Range Of Blood Pressure Values Research Articles

Blood Pressure Estimation based on Electrocardiograms

Abstract To overcome limitations of currently used blood pressure measurement devices in accuracy, continuity and comfort, we propose an approach for blood pressure estimation from electrocardiogram (ECG) signals only. Thereby, statistical signal features are extracted from the ECG which, eventually, serve as input to a random forest regression. The method is trained and tested on MIMIC III waveform data with a large range of blood pressure values. It obtains a mean absolute error ± standard deviation of 3.73 ± 5.19 mmHg for diastolic blood pressure (DBP) and 5.92 ± 7.23 mmHg for systolic blood pressure (SBP), with Pearson coefficients ΥDBP=0.92 and ΥSBP=0.91 respectively.

Cuffless Blood Pressure Estimation Based on Monte Carlo Simulation Using Photoplethysmography Signals.

Blood pressure measurements are one of the most routinely performed medical tests globally. Blood pressure is an important metric since it provides information that can be used to diagnose several vascular diseases. Conventional blood pressure measurement systems use cuff-based devices to measure the blood pressure, which may be uncomfortable and sometimes burdensome to the subjects. Therefore, in this study, we propose a cuffless blood pressure estimation model based on Monte Carlo simulation (MCS). We propose a heterogeneous finger model for the MCS at wavelengths of 905 nm and 940 nm. After recording the photon intensities from the MCS over a certain range of blood pressure values, the actual photoplethysmography (PPG) signals were used to estimate blood pressure. We used both publicly available and self-made datasets to evaluate the performance of the proposed model. In case of the publicly available dataset for transmission-type MCS, the mean absolute errors are 3.32 ± 6.03 mmHg for systolic blood pressure (SBP), 2.02 ± 2.64 mmHg for diastolic blood pressure (DBP), and 1.76 ± 2.8 mmHg for mean arterial pressure (MAP). The self-made dataset is used for both transmission- and reflection-type MCSs; its mean absolute errors are 2.54 ± 4.24 mmHg for SBP, 1.49 ± 2.82 mmHg for DBP, and 1.51 ± 2.41 mmHg for MAP in the transmission-type case as well as 3.35 ± 5.06 mmHg for SBP, 2.07 ± 2.83 mmHg for DBP, and 2.12 ± 2.83 mmHg for MAP in the reflection-type case. The estimated results of the SBP and DBP satisfy the requirements of the Association for the Advancement of Medical Instrumentation (AAMI) standards and are within Grade A according to the British Hypertension Society (BHS) standards. These results show that the proposed model is efficient for estimating blood pressures using fingertip PPG signals.

Target blood pressure and kidney protection

For many years, low on-treatment blood pressure values were widely regarded as necessary to maximise renal protection in individuals with high blood pressure. This notion was generated by several lines of evidence. Findings suggested that low blood pressure values could diminish or eliminate glomerular protein excretion, 1 Mancia G Schumacher H Redon J et al. Blood pressure targets recommended by guidelines and incidence of cardiovascular and renal events in the Ongoing Telmisartan Alone and in Combination With Ramipril Global Endpoint Trial (ONTARGET). Circulation. 2011; 124: 1727-1736 Crossref PubMed Scopus (137) Google Scholar which might lead to renal damage. Furthermore, the kidney can autoregulate its blood flow effectively over a wide range of blood pressure values, lessening concerns that low blood pressure might trigger renal underfusion, renal ischaemia, and a J-shaped relation with cardiac events. 2 Mancia G Grassi G Aggressive blood pressure lowering is dangerous: the J-curve. Hypertension. 2014; 63: 29-36 Crossref PubMed Scopus (89) Google Scholar Finally, in clinical studies, a progressive reduction in the glomerular filtration rate was attenuated in patients with intense treatment-induced blood pressure reductions versus less intense lowering of blood pressure, 3 Jafar TH Stark PC Schmid CH et al. Progression of chronic kidney disease: the role of blood pressure control, proteinuria, and angiotensin-converting enzyme inhibition: a patient-level meta-analysis. Ann Intern Med. 2003; 139: 244-252 Crossref PubMed Scopus (957) Google Scholar which also seemed to occur in patients with pronounced proteinuria. In the Modification of Diet in Renal Disease study in patients with non-diabetic nephropathy, 4 Peterson JC Adler S Burkart JM et al. Blood pressure control, proteinuria, and the progression of renal disease: the Modification of Diet in Renal Disease Study. Ann Intern Med. 1995; 123: 754-762 Crossref PubMed Scopus (1228) Google Scholar cutting mean arterial pressure to 92 mm Hg rather than 107 mm Hg was associated with a lesser decline in renal function in the subgroup of individuals with urinary protein excretion greater than 3 g/day. Intensive systolic blood pressure control and incident chronic kidney disease in people with and without diabetes mellitus: secondary analyses of two randomised controlled trialsIntensive lowering of systolic blood pressure increased the risk of incident chronic kidney disease in people with and without type 2 diabetes. However, the absolute risk of incident chronic kidney disease was higher in people with type 2 diabetes. Our findings suggest the need for vigilance in monitoring kidney function during intensive antihypertensive drug treatment, particularly in adults with diabetes. Long-term studies are needed to understand the clinical implications of antihypertensive treatment-related reductions in eGFR. Full-Text PDF

