A New Pulse Contour Analysis for Cardiac Output Estimation: The Systolic Volume Balance Method

2012 ◽  
Author(s):  
Orestis Vardoulis ◽  
Theodore G. Papaioannou ◽  
Nikos Stergiopulos
Keyword(s):  
Cardiac Output ◽  
Arterial Compliance ◽  
Intraclass Correlation ◽  
Pulse Contour ◽  
Waveform Analysis ◽  
Dimensional Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Systolic Volume ◽  
Volume Balance

Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several methods have been proposed for CO estimation based on arterial pressure waveform analysis, known as “pulse contour cardiac output” (PCCO) monitoring. Most of them are based on invasive recording of blood pressure and require repeated calibrations, while they are still subject to inaccuracy under specific conditions. The Systolic Volume Balance (SVB) method was developed as a new non-invasive method based on physical principles and was further validated by a one-dimensional model of the systemic arterial tree. CO estimates were compared against the “real” CO values of the one dimensional model. 507 different hemodynamic cases were simulated by altering heart rate (HR), total arterial compliance (C) and total arterial resistance (R). It was found that CO can be accurately estimated by the new SVB formula. The bias between the brachial PCCO and the model’s CO was 0.042 L/min with 0.341 L/min SD of difference. The limits of agreement were −0.7–0.6 L/min indicating high precision. The intraclass correlation coefficient and the root mean square error between estimated and “real” CO values were 0.861 and 0.041 L/min respectively, indicating good accuracy and agreement.

The “systolic volume balance” method for the noninvasive estimation of cardiac output based on pressure wave analysis

2012 ◽  
Vol 302 (10) ◽  
pp. H2064-H2073 ◽  
Author(s):  
Theodore G. Papaioannou ◽  
Orestis Vardoulis ◽  
Nikos Stergiopulos
Keyword(s):  
Cardiac Output ◽  
Pressure Wave ◽  
Arterial Compliance ◽  
Arterial System ◽  
Waveform Analysis ◽  
Wave Analysis ◽  
Empirical Coefficient ◽  
Systolic Volume ◽  
Volume Balance ◽  
Cardiac Period

Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific conditions. A new systolic volume balance (SVB) method, including a simpler empirical form (eSVB), was derived from basic physical principles that govern blood flow and, in particular, a volume balance approach for the conservation of mass ejected into and flowed out of the arterial system during systole. The formulas were validated by a one-dimensional model of the systemic arterial tree. Comparisons of CO estimates between the proposed and previous methods were performed in terms of agreement and accuracy using “real” CO values of the model as a reference. Five hundred and seven different hemodynamic cases were simulated by altering cardiac period, arterial compliance, and resistance. CO could be accurately estimated by the SVB method as follows: CO = C × PPao/( T − Psm × Ts/Pm) and by the eSVB method as follows: CO = k × C × PPao/ T, where C is arterial compliance, PPao is aortic pulse pressure, T is cardiac period, Psm is mean systolic pressure, Ts is systolic duration, Pm is mean pressure, and k is an empirical coefficient. SVB applied on aortic pressure waves did not require calibration or empirical correction for CO estimation. An empirical coefficient was necessary for brachial pressure wave analysis. The difference of SVB-derived CO from model CO (for brachial waves) was 0.042 ± 0.341 l/min, and the limits of agreement were −0.7 to 0.6 l/min, indicating high accuracy. The intraclass correlation coefficient and root mean square error between estimated and “real” CO were 0.861 and 0.041 l/min, respectively, indicating very good accuracy. eSVB also provided accurate estimation of CO. An in vivo validation study of the proposed methods remains to be conducted.

One Dimensional Model of the Systemic Arterial Tree Including Cerebral Circulation

2007 ◽  
Author(s):  
Philippe Reymond ◽  
Fabrice Merenda ◽  
Fabienne Perren ◽  
Daniel Rüfenacht ◽  
Nikos Stergiopulos
Keyword(s):  
Cerebral Circulation ◽  
Cerebral Arteries ◽  
Distributed Model ◽  
Dimensional Model ◽  
Heart Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Distributed Models ◽  
The Past ◽  
Systemic Arterial Tree

The aim of this study is to develop a distributed model of the entire systemic arterial tree, coupled to a heart model and including a detailed description of the cerebral arteries. Distributed models of the arterial tree have been studied extensively in the past (Avolio [1]; Cassot et al [2]; Meister [3]; Schaaf and Abbrecht [4]; Stergiopulos et al [5]; Westerhof et al [6]; Zagzoule and Marc-Vergnes [7]), however, no model has been developed so far that offers a physiologically relevant coupling to the heart and includes the entire cerebral artery network.

Validation of a patient-specific one-dimensional model of the systemic arterial tree

2011 ◽  
Vol 301 (3) ◽  
pp. H1173-H1182 ◽  
Author(s):  
Philippe Reymond ◽  
Yvette Bohraus ◽  
Fabienne Perren ◽  
Francois Lazeyras ◽  
Nikos Stergiopulos
Keyword(s):  
Arterial Wall ◽  
Specific Model ◽  
Constitutive Law ◽  
Distributed Model ◽  
Patient Specific ◽  
Dimensional Model ◽  
Arterial Tree ◽  
One Dimensional ◽  
Flow Waveforms ◽  
Systemic Arterial Tree

