Physiological and fluid-dynamic investigations of the transthoracic impedance plethysmography method for measuring cardiac output. Part II—Analysis of the transthoracic impedance wave by perfusing dogs

1976 ◽  
Vol 14 (4) ◽  
pp. 373-378 ◽  
Author(s):  
Hiroshi Ito ◽  
Ken-ichi Yamakoshi ◽  
Akio Yamada
Keyword(s):  
Cardiac Output ◽  
Fluid Dynamic ◽  
Impedance Plethysmography ◽  
Transthoracic Impedance

Comparison of two noninvasive techniques for estimating cardiac output during exercise

1986 ◽  
Vol 61 (1) ◽  
pp. 155-159 ◽  
Author(s):  
D. D. Hatcher ◽  
O. D. Srb
Keyword(s):  
Cardiac Output ◽  
Large Range ◽  
Impedance Plethysmography ◽  
Cycle Ergometer ◽  
O2 Consumption ◽  
Noninvasive Techniques ◽  
Transthoracic Impedance ◽  
The Mean ◽  
The Difference ◽  
Male Subjects

This study presents the comparison of two different noninvasive techniques for the estimation of cardiac output (Q). The two techniques used were transthoracic impedance plethysmography (Z) and the indirect Fick CO2 rebreathing (RB) method. Paired estimates of Q were made on 60 different male subjects at rest and during graded increments of work on a cycle ergometer. The mean resting Q as measured by the Z technique (COZ) was 7.46 +/- 0.35 and 5.96 +/- 0.43 l/min using the RB (CORB) technique. At 200 W the mean COZ was 18.67 +/- 0.72 l/min and the CORB was 23.73 +/- 0.84 l/min. Both the techniques were linearly correlated (R) with O2 consumption; i.e., RZ = 0.752, RRB = 0.855. The difference between these two R values is statistically significant (P less than 0.001). A linear relationship was found between the Z and RB techniques at all work loads (R = 0.75). This study suggests that both techniques are equally as reliable over a large range of work loads, with the Z technique being the simplest and most efficient to implement. It was also found that lung volume had no effect on the calculated COZ.

Non-Invasive Monitoring of Hemodynamic Parameters during Hemodialysis

1995 ◽  
Vol 18 (9) ◽  
pp. 499-503 ◽  
Author(s):  
F. Pizzarelli ◽  
P. Dattolo ◽  
M. Piacenti ◽  
M.A. Morales ◽  
T. Cerrai ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Blood Volume ◽  
Impedance Cardiography ◽  
Hemodynamic Parameters ◽  
Non Invasive ◽  
Transthoracic Impedance ◽  
Cardiac Output Index ◽  
On Line ◽  
Two Parameters

We studied in 13 hemodialysis patients intradialytic variations of blood volume (BV) and cardiac output, by means of non-invasive methods. We found a weak correlation, r 0.2 or less, between BV variations and intradialysis blood pressure variations. The sensitivity of the former in describing the variations of the latter was only 32%. During the 30 min preceeding the hypotensive crisis the percent BV variations did not show any predictive trend. On the contrary, refilling increased as blood pressure dropped and a weak inverse relation (r -0.35) was found between these two parameters. Unstable patients had predialytic blood volume values significantly lower than stable ones and comparable to healthy subjects. On the contrary, the correlation between percent variations of cardiac output index and MAP was 0.68 with a sensitivity and specificity of 90% and 59%, respectively. Unfortunately these promising results were obtained only with an estimate of cardiac output obtained by echocardiography and not by transthoracic impedance cardiography, which is much more feasible than the former as on-line monitoring of cardiac output. On-line monitoring of hemodynamic parameters is an appealing but still unsolved task.

Continuous determination of cardiac output during exercise by the use of impedance plethysmography

1981 ◽  
Vol 19 (5) ◽  
pp. 638-644 ◽  
Author(s):  
Y. Miyamoto ◽  
M. Takahashi ◽  
T. Tamura ◽  
T. Nakamura ◽  
T. Hiura ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Impedance Plethysmography ◽  
Continuous Determination

Transthoracic admittance plethysmograph for measuring cardiac output

1976 ◽  
Vol 40 (3) ◽  
pp. 451-454 ◽  
Author(s):  
H. Ito ◽  
K. I. Yamakoshi ◽  
T. Togawa
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Correlation Coefficient ◽  
Healthy Subjects ◽  
Regression Line ◽  
Correlation Study ◽  
Impedance Method ◽  
Ventricular Stroke Volume ◽  
Transthoracic Impedance ◽  
Admittance Method

A plethysmograph for measuring ventricular stroke volume (SV) from the transthoracic admittance variation was developed. A correlation study between the SV values determined by this method (SVy) and those measured by Kubicek's transthoracic impedance method (SVz) was carried out on 24 healthy subjects; the correlation coefficient was r = 0.99 and the regression line of SVY on SVz was y = 1.03x - 0.47. Based on the results obtained through the study, it was concluded that the admittance method was more advantageous than the impedance method for measuring SV.

Noninvasive Fluid Dynamic Power Loss Assessments for Total Cavopulmonary Connections Using the Viscous Dissipation Function: A Feasibility Study

2001 ◽  
Vol 123 (4) ◽  
pp. 317-324 ◽  
Author(s):  
Timothy M. Healy ◽  
Carol Lucas ◽  
Ajit P. Yoganathan
Keyword(s):  
Cardiac Output ◽  
Viscous Dissipation ◽  
Velocity Gradient ◽  
Power Loss ◽  
Control Volume ◽  
Fluid Dynamic ◽  
Dissipation Function ◽  
Power Losses ◽  
Dynamic Power ◽  
The Right

The total cavopulmonary connection (TCPC) has shown great promise as an effective palliation for single-ventricle congenital heart defects. However, because the procedure results in complete bypass of the right-heart, fluid dynamic power losses may play a vital role in postoperative patient success. Past research has focused on determining power losses using control volume methods. Such methods are not directly applicable clinically without highly invasive pressure measurements. This work proposes the use of the viscous dissipation function as a tool for velocity gradient based estimation of fluid dynamic power loss. To validate this technique, numerical simulations were conducted in a model of the TCPC incorporating a 13.34 mm (one caval diameter) caval offset and a steady cardiac output of 2 Ls˙min−1. Inlet flow through the superior vena cava was 40 percent of the cardiac output, while outflow through the right pulmonary artery (RPA) was varied between 30 and 70 percent, simulating different blood flow distributions to the lungs. Power losses were determined using control volume and dissipation function techniques applied to the numerical data. Differences between losses computed using these techniques ranged between 3.2 and 9.9 percent over the range of RPA outflows studied. These losses were also compared with experimental measurements from a previous study. Computed power losses slightly exceeded experimental results due to different inlet flow conditions. Although additional experimental study is necessary to establish the clinical applicability of the dissipation function, it is believed that this method, in conjunction with velocity gradient information derived from imaging modalities such as magnetic resonance imaging, can provide a noninvasive means of assessing power losses within the TCPC in vivo.

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