The use of the electrical-impedance technique for the monitoring of cardiac output and limb bloodflow during anaesthesia

Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice

“…In ICG, the applied electrical current is typically in the 10–100kHz and 1–5 mA range [82–84, 88, 89]. The cardiac component relative to the respiratory component increases with decreasing excitation frequency [62].…”

“…Similar to ICG, the electrodes must be positioned along the length of the limb such that blood is flowing from one set of electrodes to the other. The frequency ranges and currents used in these configurations are similar to ICG [88, 89, 91]. Note that the respiratory component is minimal however.…”

Alterations in left ventricular function in normal man on exposure to high altitude (3658 m).

“…It yielded two additional parameters of myocardial function, that is RZ interval and dZ RZ index. In addition, data could be simultaneously obtained noninvasively in respect of stroke index, cardiac index, and thoracic extravascular fluid volume (Kubicek et al, 1966;Geddes and Baker, 1968;Siegel et al, 1970;Lababidi et al, 1970;Hill and Lowe, 1973;Luepker et al, 1973;Balasubramanian and Hoon, 1976;Hill and Merrifield, 1976).…”

“…resistivity constant of blood (150 at 37°C) (Hill and Lowe, 1973), L = mean distance in cm between the inner electrodes, Zo = mean transthoracic electrical impedance in ohms, VET = ventricular ejection time in seconds measured from the onset of the dZ/dt wave form to 'X' point, a clear dip synchronous with aortic closure (Fig. 4).…”

Electrical impedance cardiogram in derivation of systolic time intervals.

“…The method has become viable after intense effort by a number of workers who refined and standardised the techniques (Kubicek et al, 1966(Kubicek et al, , 1974Van De Water et -.al., 1973;Hill and Lowe, 1973;Hill and Merrifield, 1976). The method is yet to find a place in any of the leading textbooks of cardiology or in (Weissler et al, 1972;Hurst, 1974;Weissler, 1974;Zoneraich, 1974).…”