Arterial stiffness as underlying mechanism of disagreement between an oscillometric blood pressure monitor and a sphygmomanometer

Oscillometric blood pressure devices tend to overestimate systolic blood pressure and underestimate diastolic blood pressure compared with sphygmomanometers. Recent studies indicate that discrepancies in performance between these devices may differ between healthy and diabetic subjects. Arterial stiffness in diabetics could be the underlying factor explaining these differences. We studied differences between a Dinamap oscillometric blood pressure monitor and a random-zero sphygmomanometer in relation to arterial stiffness in 1808 healthy elderly subjects. The study was conducted within the Rotterdam Study, a population-based cohort study of subjects aged 55 years and older. Systolic and diastolic blood pressure differences between a Dinamap and a random-zero sphygmomanometer were related to arterial stiffness, as measured by carotid-femoral pulse wave velocity. Increased arterial stiffness was associated with higher systolic and diastolic blood pressure readings by the Dinamap compared with the random-zero sphygmomanometer, independent of age, gender, and average mean blood pressure level of both devices. The beta-coefficient (95% CI) was 0.25 (0.00 to 0.50) mm Hg/(m/s) for the systolic blood pressure difference and 0.35 (0.20 to 0.50) mm Hg/(m/s) for the diastolic blood pressure difference. The results indicate that a Dinamap oscillometric blood pressure device, in comparison to a random-zero sphygmomanometer, overestimates systolic and diastolic blood pressure readings in subjects with stiff arteries

Blood pressure in atrial fibrillation

Introduction: Hypertension is a leading risk factor for cardiovascular morbidity and premature death. Prevalence of hypertension in the adult population in Sweden has been estimated to 27%. Atrial fibrillation (AF) is the most prevalent sustained arrhythmia of clinical relevance with an estimated prevalence of at least 2.9% among adults in Sweden. Similarly to hypertension, AF is independently associated with an increased risk for cardiovascular morbidity and with a two-fold increased risk of death. The underlying mechanisms responsible for this association however, are not fully known. Both conditions may impose a heavy burden upon affected patients as well as on the health care system. AF and hypertension are closely intertwined and often coexist. Hypertension is the major risk factor for AF development and conversely, AF affects blood pressure (BP). The irregular heart rhythm in AF is one factor influencing BP, but also other factors may play a part. Furthermore, the presence of AF has implications for conventional BP measurement. AF-related effects on BP are studied to a very limited extent. Possibly, AF-induced BP effects may have pathophysiological consequences and may also influence BP measurement accuracy. Consequently, these factors may negatively influence risk assessment and prognosis in patients with AF. The aims of this thesis were 1) to systematically quantify beat-to-beat BP variability in patients with AF compared to sinus rhythm (SR); 2) to study how BP, as measured with different techniques, is affected by the presence of AF; 3) to investigate the relationship between peripheral and central intra-arterial BP, in patients with AF compared to SR; 4) to evaluate the accuracy of conventional BP measurement in relation to peripheral and central intra-arterial BP, in patients with AF and compared to SR. Methods and results: In the prospective study I, patients scheduled for a coronary angiography were recruited. Participants included 21 patients in AF and 12 patients with SR. Intra-arterial BP was recorded from the radial and brachial artery and from the ascending aorta. The primary outcome measure was beat-to-beat BP variability, defined as average systolic and diastolic BP difference between consecutive beats, at each site of measurement. A significant difference (p<0.001) in BP variability, in AF compared to SR, was observed for all locations of measurement. Systolic BP variability was roughly doubled in patients with AF (4.9 vs 2.4 mmHg), whereas diastolic BP variability was approximately six times as high (7.5 vs 1.2 mmHg) in patients with AF compared to SR. Study II was a retrospective registry analysis based on data from electronic medical records. 487 patients, treated with electrical cardioversion (ECV) for persistent AF, were included in the study. Information regarding auscultatory sphygmomanometric BP and rhythm, on the day before and 7 days after ECV, was obtained. The primary outcome measure was BP change in patients with restored SR after ECV. In this group with restored SR, systolic BP increased by 9 mmHg (p<0.01), whereas diastolic BP decreased by 3 mmHg (p<0.01). Furthermore, the proportion of patients with a hypertensive BP-level (≥140/90) increased by 40% in this group. In study III, 98 patients with persistent AF undergoing ECV were prospectively recruited. BP was evaluated with 24-h ambulatory BP monitoring before and approximately one week after ECV. The primary outcome measure was BP change in patients with restored SR after ECV. Among 60 patients maintaining SR, mean systolic 24-h ambulatory BP increased by 5.6 mmHg (p<0.001) and mean diastolic 24-h ambulatory BP decreased by 4.7 mmHg (p<0.001). Accordingly, a 10.4 mmHg (25%) increase in pulse pressure was observed among patients with restored SR. Study IV comprised the same individuals as study I. Conventional BP (auscultatory sphygmomanometric and automated oscillometric) and intra-arterial BP was measured simultaneously. The first aim was to investigate how intra-arterial BP changes throughout the arterial tree in patients with AF in comparison to patients in SR. The second aim was to evaluate the accuracy of conventional BP measurement in patients with AF in comparison to central and peripheral intra-arterial BP, and in comparison to patients in SR. BP changes throughout the arterial tree was similar in patients with AF compared to SR. Conventional BP was in general very accurate in comparison to diastolic intra-arterial BP, both in AF and SR. In patients with AF, oscillometric blood pressure overestimated systolic intra-arterial brachial (4.1 mmHg, p=0.07) and central (5.0 mmHg, p=0.04) BP. With measurement bias in SR taken into account, oscillometric BP over-estimated systolic intra-arterial brachial BP by 14.1 mmHg (p<0.01) and central BP by 9.0 mmHg (p=0.01) in patients with AF. Conclusions: Beat-to-beat BP variability is increased in patients with AF compared to SR. According to the results from studies in this thesis, systolic BP is lower and diastolic BP is higher in AF compared to SR, as measured by auscultatory sphyghmomanometry or by oscillometric 24-h ambulatory BP monitoring. As a consequence, pulse pressure is markedly lower in AF compared to SR. Intra-arterial BP change throughout the arterial tree is similar in patients with AF and SR. Conventional BP measurement was accurate in relation to diastolic intra- arterial BP, but oscillometric BP measurement overestimated intra-arterial brachial and central systolic BP in patients with AF, in particular when compared to patients in SR. The presence of AF affects BP. This may have implications for the accuracy of conventional BP measurement and may possibly also have pathophysiological consequences. Suboptimal understanding, measurement and treatment of BP may negatively influence prognosis in patients with AF

