Estimating arterial resistance and compliance during transient conditions in humans

1989 ◽  
Vol 257 (1) ◽  
pp. H190-H197 ◽  
Author(s):  
F. C. Yin ◽  
Z. R. Liu
Keyword(s):  
Pressure Difference ◽  
Arterial Compliance ◽  
Quantitative Difference ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Hemodynamic Parameters ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Highly Correlated ◽  
Almost All

Almost all existing methods for estimating hemodynamic parameters are valid only during steady-state conditions. There is often a need, however, for estimating peripheral resistance and total arterial compliance during beat-to-beat transients such as during atrial fibrillation. During such transients the pressure at the onset and end of a cardiac cycle usually differ. This pressure difference necessitates a modification of usual methods used for estimating these hemodynamic parameters. In this paper we formulate a method for estimating resistance and total arterial compliance during such beat-to-beat transients. For simplicity the expressions are derived for a two-element windkessel model of the circulation. The method is a generalization of one we previously proposed. Rather than using parameter estimation techniques or having to assume a monoexponential pressure decay during diastole, our method uses the areas under the systolic and diastolic portions of the aortic pressure versus time tracing to obtain explicit expressions for compliance; both for the case where it is constant and when it is assumed to be nonlinear (exponential) function of pressure. Aortic pressure and flow data from patients undergoing cardiac catheterization are employed to illustrate the method. Results illustrate the quantitative difference between uncorrected and corrected estimates of both resistance and compliance as a function of the pressure difference between the onset and end of each beat. The uncorrected parameters were found to be linearly and highly correlated with these pressure differences. Regressions of pressure difference against normalized values revealed that the pooled data for all patients defined a single relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Use of the Kalman Filter for Aortic Pressure Waveform Noise Reduction

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Frank Lam ◽  
Hsiang-Wei Lu ◽  
Chung-Che Wu ◽  
Zekeriya Aliyazicioglu ◽  
James S. Kang
Keyword(s):  
Kalman Filter ◽  
Arterial Compliance ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Hemodynamic Parameters ◽  
Windkessel Model ◽  
Estimation Algorithms ◽  
Intensive Care Patients ◽  
Aortic Impedance ◽  
Aortic Blood Pressure

Clinical applications that require extraction and interpretation of physiological signals or waveforms are susceptible to corruption by noise or artifacts. Real-time hemodynamic monitoring systems are important for clinicians to assess the hemodynamic stability of surgical or intensive care patients by interpreting hemodynamic parameters generated by an analysis of aortic blood pressure (ABP) waveform measurements. Since hemodynamic parameter estimation algorithms often detect events and features from measured ABP waveforms to generate hemodynamic parameters, noise and artifacts integrated into ABP waveforms can severely distort the interpretation of hemodynamic parameters by hemodynamic algorithms. In this article, we propose the use of the Kalman filter and the 4-element Windkessel model with static parameters, arterial compliance C, peripheral resistance R, aortic impedance r, and the inertia of blood L, to represent aortic circulation for generating accurate estimations of ABP waveforms through noise and artifact reduction. Results show the Kalman filter could very effectively eliminate noise and generate a good estimation from the noisy ABP waveform based on the past state history. The power spectrum of the measured ABP waveform and the synthesized ABP waveform shows two similar harmonic frequencies.

Estimation of total arterial compliance: an improved method and evaluation of current methods

1986 ◽  
Vol 251 (3) ◽  
pp. H588-H600 ◽  
Author(s):  
Z. Liu ◽  
K. P. Brin ◽  
F. C. Yin
Keyword(s):  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Improved Methods ◽  
Mean Aortic Pressure

Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that compliance is constant, i.e., that arterial pressure-volume (P-V) relations are linear, and they also assume that diastolic aortic pressure decay is an exponential function of time. Both of these assumptions, however, are questionable. This study proposes improved methods of estimating compliance based on a Windkessel model of the arterial system but which utilize the area under the pressure tracing rather than the waveform itself. Formulations accounting for both linear and three hypothetical nonlinear arterial P-V relations (exponential, logarithmic, and parabolic) are presented. Data from patients with congestive heart failure and hypertension are used for illustration. Compliances assuming linear P-V relations are reasonably close to those assuming nonlinear P-V relations only at mean aortic pressure. At end-diastolic pressure the linear assumption underestimates and at peak systolic it overestimates the compliances obtained assuming nonlinear P-V relations. The simpler linear assumption still allows a first approximation to compliance, but we show that existing methods for obtaining compliance under this assumption have severe theoretical as well as practical shortcomings. Our proposed method avoids these shortcomings primarily because deviations from an exact exponential form of the pressure wave have less influence on these compliance estimates than currently used methods.

