Impedance Cardiography Essay

Impedance cardiography is a noninvasive technique for assessing stroke volume (and thus cardiac output) as well as pre-ejection period (systolic time intervals). To measure impedance, four dual-electrodes recorded basal transthoracic impedance (Z0) and the first derivative of that impedance, the change in impedance over time (dZ/dt). Biopac EL-500 dual-electrodes were placed on each side of the neck and on both sides of the abdomen (under the arms) at the level of the thoracic xiphisternal junction. An AC current of 4 mA at 100 kHz was passed through the four outer electrodes (the top electrodes on the neck and the bottom electrodes on the abdomen), and Z0 was measured from the four inner electrodes. Biopac's EBI100C Electrical Bioimpedance Amplifier was used to record the impedance parameters. Finally, using Biopac's NIBP100A noninvasive blood pressure system, continual recordings of blood pressure were measured from the participant's radial artery of the nonpreferred arm.

Four cardiovascular responses are used to differentiate challenge and threat. Ventricular contractility (VC), which is indexed by a decrease in pre-ejection period, a measure of the contractile force of the heart or the time from the initiation of left ventricular contraction until the aortic valve opens, was assessed in …show more content…
In addition, they have been used in numerous published tests of personality and social psychological theories (e.g., social facilitation, social comparison, stigma, self-esteem, religiosity, etc.—see Blascovich, 2008 and Blascovich and Seery, 2007, for recent reviews) providing convergent validation. Indeed, there are few, if any more well-validated cardiovascular indexes of any psychological