Office blood pressure measurement: A comprehensive review

The conventional auscultatory methods for measuring blood pressure have been used to screen, diagnose, and manage hypertension since long. However, these have been found to be prone to errors especially the white coat phenomena which cause falsely high blood pressure readings. The Mercury sphygmomanometer and the Aneroid variety are no longer recommended by WHO for varying reasons. The Oscillometric devices are now recommended with preference for the Automated Office Blood Pressure measurement device which was found to have readings nearest to the Awake Ambulatory Blood Pressure readings. The downside for this device is the cost barrier. The alternative is to use the simple oscillometric device, which is much cheaper, with the rest and isolation criteria of the SPRINT study. This too may be difficult due to space constraints and the post-clinic blood measurement is a new concept worth further exploration

2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents

Increasing prevalence of hypertension (HTN) in children and adolescents has become a significant public health issue driving a considerable amount of research. Aspects discussed in this document include advances in the definition of HTN in 16 year or older, clinical significance of isolated systolic HTN in youth, the importance of out of office and central blood pressure measurement, new risk factors for HTN, methods to assess vascular phenotypes, clustering of cardiovascular risk factors and treatment strategies among others. The recommendations of the present document synthesize a considerable amount of scientific data and clinical experience and represent the best clinical wisdom upon which physicians, nurses and families should base their decisions. In addition, as they call attention to the burden of HTN in children and adolescents, and its contribution to the current epidemic of cardiovascular disease, these guidelines should encourage public policy makers to develop a global effort to improve identification and treatment of high blood pressure among children and adolescents

What is the optimal interval between successive home blood pressure readings using an automated oscillometric device?

Objectives: To clarify whether a shorter interval between three successive home blood pressure (HBP) readings (10 s vs. 1 min) taken twice a day gives a better prediction of the average 24-h BP and better patient compliance. Design: We enrolled 56 patients from a hypertension clinic (mean age: 60 ± 14 years; 54% female patients). The study consisted of three clinic visits, with two 4-week periods of self-monitoring of HBP between them, and a 24-h ambulatory BP monitoring at the second visit. Using a crossover design, with order randomized, the oscillometric HBP device (HEM-5001) could be programmed to take three consecutive readings at either 10-s or 1-min intervals, each of which was done for 4 weeks. Patients were asked to measure three HBP readings in the morning and evening. All the readings were stored in the memory of the monitors. Results: The analyses were performed using the second–third HBP readings. The average systolic BP/diastolic BP for the 10-s and 1-min intervals at home were 136.1 ± 15.8/77.5 ± 9.5 and 133.2 ± 15.5/76.9 ± 9.3 mmHg (P = 0.001/0.19 for the differences in systolic BP and diastolic BP), respectively. The 1-min BP readings were significantly closer to the average of awake ambulatory BP (131 ± 14/79 ± 10 mmHg) than the 10-s interval readings. There was no significant difference in patients' compliance in taking adequate numbers of readings at the different time intervals. Conclusion: The 1-min interval between HBP readings gave a closer agreement with the daytime average BP than the 10-s interval

Abnormal wave reflections and left ventricular hypertrophy late after coarctation of the aorta repair

