mean difference (SBP/DBP) between ABPM and SBPM was 4.6 +/- 10.4/3.5 +/- 7.1 at baseline and 3.5 +/- 10.0/4.0 +/- 7.0 at the end of the treatment period. The correlation between SBPM and ABPM expressed by the r coefficient and the P values were the following: at baseline 0.79/0.70 (< 0.001/< .0001), with active treatment 0.74/0.69 (0.0001/.0001). Hourly and 24-h reproducibility of blood pressure response was quantified by the standard deviation of BP response. Compared with office blood pressure, both global and hourly SBPM responses exhibited a lower standard deviation. Hourly reproducibility of SBPM response (10.8 mm Hg/6.9 mm Hg) was lower than hourly reproducibility of ABPM response (15.6 mm Hg/11.9 mm Hg). In conclusion, SBPM was easier to perform than ABPM. There was a good agreement between these two methods whereas concordance between SBPM or ABPM and office measurements was weak. As hourly reproducibility of SBPM response is better than reproducibility of both hourly ABPM and office BP response, SBPM seems to be the most appropriate method for evaluating residual antihypertensive effect.

Which aspects of breathing during sleep influence the overnight fall of blood pressure in a community population?

BACKGROUND

Obstructive sleep apnoea (OSA) causes recurrent rises in blood pressure during sleep, and recent community surveys have suggested a link between mild OSA and diurnal hypertension. The fact that OSA and hypertension share some risk factors, as well as problems accurately quantifying OSA severity, have diluted the power of such studies. This study tries to circumvent some of these problems by measuring the overnight change in blood pressure and relating it to relevant measures of the severity of upper airway obstruction on the same night.

METHODS

Men born between 1930 and 1960 and their wives living in a market town north of Oxford were identified from a GP practice register. Enough couples were recruited to provide approximately 10 (20 individuals) per year of birth. Subjects were visited at home where a questionnaire was administered, anthropometric measurements made, blood pressures taken (including by the subject), and sensors applied for a subsequent overnight sleep study. The sleep study measured indices of hypoxia, snoring, autonomic arousal, degree of respiratory effort; the last two of these derived from measurements of pulse transit time (indirect beat to beat blood pressure). After waking the following morning, the subjects took their own blood pressures again.

RESULTS

Data were available from 224 couples (448 subjects). On average, systolic BP fell 8 mm Hg from evening to morning. Only hypoxic dips (>4% SaO(2) dips/h) and the measure of degree of respiratory effort were significant independent predictors of this overnight change in systolic BP, together accounting for 7-10% of the variation (p<0.0001). Dividing the subjects into quartiles according to the respiratory effort overnight showed a progressive reduction in the fall of systolic BP overnight: 13.6, 10.8, 7.3, and 5.6 mm Hg, lowest to highest quartiles.

CONCLUSIONS

This study suggests that increased respiratory effort during sleep (seen in OSA and related syndromes of increased upper airway resistance during sleep) offsets the normal fall in BP that occurs overnight, even within this community population. This may be one of the mechanisms by which hypertension is carried over into the waking hours in patients with OSA.

Effects of vitamin E on clinic and ambulatory blood pressure in treated hypertensive patients. Collaborative Group of the Primary Prevention Project (PPP)--Hypertension study

A randomized controlled open trial studied the effect of vitamin E supplementation (300 mg/day) on clinic and 24-h ambulatory blood pressure (BP) in 142 treated hypertensive patients. After 12 weeks, clinic BP decreased whether or not patients were randomized to vitamin E. Ambulatory BP showed no change in systolic BP and a small decrease in diastolic BP (-1.6 mm Hg, 95% confidence intervals from -2.8 to -0.4 mm Hg), approaching statistical significance in comparison to the control group (P = .06). Vitamin E supplementation thus seems to have no clinically relevant effect on BP in hypertensive patients already under controlled treatment.

