Дисертації з теми "Arterial blood pressure estimation"
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1
Zakrzewski, Aaron Michael. "Arterial blood pressure estimation using ultrasound." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111743.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 155-163).
While blood pressure is commonly used by doctors as an indicator of patient health, the available techniques to measure the quantity suffer from many inconveniences such as cutting off blood flow, being cumbersome to use, being invasive, or being inaccurate. The research addresses many of these inconveniences by developing and evaluating a novel ultrasound-based blood pressure measurement technique that is non-invasive and non-occlusive. The technique proceeds in three steps: data acquisition, data reduction, and optimization. In the data acquisition step, an ultrasound probe is placed on a patient's artery and a force sweep is conducted such that the contact force gradually increases; both the applied force and B-Mode images are recorded. In the data-reduction step, the Star-Kalman filter is applied in order to find the size of the artery in each image frame captured. The segmentation data and contact force data are inputs into the optimization step which consists of two sequential optimizations; the first makes many modeling assumptions and gives an estimate of pulse pressure while the second makes less assumptions and uses the approximation of pulse pressure to obtain absolute values of systolic and diastolic blood pressure. Central to the optimization algorithm is a computational biomechanical model of the artery and surrounding tissue, which is numerically modeled using finite elements. The impact of major modeling assumptions is corrected with a one time calibration. The technique is validated on a number of different data sets. Major data sets discussed include data taken on the carotid artery of (1) 24 single-visit nominally healthy volunteers, (2) two multi-visit nominally healthy volunteers, (3) one multi-visit hypertensive volunteer, and (4) one multi-visit hypotensive volunteer; additional miscellaneous data sets are taken and analyzed as part of this dissertation. The algorithm performance is quantified against readings from an automatic oscillometric cuff. Results show that systolic and diastolic blood pressures can be predicted by the algorithm. The technology discussed in this dissertation represents a proof-of-concept of a blood pressure measurement technique that could occupy a clinical middle ground between the invasive catheter and cuff-based techniques.
by Aaron Michael Zakrzewski.
Ph. D.
2
Baktash, Seddigheh. "Ratio-Independent Arterial Stiffness-Based Blood Pressure Estimation." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30971.
Повний текст джерелаАнотація:
Blood pressure is one of the crucial vital signs that still lacks measurement accuracy in clinical environments. It is reported by physicians that automated non-invasive blood pressure measurement devices, which are usually based on the oscillometric method, do not provide accurate estimation of blood pressure. This problem has been addressed in this work by incorporating arterial stiffness in blood pressure measurement. Pulse transit time is first used to estimate arterial stiffness parameters. Afterwards, these parameters are fixed into a model of the oscillometric envelope which can then be used to curve fit measured data using only four free parameters: systolic, diastolic, mean blood pressure and minimum lumen area. The proposed individualized technique is independent of any experimentally determined ratio, commonly used in existing oscillometric methods. The accuracy of the proposed technique is evaluated by comparing with (1) the same model without incorporation of arterial stiffness (i.e. a purely oscillometric technique), and (2) Omron device measurements. The results are promising and meet the criteria recommended by the ANSI/AAMI SP - 10 standard for non-invasive blood pressure measurement techniques.
3
Sun, James Xin. "Cardiac output estimation using arterial blood pressure waveforms." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41625.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 73-74).
Cardiac output (CO) is a cardinal parameter of cardiovascular state, and a fundamental determinant of global oxygen delivery. Historically, measurement of CO has been limited to critically-ill patients, using invasive indicator-dilution methods such as thermodilution via Swan-Ganz lines, which carry risks. Over the past century, the premise that CO could be estimated by analysis of the arterial blood pressure (ABP) waveform has captured the attention of many investigators. This approach of estimating CO is minimally invasive, cheap, and can be done continuously as long as ABP waveforms are available. Over a dozen different methods of estimating CO from ABP waveforms have been proposed and some are commercialized. However, the effectiveness of this approach is nebular. Performance validation studies in the past have mostly been conducted on a small set of subjects under well-controlled laboratory conditions. It is entirely possible that there will be circumstances in real world clinical practice in which CO estimation produces inaccurate results. In this thesis, our goals are to (1) build a computational system that estimates CO using 11 of the established methods; (2) evaluate and compare the performance of the CO estimation methods on a large set clinical data, using the simultaneously available thermodilution CO measurements as gold-standard; and (3) design and evaluate an algorithm that identifies and eliminates ABP waveform segments of poor quality. Out of the 11 CO estimation methods studied, there is one method (Liljestrand method) that is clearly more accurate than the rest. Across our study population of 120 subjects, the Liljestrand method has an error distribution with a 1 standard deviation error of 0.8 L/min, which is roughly twice that of thermodilution CO. These results suggest that although CO estimation methods may not generate the most precise values, they are still useful for detecting significant (>1 L/min) changes in CO.
by James Xin Sun.
M.Eng.
4
Beeks, Kyle A. "Arterial blood pressure estimation using ultrasound technology and transmission line arterial model." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121663.
Повний текст джерелаАнотація:
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 67-69).
This thesis describes the application of a transmission line model to arterial measurements in order to derive useful cardiovascular parameters. Non-invasive ultrasound techniques are used to make these measurements, which has several benefits over invasive methods such as arterial catheterization. However, invasive methods are seen as the "gold standard" measurements and therefore the most accurate. Having accurate measurements that can be done non-invasively would be very desirable for cardiologists to determine their patients' risk of developing cardiovascular disease. This work details how to obtain the blood flow and pulse pressure waveforms using ultrasound transducers. Two transducers, one for imaging and one for Doppler, can be used together to derive these waveforms from distension and blood flow velocity measurements. Unfortunately, the only blood pressure waveform that can be obtained is the pulse pressure, which does not contain diastolic information. By decomposing the backward and forward pulse and flow waves and using the transmission line model, the diastolic pressure can be determined and the complete arterial blood pressure waveform can be obtained.
by Kyle A. Beeks.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
5
Koohi, Iraj. "Methods for Non-invasive Trustworthy Estimation of Arterial Blood Pressure." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35830.
Повний текст джерелаАнотація:
The trustworthiness of the blood pressure (BP) readings acquired by oscillometric home-based monitoring systems is a challenging issue that requires patients to see the doctor for trusted measurements, especially those who are obese or have cardiovascular diseases such as hypertension or atrial fibrillation. Even with the most accurate monitors one may get different readings if BP is repeatedly measured. Trusted BP readings are those measured with accurate devices at proper measurement conditions. The accurate monitors need an indicator to assure the trustworthiness of the measured BP. In this work, a novel algorithm called the Dynamic Threshold Algorithm (DTA) is proposed that calculates trusted boundaries of the measured systolic and diastolic pressures from the recorded oscillometric waveforms. The DTA determines a threshold from the heart rate of subjects to locate the oscillometric pulse at the mean arterial pressure (PULSEMAP) and uses the peak, trough, and pressure of the located pulse to calculate the trusted boundaries.
In terms of accuracy, a modeling approach is employed to estimate BP from the arterial lumen area oscillations model in the diastolic region (ALA-based). The model requires compliance parameter ‘c’ to estimate BP. To this end, a pre-developed linear regression model between ‘c’ and the corresponding amplitude ratio of the PULSEMAP is employed to evaluate ‘c’. The proposed method uses ‘c’ and estimates BP by minimizing differences between peak and trough amplitudes of the actual and corresponding simulated waveforms.
The proposed DTA and ALA-based methods were tested on two datasets of healthy subjects and one dataset of sick subjects with cardiovascular diseases, and results were validated against corresponding references and compared with two popular maximum amplitude and maximum/minimum slope algorithms. Mean absolute error (MAE) and standard deviation of errors (STDE) are used to evaluate and compare the results. For healthy subjects, the MAE of the estimated systolic (SBP) and diastolic (DBP) blood pressures was improved up to 57% and 57% with an STDE of 55% and 62%, respectively. For sick subjects, the MAE was improved up to 40% and 29% with an STDE of 36% and 20% for SBP and DBP, respectively.
6
Tannous, Milad. "Robust Estimation of Mean Arterial Pressure in Atrial Fibrillation Using Oscillometry." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31707.
Повний текст джерелаАнотація:
Blood pressure measurement has been and continues to be one of the most important measurements in clinical practice and yet, it remains one of the most inaccurately performed. The use of oscillometric blood pressure measurement monitors has become common in hospitals, clinics and even homes. Typically, these monitors assume that the heartbeat rate remains stable, which is contrary to what happens in atrial fibrillation. In this thesis, a new method that provides a more precise estimate of Mean Arterial Pressure (MAP) is proposed using anon-invasive oscillometric blood pressure monitor. The proposed method is based on calculating a ratio of peak amplitude to trough amplitude for every pulse, then identifying where the ratio first reaches a value of 2. The performance of the proposed method is assessed by comparing the accuracy and variability of the readings against reference monitors -first in healthy subjects, then in atrial fibrillation patients. In healthy subjects and in atrial fibrillation patients, the proposed method achieved a performance accuracy that is well within the ANSI/AAMI SP10 protocol requirements of the reference monitors. The presence of atrial fibrillation diminished the performance of the reference monitor by increasing the variability of the reference readings. The proposed algorithm, on the other hand, performed better by achieving substantially lower variability in the readings than the reference device.
7
Arai, Tatsuya. "Estimation of cardiovascular indices by analysis of the arterial blood pressure signal." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67751.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 175-177).