Pulse Wave Cycle Features Analysis of Different Blood Pressure Grades in the Elderly.

Background and Objective The same range of blood pressure values may reflect different vascular functions, especially in the elderly. Therefore, a single blood pressure value may not comprehensively reveal cardiovascular function. This study focused on identifying pulse wave features in the elderly that can be used to show functional differences when blood pressure values are in the same range. Methods First, pulse data were preprocessed and pulse cycles were segmented. Second, time domain, higher-order statistics, and energy features of wavelet packet decomposition coefficients were extracted. Finally, useful pulse wave features were evaluated using a feature selection and classifier design. Results A total of 6,075 pulse wave cycles were grouped into 3 types according to different blood pressure levels and each group was divided into 2 categories according to a history of hypertension. The classification accuracy of feature selection in the 3 groups was 97.91%, 95.24%, and 92.28%, respectively. Conclusion Selected features could be appropriately used to analyze cardiovascular function in the elderly and can serve as the basis for research on a cardiovascular risk assessment model based on Traditional Chinese Medicine pulse diagnosis.

Cerebral autoregulation and white matter lesions in Parkinson's disease and multiple system atrophy

Cerebral autoregulation is a complex homeostatic process which ensures constant brain blood supply, despite continuous blood pressure fluctuations. Recent evidence suggests that in Parkinson's disease (PD) and multiple system atrophy (MSA) this process is maintained in a broadened range of blood pressure values, consistent with an adaptive mechanism to increase tolerance to orthostatic hypotension. In PD and MSA orthostatic hypotension may be accompanied by supine hypertension which has been recently linked with cerebral white matter lesions in these conditions. We hypothesize that cerebral autoregulation adaptation to chronic orthostatic hypotension may be directly related with an increase susceptibility to hypertensive peaks.Evaluation of cerebral autoregulatory behavior may thus represent a novel approach to simultaneously target orthostatic symptoms and silent end-organ damage in alpha-synucleinopathies, with a beneficial impact on cerebrovascular and cognitive outcome.

Assessing the challenges of a pulse wave velocity based blood pressure measurement in surgical patients.

Development of a continuous noninvasive blood pressure (cNIBP) monitor that is unobtrusive to patients is an attractive alternative to the cuff based measurements performed on medical-surgical floors in the hospital. Pulse wave velocity (PWV) provides a means to continuously monitor blood pressure in these patients. However, a PWV based cNIBP monitor faces a number of challenges in order to accurately measure blood pressure. In our study, we investigated some of the challenges faced by a body-worn cNIBP monitor (i.e. ViSi Mobile) on data collected on patients undergoing surgery. Results indicated that 1) pulse arrival time (PAT) values from ViSi Mobile were well correlated with PAT values obtained from an invasive reference; 2) the reciprocal of the PAT measurements were linearly correlated with blood pressure but the calibration curve was altered by administration of certain vasoactive substances; and 3) there are deterministic correlations between systolic pressure, diastolic pressure and the corresponding mean arterial pressure over a wide range of blood pressure values.

