Traditional Blood Pressure Measurement Research Articles

Real-time Blood Pressure Prediction on Wearable Devices using Edge Based Deep Neural Networks: A Hardware-software Co-design Approach

This paper presents the hardware realization of a real-time blood pressure (BP) prediction model for wearable devices, utilizing long short-term memory (LSTM) deep neural networks (DNNs). The proposed system uses both electrocardiogram (ECG) and photoplethysmogram (PPG) signal values for BP prediction. It aims to address the limitations of traditional BP measurement methods, providing a low error, minimal computational overhead, more accurate and convenient alternative system for individuals with hypertension or at risk for cardiovascular diseases. The utilization of split matrix approach leads to a reduction in hardware complexity across the entire system. This technique involves breaking down the larger weight matrices used in the computations of DNNs into smaller matrices. This fragmentation results in a decrease in the complexity of the hardware responsible for performing matrix vector multiplications (MVMs) within LSTMs. The resultant architecture of the predictive model gains several advantages, including a lowered level of complexity in terms of the space occupied by individual cells, decreased processing delay, and reduced power consumption. Furthermore, this approach enables the achievement of a notably improved minimum achievable clock period of 2.972 ns. This prediction model can operate locally on wearable devices, reducing the reliance on cloud computing and improving privacy and security. The performance evaluations are carried out using both analytical and implementation results. The results indicate that the proposed model can be practically applied to real-world problems and can potentially enhance the accuracy of various machine-learning tasks.

Hybrid CNN-SVR Blood Pressure Estimation Model Using ECG and PPG Signals.

Continuous blood pressure (BP) measurement is vital in monitoring patients' health with a high risk of cardiovascular disease. The complex and dynamic nature of the cardiovascular system can influence BP through many factors, such as cardiac output, blood vessel wall elasticity, circulated blood volume, peripheral resistance, respiration, and emotional behavior. Yet, traditional BP measurement methods in continuously estimating the BP are cumbersome and inefficient. This paper presents a novel hybrid model by integrating a convolutional neural network (CNN) as a trainable feature extractor and support vector regression (SVR) as a regression model. This model can automatically extract features from the electrocardiogram (ECG) and photoplethysmography (PPG) signals and continuously estimates the systolic blood pressure (SBP) and diastolic blood pressure (DBP). The CNN takes the correct topology of input data and establishes the relationship between ECG and PPG features and BP. A total of 120 patients with available ECG, PPG, SBP, and DBP data are selected from the MIMIC III database to evaluate the performance of the proposed model. This novel model achieves an overall Mean Absolute Error (MAE) of 1.23 ± 2.45 mmHg (MAE ± STD) for SBP and 3.08 ± 5.67 for DBP, all of which comply with the accuracy requirements of the AAMI SP10 standard.

ADVANTAGES AND LIMITATIONS OF USING THE AKTIIA CUFFLESS BRACELET FOR A HYPERTENSION SPECIALIST

Objective: The AKTIIA bracelet was the first cuffless blood pressure monitor available in Europe over the counter. While published medical data show the validity of the measurement system compared to traditional blood pressure measurements, the objective of this preliminary study was to assess the value of the AKTIIA bracelet in the care of treated hypertensive patients. Design and method: Two bracelets were provided by the manufacturer to university cardiologist, specialist in hypertension. They were assigned to two hypertensive patients treated with antihypertensive drugs: one 62 years old treated with nebivolol 5 mg for 1 month and then with nebivolol 5 mg + candesartan 4 mg for the following 2 months, the other 52 years old treated with irbesartan 150 mg for 3 months. They were instructed to wear the bracelet for 3 consecutive months and following the manufacturer’s instructions to perform a calibration on 3 occasions. The patients performed also home blood pressure monitoring for 3 days with 6 measures per day once a month while wearing the bracelet on the other arm. Results: Over the same time periods, SYS/DIA values were accurately comparable between the AKTIIA bracelet and HBPM Conclusions: The AKTIIA bracelet, the first cuffless blood pressure monitor available in Europe over the counter, is currently proposed for blood pressure monitoring in healthy subjects. Its technological properties make it possible to use it for the follow-up of patients treated for hypertension. Some evolutions are desirable to facilitate its use by hypertension specialists. The cuffless method which allows blood pressure measurements without disturbing sleep constitutes a breakthrough in the management of hypertensive patients.

