Impedance Cardiography: Non-Invasive Monitoring of Hemodynamics in the ICU

Monitoring of hemodynamics is routinely performed in the ICU. With the introduction of the pulmonary artery catheter, the facility was created for accurate measurement of stroke volume (SV) and pulmonary capillary wedge pressure (PCWP) [1]. Although this was a major step forward, the invasive character of this technique, sometimes leading to serious complications [2–4], made people reluctant to use it. A non-invasive reliable method to monitor hemodynamics including SV, ejection fraction, contractility index and PCWP, would be of enormous benefit. Impedance cardiography might be such a method. It has been actively used to monitor cardiac events for almost thirty years now [5]. This review will discuss the underlying theory, validation, application and recent developments of this non-invasive method.