This thesis introduces novel mathematical algorithms that track changes in stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) by analysis of the arterial blood pressure (ABP) signal. The algorithms incorporate cardiovascular physiology within the framework of a generalized Windkessel model, which is a widely accepted cardiovascular model. Algorithms to identify end systole were also developed and implemented in the new and existing SV, CO, and TPR estimation algorithms. The algorithms were validated by applying them to previously recorded Yorkshire swine data sets that include directly measured aortic blood flow (ABF), SV, CO, as well as central and peripheral ABP. Among the algorithms using the end systole identification algorithms, Parabolic Method, Modified Herd's Method, Kouchoukos Correction Method, and Corrected Impedance Method achieved low root normalized mean squared errors (RNMSEs). This thesis also introduces and validates a novel algorithm to reconstruct instantaneous ABF waveforms from the ABP signal. The algorithm utilizes an auto-regressive with exogenous input (ARX) model to describe the filter between ABF and ABP. Because ABF (the exogenous input to the peripheral circulation) is approximately zero during diastole, the diastolic ABP waveforms can be regarded as auto-regressive (AR). By the AR analysis of multiple diastolic ABP waveforms, the AR parameters are obtained. The AR parameters were applied to the ABP waveforms (both systolic and diastolic) to compute beat-to-beat ABF waveforms. The errors of skewness and kurtosis of the estimated ABF waveforms were statistically smaller than those estimated by the standard Windkessel model. The estimated ABF waveforms were further processed to estimate SV, CO, and TPR. The algorithm achieved RNMSEs of 15.3, 19.6, and 21.8% in SV estimation; 12.7, 15.2, and 15.8% in CO estimation; and 14.3, 20.9, and 19.4 % in TPR estimation derived from central, femoral, and radial ABP, respectively.
by Tatsuya Arai.
Ph.D.
8
Dastmalchi, Azadeh. "Beat-to-Beat Estimation of Blood Pressure by Artificial Neural Network." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31962.
Повний текст джерелаАнотація:
High blood pressure is a major public health issue. However, there are many physical and non-physical factors that affect the measurement of blood pressure (BP) over very short time spans. Therefore, it is very difficult to write a mathematical equation which includes all relevant factors needed to estimate accurate BP values. As a result, a possible solution to overcome these limitations is the use of an artificial neural network (ANN). The aim of this research is to design and implement a new ANN approach, which correlates the arterial pulse waveform shape to BP values, for estimation of BP in a single heartbeat. To test the feasibility of this approach, a pilot study was performed on an arterial pulse waveform dataset obtained from 11 patients with normal BP and 11 patients with hypertension. It was found that the proposed method can accurately estimate BP in single heartbeats and satisfy the requirements of the ANSI/AAMI standard for non-invasive measurement of BP.
9
Chen, Tiffany. "Cardiac output estimation from arterial blood pressure waveforms using the MIMIC II database." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53096.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 115-118).
The effect of signal quality on the accuracy of cardiac output (CO) estimation from arterial blood pressure (ABP) was evaluated using data from the Multi-Parameter Intelligent Patient Monitoring for Intensive Care (MIMIC) II database. Thermodilution CO (TCO) was the gold standard, and a total of 121 records with 1,497 TCO measurements were used. Six lumped-parameter and systolic area CO estimators were tested, using ABP features and a robust heart rate (HR) estimate. Signal quality indices for ABP and HR were calculated using previously described metrics. For retrospective analysis, results showed that the Liljestrand estimator yielded the lowest error for all levels of signal quality and for any single estimator when using five or more calibration points. Increasing signal quality decreased error and only marginally reduced the amount of available data, as a signal quality level of 90% preserved sufficient data for almost continuous CO estimation. At the recommended signal quality thresholds, the lowest gross root mean square normalized error (RMSNE) was found to be 15.4% (or 0.74 L/min) and average RMSNE was 13.7% (0.71 L/min). Based on these results, a linear combination (LC) of the six CO estimation methods was developed and proved superior to all other methods when up to 13 TCO calibration values were used. The clinical utility of the CO estimates were examined by correlating changes in four vasoactive medication doses with corresponding changes in estimated resistance, which was derived from mean ABP and estimated CO.
(cont.) Both the Liljestrand estimator and the LC estimator were used to estimate CO. Regression analysis failed to show a clear correlation between dose level and estimated resistance for either estimator except for neosynephrine, revealing the limitations of current SQI methods in ensuring signal fidelity. Examples of types of non-physiological or artifactual ABP waveforms are shown, and a potential damping detection method is proposed.
by Tiffany Chen.
M.Eng.
10
Francis, Said Elias. "Continuous estimation of cardiac output and arterial resistance from arterial blood pressure using a third-order Windkessel model." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41641.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 85-89).
Intensive Care Units (ICUs) have high impact on the survival of critically-ill patients in hospitals. Recent statistics have shown that only 10% of the 5 million patients admitted to ICUs in the United States die each year. In modern ICUs, the heart's electrical and mechanical activity is routinely monitored using various sensors. Arterial blood pressure (ABP) and heart rate (HR) are the most commonly recorded waveforms which provide key information to the ICU clinical staff. However, clinicians find themselves in many cases unable to determine the causes behind abnormal behavior of the cardiovascular system because they lack frequent measures of cardiac output (CO), the average blood flow out of the left ventricle. CO is monitored via intermittent thermodilution measurements which are highly invasive and only applied to the sickest ICU patients. The lack of frequent CO measurements has encouraged researchers to develop estimation methods for cardiac output from routinely measured arterial blood pressure waveforms. The prospects of estimating cardiac output from minimally-invasive blood pressure measurements has resulted in numerous estimation algorithms, however, there is no consensus on the performance of the algorithms that have been proposed. In this thesis, we investigate the use of a third-order variation of the Windkessel model, which is referred to as the modified Windkessel model. We validate its ability to generate well-behaved proximal and distal pressure waveforms for a given flow waveform and thus characterize the arterial tree. We also develop a model-based CO estimation algorithm which uses central and peripheral blood pressure waveforms to obtain reliable estimates of CO and the total peripheral resistance (TPR). We applied the estimation algorithm to a porcine data set.
(cont.) The results of our estimation algorithm are promising: the weighted-mean root-mean-squared-normalized-error (RMSNE) is about 13.8% over four porcine records. In each porcine experiment, intravenous drug infusions were used to vary CO, ABP, and HR over wide ranges. Our results suggest that the modified Windkessel model is a good representation of the arterial tree and that the estimation algorithm yields reliable estimates of CO and TPR under various hemodynamic conditions.
by Said Elias Francis.
M.Eng.
11
Swoboda, Marek Lec Ryszard Joseph Jeffrey. "Implantable arterial blood pressure sensor /." Philadelphia, Pa. : Drexel University, 2004. http://hdl.handle.net/1860/2968.
Повний текст джерела
12
Citty, Sandra Wolfe. "Ambulatory blood pressure biosituational feedback and systolic blood pressure estimation." [Gainesville, Fla.]: University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000663.
Повний текст джерела
13
Soueidan, Karen. "Augmented blood pressure measurement through the estimation of physiological blood pressure variability." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28828.
Повний текст джерелаАнотація:
Current noninvasive blood pressure (BP) measurement methods estimate the systolic and diastolic blood pressure (SBP and DBP) at two random instants in time. The BP variability and its serious consequences on the measurement are not recognized by most physicians. The standard for automated BP devices sets a maximum allowable system error of +/- 5 mmHg, even though natural BP variability often exceeds these limits. This thesis characterizes the variability of SBP and DBP and proposes a new approach to augment the conventional noninvasive measurement using simultaneous recordings of the oscillometric and continuous arterial pulse waveforms by providing: 1) The mean SBP (or DBP) over the measurement interval, 2) Their respective standard deviations, and 3) An indicator as to whether or not the oscillometric reading is an outlier. Recordings with healthy subjects showed that the approach has prominent potential and does not suffer from bias relative to the conventional method.
14
Emeagwali, Ijeoma. "Using distributed machine learning to predict arterial blood pressure." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91441.
Повний текст джерелаАнотація:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.3
Cataloged from PDF version of thesis.
Includes bibliographical references (page 57).
This thesis describes how to build a flow for machine learning on large volumes of data. The end result is EC-Flow, an end to end tool for using the EC-Star distributed machine learning system. The current problem is that analysing datasets on the order of hundreds of gigabytes requires overcoming many engineering challenges apart from the theory and algorithms used in performing the machine learning and analysing the results. EC-Star is a software package that can be used to perform such learning and analysis in a highly distributed fashion. However, there are many complexities to running very large datasets through such a system that increase its difficulty of use because the user is still exposed to the low level engineering challenges inherent to manipulating big data and configuring distributed systems. EC-Flow attempts to abstract a way these difficulties, providing users with a simple interface for each step in the machine learning pipepline.
by Ijeoma Emeagwali.
M. Eng.
15
Mafi, Majid. "Blood Pressure Estimation Using Oscillometric Pulse Morphology." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20630.
Повний текст джерелаАнотація:
This thesis work presents the analysis of Oscillometric blood pressure pulse waveform under different pressure points (Systolic, Mean Arterial, and Diastolic Pressures). Pulse waveforms' characteristics were determined from the waveforms at three different pressures and are compared for subjects at three different age groups. Estimation of blood pressure using a morphology based approach was done by using the change of pulse waveform characteristics at different pressure points. Pulse waveforms' characteristics that were obtained from pulse waveforms are utilized to estimate SBP, MAP, and DBP. The estimates obtained with pulse morphology based technique are compared with a BP measurement device and Maximum Amplitude Algorithm. Maximum slope of the pulse was also used for blood pressure estimation. The effect of movement and breathing on proposed method and MAA were compared and it was observed that breathing artifacts affect less the proposed method.
16
Sridharan, Mathura J. "Risk stratification of ICU patients using arterial blood pressure waveforms." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85506.
Повний текст джерелаАнотація:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis. "May 24, 2013."
Includes bibliographical references (pages 109-110).