Unattended compared to traditional blood pressure measurement in patients with rheumatoid arthritis: a randomised cross-over study

Background Hypertension is characterised by a high prevalence, low awareness and poor control among rheumatoid arthritis (RA) patients. Correct blood pressure (BP) measurement is highly important in these subjects. The “unattended” BP measurement aims to reduce the “white-coat effect,” a phenomenon associated with cardiovascular risk. Data on “unattended” BP measurement in RA and its impact on hypertensive organ damage are very limited. Methods BP was measured in the same patient both traditionally (“attended” BP) and by the “unattended” protocol (3 automated office BP measurements, at 1-min intervals, after 5 min of rest, with patient left alone) by a randomised cross-over design. Patients underwent clinical examination, 12-lead electrocardiography and trans-thoracic echocardiography to evaluate cardiac damage. Results Sixty-two RA patients (mean age 67 ± 9 years, 87% women) were enrolled. Hypertension was diagnosed in 79% and 66% of patients according to ACC/AHA and ESC/ESH criteria, respectively. Concordance correlation coefficients between the two techniques were 0.55 (95%, CI 0.38–0.68) for systolic BP and 0.73 (95%, CI 0.60–0.82) for diastolic BP. “Unattended” (121.7/68.6 mmHg) was lower than “attended” BP (130.5/72.8 mmHg) for systolic and diastolic BP (both p < .0001). Among the two techniques, only “unattended” systolic BP showed a significant association with left ventricular mass (r = 0.11; p = .40 for “attended” BP; r = 0.27; p = .036 for unattended BP; difference between slopes: z = 3.92; p = .0001). Conclusions In RA patients, “unattended” BP is lower than traditional (“attended”) BP and more closely associated with LV mass. In these patients, the “unattended” automated BP measurement is a promising tool which requires further evaluation. KEY MESSAGES “Unattended” automated blood pressure registration, aimed to reduce the “white-coat effect” is lower than “attended” value in rheumatoid arthritis patients. “Unattended” blood pressure is more closely associated with left ventricular mass than “attende” registration.

Cuffless Blood Pressure Monitoring from an Array of Wrist Bio-Impedance Sensors Using Subject-Specific Regression Models: Proof of Concept.

Continuous and beat-to-beat monitoring of blood pressure (BP), compared to office-based BP measurement, provides significant advantages in predicting future cardiovascular disease. Traditional BP measurement methods are based on a cuff, which is bulky, obtrusive and not applicable to continuous monitoring. Measurement of pulse transit time (PTT) is one of the prominent cuffless methods for continuous BP monitoring. PTT is the time taken by the pressure pulse to travel between two points in an arterial vessel, which is correlated with the BP. In this paper, we present a new cuffless BP method using an array of wrist-worn bio-impedance sensors placed on the radial and the ulnar arteries of the wrist to monitor the arterial pressure pulse from the blood volume changes at each sensor site. BP is accurately estimated by using AdaBoost regression model based on selected arterial pressure pulse features such as transit time, amplitude and slope of the pressure pulse, which are dependent on the cardiac activity and the vascular properties of the wrist arteries. A separate model is developed for each subject based on calibration data to capture the individual variations of BP parameters. In this pilot study, data was collected from 10 healthy participants with age ranges from 18 to 30 years after exercising using our custom low-noise bio-impedance sensing hardware. Post-exercise BP was accurately estimated with an average correlation coefficient and root mean square error (RMSE) of 0.77 and 2.6 mmHg for the diastolic BP and 0.86 and 3.4 mmHg for the systolic BP.