Apparent arterial compliance

1998 ◽  
Vol 274 (4) ◽  
pp. H1393-H1403 ◽  
Author(s):  
Christopher M. Quick ◽  
David S. Berger ◽  
Abraham Noordergraaf
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Arterial Compliance ◽  
Complex Function ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Lumped Model ◽  
Total Arterial Compliance

Recently, there has been renewed interest in estimating total arterial compliance. Because it cannot be measured directly, a lumped model is usually applied to derive compliance from aortic pressure and flow. The archetypical model, the classical two-element windkessel, assumes 1) system linearity and 2) infinite pulse wave velocity. To generalize this model, investigators have added more elements and have incorporated nonlinearities. A different approach is taken here. It is assumed that the arterial system 1) is linear and 2) has finite pulse wave velocity. In doing so, the windkessel is generalized by describing compliance as a complex function of frequency that relates input pressure to volume stored. By applying transmission theory, this relationship is shown to be a function of heart rate, peripheral resistance, and pulse wave reflection. Because this pressure-volume relationship is generally not equal to total arterial compliance, it is termed “apparent compliance.” This new concept forms the natural counterpart to the established concept of apparent pulse wave velocity.

Estimation of total systemic arterial compliance in humans

1990 ◽  
Vol 69 (1) ◽  
pp. 112-119 ◽  
Author(s):  
W. K. Laskey ◽  
H. G. Parker ◽  
V. A. Ferrari ◽  
W. G. Kussmaul ◽  
A. Noordergraaf
Keyword(s):  
Heart Failure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Idiopathic Dilated Cardiomyopathy ◽  
Windkessel Model ◽  
Failure Group ◽  
Control Subjects ◽  
Total Arterial Compliance

Systemic arterial compliance, a major component of aortic input impedance, was determined in 10 patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy and 11 age-matched control subjects found free of detectable cardiovascular disease. Total arterial compliance was determined from high-fidelity ascending aortic pressure and velocity recordings using 1) the traditional monoexponential aortic diastolic pressure decay and 2) the direct solution of the equation, which describes the three-element windkessel model of the arterial system. Resting values for total arterial compliance (x10(-3) cm5/dyn) derived from method 1 were significantly correlated with compliance derived from method 2 (r = 0.89, P less than 0.01). However, method 1 values (control mean 1.15 +/- 0.27, heart failure mean 1.18 +/- 0.54) were consistently and significantly lower (P less than 0.001) than method 2 values (control mean 1.59 +/- 0.50, heart failure mean 1.38 +/- 0.60). Resting total arterial compliance in heart-failure patients was not significantly different from control subjects. Total arterial compliance did not significantly change with exercise in either group despite increases in arterial pressure. However, nitroprusside administration in the heart-failure group increased total arterial compliance both at rest and on exercise compared with the unmedicated state. These different methodological approaches to the estimation of total arterial compliance in humans resulted in significantly different absolute values for compliance, although both methods provided concordant results with respect to the response of arterial compliance to physiological and pharmacological interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Beat-to-beat estimation of peripheral resistance and arterial compliance during pressure transients

1987 ◽  
Vol 252 (6) ◽  
pp. H1275-H1283 ◽  
Author(s):  
G. P. Toorop ◽  
N. Westerhof ◽  
G. Elzinga
Keyword(s):  
Heart Rate ◽  
Arterial Compliance ◽  
Peripheral Resistance ◽  
Estimation Method ◽  
Aortic Pressure ◽  
Autonomous Nervous System ◽  
Mean Flow ◽  
Arterial Tree ◽  
Total Arterial Compliance