Identifying patients at high risk for adverse events is very important to the practice of clinical medicine. Non-invasive ECG-based methods of risk stratification such as T wave Alterans, Morphological Variability, and Heart Rate Variability extract prognostic information from the electrocardiograph. However, there is still a wealth of data collected from ICU patients and left unused every year that can augment risk-stratification methods. This thesis extends non-invasive risk stratification to Arterial Blood Pressure (ABP) Waveforms. We derive and analyze classifiers based on the morphological distance time series (derived from beat-to-beat morphology changes in the ABP waveform) including ASDNNmd, SDANNmd, rMSSDmd, the MVABP score etc. We also derive and analyze classifiers based on the Downstroke Time Series (derived from the decay from peak systole to diastole) including ASDNNDownstroke, SDANNDownstroke, rMSSDDownstroke, etc. While this body of work suggests the classifiers we developed are not effective in risk stratification of ICU patients, we discuss other methods which may extract prognostic information from the ABP waveform more effectively.
by Mathura J. Sridharan.
M. Eng.
17
McGowan, Cheri L. McCartney Neil MacDonald Maureen J. "Isometric handgrip training and arterial blood pressure : effects and mechanisms /." *McMaster only, 2006.
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18
Cai, Ye Tan. "Assessment of central arterial hemodynamics, arterial stiffness, and vascular structure in children and adolescents." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/22921.
Повний текст джерелаАнотація:
Background Central arterial hemodynamics, arterial stiffness and arterial structure are predictive of cardiovascular events and outcomes in adulthood. The tools to measure these parameters have largely been developed and validated in adults, but poorly investigated in children. With increasing interest in cardiovascular risk assessments earlier in life, it is imperative to critically appraise the techniques to measure these parameters in childhood to ensure validity of measurement, and to understand what these parameters mean with regards to association with future cardiovascular disease outcomes. Aims We sought to test whether the currently available methodologies for assessing central arterial hemodynamics and arterial stiffness in adults would be similarly accurate and valid in children. These included the use of generalized transfer functions to estimate central hemodynamic parameters, and methods for estimating pulse wave velocity. Furthermore, we aimed to explore carotid extra-medial thickness as a potential cardiovascular risk marker in childhood. This included determining the association between carotid extra-medial thickness, a measure of arterial adventitial structure, and arterial stiffness in early life. Results In chapter 2, 3, 4, and 5 we found that adult transfer functions are sufficient for central blood pressure assessment in early life with correct pulse pressure calibration, but age-appropriate transfer functions are required for more accurate assessment of central waveform features in children. In chapter 6, we find that pulse wave velocity can be accurately measured in children and adolescents using a leg cuff-based approach, but can be improved upon with age-appropriate algorithm changes. In chapter 7 and 8, we found a small but significant association between carotid extra-medial thickness and carotid artery stiffness in children, but no association between this measure of arterial structure and cardiovascular outcomes later in life. Conclusions Assessments of central arterial hemodynamics and arterial stiffness in children benefit from age-appropriate adjustments to their measurement methodologies. Carotid adventitial structure, while associated with arterial stiffness in early life, is not a predictor of cardiovascular outcomes in adulthood.
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Tafuna'i, Nicole Denney. "Arterial Blood Flow at Rest and During Exercise with Blood Flow Restriction." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/9003.
Повний текст джерелаАнотація:
PURPOSE: This study comparted arterial occlusion pressure (AOP) of the superficial femoral artery (SFA) between the dominant and nondominant legs and the relationship between blood flow and occlusion pressure at rest and during muscle contractions in males and females. METHODS: The AOP of the SFA was measured using Doppler ultrasound in the dominant and nondominant legs of 35 (16 males, 19 females) apparently healthy, normotensive young adults. Blood flow in the SFA was measured in the resting state (REST) and during plantar flexion exercise (EXC) at occlusion pressures ranging from 0% to 100% of AOP. ANOVA was used to compare AOP between the dominant and nondominant legs and between males and females. Regression analysis was used to evaluate the influence of relevant variables on AOP. A mixed model was used to evaluate the relationship between blood flow and occlusion pressure at REST and during EXC. RESULTS: There was a significant difference in the AOP between the dominant and nondominant legs in males (230 ± 41 vs 209 ± 37 mmHg) and females (191 ± 27 vs 178 ± 21 mmHg), respectively. There was also a significant sex difference in the AOP in the dominant (230 ± 41 vs 191 ± 27 mmHg; p = 0.002) and nondominant (209 ± 37 vs 178 ± 21 mmHg; p = 0.004) legs, respectively. Regression analysis revealed that after accounting for leg circumference, age, sex, blood pressure, and skinfold thickness were not independent predictors of AOP. At REST and during EXC, there was a linear relationship between relative blood flow and occlusion pressure. CONCLUSIONS: Differences in leg circumference contribute to a portion of the differences in AOP between the dominant and nondominant legs and between sexes. The linear relationship between relative blood flow and occlusion pressure suggests that occlusion pressures during blood flow restriction exercise should be chosen carefully. A large variance in blood flow measurements at different occlusion pressures suggests the need for evaluating the reliability of blood flow measurements and standardization of methods.
20
Zienkiewicz, A. (Aleksandra). "Blood pressure estimation using pulse transit time models." Master's thesis, University of Oulu, 2017. http://jultika.oulu.fi/Record/nbnfioulu-201712063289.
Повний текст джерелаАнотація:
Abstract. Blood pressure (BP) is an important indicator of human health. Common methods for measuring BP continuously are either invasive, intermittent or they require using a cumbersome cuff. Pulse Transmit Time (PTT) -based measurement can be an alternative for such methods, as it ensures continue and non-invasive monitoring. However, since the method is indirect, it requires careful modelling of PTT-BP relation. In this thesis, three approaches of BP estimation from PTT are tested: linear regression, nonlinear Moens and Korteweg model and nonlinear model developed by Gesche. In the experiments, cardiovascular pulses for PTT were sensed using two fiber optics based accelerometers developed at the University of Oulu.
To evaluate feasibility of presented models, the results were compared with reference BP values, measured using methods accepted for the commercial use. There were two groups of data. One was compared with BP measured using invasive catheter. Second group was compared with BP measured using volume clamp method. Obtained results suggest, that the presented calculation methods in present state still require further development in order to provide accurate BP values, however, they can be potentially used for observation of BP changes.
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Svensson, Per. "Blood pressure, blood pressure variability and myocardial ischemia : studies in patients with peripheral arterial disease and matched control subjects /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-826-2.
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Winn, M. J. "Factors influencing the control of arterial blood pressure in conscious rats." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372016.
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Arvela, Sofia Coelho. "Medição da pressão arterial em canídeos e felinos." Master's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2013. http://hdl.handle.net/10400.5/5978.
Повний текст джерелаАнотація:
Dissertação de Mestrado Integrado em Medicina VeterináriaNeste trabalho realizou-se um estudo sobre as metodologias disponíveis para avaliação da pressão arterial em canídeos e em felinos, focando aquelas metodologias exequíveis na prática clínica de forma a obter a pressão arterial de animais conscientes de uma forma rápida e prática. Realizaram-se 87 medições de pressão arterial em canídeos e felinos, incluindo animais doentes e saudáveis utilizando um aparelho oscilométrico: “PetMAP”. Os valores de pressão arterial sistólica, média e diastólica alcançados para animais saudáveis da espécie canina foram 180,73 (+/- 28,04); 124,03 (+/- 20,13) e 95,59 (+/- 17,63) respetivamente. Para animais saudáveis da espécie felina foram 166,25 (+/- 28,38); 126,36 (+/- 22,82) e 105,45 (+/- 21,04) respetivamente. O estudo da relação da pressão arterial com fatores que a influenciam demonstrou que na espécie canina é o peso que provoca variações no valor da pressão arterial enquanto que na espécie felina é a idade. Conclui-se que apesar deste tipo de aparelhos de medição indireta sobrevalorizarem ou subestimarem o valor real da pressão arterial, constituem uma ferramenta de trabalho importante para a obtenção de dados fiáveis acerca do animal alvo de medição, quando utilizados rotineiramente recorrendo a uma metodologia constante e padronizada.
ABSTRACT - In this work we conducted a study on the available methodologies to assess blood pressure in dogs and cats, focusing on those there are feasible in clinical practice in order to be able to get the blood pressure of conscious animals in a quick and convenient way. We performed 87 measurements of blood pressure in dogs and cats either sick or healthy, using an oscillometric device: PetMAP. The values of systolic, mean and diastolic blood pressure achieved for healthy animals of the canine specie were 180,73 (+/- 28,04); 124,03 (+/- 20,13) and 95,59 (+/ - 17,63) respectively. For healthy animals of the feline specie were 166,25 (+/- 28,38); 126,36 (+/- 22,82) and 105,45 (+/- 21,04) respectively . The study of the relationship of blood pressure with factors that influence it demonstrated that in dogs is the weight that causes variations in blood pressure value while in the feline specie is age. We can therefore state that in spite the fact that this indirect method overestimate or underestimate the real value of arterial pressure, it is an important working tool to obtain reliable data about the animal being examined when used routinely performing a methodology consistent and standardized.
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Furusawa, Erika Arai. "Comparação das medidas de pressão arterial no consultório, no domicílio e pela monitorização ambulatorial da pressão arterial (MAPA) em crianças com hipertensão arterial." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5141/tde-18122008-122329/.
