Does the Time Between the End of Vascular Filling and Evaluation of Its Effectiveness Modify Fluid Challenge Results in Septic Shock?

Inclusion Criteria: * The patient has given his/hers consent or the patient is in an emergency situation (commitment to obtain the consent of the patient as soon as his/her condition permits) * Patient affiliated or beneficiary of a health insurance plan * Patient with septic shock: proven or suspected infection associated with hypotension or lactate\> 4 mmol / l or organ dysfunction. Hypotension despite fluid resuscitation of 20 to -40 ml / kg. * Patient under controlled mechanical ventilation * Patient requiring vascular filling according to the following criteria: * oliguria \<0.5 ml / kg / h for at least 2h * skin mottling * Arterial Lactate \> 2 mmol / l * SvcO2 \<70% or SvO2 \<65% * Patient on noradrenaline. Exclusion Criteria: * The patient is has in another interventional study that might change the results of this study within the past 3 months * The patient is under judicial protection, under tutorship or curatorship * The patient refuses to sign the consent * The patient is pregnant, parturient, or breastfeeding * Valvular pathology: grade III and IV aortic or mitral insufficiency * Non sinus electrocardiogram * Non-echogenic patient * Patient with any spontaneous breathing * Moribund patient