Control and Modulation of Fluid Flow in the Rat Kidney

We have developed a mathematical model of the rat's renal hemodynamics in the nephron level, and used that model to study flow control and signal transduction in the rat kidney. The model represents an afferent arteriole, glomerular filtration, and a segment of a short-loop nephron. The model afferent arteriole is myogenically active and represents smooth muscle membrane potential and electrical coupling. The myogenic mechanism is based on the assumption that the activity of nonselective cation channels is shifted by changes in transmural pressure, such that elevation in pressure induces vasoconstriction, which increases resistance to blood flow. From the afferent arteriole's fluid delivery output, glomerular filtration rate is computed, based on conservation of plasma and plasma protein. Chloride concentration is then computed along the renal tubule based on solute conservation that represents water reabsorption along the proximal tubule and the water-permeable segment of the descending limb, and chloride fluxes driven by passive diffusion and active transport. The model's autoregulatory response is predicted to maintain stable renal blood flow within a physiologic range of blood pressure values. Power spectra associated with time series predicted by the model reveal a prominent fundamental peak at ∼165mHz arising from the afferent arteriole's spontaneous vasomotion. Periodic external forcings interact with vasomotion to introduce heterodynes into the power spectra, significantly increasing their complexity.

Reducing cardiovascular risk in diabetes: insights from the ADVANCE study

BACKGROUND Blood pressure is an important determinant of the risks of macrovascular and microvascular complications of type 2 diabetes. That’s why guidelines recommend intensive lowering of blood pressure in those patients. The ADVANCE (Action in Diabetes and Vascular disease: preterAx and diamicroN-MR Controlled Evaluation) study has been recently introduced. It assessed the effects of such an approach on vascular disease using a fixed combination of the ACE-inhibitor perindopril, and the diuretic indapamide, in a population of patients with type 2 diabetes and a broad range of blood pressure values. METHODS After a 6-week active run-in period, 11,140 patients with type 2 diabetes were randomised to treatment with a fixed combination of perindopril and indapamide or matching placebo, in addition to current therapy. Primary end-points: major macrovascular and microvascular events, defined as death from cardiovascular disease, non-fatal stroke or non-fatal myocardial infarction, and new or worsening renal or diabetic eye disease. The macrovascular and microvascular composites were analysed jointly and separately. RESULTS To the end of the follow-up a meaningful reduction of the deaths has been obtained, both for cardiovascular causes and for macro and microvascular events, examined in together (in the total) (separately significance has not turned out). The best result has been obtained in the reduction of the renal events. DISCUSSION AND CONCLUSIONS The authors conclude that routine administration of a fixed combination of perindopril and indapamide to patients with type 2 diabetes and with a good controlled blood pressure, was well tolerated and reduced the risks of major vascular events, including death, but it remains the doubt if these results have been obtained because of the better pressure control or are specific of this preconstructed association.

Central Pulse Pressure Is an Independent Determinant of Vascular Remodeling in the Retinal Circulation