Повний текст джерелаАнотація:
O diagnóstico e acompanhamento da hipertensão arterial (HA) no paciente pediátrico dependem da acurácia e da representatividade da medida da pressão arterial (PA). A monitorização ambulatorial da pressão arterial (MAPA), apesar de suas vantagens em relação à medida casual, apresenta custo elevado e pode trazer desconforto ao paciente. A medida residencial da pressão arterial (MRPA), apesar de pouco estudada na criança, apresenta-se como um alternativo potencial à MAPA. Os objetivos deste estudo foram comparar as medidas da PA aferidas no consultório, na MRPA, na Liga de Hipertensão e pela MAPA avaliando o efeito do ambiente/observador e determinando a freqüência de valores compatíveis com HA nessas 4 situações. Este estudo foi transversal,prospectivo e foram incluídos pacientes com HA e PA controlada ou não no consultório. Foram analisadas as médias das pressões arteriais sistólicas e diastólicas. A MRPA foi realizada com aparelho OMRON HEM 705 CP por 14 dias, em dois períodos (manhã ou tarde e noite). Na véspera do início da MRPA, o paciente compareceu à Liga de Hipertensão do HC-FMUSP para colocação do equipamento da MAPA (SPACELABS 90207). Foram analisados os dados de 40 pacientes (14 meninas e 26 meninos), idade média 12,1±3,6 anos. Não houve diferença estatística entre as médias das pressões sistólicas (ANOVA p=0,3100) e diastólicas (ANOVA p=0,7700) no consultório com as médias diurnas da MRPA e nem com as médias sistólicas (ANOVA p=0,8240) e diastólicas(ANOVA p=0,1530) do período noturno da MRPA. As médias das pressões sistólicas e diastólicas da Liga e da MAPA foram maiores do que as médias do consultório e da MRPA (p<0,001), porém não houve diferença estatística entre as médias sistólicas e diastólicas da Liga com a MAPA (p=0,077) e (p=0,962) respectivamente. As médias das pressões diastólicas da MRPA foram menores do que as médias do consultório (p=0,001). Em relação à freqüência de pacientes com PA não controlada, esta foi maior na Liga de Hipertensão (Mc Nemar p<0,005), enquanto as comparações entre consultório MRPA diurna, consultório-MAPA vigília, MRPA diurna- MAPA vigília não foram significantes (Mc Nemar p>0,05). Na MAPA sono, os pacientes apresentaram maior freqüência de PA controlada do que na MRPA noturna. Dez pacientes apresentaram PA não controlada no consultório, a MAPA confirmou o diagnóstico em 7/10 (17,5%) pacientes, enquanto 5/10 (12,5%) confirmaram pela MRPA. Nesse grupo, a hipertensão do avental branco ocorreu em 3/10 (7,5%) pacientes diagnosticados pela MAPA e em 5/10 (12,5%) diagnosticados pela MRPA.Trinta pacientes apresentaram valores de PA controlados no consultório, destes 24/30 (60%) pacientes confirmaram o diagnóstico pela MAPA e 26/30 (65%) pela MRPA. A hipertensão mascarada ocorreu em 6/30 (15%) pacientes diagnosticados pela MAPA e em 4/30 (10%) diagnosticados pela MRPA. Nesse estudo demonstrou-se concordância entre MAPA e MRPA (teste de Mc Nemar p<0,01) com boa reprodutibilidade à avaliação do índice Kappa (0,557).The diagnosis and monitoring of hypertension in pediatric patients depend on the accuracy and reproducibility of blood pressure (BP) measurement. Ambulatory blood pressure monitoring (ABPM), despite its advantages over office BP, is costly and can cause discomfort to the patient. The blood pressure measured at home (HBP), although poorly studied in children, represents a potential alternative to ABPM. The objectives of this study were to compare BP measurement in four clinical conditions: office BP , casual BP measured at Liga de Hipertensão, HBP and ABPM, evaluate the effect of environment / observer and to determine the frequency of BP values compatible with the diagnosis of hypertension. This study was cross-sectional and prospective and included patients with arterial hypertension with/without properly controlled BP in the office. The means of systolic and diastolic BP were analyzed in the 4 clinical conditions. HBP was measured for 14 days using a validated fully automatic Omron HEM 705 CP device. ABPM was measured with SpaceLabs 90207 non-invasive portable oscilometric device. We analyzed data from 40 patients (14 girls and 26 boys), mean age 12.1 ± 3.6 (SD) years. There was no difference between systolic (ANOVA p = 0.3100) and diastolic (ANOVA p= 0.7700) BP in the office and daytime HBP nor with nightime systolic HBP ( ANOVA p = 0.8240) and diastolic HBP(ANOVA p = 0.1530). The average systolic and diastolic BP at the Liga de Hipertensão and ABPM were higher than office and HB P (p <0001), but there was no difference in the average systolic (p= 0.077) and diastolic (p = 0.962) BP between Liga and ABPM. The diastolic HBP was lower than office diastolic BP (p = 0001). The frequency of BP values compatible with hipertension was higher at the Liga de Hipertensão (Mc Nemar p <0005), while comparisons between officedaytime HBP, office- daytime ABPM and daytime HBP-ABPM were not significant (Mc Nemar p> 0.05). The BP measurements during nightime ABPM showed a higher frequency of values compatible with hypertension than the night HBP one. Ten patients were diagnosed hypertension in the office, ABPM confirmed the diagnosis in 7 / 10 (17.5%) patients, while 5 / 10 (12.5%) were confirmed by HBP. In this group, white-coat hypertension occurred in 3 / 10 (7.5%) patients as diagnosed by the ABPM and 5 / 10 (12.5%) as diagnosed by HBP.Thirty patients presented BP values within normal limits in the office, 24 / 30 (60%) patients confirmed this diagnosis by ABPM and 26/30 (65%) by HBP. Masked hypertension was diagnosed in 6 / 30 (15%) patients diagnosed by the ABPM and in 4 / 30 (10%) by HBP. This study confirmed a correlation between ABPM and HBP measurements (Mc Nemar test p <0.01) with good reproducibility as evaluated by the Kappa index (0.557).
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Plett, Melani Irene. "Ultrasonic arterial vibrometry with wavelet based detection and estimation /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5938.
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Roy, Matthew S. "Acute effects of facial cooling on arterial stiffness and wave reflection." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 56 p, 2007. http://proquest.umi.com/pqdweb?did=1397914231&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Liu, Yi. "A study of mathematical modelling and signal processing of cerebral autoregulation." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273880.
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Smirl, Jonathan David. "The relationship between arterial blood pressure and cerebral blood flow : insights into aging, altitude and exercise." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54000.
Повний текст джерелаАнотація:
The majority of previous research on the relationship between blood pressure and cerebral blood flow (CBF) through the application of transfer function analysis (TFA) has been performed under spontaneous conditions. Under these circumstances, there is little input signal power (blood pressure), which makes linear interpretation of the output (CBF) results tenuous. In five experimental studies, the general aim of this thesis was to provide new insights on the relationship(s) between blood pressure and CBF throughout the aging spectrum. The first study determined the reproducibility of TFA metrics during spontaneous and driven blood pressure oscillations. The results revealed that squat-stand maneuvers were the most robust and reliable method to evaluate this relationship throughout aging. Consequently, this methodology was employed for the research studies. The second study examined the pressure-flow response in younger adults with acutely elevated cerebrovascular resistance index (CVRi). Augmenting CVRi, even without changes in CO₂, resulted in increased phase lead and reduced amplitude modulation; therefore, the impact of CVRi needs to be considered for the parsimonious interpretation of TFA metrics. The third experiment examined the pressure-flow relationship in three adult populations: young and old healthy adults, and heart transplant recipients. Findings revealed comparable cerebral pressure-flow responses in all groups, despite elevated CVRi (older groups), and blunted cardiac baroreceptors (long-term heart transplant recipients). Thus, it appears the acutely increased phase and decreased gain noted in the second study may not accurately reflect the chronic elevations in CVRi in older adults.
Through the unique approach of oscillating blood pressure during exercise, the fourth study demonstrated that the cerebrovasculature high-pass filter model is intact in both young and older populations. The final study at high-altitude (5050m) explored the cerebral pressure-flow relationship prior to, during acclimatization, and return from high-altitude. Despite the marked oxygen desaturation, there were no changes to the pressure-flow response across the entire range of exposure acclimatization timelines. In conclusion: 1) squat-stand maneuvers provide a meritorious way to examine cerebral-pressure flow responses; and 2) effective pressure-flow relationships are maintained during healthy aging and exercise, and persist despite blunting of cardiac baroreflexes and reductions in arterial oxygen saturation.Graduate Studies, College of (Okanagan)
Graduate
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Jacobs, Samier. "The comparison of non-invasive blood pressure monitoring with brachial intra-arterial blood pressure monitoring in patients with severe pre-eclampsia." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95901.
Повний текст джерелаАнотація:
Thesis (MMed)--Stellenbosch University, 2014.ENGLISH ABSTRACT: OBJECTIVE: The aim of this study was to compare the accuracy of non-invasive brachial blood pressure measurements, using automated and manual devices, to invasive brachial intra-arterial blood pressure measurements in patients with preeclampsia, during acute severe hypertension. STUDY DESIGN: A prospective descriptive cross sectional study was conducted in the Obstetrics Critical Care Unit (OCCU) of Tygerberg Hospital. Pre-eclamptic patients with acute severe hypertension, who required the placement of brachial intra-arterial lines due to failed radial intra-arterial line placement, were included in the study. Both automated oscillometric and blinded manual aneroid sphygmomanometric blood pressures were recorded during hypertensive peaks and after stabilization of BP using intravenous Labetalol or Nepresol. These two noninvasive methods of blood pressure measurements were compared to brachial intraarterial blood pressure measurements. RESULTS: There was weak correlation between manual and intra-arterial SBP (r = 0.27, p = 0.048) for SBP≥160mmHg. The calculated mean difference between manual SBP compared to the intra-arterial SBP in this group was -23.19mmHg (+/- 19.40). There was moderate correlation between automated and intra-arterial SBP (r = 0.69, p < 0.05). The calculated mean difference between automated SBP compared to the intra-arterial SBP in this group was -16.85mmHg (+/- 11.58). CONCLUSION: This study of pre-eclamptic women demonstrated that both non-invasive methods of BP measurement were inaccurate measures of the true systolic intra-arterial BP and significantly underestimated SBP≥160mmHg when compared to brachial intra-arterial measurements. The SBP was also underestimated, to a lesser degree, for mild moderate hypertension. This study also demonstrated that direct invasive BP monitoring using the brachial artery is a safe method for accurate haemodynamic monitoring. We recommend the use of intra-arterial BP monitoring in pre-eclamptic women with acute severe hypertension. Radial arterial cannulation should be used as the first option and the brachial artery should be used if the first option fails.