The aim of this study is to develop and validate a patient-specific distributed model of the systemic arterial tree. This model is built using geometric and hemodynamic data measured on a specific person and validated with noninvasive measurements of flow and pressure on the same person, providing thus a patient-specific model and validation. The systemic arterial tree geometry was obtained from MR angiographic measurements. A nonlinear viscoelastic constitutive law for the arterial wall is considered. Arterial wall distensibility is based on literature data and adapted to match the wave propagation velocity of the main arteries of the specific subject, which were estimated by pressure waves traveling time. The intimal shear stress is modeled using the Witzig-Womersley theory. Blood pressure is measured using applanation tonometry and flow rate using transcranial ultrasound and phase-contrast-MRI. The model predicts pressure and flow waveforms in good qualitative and quantitative agreement with the in vivo measurements, in terms of wave shape and specific wave features. Comparison with a generic one-dimensional model shows that the patient-specific model better predicts pressure and flow at specific arterial sites. These results obtained let us conclude that a patient-specific one-dimensional model of the arterial tree is able to predict well pressure and flow waveforms in the main systemic circulation, whereas this is not always the case for a generic one-dimensional model.

scholarly journals On the importance of the nonuniform aortic stiffening in the hemodynamics of physiological aging

2019 ◽  
Vol 317 (5) ◽  
pp. H1125-H1133
Author(s):  
Stamatia Z. Pagoulatou ◽  
Vasiliki Bikia ◽  
Bram Trachet ◽  
Theodore G. Papaioannou ◽  
Athanase D. Protogerou ◽  
...  
Keyword(s):  
Aortic Flow ◽  
Patient Specific ◽  
Diagnostic Tools ◽  
Dimensional Model ◽  
Arterial Tree ◽  
Simple Method ◽  
Peripheral Vessel ◽  
One Dimensional ◽  
Noninvasive Measurements ◽  
Effects Of Aging

Mathematical models of the arterial tree constitute a valuable tool to investigate the hemodynamics of aging and pathology. Rendering such models as patient specific could allow for the assessment of central hemodynamic variables of clinical interest. However, this task is challenging, particularly with respect to the tuning of the local area compliance that varies significantly along the arterial tree. Accordingly, in this study, we demonstrate the importance of taking into account the differential effects of aging on the stiffness of central and peripheral arteries when simulating a person’s hemodynamic profile. More specifically, we propose a simple method for effectively adapting the properties of a generic one-dimensional model of the arterial tree based on the subject’s age and noninvasive measurements of aortic flow and brachial pressure. A key element for the success of the method is the implementation of different mechanisms of arterial stiffening for young and old individuals. The designed methodology was tested and validated against in vivo data from a population of n = 20 adults. Carotid-to-femoral pulse wave velocity was accurately predicted by the model (mean error = 0.14 m/s, SD = 0.77 m/s), with the greatest deviations being observed for older subjects. In regard to aortic pressure, model-derived systolic blood pressure and augmentation index were both in good agreement (mean difference of 2.3 mmHg and 4.25%, respectively) with the predictions of a widely used commercial device (Mobil-O-Graph). These preliminary results encourage us to further validate the method in larger samples and consider its potential as a noninvasive tool for hemodynamic monitoring. NEW & NOTEWORTHY We propose a technique for adapting the parameters of a validated one-dimensional model of the arterial tree using noninvasive measurements of aortic flow and brachial pressure. Emphasis is given on the adjustment of the arterial tree distensibility, which incorporates the nonuniform effects of aging on central and peripheral vessel elasticity. Our method could find application in the derivation of important hemodynamic indices, paving the way for novel diagnostic tools.

scholarly journals Cardiac output changes from prior to pregnancy to post partum using two non-invasive techniques

Heart ◽  
2018 ◽  
Vol 105 (9) ◽  
pp. 715-720 ◽  
Author(s):  
Giulia Masini ◽  
Lin F Foo ◽  
Jérôme Cornette ◽  
Jasmine Tay ◽  
Dimitris Rizopoulos ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Linear Mixed Model ◽  
Post Partum ◽  
Intraclass Correlation ◽  
Longitudinal Change ◽  
Waveform Analysis ◽  
Specific Reference ◽  
Reference Ranges ◽  
Cross Sectional ◽  
Time Points

ObjectivesWe aimed to describe cardiac output (CO) trend from prepregnancy to post partum using an inert gas rebreathing (IGR) device and compare these measurements with those obtained by a pulse waveform analysis (PWA) technique, both cross-sectionally and longitudinally.MethodsNon-smoking healthy women, aged 18–44 years, with body mass index <35 were included in this prospective observational study. CO measurements were collected at different time points (prepregnancy, at four different gestational epochs and post partum) using IGR and PWA. A linear mixed model analysis tested whether the longitudinal change in CO differed between the techniques. Bland-Altman analysis and intraclass correlation coefficient (ICC) were used for cross-sectional and a four-quadrant plot for longitudinal comparisons.ResultsOf the 413 participants, 69 had a complete longitudinal assessment throughout pregnancy. In this latter cohort, the maximum CO rise was seen at 15.2 weeks with IGR (+17.5% from prepregnancy) and at 10.4 weeks with PWA (+7.7% from prepregnancy). Trends differed significantly (p=0.0093). Cross-sectional analysis was performed in the whole population of 413 women: the mean CO was 6.14 L/min and 6.38 L/min for PWA and IGR, respectively, the percentage of error was 46% and the ICC was 0.348, with similar results at all separate time points. Longitudinal concordance was 64%.ConclusionsDespite differences between devices, the maximum CO rise in healthy pregnancies is more modest and earlier than previously reported. The two methods of CO measurement do not agree closely and cannot be used interchangeably. Technique-specific reference ranges are needed before they can be applied in research and clinical settings.

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