Pulse pressure has been recognized as a risk factor for stroke. Moreover, it was shown that central pulse pressure relates more strongly to vascular disease and outcome than (peripheral) brachial pulse pressure. Because vascular remodeling in the retinal circulation mirrors the 1 in the cerebral circulation and represents an easy, noninvasive possibility to assess microvascular changes in humans, we analyzed the impact of central pulse pressure on retinal vascular structure in humans. The study cohort comprised 135 nondiabetic patients across a wide range of blood pressure values. Parameter of retinal arteriolar remodeling (wall-to-lumen ratio) was assessed noninvasively and in vivo by scanning laser Doppler flowmetry. Central pulse pressure and augmentation index normalized to a heart rate of 75 beats per minute were assessed by pulse wave analysis. Central pulse pressure correlated with wall-to-lumen ratio (r=0.302; P<0.001), central augmentation index normalized to a heart rate of 75 beats per minute correlated with wall-to-lumen ratio (r=0.190; P=0.028), and in accordance pulse pressure amplification (peripheral pulse pressure/central pulse pressure) was negatively correlated with wall-to-lumen ratio (r=-0.223; P=0.009). In contrast, central mean arterial pressure was not correlated with wall-to-lumen ratio (r=0.110; P=0.203). Multiple regression analysis revealed an independent relationship between wall-to-lumen ratio and central pulse pressure (β=0.277; P=0.009), but not with other classical cardiovascular risk factors. Thus, central pulse pressure, indicative of changes in large conduit arteries is an independent determinant of vascular remodeling in small retinal arterioles. Such a relationship indicates a coupling and crosstalk between the microvascular and macrovascular changes attributable to hypertension.

Does the blood pressure-lowering effect of statins contribute to their beneficial cardiovascular effects?

Not all cardiovascular protection provided by statins is explained by their beneficial effects on lipoproteins. Old (e.g., clofibrate) and new (e.g., torcetrapib and ezetimibe) agents, with similar or more intense beneficial effect over lipoproteins, do not reproduce the beneficial effects of statins. Besides their anti-inflammatory and other pleiotropic effects, a blood pressure-lowering effect could be an additional mechanism of cardiovascular protection of statins. Large trials of statins in the primary and secondary prevention of cardiovascular disease did not report an effect on blood pressure, but the use of blood pressure-lowering agents was left to the discretion of physicians during the trial. Post hoc analyses of small trials and a meta-analysis of some of them have suggested that statins could lower systolic blood pressure by approximately 4 mmHg, particularly in patients with high blood pressure. Most studies, however, had small samples and were not blinded. Others had a cross-over or observational design. The overall view of these studies rules out a substantial blood pressure-lowering effect of statins. An effect restricted to subjects with high blood pressure could ultimately derive from the anti-inflammatory effect of statins, since higher levels of C-reactive protein are associated with higher blood pressure. An unequivocal demonstration of an antihypertensive effect of statins, however, is still lacking, and a randomized trial with enough power to evaluate blood pressure variation in a large range of blood pressure values is required to demonstrate whether statins definitely have an antihypertensive effect.

Blood Pressure during the First 7 Days in Premature Infants Born at Postmenstrual Age 23 to 25 Weeks

Our aims were to identify the range of blood pressure values during the first postnatal week in infants born between 23 and 25 weeks postmenstrual age who were not considered in need of treatment for hypotension, and to describe the clinical course of these untreated infants compared with those who were treated for hypotension. We reviewed retrospectively the charts of 142 consecutive inborn infants over a 6-year period. For 86 infants who survived the first postnatal week without being treated for hypotension, the mean arterial pressure (MAP) increased 0.3 mm Hg/h during the first 24 hours, 0.1 mm Hg/h from the 25th to the 48th hour, and then stabilized for the remainder of the week. MAP values < or = 25 mm Hg were not uncommon and were not associated with apparent consequences. Thirty-five infants treated for hypotension differed significantly from untreated infants in several clinical variables present at birth, suggesting a different degree of fetal compromise. Treated infants were less likely to survive (43 versus 85%; P < 0.001) or survive without a major morbidity (29 versus 53%; P = 0.013) than untreated infants. It was not apparent from our data that the treatment of hypotension was helpful.

