Evaluation of the theory of cardiac-output computation from transthoracic impedance plethysmogram

1977 ◽  
Vol 15 (5) ◽  
pp. 479-488 ◽  
Author(s):  
Ken-ichi Yamakoshi ◽  
Tatsuo Togawa ◽  
Hiroshi Ito
Keyword(s):  
Cardiac Output ◽  
Transthoracic Impedance

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.

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.

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.

Cardiac Output Measured by Transthoracic Impedance Cardiography at Rest, during Exercise and at Various Lung Volumes

1982 ◽  
Vol 63 (2) ◽  
pp. 107-113 ◽  
Author(s):  
A. T. Edmunds ◽  
S. Godfrey ◽  
Marion Tooley
Keyword(s):  
Cardiac Output ◽  
Lung Volume ◽  
Impedance Cardiography ◽  
Close Correlation ◽  
Invasive Technique ◽  
Breath Holding ◽  
Impedance Measurements ◽  
Respiratory Illnesses ◽  
Non Invasive ◽  
Transthoracic Impedance

1. Cardiac output measured by transthoracic impedance cardiography has been compared with simultaneous measurements made by the indirect Fick CO2 rebreathing method in nine adults and 14 children. All were healthy normal volunteers. Sixty-six comparisons were made at rest and during steady exercise at work loads up to 100 W. 2. Impedance measurements of cardiac output were consistently higher than indirect Fick measurements of cardiac output, but after application of a correction factor related to packed cell volume there was close correlation between the results obtained by the two methods (r = 0·94). 3. The mean coefficient of variation of impedance measurements of cardiac output was 13% at rest and 5% during steady-state exercise. 4. Changes of lung volume due to breath holding or resulting from addition of an expiratory resistance did not affect the measurement of cardiac output by impedance. 5. Transthoracic impedance cardiography is a rapid, non-invasive technique for measurement of cardiac output. It requires very little active co-operation from the subject. The method would probably give reliable results for patients with respiratory illnesses such as acute asthma or bronchiolitis, during which changes of lung volume may be expected to occur.

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