Ambulatory blood pressure monitoring on admission in survivors of recent stroke entering inpatient rehabilitation.

Arterial hypertension (AHT) is a major risk factor for stroke, yet blood pressure (BP) goals thereafter remain uncertain. Although additional prognostic value of 24-hour ambulant BP monitoring (ABPM) is acknowledged, its clinical impacts remain limited. We suspected that routine ABPM could identify characteristic circadian BP patterns in different brain lesion types, the knowledge of which might, in turn, be helpful in improving overall BP management in patients after stroke. In our study, we compared cardiovascular parameters derived from ABPM and traditional blood pressure measurements (TBPM) among 105 stroke survivors who entered our inpatient neuro-rehabilitation program. The mean age of mostly male (64.8%) patients was 71 ± 12 years. Ischemic strokes were predominant (75.2%). Despite normotensive systolic BP means in TBPM (133.5 ± 18.2 mmHg) and ABPM (24 h: 122.8 ± 14.7 mmHg), AHT persisted in up to 67.6% of all patients, with ABPM uncovering nocturnal systolic non- or reversed dipping in 89.5% and 53.3%, respectively. The latter was predominant (85.7%) in the hemorrhagic subgroup which also displayed lower daytime SBP than the ischemic one (ABPM: 117.1 ± 11.8 vs 124.7 ± 14.7 mmHg, p = 0.033). Further differences were present among distinct brain lesion types. Sufficient dippers were younger (58 ± 12 vs 75 ± 11 years, p < 0.001), but adjusting for age yielded no independent correlations. In spite of normotensive daytime BP measurements, ABPM detects latent AHT and insufficient nocturnal BP dipping after the acute phase of stroke. Further studies are needed to elucidate the role of increased nocturnal BP in patients after stroke.

Predicting blood pressure from physiological index data using the SVR algorithm

BackgroundBlood pressure diseases have increasingly been identified as among the main factors threatening human health. How to accurately and conveniently measure blood pressure is the key to the implementation of effective prevention and control measures for blood pressure diseases. Traditional blood pressure measurement methods exhibit many inherent disadvantages, for example, the time needed for each measurement is difficult to determine, continuous measurement causes discomfort, and the measurement process is relatively cumbersome. Wearable devices that enable continuous measurement of blood pressure provide new opportunities and hopes. Although machine learning methods for blood pressure prediction have been studied, the accuracy of the results does not satisfy the needs of practical applications.ResultsThis paper proposes an efficient blood pressure prediction method based on the support vector machine regression (SVR) algorithm to solve the key gap between the need for continuous measurement for prophylaxis and the lack of an effective method for continuous measurement. The results of the algorithm were compared with those obtained from two classical machine learning algorithms, i.e., linear regression (LinearR), back propagation neural network (BP), with respect to six evaluation indexes (accuracy, pass rate, mean absolute percentage error (MAPE), mean absolute error (MAE), R-squared coefficient of determination (R2) and Spearman’s rank correlation coefficient). The experimental results showed that the SVR model can accurately and effectively predict blood pressure.ConclusionThe multi-feature joint training and predicting techniques in machine learning can potentially complement and greatly improve the accuracy of traditional blood pressure measurement, resulting in better disease classification and more accurate clinical judgements.