AFRIKAANSE OPSOMMING: DOELWIT: Die doel van hierdie studie was om die akuraatheid van nie indringende bragiale bloeddruk metings, wat met outomatiese en manuele aparate geneem is, te vergelyk met bragiale intra-arteriele bloeddruk metings gedurend akute erge hipertensie in pasiente met pre-eklampsie, STUDIE ONTWERP: ʼn Prospektiewe beskrywende dwarssnit studie was in die Obstetriese Kritiese Sorg Eenheid (OCCU) van Tygerberg Hospitaal uit gevoer. Preeklamptiese pasiente met akute erge hipertensie, wat bragiale intra-arteriele lyne nodig gehad het, as gevolg van gefaalde radiale intra-arteriele lyn plasing, was in hierdie studie ingesluit. Beide outomatiese ossilometriese en geblinde aneroide sfigmomanometriese bloeddrukke, tydens hipertensiewe pieke en na stabilisering van bloeddrukke met binneaarse Labetalol of Nepresol, was aangeteken, Die twee nie indringende metodes van bloeddruk meting was met bragiale intra-arteriele bloeddruk metings vergelyk. RESULTATE: Daar was ʼn swak korrelasie tussen manuele en intra-arteriele sistoliese bloedrukke SBP (r = 0.27, p = 0.048) vir SBP≥160mmHg. Die berekende gemiddelde verskil tussen manuele SBP en intra-arteriele SBP was -23.19mmHg (+/- 19.40) in hierdie groep. Daar was ʼn matige korrelasie tussen outomatiese en intra-arteriele SBP (r = 0.69, p < 0.05). Die berekende gemiddelde verskil tussen outomaties SBP vergelyk met intra-arteriele SBP was -16.85mmHg (+/- 11.58) in hierdie groep. GEVOLGTREKKING: Hierdie studie van pre-eklamptiese vrouens, het getoon dat beide nie indringende metodes van bloeddruk meting, nie akurate metings van ware sistoliese intraarteriele bloeddruk is nie, en SBP≥160mmHg word aansienlik onderskat wanneer dit met bragiale intra-arteriele metings vergelyk word. Die SBP was ook tot ʼn minder mate onderskat vir matige hipertensie. Die studie het ook getoon dat die direkte bragiale intra-arteriele metode van bloeddruk monitering, ʼn veilige metode van hemodinamiese monitering is. Ons beveel die gebruik van intra-arteriele bloeddruk monitering aan, in preeklamptiese vrouens met akute erge hipertensie. Radiale arteriele kanulasie moet gebruik word as die eerste opsie en die bragiale arterie moet gebruik word as die eerste opsie faal.
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Loudon, Mary. "Arterial wall renin-like activity and blood pressure regulation in the rat." Thesis, University of Leicester, 1985. http://hdl.handle.net/2381/34141.
Повний текст джерелаАнотація:
In this study the Importance of the generation of angiotensin II within the blood vessel wall in determining the pressor response to injected renin was investigated. An injection of renin, given to rats after bilateral nephrectomy, produced a pressor response. The level of circulating renin, although initially elevated, returned to the normal range within three hours. However, the level of renin present in the aortic wall remained significantly elevated for six hours after the injection, as did the pressor response. Infusions of the angiotensin II antagonist saralasin at three and six hours after the renin injection confirmed that the pressor response was maintained by the renin-angiotensin system. An injection of renin into normal rats produced the same initial pressor response as was observed in the nephrectomised rats. However, the blood pressure subsequently returned to the pre-injection level after one hour. In the normal rats the pressor response was not related to the level of renin present within the aortic wall. It was concluded that the activity of the renin present within the blood vessel wall was more relevant to the control of blood pressure than the circulating level. However, when the kidneys were present this local action of the renin-angiotensin system was overriden by renal anti-hypertensive systems. This was not dependent on the presence of the renal medulla since the pressor response after chemical renal medullectomy was the same as that observed in the normal rats. The increase in the level of renin within the aortic wall after the injection of exogenous renin confirmed that renin can enter the walls of blood vessels from the circulation. It was concluded that this occurred by a process of passive diffusion.
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Bechtold, Andrea Galvan Scheuer Deborah A. "Effects of systemic and dorsal hindbrain glucocorticoids on arterial baroreceptor reflex control of heart rate." Diss., UMK access, 2005.
Знайти повний текст джерелаАнотація:
Thesis (Ph. D.)--School of Pharmacy. University of Missouri--Kansas City, 2005."A dissertation in pharmacology and pharmaceutical sciences." Typescript. Advisor: Deborah A. Scheuer. Vita. Title from "catalog record" of the print edition Description based on contents viewed May 31, 2006. Includes bibliographical references (leaves 238-274). Online version of the print edition.
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Jonnada, Srikanth. "Cuff-less Blood Pressure Measurement Using a Smart Phone." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115102/.
Повний текст джерелаАнотація:
Blood pressure is vital sign information that physicians often need as preliminary data for immediate intervention during emergency situations or for regular monitoring of people with cardiovascular diseases. Despite the availability of portable blood pressure meters in the market, they are not regularly carried by people, creating a need for an ultra-portable measurement platform or device that can be easily carried and used at all times. One such device is the smartphone which, according to comScore survey is used by 26.2% of the US adult population. the mass production of these phones with built-in sensors and high computation power has created numerous possibilities for application development in different domains including biomedical. Motivated by this capability and their extensive usage, this thesis focuses on developing a blood pressure measurement platform on smartphones. Specifically, I developed a blood pressure measurement system on a smart phone using the built-in camera and a customized external microphone. the system consists of first obtaining heart beats using the microphone and finger pulse with the camera, and finally calculating the blood pressure using the recorded data. I developed techniques for finding the best location for obtaining the data, making the system usable by all categories of people. the proposed system resulted in accuracies between 90-100%, when compared to traditional blood pressure meters. the second part of this thesis presents a new system for remote heart beat monitoring using the smart phone. with the proposed system, heart beats can be transferred live by patients and monitored by physicians remotely for diagnosis. the proposed blood pressure measurement and remote monitoring systems will be able to facilitate information acquisition and decision making by the 9-1-1 operators.
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Zanoli, Luca Maria. "Inflammation and arterial stiffness." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1088.
Повний текст джерелаАнотація:
Arterial stiffness is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall. It is well known that increased large artery stiffness independently predicts the cardiovascular risk in a variety of populations. The identification of populations at higher risk of increased arterial stiffness and the knowledge of the mechanisms involved in arterial stiffening may help to identificate pharmacological and other treatments to reduce the arterial stiffness and improve the outcome of the patients. Recently, new advances have been proposed about the active role of inflammation and endothelial dysfunction in arterial stiffening and early atherosclerosis. The aims of this thesis were to review the literature and to study, for the first time, the arterial stiffness in inflammatory bowel disease.
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Lenz, Maria do Carmo Sfreddo. "Efeito dos acordares na monitorização ambulatorial da pressão arterial." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/10329.
Повний текст джерелаАнотація:
Objetivo: Investigar o efeito de se distinguir a pressão arterial noturna da pressão arterial no sono pelo registro simultâneo da monitorização ambulatorial da pressão arterial e da polissonografia. Métodos: Recrutaram-se 36 pacientes, 29 homens e 7 mulheres, com suspeita de síndrome das apnéias e hipopnéias obstrutivas do sono (SAHOS), encaminhados à clínica do sono para investigação diagnóstica e que concordaram usar o monitor ambulatorial de pressão arterial (MAPA) Spacelabs 90207 ABP durante a polissonografia (PSG). A média de idade dos indivíduos era 45 ± 11 anos; o índice de massa corporal (IMC), 30,8 ± 5,4 Kg/m2; o índice de apnéias e hipopnéias, 35 ± 29 AH/h. Um microfone acoplado ao monitor ambulatorial de PA registrou os sons característicos de sua atividade em um canal da polissonografia e permitiu determinar, de modo eletrográfico, se a PA foi medida em sono (e-sono) ou vigília (e-vigília).Resultados: Os pacientes encontravam-se dormindo durante (média+DP) 61+24% (variando de 0 a 100%), das 14+1 medidas de pressão arterial durante a noite. Leituras de pressão sistólica e diastólica na MAPA foram significativamente maiores durante o evigília (121 + 12 / 73 + 9 mm Hg) que durante o total do período noturno (119 + 11 / 70 + 8 mmHg) e e-sono (116 + 13 / 68 + 9 mm Hg). Baseado nas medidas do período noturno, 22 pacientes (61%) tinham hipertensão noturna; baseado nas medidas do período de e-sono, 12 pacientes tinham hipertensão noturna (33%; qui-quadrado= 5,54; p= 0,018). Um modelo de regressão linear múltipla mostrou que a percentagem de medidas feitas durante o e-sono foi a única variável que explicou significantemente a diferença entre os valores de PA noturna e PA em e-sono, controlando para gênero, idade, IMC, IAH, e SaO2 mínima. Conclusão: Durante a MAPA as leituras de PA noturnas são mais altas que as leituras durante e-sono.Objective: Investigate the effect of distinguishing nighttime and sleep on nocturnal blood pressure results in ambulatory blood pressure monitoring (ABPM). Methods: We recruited 36 patients, 28 male, with suspected OSAHS attending a sleep clinic for diagnostic polysomnography (PSG) and who agreed to wear a Spacelabs 90207 ABP monitor during PSG. Their mean age was 45±11 years; body mass index (BMI), 30.8±5.4 kg/m2; apnea-hypopnea index (AHI), 35±29 AH/h; 13 had history of hypertension. A microphone attached to the ABP monitor recorded its sounds in the polygraph and allowed to classify each ABPM measurement as being made in electrographically-determined wake (e-wake) or sleep state (e-sleep). Results: Patients were asleep during (mean±SD) 61±24% (range 0 to 100%) of the 14±1 nighttime BP measurements. Systolic and diastolic ABPM readings were significantly higher during e-wake (121±12 / 73±9 mm Hg) than during total nighttime (119±11/70±8 m Hg) and e-sleep (116±13 / 68±9 mm Hg). Based on nighttime measurements 22 patients (61%) had nocturnal hypertension. Based on measurements made during e-sleep, nocturnal hypertension was diagnosed in 12 patients (33%; chisquare= 5.54; p= 0.018). A multiple linear regression model showed that the percentage of measurements made in e-sleep was the only variable that significantly explained the difference between nighttime and e-sleep BP figures, when controlling for gender, age, BMI, AHI, and lowest SaO2. Conclusion: During ABPM, nighttime BP readings are higher than during e-sleep and this changes dipping and nocturnal hypertension classification.