Patients with repaired coarctation of the aorta are thought to have increased afterload due to abnormalities in vessel structure and function. We have developed a novel cardiovascular magnetic resonance protocol that allows assessment of central hemodynamics, including central aortic systolic blood pressure, resistance, total arterial compliance, pulse wave velocity, and wave reflections. The main study aims were to (1) characterize group differences in central aortic systolic blood pressure and peripheral systolic blood pressure, (2) comprehensively evaluate afterload (including wave reflections) in the 2 groups, and (3) identify possible biomarkers among covariates associated with elevated left ventricular mass (LVM). Fifty adult patients with repaired coarctation and 25 age- and sex-matched controls were recruited. Ascending aorta area and flow waveforms were obtained using a high temporal-resolution spiral phase-contrast cardiovascular magnetic resonance flow sequence. These data were used to derive central hemodynamics and to perform wave intensity analysis noninvasively. Covariates associated with LVM were assessed using multivariable linear regression analysis. There were no significant group differences (P≥0.1) in brachial systolic, mean, or diastolic BP. However central aortic systolic blood pressure was significantly higher in patients compared with controls (113 versus 107 mm Hg, P=0.002). Patients had reduced total arterial compliance, increased pulse wave velocity, and larger backward compression waves compared with controls. LVM index was significantly higher in patients than controls (72 versus 59 g/m(2), P<0.0005). The magnitude of the backward compression waves was independently associated with variation in LVM (P=0.01). Using a novel, noninvasive hemodynamic assessment, we have shown abnormal conduit vessel function after coarctation of the aorta repair, including abnormal wave reflections that are associated with elevated LVM

Development of equations for converting random-zero to automated oscillometric blood pressure values

Abstract Objective This study aimed to collect data to compare blood pressure values between random-zero sphygmomanometers and automated oscillometric devices and generate equations to convert blood pressure values from one device to the other. Methods Omron HEM-907, a widely used automated oscillometric device in many epidemiologic surveys and cohort studies, was compared here with random-zero sphygmomanometers. Two hundred and one participants aged 40-79 years (37% men) were enrolled and randomly assigned to one of two groups with blood pressure measurement first taken by automated oscillometric devices or by random-zero sphygmomanometers. The study design enabled comparisons of blood pressure values between random-zero sphygmomanometers and two modes of this automated oscillometric device – automated and manual, and assessment of effects of measurement order on blood pressure values. Results Among all participants, mean blood pressure levels were lowest when measured with random-zero sphygmomanometers compared with both modes of automated oscillometric devices. Several variables, including age and gender, were found to contribute to the blood pressure differences between random-zero sphygmomanometers and automated oscillometric devices. Equations were developed using multiple linear regression after taking those variables into account to convert blood pressure values by random-zero sphygmomanometers to automated oscillometric devices. Conclusion Equations developed in this study could be used to compare blood pressure values between epidemiologic and clinical studies or identify shift of blood pressure distribution over time using different devices for blood pressure measurements

The impact of arm position and pulse pressure on the validation of a wrist-cuff blood pressure measurement device in a high risk population

Despite the increasing popularity of blood pressure (BP) wrist monitors for self-BP measurement at home, device validation and the effect of arm position remains an issue. This study focused on the validation of the Omron HEM-609 wrist BP device, including an evaluation of the impact of arm position and pulse pressure on BP measurement validation. Fifty patients at high risk for cardiovascular disease were selected (age 65 ± 10 years). Each patient had two measurements with a mercury sphygmomanometer and three measurements with the wrist BP device (wrist at the heart level while the horizontal arm supported [HORIZONTAL], hand supported on the opposite shoulder [SHOULDER], and elbow placed on a desk [DESK]), in random order. The achieved systolic BP (SBP) and diastolic BP (DBP) wrist-cuff readings were compared to the mercury device and the frequencies of the readings within 5, 10, and 15 mmHg of the gold standard were computed and compared with the British Hypertension Society (BHS) and Association for the Advancement of Medical Instrumentation (AAMI) protocols. The results showed while SBP readings with HORIZONTAL and SHOULDER positions were significantly different from the mercury device (mean difference = 7.1 and 13.3 mmHg, respectively; P < 0.05), the DESK position created the closest reading to mercury (mean difference = 3.8, P > 0.1). Approximately 71% of SBP readings with the DESK position were within ±10 mmHg, whereas it was 62.5% and 34% for HORIZONTAL and SHOULDER positions, respectively. Wrist DBP attained category D with BHS criteria with all three arm positions. Bland–Altman plots illustrated that the wrist monitor systematically underestimated SBP and DBP values. However a reading adjustment of 5 and 10 mmHg for SBP and DBP (DESK position) resulted in improvement with 75% and 77% of the readings being within 10 mmHg (grade B), respectively. AAMI criteria were not fulfilled due to heterogeneity. The findings also showed that the mismatch between the mercury and wrist-cuff systolic BP readings was directly associated with pulse pressure. In conclusion the DESK position produces the most accurate readings when compared to the mercury device. Although wrist BP measurement may underestimate BP measured compared to a mercury device, an adjustment by 5 and 10 mmHg for SBP and DBP, respectively, creates a valid result with the DESK position. Nevertheless, considering the observed variations and the possible impact of arterial stiffness, individual clinical validation is recommended