RF65 PULSE OXIMETER USEFULNESS FOR BLOOD PRESSURE MONITORING IN PATIENTS IMPLANTED WITH LVAD (LEFT VENTRCLE ASSIST DEVICE)

BACKGROUND AND AIM: The measurement of blood pressure (BP) in patients with CF-VADs can present unique challenges because traditional BP measurement by auscultation or automated cuff is less reliable. We tested the efficacy of blood pressure estimation by using the Sphygmomanometry combined with finger pulse oximetry. METHODS: 51 patients, 24 implanted with HM II, 4 implanted with HVAD, 23 implanted with HM3 were prospectively studied during follow up period and mean arterial pressure was estimated by using 3 different methodologies; ultrasound doppler, pulse oximeter and automated blood pressure cuff. For each method 3 consecutive evaluations were conducted in 3 follow-up visits. RESULTS: For each patient 9 different evaluations were obtained, 3 for each method. The overall success rate was 100% for blood pressure assessment conducted with doppler and pulse oximeter, 80% - 87% the rate for automated monitor evaluations. 100 was the percentage of three successfull consecutive measurements for the first two methodologies and 60 the percentage for the last one. Pearson's correlation analysis showed a good correlation when measurements of doppler and pulse oximeter were compared. High variability emerged between estimations obtained by using automated monitor and poor correlation was found when this method was compared with doppler an pulse oximeter. CONCLUSION: According to our results pulse oximeter method showed high success rate and a good correlation level with the standard proedure. Our data encourage the use of oximter for domiciliary blood pressure assessment in patients implanted with continuous flow device.

Metabolomic study for essential hypertension patients based on dried blood spot mass spectrometry approach.

Hypertension is an increasingly serious public-health challenge worldwide. The traditional blood pressure measurement method could easily and reliably detect blood pressure. However, the delayed symptom onset may influence the screening of essential hypertension (EH). In addition, EH is significantly associated to cardiovascular disease, stroke and kidney disease. Hence, it is urgent to define associated biomarkers with early diagnosis potential for EH. A dried blood spot method integrated with direct infusion mass spectrometry (MS) metabolomic analysis was applied for the detection of metabolites toward 87 EH patients and 91 healthy controls (HC). Multiple algorithms were run on training set (62 EH and 64 HC) for selecting differential metabolites as potential biomarkers. A test set (25 EH and 27 HC) was used to verify and evaluate selected potential biomarkers. A novel blood biomarker model based on Gly, Orn, C10, Orn/Cit, Phe/Tyr, and C5-OH/C8 exhibited potential to differentiate EH patients from HC individuals, with a sensitivity of 0.8400 and a specificity of 0.8889 in test set. The metabolomic analysis of EH is beneficial to the definition of disease-associated biomarkers and the development of new diagnostic approaches. © 2018 IUBMB Life, 70(8):777-785, 2018.

Pulse Oximeter Usefulness for Blood Pressure Monitoring in Patients Implanted With Latest-Generation Continuous-Flow Device HeartMate 3

IntroductionThe measurement of blood pressure (BP) and the management of hypertension in patients with continuous-flow ventricular assist devices (CF-VADs) can present unique challenges. Patients with CF-VADs often do not have a palpable pulse, and therefore traditional blood pressure measurement by auscultation or automated cuff is less reliable. We tested the efficacy of blood pressure estimation using sphygmomanometry combined with finger pulse oximetry only after a hemodynamic optimization was effected to make the values estimated approximately similar to mean arterial pressure. MethodsFifteen consecutive patients with a mean age of 57.8 ± 11.2 years were implanted with HeartMate 3 between November 2015 and March 2017. All patients underwent pump speed optimization by conducting a ramp test during right heart catheterization. The patients were prospectively studied during the follow-up period and mean arterial pressure was estimated using 3 different methodologies: Doppler ultrasound, pulse oximeter, and automated blood pressure cuff. For each method 3 consecutive evaluations were conducted during 3 follow-up visits. ResultsFor each patient, 9 different evaluations were obtained (3 for each method). The overall success rate was 100% for blood pressure assessment conducted with Doppler ultrasound and pulse oximeter and 80%-87% for automated monitor evaluations. The first 2 methodologies were 100% successful, while the third was 60% successful. Pearson's correlation analyses for the Doppler ultrasound and pulse oximeter measurements showed a good correlation when evaluations conducted with the same method were compared. A high variability emerged between estimations obtained by using an automated monitor and a poor correlation was found when this method was compared to the Doppler ultrasound and pulse oximeter measurements. ConclusionAccording to our results, the pulse oximeter method showed a high success rate and a good correlation level with the standard procedure. Our data encourage the use of oximeters for domiciliary blood pressure assessment in patients implanted with a continuous flow device.