Electronic pill-boxes in the evaluation of antihypertensive treatment compliance: comparison of once daily versus twice daily regimen

The objective was to compare the compliance of hypertensive patients treated with captopril twice daily or trandolapril once daily. After a 2-week placebo period, hypertensive patients (diastolic BP 95-115 mm Hg) were randomly allocated to trandolapril 2 mg once daily or to captopril 25 mg twice daily for 6 months. Trandolapril and captopril were packed in electronic pill-boxes equipped with a microprocessor that recorded date and time of each opening (MEMS). Patients' compliance was assessed both by standard pill-count and by electronic monitoring. Blood pressure was measured using a validated semi-automatic device at the end of the placebo period and of the treatment period. One hundred sixty-two patients entered the study. Compliance data were evaluable for 133 patients (62 in the captopril group and 71 in the trandolapril group). Treatment groups were comparable at baseline except for age (P = .046). Using electronic pill-box, overall compliance was 98.9% in the trandolapril group and 97.5% in the captopril group (P = .002). The percentage of missed doses was 2.6% in the trandolapril group and 3.3% in the captopril group (P = .06). The percentage of delayed doses was 1.8% in the trandolapril group and 11.7% in the captopril group (P = .0001). The percentage of correct dosing periods, ie, a period with only one correct recorded opening, was 94.0% in the trandolapril group and 78.1% in the captopril group (P = .0001). Results were unchanged when adjusted for age. At the end of the study, 41% of patients in the trandolapril group and 27% in the captopril group (NS) had their blood pressure normalized (systolic BP <140 and diastolic BP <90 mm Hg). In this 6-month study, the electronic pill-box allowed refined analysis of compliance of hypertensive patients. Patients' compliance with once daily trandolapril was higher than with twice daily captopril. The between-group difference is mainly explained by an increase in delayed doses in the twice daily group.

Job strain, blood pressure and response to uncontrollable stress

OBJECTIVE

The association between cardiovascular disease risk and job strain (high-demand, low-control work) may be mediated by heightened physiological stress responsivity. We hypothesized that high levels of job strain lead to increased cardiovascular responses to uncontrollable but not controllable stressors. Associations between job strain and blood pressure reductions after the working day (unwinding) were also assessed.

DESIGN

Assessment of cardiovascular responses to standardized behavioral tasks, and ambulatory monitoring of blood pressure and heart rate during a working day and evening.

PARTICIPANTS

We studied 162 school teachers (60 men, 102 women) selected from a larger survey as experiencing high or low job strain.

METHODS

Blood pressure, heart rate and electrodermal responses to an externally paced (uncontrollable) task and a self-paced (controllable) task were assessed. Blood pressure was monitored using ambulatory apparatus from 0900 to 2230 h on a working day.

RESULTS

The groups of subjects with high and low job strain did not differ in demographic factors, body mass or resting cardiovascular activity. Blood pressure reactions to the uncontrollable task were greater in high than low job-strain groups, but responses to the controllable task were not significantly different between groups. Systolic and diastolic blood pressure did not differ between groups over the working day, but decreased to a greater extent in the evening in subjects with low job strain.

CONCLUSIONS

Job strain is associated with a heightened blood pressure response to uncontrollable but not controllable tasks. The failure of subjects with high job strain to show reduced blood pressure in the evening may be a manifestation of chronic allostatic load.

Blood pressure outcome of angioplasty in atherosclerotic renal artery stenosis: a randomized trial. Essai Multicentrique Medicaments vs Angioplastie (EMMA) Study Group

Data for the effects on blood pressure of renal artery balloon angioplasty are mostly from uncontrolled studies. The aim of this study was to document the efficacy and safety of angioplasty for lowering blood pressure in patients with atherosclerotic renal artery stenosis. Patients were randomly assigned antihypertensive drug treatment (control group, n = 26) or angioplasty (n = 23). Twenty-four-hour ambulatory blood pressure, the primary end point, was measured at baseline and at termination. Termination took place 6 months after randomization or earlier in patients who developed refractory hypertension. In those allocated angioplasty, antihypertensive treatment was discontinued after the procedure but was subsequently resumed if hypertension persisted. Secondary end points were the treatment score and the incidence of complications. Two patients in the control group and 6 in the angioplasty group suffered procedural complications (relative risk, 3.4; 95% confidence interval, 0.8 to 15.1). Early termination was required for refractory hypertension in 7 patients in the control group. Antihypertensive treatment was resumed in 17 patients in the angioplasty group. Mean ambulatory blood pressure at termination did not differ between control (141+/-15/84+/-11 mm Hg) and angioplasty (140+/-15/81+/-9 mm Hg) groups. Angioplasty reduced by 60% the probability of having a treatment score of 2 or more at termination (relative risk, 0.4; 95% confidence interval, 0.2 to 0.7). There was 1 case of dissection with segmental renal infarction and 3 of restenosis in the angioplasty group. No patient suffered renal artery thrombosis. In unilateral atherosclerotic renal artery stenosis, angioplasty is a drug-sparing procedure that involves some morbidity. Previous uncontrolled and unblinded assessments of angioplasty overestimated its potential for lowering blood pressure.