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Forouzanfar, Mohamad. "A Modeling Approach for Coefficient-Free Oscillometric Blood Pressure Estimation." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31213.
Повний текст джерелаАнотація:
Oscillometry is the most common measurement method used in automatic blood pressure (BP) monitors. However, most of the oscillometric algorithms are without physiological and theoretical foundation, and rely on empirically derived coefficients for systolic and diastolic pressure evaluation which affects the reliability of the technique. In this thesis, the oscillometric BP estimation problem is addressed using a comprehensive modeling approach, based on which coefficient-free estimation of BP becomes possible. A feature-based neural network approach is developed to find an implicit relationship between BP and the oscillometric waveform (OMW). The modeling approach is then extended by developing a mathematical model for the OMW as a function of the arterial blood pressure, cuff pressure, and cuff-arm-artery system parameters. Based on the developed model, the explicit relationship between the OMW and the systolic and diastolic pressures is found and a new coefficient-free oscillometric BP estimation method using the trust region reflective algorithm is proposed. In order to improve the reliability of BP estimates, the electrocardiogram signal is recorded simultaneously with the OMW, as another independent source of information. The electrocardiogram signal is used to identify the true oscillometric pulses and calculate the pulse transit time (PTT). By combining our developed model of oscillomtery with an existing model of the pulse wave velocity, a new mathematical model is derived for the PTT during the cuff deflation. The derived model is incorporated to study the PTT-cuff pressure dependence, based on which a new coefficient-free BP estimation method is proposed. In order to obtain accurate and robust estimates of BP, the proposed model-based BP estimation method sare fused by computing the weighted arithmetic mean of their estimates. With fusion of the proposed methods, it is observed that the mean absolute error (MAE) in estimation of systolic and diastolic pressures is 4.40 and 3.00 mmHg, respectively, relative to the Food and Drug Administration-approved Omron monitor. In addition, the proposed feature-based neural network was compared with auscultatory measurements by trained observers giving MAE of 6.28 and 5.73 mmHg in estimation of systolic and diastolic pressures, respectively. The proposed models thus show promise toward developing robust BP estimation methods.
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McGregor, Brian. "The left ventricle, aortic valve, and arterial tree - a fresh engineering perspective." Thesis, University of Ulster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339346.
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Chin, Kong Yien. "A new approach for non-invasive continuous arterial blood pressure measurement in human." Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/10253.
Повний текст джерелаАнотація:
The need for continuous noninvasive arterial blood pressure (ABP) monitoring from an artery closer to the heart (i.e. the ascending aorta) has led to the research and development work presented in this thesis. Clinical applications of continuous ABP waveform include assessments of cardiac function, cerebral autoregulation, autonomic function, arterial elasticity, physiological measurements in aerospace research, and also monitoring in anaesthesia and critical care. The superficial temporal artery (STA) was chosen as the measurement site and the measurement technique was the arterial volume clamping with photoplethysmography (PPG). The optoelectronic circuitry to measure PPG is contained in a specially designed probe placed over the STA and kept in place with a lightweight aluminium head frame. The complete prototype device (STAbp) also includes original designs for the pneumatic, electronic, signal processing, control and display sub-systems. A self-calibration feature that regularly updates the PPG reference level (Setpt) was also included to ensure accurate continuous ABP recording. The performance of the STAbp was compared against the Finapres®. Five parameters were evaluated: resting ABP (agreement, signal bandwidth, frequency response and magnitude squared coherence, and assessment of drift) and ABP dynamic change during isometric handgrip exercise. The agreement of resting ABP gave bias (SD) of -23.1 (15.05), -10.8 (13.83) and -12.4 (12.93) mmHg for systolic, mean (MAP) and diastolic pressures respectively. Further investigations were carried out to understand factors that can affect the accuracy of ABP measurements, notably the sensitivity of ABP to perturbation of the Setpt. Also, differences between the external compressing pressure at the PPG peak pulsation amplitude and the MAP were found to be normally distributed with mean (SD) of -4.7 (5.63) mmHg. In conclusion, it is demonstrated that the new STAbp device has great potential as a new tool for a wide range of clinical and research applications which require continuous ABP waveforms.
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Hendy, Emma Bernice. "Sites and mechanisms within the brainstem for chronic regulation of arterial blood pressure." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528103.
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Darekar, Angela Anagha. "The BOLD MRI response of the brain to alterations in arterial blood pressure." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/196567/.
Повний текст джерелаАнотація:
The impact of blood pressure changes on cerebral blood flow is an important area of investigation. The cerebral autoregulation mechanism acts to maintain blood supply to the brain, despite changes in blood pressure. Blood flow alterations are closely linked to neuronal activation, and this activity can be visualised using blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) – functional MRI. The aim of this project is to investigate the effect of dynamic blood pressure stimuli on the BOLD MRI signal in the brain. Two blood pressure stimuli were employed; thigh cuff deflation and the Valsalva manoeuvre. BOLD MRI signal changes were measured throughout both challenges. Arterial and venous blood pressure and tympanic membrane displacement (TMD) measurements were also made during these challenges. Blood pressure data was used to drive two linked models. The first model represented cerebral vascular physiology (Ursino) and this fed into a second model (Buxton), which predicted the resulting BOLD signal changes. This allowed comparison with experimental BOLD data. TMD data was also compared to intracranial pressure changes predicted by the Ursino model. The experimental BOLD data was found to agree reasonably well with the BOLD signal changes predicted by the modelling. BOLD signal changes are most influenced by deoxyhaemoglobin changes, predominantly as a result of blood flow alterations during the blood pressure challenges, which are not immediately compensated for by the autoregulation mechanism. TMD changes did not reflect intracranial pressure changes predicted by the modelling. In conclusion, if such blood pressure changes do occur during a functional MRI experiment, they may cause changes in the BOLD signal that are not due to neuronal activation. These signal changes may be employed to investigate the cerebral autoregulation mechanism across the brain, or to correct for inaccuracies in functional MRI data in patients with impaired cerebral autoregulation
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Nevala, Riikka. "Effects of genistein and daidzein on arterial tone and blood pressure in rats." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/biola/vk/nevala/.
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Cunha, Marcos Guimarães de Souza [UNESP]. "Análise do fluxo sanguíneo da artéria braquial em diferentes pressões no manguito do esfigmomanômetro." Universidade Estadual Paulista (UNESP), 2003. http://hdl.handle.net/11449/97138.
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cunha_mgs_me_guara.pdf: 2546988 bytes, checksum: 7f90dfedf806a463275bbea800769557 (MD5)O presente trabalho consiste no estudo do comportamento do fluxo sangüíneo na artéria braquial, através de sinais captados por um microfone acoplado no estetoscópio e utilizado para transformar o sinal acústico (sonoro) em elétrico, e enviá-lo para o computador. O estudo foi realizado oferecendo-se diferentes pressões no esfigmomanômetro, o qual foi adaptado com dois manômetros. Um dos manômetros, graduado em mmHg, não foi modificado, possui o selo do INMETRO e atuou como referência, ao outro foi inserido um extensômetro, que transformou o sinal de pressão em sinal elétrico, utilizando uma ponte amplificada, enviando-o para uma placa de aquisição de dados no computador. Foi traçada uma curva de calibração do sinal elétrico (em mV) com relação ao manômetro graduado em mmHg. Foi proposto um protocolo para aquisição destes sinais a serem analisados, baseado em protocolos de aferição de pressão arterial. O comportamento do fluxo sangüíneo foi comparado às diferentes pressões exercidas pelo esfigmomanômetro. Ao analisar estes dados, foram propostos limites de normalidades da intensidade do sinal do fluxo sangüíneo em diferentes freqüências nas cinco fases da escala de Koroktov. O trabalho mostrou também os limites de normalidade da pressão arterial, utilizando-se o sinal adquirido pela extensometria. Finalmente, foi oferecido mais um auxílio no diagnóstico de patologias do sistema cardiovascular.
The present work consists to study the features of blood flow in to the brachial artery through signals detected by a microphone coupled together a stethoscope. This apparatus changes the acoustics in eletric signal and, then, sends to the computer. This study was implemented exhibiting different pressures in the sphygnomanometer, where two manometers, graded in mmHg, were coulpled. One that has the INMETRO certificate of gauging instruments was not modificate and, then, it was used as the standard. In the other, an extensometer was coupled together, which through an amplifier bridge, pressure signals are transformed in electric signals and sent to a data adapter unit connected to the computer. A gauging curve for the eletric signals versus pressure signals was ploted. It was proposed a protocol to adquire these data signals, based on the protocol of brachial pressure measurement. The features of blood flow were compared at different sphygnomanometer pressures. In the analysis process of the data, normality boundaries of intensity were proposed to the blood flow signal at different frequencies in the five phases of the Koroktov scale. The work also showed the normality boundaries of brachial pressure using the data signals adquired by the extensometry process. Finally, it was provided an one more aid in to diagnose pathologies in the cardiovascular system.