PP.26.08] THE INFLUENCE OF BLOOD PRESSURE VARIABILITY AT HOME TO LEFT VENTRICULAR MASS OF HYPERTENSIVE PATIENTS

Objective: Was to examine the correlation of blood pressure variability (BP) at home to left ventricular mass in hypertensive patients. Design and method: We studied 656 hypertensive patients (mean age 57.7 years old,mean systolic/diastolic blood pressure:148.1/91.7 mmHg, 54% female sex) treated or newly diagnosed with hypertension. Blood pressure variability at home and ambulatory blood pressure variability were measured. Left ventricular mass and left ventricular mass index were measured with transthoracic ultrasound. Pearson method was used to correlate blood pressure variability (BPV) to left ventricular mass (LVM) and left ventricular mass index (LVMI).Conclusions: Blood pressure variability at home does not correlate to left ventricular mass and left ventricular mass index in hypertensive patients, while the traditional blood pressure measurement has a high correlation to the aforementioned parameters.

Clinical value of ambulatory blood pressure: evidence and limits.

This article reviews the clinical value of ambulatory blood pressure (BP) vis-à-vis the traditional BP measurements taken in the physician's office or in the hospital. Mention is initially made that longitudinal studies conducted in the general population or in hypertensive cohorts have shown that ambulatory BP provides a more accurate prediction of outcome than office BP. Namely, that (1) the risk of cardiovascular events increases in a less steep fashion with office than with 24-hour mean BP, (2) the 24-hour BP-dependent prediction is maintained after adjustment for office BP values, and (3) among individuals with normal office BP, those with increased ambulatory BP (masked hypertension) have an increased prevalence of organ damage, a more frequent unfavorable metabolic profile and a higher risk of new onset sustained hypertension, diabetes mellitus, and cardiovascular events than those with normal ambulatory BP. It is further mentioned, however, that more recently similar observations have been made for individuals with high office but normal ambulatory BP (white coat hypertension) suggesting a complementary role of out-of-office and office BP values in the determination of patients' prognosis. The evidence in favor of an independent prognostic value also of some within 24-hour BP phenomena (night BP reduction or absolute values, short-term BP variations, and morning BP surge) is then critically appraised for its elements of strength and weakness. Finally, whether the clinical advantages of ambulatory BP make this approach necessary for all patients with hypertension is discussed. The conclusion is that this is at present still premature because crucial evidence pro or against routine use of this approach in untreated and treated hypertensives is not yet available. It will be crucial for future studies to determine whether, compared with a treatment guided by office BP, a treatment tailored on ambulatory BP allows to improve prevention or regression of organ damage as well as protection from major cardiovascular complications to a degree that justifies the complexity and cost of the procedure.

A New Approach on Digital Blood Pressure Measurement Method for u-Healthcare Systems

The traditional blood pressure measurement method so called Kortokoff method has to apply strong air pressure on patient’s artery that could give severe damage on artery, and has the problem that method cannot measure the blood pressure in a series or continuously. But recent engineering technology can give new solutions that can solve the problems by using digital sensors and microcomputer. In this paper, we proposed a kind of non-Kortokoff method that can get the blood pressure from patient’s digitalized arterial pulse waveform analysis without air pressure on patient’s artery. This method can check patient’s blood pressure in a series through converting the continuous arterial pulse waveform into the absolute systolic and diastolic values with pre-defined blood pressure mapping equation from experiments. The experimental results showed that the proposed non-Kortokoff blood pressure measurement method has very good accuracy over 95% compare to commercial tonometers in continuous measurement. Also, the proposed non-Kortokoff blood pressure measurement method can be designed and implemented as a small device since it has no mechanical air pressure compartment, and applied on the u-Healthcare service areas very effectively such as a digital blood pressure checker for usual life blood pressure monitoring along with the medical device for home and hospitals.

