TTE is an easy noninvasive device now recommended as the first evaluation of the patient in circulatory failure but it present some limits due to poor echogenicity of patients, operator-dependent variability and cannot provide continuous hemodynamic data. TPTD is an invasive technique for CO monitoring recommended especially in shock not responsive to initial therapy.~Few studies have evaluated the level of agreement of each method (TTE and TPTD) with the reference method (pulmonary artery catheter) but they have never been compared between them with strong statistical analysis in particular trending ability.~It could be interesting to determine the level of concordance of these two methods of CO monitoring and trend ability by TPTD relative to TTE.~The investigators hypothesize that CO-TPTD are concordant with those performed by TTE.~Mechanically ventilated patients requiring hemodynamic assessment will be included. CO-TPTD will be measured via intermittent thermodilution. Blindly, a second investigator will use standard-view TTE to estimate CO-TTE as the product of stroke volume and the heart rate obtained during the measurement the blood flow velocity (using a Doppler technique) at the left ventricular outflow tract. A second measurement will be done with the two devices after a fluid challenge when patient requires it to compare trending ability.
Cardiac output monitoring is a key component for the diagnosis and management of critically ill patients. The two less invasive methods commonly used in intensive care are transthoracic echocardiography and transpulmonary thermodilution. The objective of this study is to compare accuracy and trending ability of CO measurement by TPTD and TTE in critically ill patients with sinus rhythm.