We have used a computer-based parameter estimation method to obtain peripheral resistance, total arterial compliance, and characteristic resistance from the measurement of aortic pressure and flow in the open-thorax cat, assuming the three-element windkessel as a model of the systemic arterial tree. The method can be applied on a beat-to-beat basis in the steady state and in transients. We have validated this method by analyzing nonsteady-state data obtained from an electrical analog with fixed values of the resistances and compliance and by showing that the values obtained by this procedure were within 5% of the fixed values of the circuit. Changes in total peripheral resistance and arterial compliance were studied before, during, and after acute heart rate changes in five open-thorax cats with blocked autonomous nervous system. As expected, the peripheral resistance, estimated during the heart rate transient [3.93 +/- 0.94 (SE) kPa X ml-1 X s] was the same as before the transient (3.53 +/- 0.83 kPa X ml-1 X s); total arterial compliances were also identical (0.28 +/- 0.04 vs. 0.27 +/- 0.03 ml/kPa). In six cats without nervous blockade we obtained similar results. Calculation of peripheral resistance during transients from the mean pressure-to-mean flow ratio, i.e., without correction for arterial compliance, suggested changes in resistance values of less than or equal to 57%, which shows that correction is necessary. The findings indicate that peripheral resistance and total arterial compliance can be estimated in vivo on a beat-to-beat basis, even during hemodynamic transients.

Use of pulse pressure method for estimating total arterial compliance in vivo

1999 ◽  
Vol 276 (2) ◽  
pp. H424-H428 ◽  
Author(s):  
N. Stergiopulos ◽  
P. Segers ◽  
N. Westerhof
Keyword(s):  
Pulse Pressure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Lower Limbs ◽  
Pressure Method ◽  
Total Arterial Compliance ◽  
The Difference ◽  
Pulse Pressure Method

We determined total arterial compliance from pressure and flow in the ascending aorta of seven anesthetized dogs using the pulse pressure method (PPM) and the decay time method (DTM). Compliance was determined under control and during occlusion of the aorta at four different locations (iliac, renal, diaphragm, and proximal descending thoracic aorta). Compliance of PPM gave consistently lower values (0.893 ± 0.015) compared with the compliance of DTM (means ± SE; r = 0.989). The lower compliance estimates by the PPM can be attributed to the difference in mean pressures at which compliance is determined (mean pressure, 81.0 ± 3.6 mmHg; mean diastolic pressure, over which the DTM applies, 67.0 ± 3.6 mmHg). Total arterial compliance under control conditions was 0.169 ± 0.007 ml/mmHg. Compliance of the proximal aorta, obtained during occlusion of the proximal descending aorta, was 0.100 ± 0.007 ml/mmHg. Mean aortic pressure was 80.4 ± 3.6 mmHg during control and 102 ± 7.7 mmHg during proximal descending aortic occlusion. From these results and assuming that upper limbs and the head contribute as little as the lower limbs, we conclude that 60% of total arterial compliance resides in the proximal aorta. When we take into account the inverse relationship between pressure and compliance, the contribution of the proximal aorta to the total arterial compliance is even more significant.

Development of systemic arterial mechanical properties from infancy to adulthood interpreted by four-element windkessel models

2007 ◽  
Vol 103 (1) ◽  
pp. 66-79 ◽  
Author(s):  
Roberto Burattini ◽  
Paola Oriana Di Salvia
Keyword(s):  
Arterial Compliance ◽  
Peripheral Resistance ◽  
New Paradigm ◽  
Rapid Reduction ◽  
Cross Sectional ◽  
Total Arterial Compliance ◽  
In Series ◽  
Aortic Impedance ◽  
Age Range ◽  
Bell Shaped Curve

Aortic impedance data of infants, children and adults (age range 0.8–54 yr), previously reported by others, were interpreted by means of three alternative four-element windkessel models: W4P, W4S, and IVW. The W4P and W4S are derived from the three-element windkessel (W3) by connecting an inertance ( L) in parallel or in series, respectively, with the aortic characteristic resistance ( Rc). In the IVW, L is connected in series with a viscoelastic windkessel (VW). The W4S and IVW (same input impedance) fit the data best. The W4S, however, suffers from the assumption that Rc is part of total peripheral resistance ( Rp). The IVW model offers a new paradigm for interpretation of resistive properties in terms of viscous ( Rd) properties of vessel wall motion, distinguished from Rp. Results indicated that rapid reduction of Rd/ Rp during early development is functional to modulation of decay time constant (τd) of pressure in diastole, such that normalization over heart period (τd/T) is independent of body size. Estimates of total arterial compliance ( C) vs. age were fitted by a bell-shaped curve with a maximum at 33 yr. With body weight (BW) factored out by normalization, the C/BW data scattered about a bell-shaped curve centered at 66 mmHg. Inertance was significantly higher in pediatric patients than in adults, in accordance with a lower cross-sectional area of the vasculature, commensurate to a lower aortic flow. Changes of arterial properties appear functional to control the ratio of pulsatile power to active power and keep arterial efficiency as high as 97% in infants and children.