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Jeddy, T. A. "Changes following balloon angioplasty of the superficial femoral artery and the effect of low molecular weight heparin : assessment using colourflow doppler ultrasound." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246086.
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Silva, Giovanio Vieira da. "Monitorização residencial da pressão arterial (MRPA) no controle da pressão arterial de pacientes em hemodiálise." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5148/tde-31102008-174347/.
Повний текст джерелаАнотація:
INTRODUÇÃO: Não se sabe se o ajuste da terapia anti-hipertensiva baseado na Monitorização Residencial da Pressão Arterial (MRPA) pode melhorar o controle da pressão arterial em pacientes em hemodiálise. OBJETIVOS: Comparar a redução da pressão arterial (PA) e do índice de massa ventricular esquerda (IMVE) obtido com o uso da MRPA em relação às medidas da PA pré-diálise em pacientes em hemodiálise. MÉTODOS: Pacientes hipertensos em hemodiálise foram randomizados para ter a terapia anti-hipertensiva ajustada em dois grupos: controle, baseado na PA pré-diálise, e intervenção, baseada na MRPA. Antes e após 06 meses de acompanhamento, os pacientes realizaram Monitorização Ambulatorial da Pressão Arterial (MAPA) por 24 horas, MRPA durante uma semana e ecocardiograma transtorácico. RESULTADOS: 34 e 31 pacientes completaram o estudo no grupo intervenção e controle, respectivamente. As pressões arteriais sistólica (PAS) e diastólica (PAD) no período interdialítico pela MAPA foram significativamente menores no grupo intervenção em relação ao grupo controle no final do estudo (média 24 horas: 135 ± 13mmHg / 76 ± 7mmHg versus 147 ± 15mmHg / 79 ± 8mmHg, respectivamente - p<0,05). Na análise da MRPA, o grupo intervenção apresentou redução significativa somente para a PAS em comparação ao grupo controle (média semanal: 144 ± 21mmHg versus 154 ± 22 mmHg, respectivamente - p<0,05). Não houve diferenças entre os grupos intervenção e controle em relação ao IMVE ao final do estudo (108 ± 35 g/m2 versus 110 ±33 g/m2, respectivamente - p>0,05). CONCLUSÕES: O uso sistemático da MRPA no ajuste da terapia anti-hipertensiva em pacientes em hemodiálise propiciou maior controle da PA no período interdialítico em comparação às medidas da PA pré-diálise. A MRPA pode ser usada como um instrumento adjuvante útil no controle da pressão arterial em pacientes em hemodiáliseINTRODUCTION: It is not known whether the adjustment of the antihypertensive therapy based on Home Blood Pressure Monitoring (HBPM) can improve blood pressure (BP) control in hemodialysis patients. OBJECTIVES: To compare the reduction in BP and in the left ventricular mass index (LVMI) obtained with the use of HBPM in relation to that achieved with predialysis BP measurements in hemodialysis patients. METHODS: Hypertensive patients on hemodialysis were randomized to have the antihypertensive therapy adjusted according two groups: control, based on the predialysis BP measurements, and intervention, based on HBPM. Before and after 06 months of follow-up, patients were submitted to Ambulatory Blood Pressure Monitoring (ABPM) for 24 hours, HBPM during one week and transthoracic echocardiogram. RESULTS: 34 and 31 patients completed the study in the intervention and control groups, respectively. The systolic (SBP) and diastolic (DBP) blood pressure in the interdialytic period by ABPM were significantly lower in the intervention group compared with the control group at the end of the study (mean 24-hours BP: 135 ± 13 mm Hg / 76 ± 7 mmHg versus 147 ± 15 mm Hg / 79 ± 8 mmHg, respectively - p <0.05). When the interdialytic BP was analysed by HBPM, the intervention group showed significant reduction only for the PAS in comparison with control group (mean weekly BP: 144 ± 21 mm Hg versus 154 ± 22 mm Hg, respectively - p <0.05). There were no differences between intervention and control groups in relation to LVMI at the end of the study (108 ± 36 g/m2 versus 110 ± 33 g/m2, respectively - p> 0.05). CONCLUSIONS: The systematic use of HBPM in the adjustment of antihypertensive therapy in patients on hemodialysis has led to better control of BP during interdialytic period compared to that achieved with the predialysis BP measurements. The HBPM can be used as a useful adjunct instrument to control blood pressure in hemodialysis patients
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Crossley, Kent Westerberg. "Effect of Cuff Pressure on Blood Flow DuringBlood Flow-Restricted Rest and Exercise." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8259.
Повний текст джерелаАнотація:
Purpose: The purpose of this study was to investigate the blood flow/pressure relationship (linear or nonlinear) in the superficial femoral artery when seated, as well as to investigate blood flow changes with exercise using varying cuff pressures and a preexercise (PE) condition. The presence of venous outflow with occlusion at rest and exercise was also investigated.Methods: Twenty-three subjects visited the lab on 3 occasions. First to determine linearity of blood flow using 0% to 90% arterial occlusion pressure (AOP), and venous outflow at rest and during exercise with cuff inflated to 40% AOP. Subsequent visits compared blood flow between rest and PE conditions to determine average blood flow, heart rate, systolic and diastolic blood pressure changes in response to a blood flow-restricted (BFR) exercise protocol. Results: Blood flow/pressure relationship is nonlinear at the superficial femoral artery (p < 0.01). No significant differences in average blood flow, conductance or mean arterial pressure (MAP) were found between 30% to 80% AOP (p = 1.0 to .08). Blood flow is not significantly different between rest and PE groups (p = 0.49) although initial 40% AOP and 40% exercise arterial occlusion pressure (EAOP) values were different between rest and PE groups. (p < 0.01). Conclusion: The nonlinear relationship at the superficial femoral artery demonstrates higher cuff pressures are not necessary to reduce blood flow in BFR exercise of the lower extremity. Furthermore, PE or warm-up is not necessary prior to determining EAOP as it does not alter blood flow responses during BFR exercise. We found evidence of venous outflow above the cuff both at rest and during exercise at 40% AOP.
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Miller, Mark E. "Estimation of limb occlusion pressure by adaptation of oscillometry for surgical tourniquet control." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29688.
Повний текст джерелаАнотація:
Pneumatic tourniquets are widely used in surgery of the extremities to occlude the vessels of the limb, thereby providing a bloodless field for dissection so that the surgeon may operate more quickly and accurately. Over-pressurization of the tourniquet cuff may lead to postoperative complications such as temporary or permanent paralysis of the limb. This motivated the development of adaptive tourniquet systems which could regulate the tourniquet pressure just above the limb occlusion pressure (LOP), or the minimum tourniquet pressure required to prevent blood flow past the cuff for a given duration.
Previous adaptive tourniquet systems suffered from several problems which limited their practical utility in the operating room. This thesis describes the adaptation of oscillometry, a technique widely used in the noninvasive estimation of blood pressure, to the estimation of LOP in the surgical environment for application in a clinically practical adaptive tourniquet system.
Improved oscillometric LOP estimation performance was obtained through the development of a filter for increasing the signal-to-noise ratio of the oscillometric pulses during periods of limb manipulation, the development of a heuristic real-time pattern recognition algorithm for extracting oscillometric pulses from signal data corrupted by limb movements, and the development of a new method for rapidly estimating the LOP which needs only one-third of the signal data required by a widely-used oscillometric approach to produce an estimate of comparable accuracy. In addition to these contributions, a new tourniquet cuff was developed which achieves an improved fit to the limb, thereby enhancing performance and reliability over that obtained from conventional tourniquets as both an oscillometric occlusion sensor and as a limb-occluding device.
An adaptive tourniquet system which integrated these improvements was developed and used in a clinical study involving four orthopaedic surgeons and 16 patients. Clinical trials of the latest system version in which circumstances permitted the use of adaptive control showed that the average limb-applied pressure was reduced by 35%, or from the conventional standard of 250 mm Hg to 162 mm Hg, in the upper limb surgeries, and by 38%, or from the conventional standard of 300 mm Hg to 187 mm Hg, in the lower limb surgeries. These significant reductions in the pressure indicate the potential effectiveness of adaptive tourniquet control and improved cuff design on reducing the risk of patient injuries from excessive tissue compression. Furthermore, unlike all previous implementations, this system is currently being evaluated on a routine basis in orthopaedic surgical procedures performed at Vancouver General Hospital.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Chen, Silu. "Improving Algorithms for Oscillometric Blood Pressure Estimation by Suppressing Breathing Effects." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28784.
Повний текст джерелаАнотація:
Blood pressure estimation by the oscillometry is a practice growing in popularity. Algorithms for blood pressure estimation are diverse, however little effort has been put forth to assess their performance. This thesis first surveys and assesses the algorithms used for oscillometric blood pressure estimation. Of all the known algorithms, the results of this work revealed one procedure which performed the best. These algorithms were evaluated by readings from two trained nurses. Next, we developed algorithms for extracting and suppressing breathing effects on blood pressure estimation. Breathing causes fluctuation in blood pressure and current oscillometric devices do not account for these effects. Extracting breathing signals extends the capabilities of existing oscillometric devices, such as reporting respiratory sinus arrhythmia, without the need for hardware changes. Suppression of these effects is performed by homomorphic and adaptive filtering. Results show improvement in that estimated pressure after suppression was closer to the nurse readings.
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Zakrzewski, Aaron Michael. "Multi-scale quantitative elastography and its application to blood pressure estimation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/87919.
Повний текст джерелаАнотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-119).
