3/12/2023 0 Comments Cardiograph fontBased on these curve points the stroke volume is calculated using an empirical equation. This curve is known as ICG wave form in which selected fiducial points are detected, such as the B and the X-points corresponding with the opening and the closing of the aortic valve, and the C-point which is the maximum of the ICG curve. In the result an impedance pulse wave (IMP) is recorded.įor the determination of the stroke volume the first mathematical derivative of the impedance pulse wave (IMP) is used. This voltage corresponds with impedance changes caused by pulse synchronous variations of the blood volume in the thoracic aorta and the alignment of the orientation of the erythrocytes when the blood is pumped out of the left ventricle of the heart into the aorta. The 4 inner electrodes (called measuring electrodes) are placed between the current electrodes and measure the voltage which is caused when the current flows through the thorax. ![]() The 4 outer electrodes (called current electrodes) are used to pass a very low constant and alternating current (1.5 mA, 86 kHz) through the thorax which is imperceptible to the patient and does not cause any physiological reaction. For this purpose usually 8 electrodes are placed on neck and thorax. In case of Impedance Cardiography (ICG) – often also named Thoracic Electrical Bio-impedance (TEB) – changes of electrical impedance of the thorax are measured. ![]() It is 100% non-invasive, easy to apply and operator independent. ![]() This examination method allows a real beat-to-beat measurement of the stroke volume and is, therefore, very suitable for haemodynamic monitoring, fluid management and cardio-vascular function tests.
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