The objective is to determine the sensitivity and specificity via Receiver Operating Characteristic (ROC) curve of Global Longitudinal Strain (GLS) The secondary objectives are the same for the change in the amount of carbon dioxide exhaled (ΔEtCO2) and dynamic arterial elastance (Eadyn). it will also determine the sensitivity and specificity of these indices, either individually or combined to determine persistent responders to volemic expansion.

The best practice recommendations are to evaluate the preload dependence before performing a vascular filling test. This evaluation is based on the analysis of dynamic hemodynamic indices such as the variation of pulsed pressure (VPP), the variation of the volume of ejection (VVE) or the variation of the cardiac output during the realization of a test of rising of passive leg (ELJP). However, these indices require strict validation conditions.

New hemodynamic indices have appeared recently and appear promising in the evaluation of preload dependence. Among them, the analysis of longitudinal myocardial deformity by speckle tracking (GLS) and its variation during an ELJP (ΔGLS). The analysis of changes in the amount of CO2 exhaled (ΔEtCO2) reflects cardiac output in ventilated patients or the analysis of dynamic arterial elastance (Eadyn) calculated by comparing the VPP and the EVV which is a reflection of the coupling between the left ventricle and the arterial network.

In this work the assumption that the analysis of Δ GLS, ΔEtCO2 and Eadyn can predict the response to volume expansion in the ventilated patient, in septic shock under vasopressor.

The investigators include at least 51 patients, ventilated, under vasopressors with septic shock. GLS, cardiac output, VVP, VVE, blood pressure, Eadyn, EtCO2 will be measured before and after ELJP. In the event of an increase of more than 10% in cardiac output during the ELJP, patients will receive a volume expansion of 500ml of balanced crystalloids. The same measurements will be repeated immediately at the end of the volume expansion and 20 minutes after the end of the infusion. Patients with a 15% increase in cardiac output at the end of volume expansion will be classified as responders. Patients with a 15% increase in cardiac output 20minutes after the end of volume expansion will be classified as persistent responders.

Inclusion Criteria:

• Patient presenting a shock whose etiology is considered as septic.
• Patient whose hemodynamic state justifies the infusion of vasopressor.
• Patient monitored by a cardiac output measurement system calibrated by transpulmonary thermodilution.
• Intubated patient with expired capnia monitoring
• Patient with signs of low cardiac output

Exclusion Criteria:

• Patient with a contraindication in the leg lift test.
• Patient with abdominal compartment syndrome.
• Patient with amputation of one or both lower limbs.
• Pregnant woman eliminated by a systematic pregnancy test at the entrance to the intensive care unit.
• Minor patient.
• Refusal to participate in the study.