| Abstract | | In critically ill patients, cardiac output measurement is required for diagnosis and assessment of therapy for early normalization of oxygen delivery. Electric velocimetry is a new, noninvasive, continuous method for measuring cardiac output, based on impedance cardiography. The aim of our study was to estimate the reliability of cardiac output measurements using electric velocimetry as compared to intermittent thermodilution as a standard reference method before and immediately after CABG surgery, and in the intensive care unit. We also wanted to estimate the influence of preload on the reliability of cardiac output measurement with electric velocimetry. Electrical velocimetry and intermittent thermodilution were used simultaneously to measure cardiac output in four different body positions before and immediately after CABG surgery, and in the horizontal position in the intensive care unit. At the same time we measured the central venous pressure, pulmonary artery wedge pressure and mean arterial pressure, the heart rate and the thoracic fluid index. The mean bias of 150 pairs of comparative measurements in l6 patients was -0.2110.78 1/min, the mean error was 40% and the correlation coefficient was 0.75. Before skin incision the mean bias was -0.040.41 1/min, the mean error was 25% and the correlation coefficient was 0.7. After skin closure the mean bias was -0.57+-0.92 1/min, the mean error 42 % and the correlation coeflicient was 0.67. In the intensive care unit the mean bias was 0.26f0.68 1/min, the mean error was 32% and the correlation coefficient was 0.75. We may conclude from our results that prior to skin incision electric velocimetry underestimates the changes in cardiac output caused by changes in body position, but immediately after CABG surgery the changes in cardiac output measured with electric velocimetry do not follow in same direction the changes in cardiac output measured with the reference method. (Abstract truncated at 2000 characters)
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