Evaluation of the Association Between Right Atrial Reservoir Strain Variation and Fluid Responsiveness in Patients With Septic Shock

Inclusion Criteria: * Adult patient (\>18 years old) * Patient hospitalized in the Intensive Care Unit at Amiens University Hospital with septic shock for less than 48 hours, defined by the presence of all the following criteria: presence of sepsis, hypotension requiring vasopressors to maintain a mean arterial pressure ≥ 65 mmHg despite adequate prior fluid resuscitation, and blood lactate levels \> 2 mmol/l (18 mg/dl). * Patient requiring fluid resuscitation with crystalloids/colloids * Patient on invasive mechanical ventilation in assisted-controlled mode. * Blood pressure monitored via a radial or femoral arterial catheter connected to a MostCareUp (Vygon, France). * Patient or family informed and non-opposition documented. Exclusion Criteria: * Poor echocardiographic image quality preventing RASr assessment * Patient with a contraindication to the PLR maneuver: severe head trauma or intracranial hypertension * Patient with a history of pericardiectomy * Patient with a clinical examination consistent with abdominal compartment syndrome * Patient with aortic pathology, mitral regurgitation greater than grade 2, tricuspid regurgitation greater than grade 2, mitral stenosis, or intracardiac shunt * Patient with internal or external atrial/ventricular pacing * Pregnant woman * Patient on extracorporeal membrane oxygenation and mechanical circulatory support * Moribund patient * Patient with supraventricular or ventricular arrhythmia during echocardiographic measurement series * Patient on renal replacement therapy during echocardiographic examination