Relationship between strength of short-term systemic autoregulation and initial resistance

1994 ◽  
Vol 267 (5) ◽  
pp. R1182-R1189 ◽  
Author(s):  
R. Burattini ◽  
P. Borgdorff ◽  
N. Westerhof
Keyword(s):  
Cardiac Output ◽  
Pressure Difference ◽  
Venous Pressure ◽  
Peripheral Resistance ◽  
Vena Cava ◽  
Aortic Pressure ◽  
Reference State ◽  
Whole Body ◽  
Short Term ◽  
Initial Resistance

The relationship between strength of short-term whole body autoregulation and peripheral resistance in the reference state (initial resistance) was investigated in 9 anesthetized closed-chest dogs and 18 anesthetized open-chest cats. Baroreflex regulation was abolished in one of three ways: barodenervation, ganglionic blockade, or setting pressure constant in the isolated carotid sinuses after vagotomy. Ascending aortic pressure and flow and venous pressure were measured in the reference state and 1-3 min after partial occlusions of the inferior vena cava. Cardiac output and peripheral resistance (ratio between arteriovenous pressure difference and cardiac output) were normalized for body weight. Strength of autoregulation was quantified by a resistance gain (Gra), defined as the ratio between change in normalized peripheral resistance and corresponding change in normalized cardiac output. A broad range of values for peripheral resistance in the reference state (Ro) was obtained as a result of the different interventions used to abolish baroreflex regulation. Arteriovenous pressure difference and normalized cardiac output during multiple vena cava occlusions in the 9 dogs and in 8 of the cats were fitted with a parabola convex to the flow axis. From the best fit, Gra was estimated. In the remaining 10 cats Gra was estimated from a single occlusion of vena cava. When data of all dogs and cats were taken together, we found a linear relationship between Gra and Ro: Gra = K1.Ro + K2. The constants K1 and K2 were 17.9 x 10(-3) min.kg.ml-1 and -14.5 x 10(-3) mmHg.min2.kg2.ml-2, respectively. The correlation coefficient was 0.9.

Quantification of right ventricular afterload in patients with and without pulmonary hypertension

2006 ◽  
Vol 291 (4) ◽  
pp. H1731-H1737 ◽  
Author(s):  
Jan-Willem Lankhaar ◽  
Nico Westerhof ◽  
Theo J. C. Faes ◽  
Koen M. J. Marques ◽  
J. Tim Marcus ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Arterial Compliance ◽  
Characteristic Impedance ◽  
Peripheral Resistance ◽  
Windkessel Model ◽  
Artery Pressure ◽  
Pulmonary Arterial

Right ventricular (RV) afterload is commonly defined as pulmonary vascular resistance, but this does not reflect the afterload to pulsatile flow. The purpose of this study was to quantify RV afterload more completely in patients with and without pulmonary hypertension (PH) using a three-element windkessel model. The model consists of peripheral resistance ( R), pulmonary arterial compliance ( C), and characteristic impedance ( Z). Using pulmonary artery pressure from right-heart catheterization and pulmonary artery flow from MRI velocity quantification, we estimated the windkessel parameters in patients with chronic thromboembolic PH (CTEPH; n = 10) and idiopathic pulmonary arterial hypertension (IPAH; n = 9). Patients suspected of PH but in whom PH was not found served as controls (NONPH; n = 10). R and Z were significantly lower and C significantly higher in the NONPH group than in both the CTEPH and IPAH groups ( P < 0.001). R and Z were significantly lower in the CTEPH group than in the IPAH group ( P < 0.05). The parameters R and C of all patients obeyed the relationship C = 0.75/ R ( R2 = 0.77), equivalent to a similar RC time in all patients. Mean pulmonary artery pressure P and C fitted well to C = 69.7/P (i.e., similar pressure dependence in all patients). Our results show that differences in RV afterload among groups with different forms of PH can be quantified with a windkessel model. Furthermore, the data suggest that the RC time and the elastic properties of the large pulmonary arteries remain unchanged in PH.

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