Evaluation of the Parallel Conductor Theory for Measuring Human Limb Blood Flow by Electrical Admittance Plethysmography

Shimazu, Hideaki; Yamakoshi, Ken-ichi; Togawa, Tatsuo; Fukuoka, Masakazu; Itoh, Hiroshi

doi:10.1109/tbme.1982.324957

Cited by 23 publications

(4 citation statements)

References 12 publications

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“…Hill et alP i] showed the importance of adjusting p dependent on the haematocrit when patients with a low haematocrit are measured. This was also advocated by Kobayashi et alP 2] in normal healthy subjects during exercise, and by Costeloe et alP 3] in babies during the neonatal period. In 1981 however, Quail et alP 5] claimed, based on in vitro and in vivo investigations, that p might be considered virtually constant at a value of 135 Q • cm.…”

Section: Stroke Volume Equationsmentioning

confidence: 77%

The technique of impedance cardiography

Woltjer¹,

Bogaard²,

Vries³

1997

European Heart Journal

104

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Section: Stroke Volume Equationsmentioning

confidence: 77%

The technique of impedance cardiography

Woltjer¹,

Bogaard²,

Vries³

1997

European Heart Journal

104

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“…One study (Gotshall et al 1989) has compared both equations to thermodilution in the same, critically ill, patients; a slightly better correlation was reported when Kubicek was used (r = 0.88 for Kubicek and r = 0.77 for Sramek-Bernstein). In our recent meta-analysis of the literature (Raaijmakers et al 1998) we found that the 95% ci of the correlation between TIC and thermodilution was 0.77 to 0.86 in critically ill patients. Moreover, this meta-analysis showed that in critically ill patients, Kubicek performed significantly better (95% ci: 0.85-0.94) than Sramek-Bernstein (95% ci: 0.71-0.84).…”

Section: Discussionmentioning

confidence: 91%

The influence of extravascular lung water on cardiac output measurements using thoracic impedance cardiography

et al. 1998

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The purpose of this study was to investigate the influence of pulmonary oedema as measured with the double indicator dilution technique on the accuracy of cardiac output (CO) measurement using thoracic impedance cardiography (TIC) compared with thermodilution in thirteen sepsis patients. Differences in the Kubicek and Sramek-Bernstein equation with respect to pulmonary oedema were explored theoretically and experimentally. From a parallel two cylinder model a hypothesis can be derived that CO determined with the Kubicek equation is oedema independent, whereas CO determined using the Sramek-Bernstein equation is oedema dependent. Experimentally, CO determined using Kubicek's equation correlated better with thermodilution CO (r = 0.75) than CO determined with the Sramek-Bernstein equation (r = 0.25). The effect of oedema on the accuracy of TIC was investigated by comparing the differences in the CO of impedance and thermodilution to the extravascular lung water index. For the Kubicek equation the difference was not influenced by oedema (r = 0.04, p = 0.84), whereas for the Sramek-Bernstein equation the difference was affected by oedema (r = 0.39, p = 0.05). Thus, the effects of pulmonary oedema on the accuracy of TIC measurements can better be understood with the parallel cylinder model. Moreover, the Kubicek equation still holds when pulmonary oedema is present, in contrast to the Sramek-Bernstein equation.

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“…'' All "standard" methods, including direct Fick, PACE, Vol. 16 July 1993. Parti dye dilution, and thermodilution, the widely recognized "gold standard" of cardiac output estimation, are subject to errors of at least ± 10%.…”

Section: Accuracy Of Impedance Cardiographymentioning

confidence: 99%

“…If only the trend need be followed, the high reproducibility of impedance cardiography measurements allows small changes in cardiac PACE, Vol. 16 July 1993, Part I output to be detected on a frequent and ongoing basis. The ease and precision of impedance cardiography warrants its more widespread u.se in the assessment of pacemaker patients.…”

Section: The Place Of Impedance Cardiography Among Other Techniques Fmentioning

confidence: 99%

Impedance Cardiography for Cardiac Output Estimation in Pacemaker Patients: Review of the Literature

Ovsyshcher

Furman

1993

Pacing Clinical Electrophis

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Impedance cardiography permits noninvasive beat-to-beat determination of cardiac output, the product of the amplitude of the first derivative of thoracic impedance signal (dZ/dt), the ventricular ejection time, and heart rate corrected by the distance between the measuring electrodes. Its use is based on: (1) the dZ/dt signal that originates from the upper thorax; (2) the ventricular ejection period measured by the dZ/dt curve that occurs between the opening and closing of the aortic valve; (3) the dZ/dt curve is similar in morphology and timing to the aortic flow curve measured by an electromagnetic flowmeter with a significant linear correlation (r = 0.9) between dZ/dt and peak aortic flow; (4) similarity of the linear correlation between stroke volume, determined by the flowmeter and the impedance signal; and (5) significant reduction of the dZ/dt signal by 90% follows simultaneous occlusion of the aorta and the pulmonary artery. The rapid systolic portion of the impedance signal occurs only when blood is ejected into the aorta and is independent of right ventricular ejection. Most studies comparing impedance cardiography results with standard cardiac output determination have shown a correlation of 0.7-0.9. While the accuracy of impedance cardiography remains controversial and can be affected by the inherent limitations of the technique and by low cardiac output, intracardiac shunts, and valvular regurgitation, the high reproducibility of the method is established and may be comparable or superior to other commonly used techniques. When accurate determination of cardiac output is crucial, impedance cardiography may be used in conjunction with a standard technique to establish a baseline reference, thereby permitting further analysis. If only the trend need be followed, the high reproducibility of impedance cardiography measurements allows small changes in cardiac output to be detected on a frequent and ongoing basis. The ease and precision of this technique warrants its more widespread use in the assessment of pacemaker patients. Further use of this promising technique will allow a better definition of its role in the assessment of a wide range of cardiac patients.

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Evaluation of the Parallel Conductor Theory for Measuring Human Limb Blood Flow by Electrical Admittance Plethysmography

Cited by 23 publications

References 12 publications

The technique of impedance cardiography

The technique of impedance cardiography

The influence of extravascular lung water on cardiac output measurements using thoracic impedance cardiography

Impedance Cardiography for Cardiac Output Estimation in Pacemaker Patients: Review of the Literature

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