The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Kyoo H. Rhee - One of the best experts on this subject based on the ideXlab platform.
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CONTINUOUS ESTIMATION OF Stroke Volume WITH MEAN PULSE PRESSURE. 302
Pediatric Research, 1996Co-Authors: Kyoo H. RheeAbstract:If the area of pressure waveform created by Stroke Volume is measured instantaneously, it will be possible to monitor cardiac Stroke Volume Beat-by-beat continuously. Mean arterial pressure is calculated from pulse pressure tracing by calculating the area of the waveform and dividing it by the length of the base; the height of the rectangle is the mean arterial pressure. Thus, the rectangle drawn by the difference between mean and diastolic arterial pressure which is defined here as “mean pulse pressure” is same as the area of pressure wave created by Stroke Volume.
Peter M. J. M. De Vries - One of the best experts on this subject based on the ideXlab platform.
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Determination of Stroke Volume by means of electrical impedance tomography.
Physiological measurement, 2000Co-Authors: Anton Vonk-noordegraaf, Jean G.f. Bronzwaer, Pieter E. Postmus, André Janse, Johan T. Marcus, T.j.c. Faes, Peter M. J. M. De VriesAbstract:ECG-gated electrical impedance tomography (EIT) is a non-invasive imaging technique, developed to monitor blood Volume changes. This study is the first in comparing this non-invasive technique in measuring Stroke Volume with established techniques. The objective of this study was to validate EIT variables derived from the EIT images with paired obtained Stroke Volume measurements by thermodilution and MRI. After right cardiac catheterization, EIT measurements were performed in 25 patients. Regression analysis was used to analyse the relation between the EIT results and Stroke Volume determined by thermodilution. From the regression line an equation was derived to estimate Stroke Volume (in ml) by EIT. A strong correlation was found between EIT and Stroke Volume measured by the thermodilution method (r = 0.86). In a group of 11 healthy subjects this equation was validated to MRI. The mean and standard deviation of the difference between EIT and MRI was 0.7 ml and 5.4 ml respectively. These data indicate that EIT is a valid and reproducible method for the assessment of Stroke Volume.
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A validation study of Stroke Volume measurement by means of electrical impedance tomography
Proceedings of 18th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1Co-Authors: André Janse, T.j.c. Faes, J. T. Marcus, P. E. Postmus, A. Vonk Noordegraaf, Robert M. Heethaar, Peter M. J. M. De VriesAbstract:ECG-gated electrical impedance tomography (EIT) has been developed to monitor blood Volume changes. The aim of this study was to compare Stroke Volume measurements by EIT with established methods of thermodilution and magnetic resonance imaging (MRI). After right cardiac catheterization, EIT measurements were performed in 26 patients. Regression analysis was used to analyze the relation between the EIT results and Stroke Volume. From the regression line an equation was derived to estimate Stroke Volume (in ml) by EIT. In a group of eleven healthy subjects this equation was validated to MRI. A strong correlation was found between EIT and Stroke Volume measured by the thermodilution method (r=0.86). The reproducibility coefficient for EIT measurements was 0.98. The average standard deviation between Stroke Volume measured by EIT and MRI is 5.4 ml, the mean difference between both methods is 0.7 ml and the coefficient of variation is 8.4%. We conclude that EIT is a valid and reproducible method for the assessment of Stroke Volume in healthy controls and cardiological patients.
Robert A. Robergs - One of the best experts on this subject based on the ideXlab platform.
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A review of the Stroke Volume response to upright exercise in healthy subjects
British journal of sports medicine, 2005Co-Authors: Chantal Vella, Robert A. RobergsAbstract:Traditionally, it has been accepted that, during incremental exercise, Stroke Volume plateaus at 40% of Vo 2 max. However, recent research has documented that Stroke Volume progressively increases to Vo 2 max in both trained and untrained subjects. The Stroke Volume response to incremental exercise to Vo 2 max may be influenced by training status, age, and sex. For endurance trained subjects, the proposed mechanisms for the progressive increase in Stroke Volume to Vo 2 max are enhanced diastolic filling, enhanced contractility, larger blood Volume, and decreased cardiac afterload. For untrained subjects, it has been proposed that continued increases in Stroke Volume may result from a naturally occurring high blood Volume. However, additional research is needed to evaluate the importance of blood Volume, or other mechanisms, that influence the Stroke Volume response to exercise in untrained subjects.