Different concepts in first-line treatment of essential hypertension. Comparison of a low-dose reserpine-thiazide combination with nitrendipine monotherapy. German Reserpine in Hypertension Study Group

Low-dose combination therapy has been proposed as a rational first-line approach to hypertension treatment. We compared the efficacy and tolerability of the fixed combination of reserpine (0.1 mg) plus the thiazide clopamid (5 mg) with its single components and the calcium-antagonist nitrendipine (20 mg) in a randomized, double-blind, parallel study of 273 hypertensive patients with diastolic blood pressure (BP) between 100 and 114 mm Hg. The four groups did not differ regarding baseline characteristics (mean age, 58 years; 51% men; mean BP after a 2-week placebo period, 158 to 160/103 to 104 mm Hg). After 6 weeks of treatment with one capsule daily, mean reductions in sitting BP from baseline at 24 hours after dosing in the reserpine-clopamid combination, reserpine, clopamid, and nitrendipine groups were -23.0/-17.1, -14.0/-11.7, -13.6/-11.9, and -11.6/-12.3 mm Hg, respectively (2P < .01). The corresponding normalization rates (diastolic BP < 90 mm Hg) were 55%, 40%, 36%, and 33% (2P = .11). All patients whose BP had not been normalized at this point received two capsules of the respective medication once daily from weeks 7 to 12. At week 12, mean BP reductions were -25.7/-18.1, -14.6/-12.2, -17.7/-13.4, and -14.9/-15.3 mm Hg in the four groups, respectively (2P < .01). The respective normalization rates were 69%, 35%, 39%, and 45% (2P < .0001). Linear regression modeling indicated that reserpine and clopamid combined acted more than additively. As regards tolerability, adverse experiences were observed in 27%, 28%, 29%, and 48% of patients, respectively (2P < .05). The respective rates of premature discontinuation because of adverse effects were 3%, 3%, 7%, and 13% (2P = .06). In conclusion, a low-dose combination of reserpine and clopamid lowered BP significantly more than both the components alone and nitrendipine. Moreover, the combination was tolerated as well as its components and significantly better than nitrendipine. Thus, the use of this low-dose reserpine-thiazide combination appears to be a rational alternative to conventional monotherapy in the first-line treatment of hypertension.

Effects of bunazosin and atenolol on serum lipids and apolipoproteins in a randomised trial

The effects of bunazosin and atenolol on serum lipids and lipoproteins after 6 months of treatment were compared in this multicentric, double-blind, randomised trial. A total of 174 patients with mild to moderate essential hypertension from 15 hospitals in Germany and Poland was included in the study. Eighty-seven were treated with the alpha-receptor blocker bunazosin and the same number with the beta-blocker atenolol. Systolic and diastolic blood pressure decreased significantly in both groups, whereas only atenolol decreased pulse rate. In the bunazosin group HDL-cholesterol was significantly increased after 6 months of treatment, whereas all other analysed parameters remained unchanged. In the atenolol group total cholesterol, LDL-cholesterol, total triglycerides, apolipoprotein E, VLDL-cholesterol and VLDL-triglycerides were significantly increased after 6 months of therapy. There was a significant difference between bunazosin and atenolol for total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol, triglycerides, VLDL-triglycerides and apolipoprotein B levels. As a consequence, there was a significant difference in the atherogenic index of both groups. We conclude that bunazosin is favorable in the treatment of high blood pressure, because the coronary risk is not negatively influenced as shown for atenolol.