Augmentation index as a specific marker of large arteries distensibility

lthough high blood pressure has been undoubtedlyshown to be a major risk factor for cardiovascularmorbidity and mortality at all ages and in bothsexes, the suitability and accuracy of traditional bloodpressure measurements for cardiovascular risk staging isnow a matter of lively debate [1]. In this context, thepossible additional contribution carried by central bloodpressure values assessment and by pulse wave analysis hasbeen underlined by a number of studies [2,3].Indeed, the technique of pulse wave analysis, usingnoninvasive high fidelity arterial tonometers, has recentlybecome increasingly popular [4,5]. This method can pro-vide not only quantitative, although indirect, informationconcerning the levels of central blood pressure, but alsoqualitative data on the ascending aortic waveform. Analysisof such waveforms can, in fact, define the elastic propertiesof the arterial wall and can estimate the importance and thetransmission speed of reflected waves [6,7].In the last years, augmentation index (AIx) has beenfrequently used in the context of pulse waveform analysisand has been suggested to represent a parameter able toreliablyreflectthelevelofarterialstiffnessintheassessmentof cardiovascular risk. Assessment of AIx provides anindication of the role played by reflected waves in deter-mining pulse pressure. The contribution of the backwardwave to pulse pressure is related to the timing of its super-imposition onto the forward wave, as well as to its magni-tude and shape. AIx is calculated as the ratio between theaugmented central pressure, due to reflected waves, andpulse pressure. Conditions of markedly increased arterialstiffness are characterized by an early superimposition ofbackward waves onto the forward wave, causing anincrease in central SBP. Assessment of AIx has, thus, beenproposedasasimpleapproachtoquantifytheroleofwavereflection in determining an elevation of central bloodpressure values.However, it has to be acknowledged that several otherfactors, apart from the viscoelastic properties of the aortaand of large arteries [8], may affect AIx, in particular: themagnitude and variability of reflected waves, mainly inrelation to systemic vascular resistance; the length of theaorta (related to an individual’s height), because at anygiven level ofarterial distensibility, thenearer the reflectionsites are to the ascending aorta, the shorter is the timeneeded for the reflected wave to reach it; the participant’sheart rate, an increase in heart rate being accompanied byanincreaseinpulsewavevelocity,butalsobyadecreaseinaugmented pressure [3], that is in AIx; the phenomenon ofpressure waves attenuation while travelling along the arte-rial tree; and the role of gender, several studies havingshown significantly higher values of AIx in female than inmale individuals of comparable height (Fig. 1).Thus, given the contribution of several factors to AIxmagnitude, use of this parameter as a specific index of theviscoelastic properties of large arteries is incorrect and maylead to inaccurate estimates. In fact, in clinical practice it isnot uncommon to find a marked discrepancy betweenpulse wave velocity (considered as the gold standardmarker of arterial distensibility [9]) and AIx values, whichmay indeed be due to the multiple factors involved indetermining the latter parameter.The article by Cheng et al. [10], published in this issue ofthe Journal of Hypertension, was aimed at exploringthe potential contribution of cardiac motion and arterialproperties, respectively, to arterial pressure waveformparameters, in particular to AIx.The conclusion of this study is that AIx may not bepredominantly determined by arterial properties, but, onthe contrary, it largely depends on left ventricular systolicfunction. Thus, based on these data, the use of AIx as asurrogate index of arterial stiffness might need to be recon-sidered [10].These conclusions are based on data collected in 20healthy male individuals (median age 22.3 years), withoutcardiovascular risk factors and free of chronic diseases. Ithas to be emphasized that although the selective inclusionin this study of a healthy young male cohort has carried theadvantage of minimizing the possible confounding effects