Pieter E. Postmus - One of the best experts on this subject based on the ideXlab platform.
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Clinically Significant Change in Stroke Volume in Pulmonary Hypertension
Chest, 2010Co-Authors: Serge A. Van Wolferen, Mariëlle C. Van De Veerdonk, Gert-jan Mauritz, Wouter Jacobs, J. Tim Marcus, Koen M. Marques, Jean G.f. Bronzwaer, Martijn W. Heymans, Anco Boonstra, Pieter E. PostmusAbstract:Background Stroke Volume is probably the best hemodynamic parameter because it reflects therapeutic changes and contains prognostic information in pulmonary hypertension (PH). Stroke Volume directly reflects right ventricular function in response to its load, without the correction of compensatory increased heart rate as is the case for cardiac output. For this reason, Stroke Volume, which can be measured noninvasively, is an important hemodynamic parameter to monitor during treatment. However, the extent of change in Stroke Volume that constitutes a clinically significant change is unknown. The aim of this study was to determine the minimal important difference (MID) in Stroke Volume in PH. Methods One hundred eleven patients were evaluated at baseline and after 1 year of follow-up with a 6-min walk test (6MWT) and cardiac MRI. Using the anchor-based method with 6MWT as the anchor, and the distribution-based method, the MID of Stroke Volume change could be determined. Results After 1 year of treatment, there was, on average, a significant increase in Stroke Volume and 6MWT. The change in Stroke Volume was related to the change in 6MWT. Using the anchor-based method, an MID of 10 mL in Stroke Volume was calculated. The distribution-based method resulted in an MID of 8 to 12 mL. Conclusions Both methods showed that a 10-mL change in Stroke Volume during follow-up should be considered as clinically relevant. This value can be used to interpret changes in Stroke Volume during clinical follow-up in PH.
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Stroke Volume response during exercise measured by acetylene uptake and mri
Physiological Measurement, 2007Co-Authors: Herman Groepenhoff, Anco Boonstra, Pieter E. Postmus, Sebastiaan Holverda, Tim J Marcus, Anton VonknoordegraafAbstract:The intra-breath technique to measure acetylene absorption offers the possibility to determine augmentation of the pulmonary blood flow per heart beat (QC) as an estimate of the Stroke Volume response during exercise. However, this method has not been compared with a validated test until now. Therefore, the aim of this study was to compare QC with Stroke Volume (SVMRI) determined by magnetic resonance imaging (MRI) at rest and during exercise in healthy subjects and patients. For this purpose, ten healthy subjects and ten patients with idiopathic pulmonary arterial hypertension (iPAH) with expected impaired stoke Volume response during exercise were measured by both methods. Exercise-induced changes in QC and SVMRI were correlated in healthy controls (r = 0.75, p < 0.05). Compared to healthy controls, QC increased less during exercise in iPAH patients (11 ± 17 ml versus 33 ± 12 ml, p < 0.05). A similar difference in Stroke Volume response to exercise between the two groups was measured by MRI (−0.6 ± 8 ml versus 23 ± 12 ml, p < 0.05, respectively). Hence, intra-breath and MRI measurements showed similar differences in exercise-induced changes in Stroke Volume between controls and patients. From these results it can be concluded that the intra-breath measurement of acetylene absorption might be of value as a non-invasive tool to estimate Stroke Volume augmentation during exercise and can detect differences in Stroke Volume responses between iPAH patients and healthy subjects.
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Determination of Stroke Volume by means of electrical impedance tomography.