Feasibility study of N-of-1 trials with blood pressure self-monitoring in hypertension

The objective of this study was to assess individual responses to antihypertensive treatment by N-of-1 trials using blood pressure self-monitoring in 79 patients of both sexes referred to a hypertension clinic. Thirty-five patients who remained untreated (study 1) and 44 N-of-1 trial participants (study 2) were consecutively selected if their clinic blood pressure was between 160/95 and 220/115 mm Hg and there were no hypertensive complications. Blood pressure was measured daily at home for 21 days (three consecutive measures, morning and evening). Each N-of-1 trial was a single-blind treatment consisting of two successive 10-day treatment pairs, each pair comprising 5 days of placebo followed by 5 days of 20 mg enalapril once daily in the morning. Study 1 showed no significant blood pressure regression toward the mean over 20 days and justified the choice of 5-day treatment periods in study 2. In study 2, blood pressure fell significantly 12 hours after the first administration of enalapril and rose within 24 hours of the end of the 5-day active treatment period. Using evening blood pressure values (12 hours after enalapril intake) from the first treatment pair, 33 patients were classified as responders (diastolic blood pressure fall > or = mm Hg). In 16 of these 33 patients, the fall in blood pressure above 6 mm Hg was not maintained in the morning, 24 hours after drug intake. Response reproducibility was tested by comparison with the second treatment pair: the observed agreement was only 0.71 (chance-corrected agreement: 0.34) when defined according to both evening and morning values.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin converting enzyme inhibition does not affect the response to exogenous angiotensin II in the human forearm

Suppression of endogenous levels of angiotensin II by angiotensin converting enzyme inhibition, may result in up-regulation of vascular AT1 receptors. We have evaluated the effects of orally administered enalapril on angiotensin II induced vasoconstriction in the human forearm. Subjects received in random order, enalapril (20 mg) or matched placebo daily for 2 weeks. Forearm blood flow response to increasing doses of angiotensin II was measured using venous occlusion plethysmography at the beginning of the study and at the end of each 2 week treatment period. Treatment with enalapril significantly reduced plasma angiotensin II levels and supine blood pressure compared with placebo. The percentage reductions in forearm blood flow in the infused arm, in response to the maximum dose of angiotensin II (50,000 fmol min-1) were 48.1 +/- 3.6% at baseline, 57.5 +/- 3.6% on placebo and 54.5 +/- 4.2% on enalapril. The differences were not significantly different. This demonstrates that suppression of plasma angiotensin II for a 14 day period does not enhance the response to exogenous intra-arterial angiotensin II in the human forearm of healthy salt replete subjects.

Angiotensin converting enzyme inhibition does not affect response to exogenous angiotensin II in the forearm of mild-moderate hypertensive patients

It has been proposed that the suppression of endogenous levels of angiotensin II by angiotensin converting enzyme inhibition, may result in up-regulation of vascular AT1 receptors. This study evaluated the effects of orally administered enalapril on angiotensin II induced vasoconstriction in the human forearm of patients with mild-moderate hypertension. Patients received in random order, enalapril (20 mg) or matched placebo daily for 2 weeks. Forearm blood flow response to increasing doses of angiotensin II was measured using venous occlusion plethysmography at the beginning of the study and at the end of each 2 week treatment period. Treatment with enalapril significantly reduced plasma angiotensin II levels and supine blood pressure compared to placebo. The percentage reductions in forearm blood flow in the infused arm, in response to the maximum dose of angiotensin II (50 pmol.min-1) were 53.2% at baseline, 51.4% on placebo and 59.5% on enalapril. The differences were not significantly different. This study demonstrates that suppression of plasma angiotensin II does not enhance the response to exogenous intra-arterial angiotensin II in the human forearm of mild-moderately hypertensive patients.

A proposal for scientific validation of instruments for indirect blood pressure measurement at rest, during exercise, and in critical care

OBJECTIVE

The purpose of this study was to provide a critical review and comprehensive outline of published guidelines for the validation of monitors for indirect blood pressure (BP) measurement in light of recent research and practical clinical experience.

METHODS

Studies testing the reliability and validity of BP monitors and available guidelines for validation have been reviewed and compared.

RESULTS

The validation studies of instruments for indirect BP measurement have used a wide variety of sample pools, BP ranges, protocols, reference instruments, and statistical procedures, thereby making it impossible to reach a consensus. Few existing recommendations for validation have been found to be incomplete with respect to BP in various physiological states, sequence of procedures, sample, and statistical analysis.

