We used the CardioScreen® 1000 (medis Medizinische Messtechnik GmbH, Ilmenau, Germany) device to perform impedance cardiography. The device has been validated (as bedside monitor, named niccomo™-monitor) (16 (link), 23 (link)–25 (link)). We recorded all parameters provided by the device, including the PEP, heart rate, left ventricular ejection time, and Heather index. The Heather index is calculated as a combination of acceleration and velocity of blood flow (both as index values, relative to body surface area) and is a parameter of impedance cardiography said to represent contractility and overall sympathetic tone (26 (link)). For BP measurement, we used the validated cuff-based OnTrak 90227 device (Spacelabs® Healthcare) (27 (link)). For ensuring valid cuff-based measurement, we recorded the cuff’s pressure curves via a Y-connection, and recorded data via a SOMNOtouch™ NIBP (SOMNOmedics GmbH).
The devices were time synchronized in a two-step process. The CardioScreen® and SOMNOtouch™ devices were both initiated to within second precision during device setup. As both devices recorded an ECG, we were then able to synchronize the signals with millisecond precision.
We used a Ergometrics 900 L (ergoline GmbH, Bitz, Germany) recumbent bike ergometer with 60° inclination to enable controllable physical load while minimizing upper body movement. This is of utmost importance for the 8-lead cardio impedance device and during cuff-based BP measurement. The experimental setup, combined with quality assessment of cuff pressure curves, allowed us to maximize the quality of measurements included in the final analysis. We time synchronized all devices.
The devices were time synchronized in a two-step process. The CardioScreen® and SOMNOtouch™ devices were both initiated to within second precision during device setup. As both devices recorded an ECG, we were then able to synchronize the signals with millisecond precision.
We used a Ergometrics 900 L (ergoline GmbH, Bitz, Germany) recumbent bike ergometer with 60° inclination to enable controllable physical load while minimizing upper body movement. This is of utmost importance for the 8-lead cardio impedance device and during cuff-based BP measurement. The experimental setup, combined with quality assessment of cuff pressure curves, allowed us to maximize the quality of measurements included in the final analysis. We time synchronized all devices.
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