MODERN VIEWS ON THE VARIABILITY OF BLOOD PRESSURE

Nowadays conception of blood pressure (BP) variability (BPV) includes a number of indicators related to various physiological factors. All the indexes are calculated with the standard deviation (SD) or more complex formulas, including SD. BPV main varieties are considered a 24-hour BPV (measured by ambulatory BP monitoring – ABPM), midterm BPV (BP self-control or home BP – HBP), and long-term, visit-to-visit, BPV (traditional BP measurement or office BP – OBP). The 24-hour BPV was the main subject of study for many years. Recently significant attention has been paid to the visit-to-visit BPV assessment. Retrospective meta-analysis showed that in a cohort of patients after stroke or transient ischemic attack, this index was a strong and independent (from the average BP level) predictor of stroke. In ASCOT-BPLA study visit-to-visit systolic BPV also was a strong predictor of stroke and coronary events. Long-term BPV in patients of amlodipine/perindopril treatment group was significantly lower than this in patients of atenolol/diuretic group during the follow-up that was associated with a lower risk of cardiovascular complications. However , the concept of visit-to-visit BPV use for risk stratification and monitoring of antihypertensive therapy efficacy is associated with significant limitations (basic data is obtained in the post hoc analysis, difficulties in objective evaluation of prognostic significance of indicators, their dependence on medication adherence, etc.). The HBP self-control is a promising approach to the BPV analysis; it may be the happy medium between ABPM and OPB. New-designed prospective comparative studies are needed to evaluate the clinical significance of the various BPV parameters.

Normal growth and intravascular volume status with good metabolic control during peritoneal dialysis in infancy

The most demanding patient population on peritoneal dialysis (PD) consists of children under 2 years of age. Their growth is inferior to that of older children and maintaining euvolemia is difficult, especially in anuric patients. In this prospective study reported here, we enrolled 21 patients <2 years of age (mean 0.59 years) at onset of PD and monitored their uremia parameters and evaluated their nutrition. Since no good instrument currently exists for estimating intravascular volume status, we used traditional blood pressure measurements, echocardiography, and N-terminal atrial natriuretic peptide measurements. Growth was compared with midparental height. Metabolic control was good. Long-term hypertension was seen in 43% of the patients, but left ventricular hypertrophy decreased during the study period. Mean weekly urea Kt/V was 3.38 ± 0.66 and creatinine clearance was 49 ± 20 L/week per 1.73 m2. Catch-up growth was documented in 57% of the patients during PD. However, these children did not attain their midparental height at the end of PD at a mean age of 1.71 years. Although favorable metabolic control and good growth were achieved during PD, these children lagged in term of their midparental height. We conclude that several instruments are needed for determining the management of intravascular volume status and that the control of calcium–phosphorus status is demanding.

Endothelium-dependent vasodilation in relation to different measurements of blood pressure in the elderly: the prospective investigation of the Vasculature in Uppsala Seniors study

We have earlier showed endothelium-dependent vasodilation (EDV) in forearm resistance arteries to be mainly related to diastolic blood pressure (DBP), whereas flow-mediated vasodilation (FMD) was mainly related to systolic blood pressure (SBP) when measured with a mercury sphygmomanometer in the brachial artery. Here, we investigated whether these relationships were more powerful if blood pressure was measured invasively or by transformation to central aortic blood pressure. In the prospective study of the Vasculature in Uppsala Seniors, 1016 patients aged 70 years were evaluated by the invasive forearm technique with acetylcholine (EDV), and brachial artery ultrasound to assess FMD. Blood pressure was measured with a mercury sphygmomanometer, invasively in the brachial artery and transformed to aortic blood pressure by pulse wave analysis. EDV was related to DBP with a similar strength regardless of whether DBP was measured traditionally, invasively or as calculated aortic pressure. Similarly, FMD was related to SBP with similar strength regardless of whether SBP was measured traditionally, invasively or as calculated aortic pressure. Only FMD was significantly related to pulse pressure. Measurements of blood pressure invasively or by calculation of aortic blood pressure did not increase the power of the associations between blood pressure and EDV in the elderly, when compared with traditional blood pressure measurements.

