Impedance cardiography (ICG) is a noninvasive modality to assess hemodynamic parameters. It uses changes in impedance across the thorax. It can evaluate the thorax fluid capacity which includes extravascular, intravascular and chest water content and, indirectly, represents the degree of heart failure.
This technique allows the assessment of cardiac output (CO), cardiac index (CI), stroke volume (SV), stroke index (SI), systemic vascular resistance (SVR), systemic vascular resistance index (SVRI), left ventricular ejection fraction (LVEF), left ventricular ejection time (LVET). CO, CI, SV and SI can reflect the myocardial blood flow
SVR and SVRI can reflect systemic vascular resistance and cardiac afterload
PEP, LVEF, LVET and STR can reflect myocardial contraction (prolonged PEP, LVET shortening, increase of STR and decrease of LVEF represent the compromised cardiac function). (1, 2)