PHENOTYPING THE LEVEL OF BLOOD PRESSURE BY TELEMETRY IN MICE

1. Using telemetry, arterial blood pressure (BP) can be measured directly over long periods in freely behaving animals without recent anaesthesia or surgery. In the present review, we discuss the strengths and limitations of this method and important considerations in using the method to characterize the BP level in mice. 2. A variety of informative statistics can be used to describe the BP level and we have made available a spreadsheet template for their calculation on a routine basis. The BP level is well summarized using the average value for an entire 24 h period or for the individual light and dark phases of the day. Such long-term averages exhibit less statistical variation than those of short recording periods. In addition, averages of the dark and light phases of the day convey information concerning circadian variations of BP. 3. The frequency distribution of BP samples provides additional information concerning the range of BP values recorded over the course of the day and can be described in terms of percentiles of the distribution that correspond with the minimum and maximum BP values and their span. 4. In mice, BP can be markedly affected by locomotor activity cycles that occur frequently throughout both the light and dark phases of the day. In addition, BP is strongly affected by ambient temperature and food intake, as well as potentially by other determinants of energy balance. Consideration of these factors may help improve accuracy and precision when phenotyping the BP level in mice.

The Hypertension Prevention Trial: Assessment of the Quality of Blood Pressure Measurements

Blood pressure variability is an important consideration in hypertension trials for determining required sample size and consequently making accurate outcome statements. The Hypertension Prevention Trial was a randomized controlled trial carried out in 1983-1986 in four US clinics on men and women with high normal diastolic blood pressure. This trial provided an opportunity to assess conditions affecting blood pressure measurement variability. Trained blood pressure observers measured systolic and diastolic blood pressures twice, 30 seconds apart, using a random-zero sphygmomanometer. The quality of blood pressure measurements was assessed by computing the variability of the two readings per participant-visit for each blood pressure observer at each study clinic. Other sources of variability investigated included observer digit preference, time of day, and ambient temperature. On the basis of data from this population, it is estimated that the standard deviation of blood pressure values can be reduced by 5% by taking two measurements per participant-visit. An additional reduction of variability can be effected by having the duplicate blood pressure measurements made by different blood pressure observers. In special instances where the range of blood pressure values is very restricted, use of the random-zero sphygmomanometer can increase or decrease the among-participant variability in blood pressure values, depending upon where the distribution of blood pressure values is centered.

Blood pressure measurements in very low birth weight infants over the first week of life.

Intra-arterial blood pressure measurements recorded during the first week of life in 32 stable very low birth weight infants (20 of birth weight up to 1250 g and 12 with birth weight 1251-1500 g) were reviewed. None of the infants received inotropic drugs or were given infusions of colloids to manipulate the blood pressure during the periods from which the recordings were taken. The mean systolic, mean and diastolic blood pressure measurements for infants of birth weight greater than 1250 g were significantly higher than those recorded in the infants of birth weight of up to 1250 g (figure 1). The mean blood pressure (calculated by adding one third of the pulse pressure to the diastolic pressure) in the larger infants showed a significant increase with increasing postnatal age, but this increase was not apparent in the smaller infants (figure 2). Figure 3 shows the range of systolic, mean and diastolic blood pressure values that were recorded. The mean values were remarkably constant with diastolic blood pressure varying between 31 and 34 mmHg, mean blood pressure between 35 mmHg and 40 mmHg, and systolic blood pressure between 46 mmHg and 52 mmHg. Intra-arterial lines provide a convenient and accurate route for blood pressure monitoring. It is important that a normal range of blood pressure values in the very low birth weight infant is established so that hypotension, with the potential risk of cerebral ischemia, can be avoided.

Clinical assessment of the neonatal Dinamap 847 during anesthesia in neonates and infants.

Direct measurements of systolic, diastolic, and mean arterial blood pressure and electrocardiogram-derived heart rates were compared with indirect arterial blood pressure measurements using the Dinamap 847XT noninvasive monitor. A total of 260 paired comparisons from 16 patients were analyzed. A regression analysis of paired data over a wide range of blood pressure values gave the following results: for heart rate r = 0.97, for systolic arterial pressure r = 0.84, for mean arterial pressure r = 0.73, and for diastolic arterial pressure r = 0.52. The 95% confidence limits for systolic, mean, and diastolic arterial pressure were +/- 16 mm Hg, +/- 18 mm Hg, and +/- 21 mm Hg, respectively. The Dinamap monitor was found to be an accurate trend recorder of heart rate and blood pressure during anesthesia in neonates and small infants.