CONCLUSIONS

A new sequence of procedures for validation, including assessment of instruments during exercise and in critical care, is introduced. Previously suggested sample sizes for study subjects, age, and BP groups, as well as margins of error, are statistically challenged. Insufficiency of linear relationship and aggregate agreement alone in determining the interchangeability between a reference and test instrument is demonstrated by quantification of agreement.

Systemic hemodynamics during sleep in young or middle-aged and elderly patients with essential hypertension

Age-related changes in cardiovascular regulatory mechanisms may affect blood pressure homeostasis during sleep and in the daytime. This study compared systemic hemodynamics during the daytime and sleep between 12 young or middle-aged patients (young, 42.1 +/- 13.9 years old, mean +/- SD, less than 56 years old) and 12 elderly patients with essential hypertension (old, 65.3 +/- 2.8, 60 to 70 years old). They were all hospitalized and placed on a diet containing approximately 7 g sodium chloride per day. Intra-arterial blood pressure and electrocardiogram were recorded for 24 hours, and electroencephalogram and electroophthalmogram were recorded during the night with a telemetric method. Cardiac output was measured with patients in the supine position by the cuvette method during the daytime and stage 3 or 4 sleep at night. The averaged 24-hour blood pressure was similar in the two groups (140 +/- 2 [SEM]/85 +/- 3 mm Hg in the young group and 144 +/- 4/81 +/- 2 mm Hg in the old group). The reduction in mean blood pressure during sleep was also comparable in both groups (-18 +/- 2 in the young group and -20 +/- 2 mm Hg in the old group). Cardiac index was smaller in the old group than the young group during both the daytime and sleep (daytime, 2.3 +/- 0.1 versus 3.2 +/- 0.2 [L/min]/m2, P < .01; sleep, 2.1 +/- 0.1 versus 2.6 +/- 0.2 [L/min]/m2, P < .01). The reduction in cardiac index during sleep was greater in the young than the old group (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of lacidipine and atenolol in mild to moderate hypertension

1. The aim of this randomised, double-blind four way crossover study was to assess the interaction between the new calcium antagonist, lacidipine and atenolol, in patients with mild to moderate hypertension. 2. Sitting blood pressure at 4 h post-dosing with lacidipine (4 mg) and atenolol (100 mg) alone was significantly lower compared with placebo (137/89 +/- 3/3 mmHg; 142/89 +/- 5/3 mmHg; and 154/98 +/- 5/3 mmHg respectively; P < 0.001). Co-administration of both drugs produced a significant additive effect compared with atenolol and lacidipine alone (124/80 +/- 4/2 mmHg; P < 0.002). 3. Heart rate on treatment with lacidipine alone was significantly greater at 4 h compared with placebo (86 +/- 1 beats min-1 and 74 +/- 2 beats min-1 respectively; P < 0.001). When both drugs were used in combination, there was a significant decrease in pulse rate compared with lacidipine alone (58 +/- 1 beats min-1 and 86 +/- 1 beats min-1 respectively; P < 0.001). 4. Home blood pressure recordings confirmed the statistically significant reduction in blood pressure on co-dosing (120/82 +/- 10/2 mmHg) compared with lacidipine (140/92 +/- 5/3 mmHg) and atenolol (146/90 +/- 6/3 mmHg) given alone (P < 0.05). 5. Lacidipine alone produced a significant exercise tachycardia compared with atenolol alone and the atenolol/lacidipine combination (97 +/- 8 beats min-1; 65 +/- 4 beats min-1 and 75 +/- 7 beats min-1 respectively; P < 0.001). Exercise tolerance was not adversely affected by the co-administration of both lacidipine and atenolol.

Self blood pressure measurement at home

Forty-six untreated patients measured their blood pressure at home for three weeks using an A and D, UA 751 automatic device, and were examined three times at the outpatient clinic. Home blood pressure was significantly lower than clinic blood pressure, even at the third visit when the correlations between clinic and home values were the most significant. The differences between clinic and home values had a gaussian distribution. The variance analysis of home blood pressure values showed that 67% of the variance was attributable to the between-subject component, 2% to the day effect, 15% to the time of the day effect and 16% to the residual (the measurement error). The standard deviation of the difference between two five-day periods of self blood pressure monitoring at home (5.4 and 4.1 mm Hg) was much lower than what has been reported for clinic measurements or 24-hour ambulatory monitoring.