The pulmonary artery catheter (Swan-Ganz) is a standard tool in intensive care for measuring and monitoring cardiac index by thermodilution. The Swan-Ganz IQ™ model also allows continuous estimation of cardiac index through analysis of the right ventricular pressure wave, which could be useful for rapidly assessing changes in cardiac output during volume expansion response tests. However, the concordance between this continuous method and thermodilution remains poorly studied in real clinical conditions and may vary depending on certain clinical situations. This study therefore aims to compare the cardiac index measured by thermodilution with that estimated by right ventricular pressure waveform analysis based on data collected in clinical practice.