Ambulatory Blood Pressure for Cardiovascular Risk Stratification

Ambulatory blood pressure (ABP) monitoring is increasingly recognized as a valuable tool to refine prediction of cardiovascular risk related to blood pressure (BP).1 After the first landmark study published by Perloff and colleagues 24 years ago,2 several longitudinal event-based studies provided unequivocal evidence of an independent association between ABP and risk of cardiovascular disease. Although experimental procedures and statistical analyses varied from study to study, ABP generally improved cardiovascular risk stratification over and beyond traditional risk factors, including clinic BP.3 The Table, obtained through an electronic search of literature using the terms “ambulatory blood pressure” and “prognosis,” shows a list of longitudinal event-based studies performed by independent groups. It is worth noting that the list of available studies is longer because each group generally published other analyses of their database. Only the first-appearing or main contribution from each group has been included in the Table. View this table: Longitudinal Event-Based Studies From Independent Groups That Addressed the Prognostic Value of ABP Article p 2145 Three aspects of available investigations deserve special mention. First, the prognostic value of ABP has been examined not only in subjects with clinical diagnosis of hypertension but also in the general population and in a variety of settings, including diabetes mellitus, renal failure, and cerebrovascular disease. Second, subjects could be untreated or treated at the time of ABP monitoring. This point may raise concerns, because drug treatment could exert unpredictable effects on 24-hour ABP profile and, consequently, interpretation and applicability of results. Third, although a continuous relation emerged in most studies between ABP and cardiovascular risk, several investigators tried to define clinical categories based on arbitrary thresholds of ABP. Although such categories are potentially useful to make diagnostic and therapeutic decisions in clinical practice, their prognostic role requires confirmation from large and independent cohort …

Evaluation of mechanical arterial properties: clinical, experimental and therapeutic aspects

Ageing and disease states associated with an increase in cardiovascular events alter the physical characteristics of blood vessel walls and impair the pulsatile function of arteries. An accumulating body of evidence indicates that impaired pulsatile function of arteries provides important prognostic and therapeutic information beyond that provided by traditional blood pressure measurements. A variety of techniques are currently employed to evaluate the mechanical properties of arteries. All techniques have theoretical, technical and practical limitations that impact on their widespread application in the clinical setting and use as measurement tools to improve cardiovascular risk stratification. A detailed discussion of these issues forms the basis of this review.

Ambulatory blood pressure monitoring in hypertension.

Ambulatory blood pressure monitoring generates a greater interest among investigators and clinicians because of its potential to 1) study the mechanisms involved in cardiovascular control in daily life (particularly if monitoring is performed on a beat-to-beat basis) and 2) improve the diagnosis of hypertension, the estimate of the patient's risk and the assessment of the efficacy of antihypertensive treatment. This paper will discuss the evidence pros and cons the latter indications of this approach. It will be shown that 24 hour blood pressure values correlate more closely than clinic blood pressure with various measures of the end organ damage of hypertension, suggesting that it may reflect better than traditional blood pressure measurements the cardiovascular consequences of this condition. Wider use of ambulatory blood pressure monitoring in the medical practice, however, must await a more clear demonstration of its prognostic importance, by longitudinal studies based on cardiovascular morbidity and mortality or on surrogate end points with undisputable clinical significance (e.g. left ventricular hypertrophy). It must also await clear definition of ambulatory blood pressure normality based on population studies. Until then ambulatory blood pressure monitoring should be employed to resolve special problems, e.g. identification of white coat hypertension and false non response to treatment.