Elastography is a method that can be used to measure the elasticity of soft biological tissue and, ultimately, to detect cancerous tumors. In this thesis, quantitative compression based ultrasound elastography is developed using a fast multi-scale approach. The inverse problem optimization methods of elastography are applied to estimate noninvasively the arterial wall stiffness of a vessel as well as blood pressure. Simulation and experimental results are presented that predict the accuracy of the methods. A method is also introduced to eliminate the need for a reference pressure during the optimization over blood pressure. Using ultrasound, these techniques could provide noninvasive continuous measurement of blood pressure in major arteries and could give doctors another way to gather information about a patients cardiovascular health.
by Aaron Michael Zakrzewski.
S.M.
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Carvalho, Vera Lúcia Almeida Brazão de. "Hipertensão arterial felina." Bachelor's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2009. http://hdl.handle.net/10400.5/1005.
Повний текст джерелаАнотація:
Dissertação de Mestrado Integrado em Medicina VeterináriaNos animais saudáveis a pressão arterial (PA) mantém-se dentro de um determinado intervalo de valores. Uma elevação anormal e persistente acima do limite máximo desse intervalo define-se como hipertensão sistémica, podendo determinar patologia com ou sem expressão clínica. A hipertensão sistémica é dividida em primária (ou essencial) e secundária. Apesar da hipertensão primária (sem causa subjacente) representar mais de 90% de todos os casos de hipertensão sistémica em humanos, a hipertensão secundária, com origem em determinadas doenças, representa praticamente todos os casos de elevação da PA nos animais de companhia. A insuficiência renal crónica (IRC) e o hipertiroidismo são as causas mais comuns de hipertensão felina, o que implica que os principais sintomas em gatos hipertensos sejam a poliúria/polidipsia (PU/PD), perda de peso e alterações no apetite. O aumento da PA pode ser observado nos estadios iniciais do processo de doença, contribuindo para o seu diagnóstico precoce. A medição da PA pode ser efectuada através de métodos directos (invasivos) ou indirectos (não invasivos), com recurso a aparelhos que incorporam um cuff compressivo (método Doppler e método oscilométrico), associados a diferentes níveis de confiança. Apesar do método intra-arterial ser o mais preciso na avaliação da PA, este é tecnicamente difícil e nem sempre se torna prático nos diferentes casos clínicos. A hipertensão tem efeitos adversos para o organismo, afectando sobretudo os órgãos mais vascularizados, nos quais se incluem os olhos (descolamento de retina, cegueira súbita), rins (insuficiência renal), coração (hipertrofia ventricular esquerda, sopros cardíacos, arritmias) e sistema nervoso central (depressão, letargia, convulsões). A normalização da PA e a reversibilidade das lesões orgânicas, quando possível, são os objectivos do tratamento. Este passa pelo controlo da doença primária, mas muitas vezes é necessário efectuar um tratamento adicional com medicação antihipertensiva. A amlodipina, um bloqueador dos canais de cálcio, tem sido bastante eficaz no tratamento da hipertensão felina, e a sua crescente popularidade expandiu o seu uso na área veterinária. A relutância na comunidade veterinária em adoptar a prática da medição da PA é atribuída à incerteza que envolve a definição de hipertensão, bem como a dúvidas acerca de quais os métodos indirectos fiáveis para medição da PA. Actualmente, os veterinários têm a capacidade técnica para medir a pressão sistólica (PS) e a pressão diastólica (PD) de forma não invasiva e com resultados fiáveis. Similarmente, os diversos estudos realizados permitem chegar a um consenso quanto aos valores de PA que determinam a necessidade de tratamento antihipertensivo e quais os melhores protocolos terapêuticos que visam atingir esse objectivo. Estes mais recentes desenvolvimentos justificam que o processo de medição da PA se torne parte integrante dos cuidados veterinários actuais.
ABSTRACT - In healthy animals blood pressure is maintained within a determined range of values. An abnormal and persistent increase above the upper limit of that range is defined as systemic hypertension, which can result in pathology with or without clinical significance. Systemic hypertension is divided into primary (or essential) and secondary hypertension. Although primary hypertension (without an underlying factor) accounts for more than 90% of all cases of hypertension in humans, secondary hypertension, with origin in certain diseases, accounts for almost all identified cases of elevated blood pressure in companion animals. Chronic renal failure and hyperthyroidism are the most common causes of feline hypertension, which implies that frequent symptoms in hypertensive cats may be polyuria/polydipsia, weight loss and alterations in appetite. An increase in the blood pressure can be seen in the early stages of disease process, allowing its early diagnosis. Measurement of the patient’s blood pressure can be done by direct means (invasively) or indirectly (non-invasively) by devices that incorporate a compressive cuff (Doppler and oscillometric techniques), with different confidence levels. Although measurement by an intra-arterial mean provides the most accurate measure of arterial blood pressure, this is technically difficult and is not always practical in clinical cases. Hypertension has adverse effects on the organism, mainly affecting irrigated organs, such as eyes (retinal detachment, acute onset of blindness), kidneys (renal failure), heart (left ventricular hypertrophy, systolic murmur, arrhythmias) and central nervous system (depression, lethargy, seizures). Normalization of blood pressure and reversal of existing end-organ damage, if possible, are the goals to strive for with institution of treatment. It should tempt correction of the underlying cause for the hypertension, but additional treatment with antihypertensive drugs may be necessary. Amlodipine, a calcium channel blocker, does appear to be very effective in decreasing arterial blood pressure in cats, and has gained widespread popularity that expanded its use in the veterinary clinical practice. The reluctance of veterinary community to embrace the practice of blood pressure measurement has been attributable to the uncertainty involving the definition of hypertension, as well as confusion about which indirect blood pressure measurement techniques are accurate. Actually, veterinarians have the technical capabilities to measure systolic and diastolic blood pressure non-invasively and reliably in small animal practice. Similarly, recent studies suggest a consensus about values that determine necessity of antihypertensive treatment and what are the best therapeutical protocols to achieve this goal. These recent events justify that blood pressure measurement should become an integral part of modern veterinary medical care.
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Wijkman, Magnus. "Acute, ambulatory and central blood pressure measurements in diabetes." Doctoral thesis, Linköpings universitet, Internmedicin, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75352.
Повний текст джерелаАнотація:
Background: In patients with diabetes, high blood pressure is an established risk factor for cardiovascular disease. The aim of this thesis was to explore the associations between blood pressure levels measured with different techniques and during different circumstances, and the degree of cardiovascular organ damage and subsequent prognosis in patients with diabetes. Methods: We analysed baseline data from patients with type 2 diabetes who participated in the observational cohort study CARDIPP (Cardiovascular Risk factors in Patients with Diabetes – a Prospective study in Primary care), and longitudinal data from patients registered in the Swedish national quality registry RIKS-HIA (Register of Information and Knowledge about Swedish Heart Intensive care Admissions). Patients in CARDIPP underwent nurse-recorded, 24-hour ambulatory and non-invasive central blood pressure measurements. Patients in RIKS-HIA had their systolic blood pressure measured upon hospitalisation for acute chest pain. Results: In CARDIPP, nearly one in three patients with office normotension (<130/80 mmHg) were hypertensive during the night (≥120/70 mmHg). This phenomenon, masked nocturnal hypertension, was significantly associated with increased arterial stiffness and increased central blood pressure. Furthermore, nearly one in five CARDIPP patients with office normotension had high central pulse pressure (≥50 mmHg), and there was a significant association between high central pulse pressure and increased carotid intima-media thickness and increased arterial stiffness. Among CARDIPP patients who used at least one antihypertensive drug, those who used beta blockers had significantly higher central pulse pressure than those who used other antihypertensive drugs, but there were no significant between-group differences concerning office or ambulatory pulse pressures. In CARDIPP patients with or without antihypertensive treatment, ambulatory systolic blood pressure levels were significantly associated with left ventricular mass, independently of central systolic blood pressure levels. When RIKS-HIA patients, admitted to hospital for chest pain, were stratified in quartiles according to admission systolic blood pressure levels, the risk for all-cause one-year mortality was significantly lower in patients with admission systolic blood pressure in the highest quartile (≥163 mmHg) than in patients with admission systolic blood pressure in the reference quartile (128-144 mmHg). This finding remained unaltered when the analysis was restricted to include only patients with previously known diabetes. Conclusions: In patients with type 2 diabetes, ambulatory or central blood pressure measurements identified patients with residual risk factors despite excellent office blood pressure control or despite ongoing antihypertensive treatment. Ambulatory systolic blood pressure predicted left ventricular mass independently of central systolic blood pressure. In patients with previously known diabetes who were hospitalised for acute chest pain, there was an inverse relationship between systolic blood pressure measured at admission and the risk for one-year all-cause mortality.
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He, Shan. "Time-interval based Blood Pressure Measurement Technique and System." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38600.
Повний текст джерелаАнотація:
Smart watches in future will have smart wristband. This work analyses properties of new developed capacitive wristband sensor that measures ballistocardiogram (BCG) from single point on the wrist. In addition, it considers applications of this sensor to monitoring heart rate variability. Another application is in estimating changes (trend) in systolic blood pressure continuously when combined with lead one electrocardiogram (ECG).
BP is one of the vital signs that indicates the health condition. It is commonly measured by cuff-based monitor using either auscultatory or oscillometric method. Cuff-based BP monitor is not portable and unable to measure BP continuously which means it is difficult to attach BP monitoring function on a wearable device. Significant research is conducted in estimating BP from pulse transit time (PTT) mathematically which would enable the cuffless BP measurement.
In this work, a new time reference, RJ interval, which is the time delay between ECG and BCG signal peaks was tested whether it can be used as a surrogate of PTT in cuffless BP estimation. Based on the study done on 10 healthy people, it was shown that RJ intervals can be useful in evaluating trends of systolic blood pressure.