Physiological measurement, 2000Co-Authors: Anton Vonk-noordegraaf, Jean G.f. Bronzwaer, Pieter E. Postmus, André Janse, Johan T. Marcus, T.j.c. Faes, Peter M. J. M. De VriesAbstract:ECG-gated electrical impedance tomography (EIT) is a non-invasive imaging technique, developed to monitor blood Volume changes. This study is the first in comparing this non-invasive technique in measuring Stroke Volume with established techniques. The objective of this study was to validate EIT variables derived from the EIT images with paired obtained Stroke Volume measurements by thermodilution and MRI. After right cardiac catheterization, EIT measurements were performed in 25 patients. Regression analysis was used to analyse the relation between the EIT results and Stroke Volume determined by thermodilution. From the regression line an equation was derived to estimate Stroke Volume (in ml) by EIT. A strong correlation was found between EIT and Stroke Volume measured by the thermodilution method (r = 0.86). In a group of 11 healthy subjects this equation was validated to MRI. The mean and standard deviation of the difference between EIT and MRI was 0.7 ml and 5.4 ml respectively. These data indicate that EIT is a valid and reproducible method for the assessment of Stroke Volume.
Anton Vonk-noordegraaf - One of the best experts on this subject based on the ideXlab platform.
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Sildenafil treatment in COPD does not affect Stroke Volume or exercise capacity.
The European respiratory journal, 2007Co-Authors: Heleen Rietema, Anco Boonstra, S. Holverda, Herman J. Bogaard, J. T. Marcus, Henk Smit, Nico Westerhof, P. E. Postmus, Anton Vonk-noordegraafAbstract:In chronic obstructive pulmonary disease (COPD) patients, Stroke Volume response to exercise is impaired. The aim of the present study was to investigate whether 3 months of sildenafil treatment improves Stroke Volume and, if so, whether this improvement is related to the pulmonary artery pressure and translated into an improved exercise capacity. A total of 15 stable COPD patients (Global Initiative for Chronic Obstructive Lung Disease stage II-IV) underwent right heart catheterisation at rest and during exercise. Stroke Volume was assessed by magnetic resonance imaging (MRI) at rest and during submaximal exercise in the supine position and compared with eight age-matched controls. Additionally, a cardiopulmonary exercise test and a 6-min walking distance test were performed. Exercise tests and MRI were repeated after 12 weeks of oral therapy with 50 mg sildenafil three times daily. Stroke Volume in COPD patients was significantly lower than in healthy controls (62+/-12 versus 81+/-22 mL at rest and 70+/-15 versus 101+/-28 mL during exercise). Pulmonary hypertension (PH) was diagnosed in nine patients and was absent in six. Treatment with sildenafil had no effect on Stroke Volume or exercise capacity. Although the Stroke Volume was lower in COPD patients with associated PH in comparison with non-PH patients, there was no difference in treatment response between both groups. In the present group of 15 chronic obstructive pulmonary disease patients, a reduced Stroke Volume was found at rest and during exercise. Neither Stroke Volume nor exercise capacity were improved by 3 months of sildenafil therapy.
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Determination of Stroke Volume by means of electrical impedance tomography.
Physiological measurement, 2000Co-Authors: Anton Vonk-noordegraaf, Jean G.f. Bronzwaer, Pieter E. Postmus, André Janse, Johan T. Marcus, T.j.c. Faes, Peter M. J. M. De VriesAbstract:ECG-gated electrical impedance tomography (EIT) is a non-invasive imaging technique, developed to monitor blood Volume changes. This study is the first in comparing this non-invasive technique in measuring Stroke Volume with established techniques. The objective of this study was to validate EIT variables derived from the EIT images with paired obtained Stroke Volume measurements by thermodilution and MRI. After right cardiac catheterization, EIT measurements were performed in 25 patients. Regression analysis was used to analyse the relation between the EIT results and Stroke Volume determined by thermodilution. From the regression line an equation was derived to estimate Stroke Volume (in ml) by EIT. A strong correlation was found between EIT and Stroke Volume measured by the thermodilution method (r = 0.86). In a group of 11 healthy subjects this equation was validated to MRI. The mean and standard deviation of the difference between EIT and MRI was 0.7 ml and 5.4 ml respectively. These data indicate that EIT is a valid and reproducible method for the assessment of Stroke Volume.
