Respiratory Variations For Predicting Fluid Responsiveness 2

Inclusion Criteria: * Adult patients of the intensive care units of the Lille university-hospital and of the Valencienne general hospital. * Age greater than or equal to 18. * Patient insured * Spontaneous breathing without ventilatory support or intubation or tracheotomy. * Irregular cardiac rhythm * Prescription by the physician in charge of the patients of a 500 mL volume expansion in less than 30 minutes. * Patients with sepsis with at least one sign of acute circulatory failure: * Tachycardia with heart rate\> 100/min * systolic blood pressure \<90mmHg or a decrease \>40mmHg in previously hypertense patient * Oliguria \<0.5ml/kg/hour for at least one hour * skin mottling Exclusion Criteria: * high-grade aortic insufficiency * transthoracic echogenicity unsuitable for measuring the stroke volume or inferior vena cava diameters * clinical signs of active exhalation * clinical or ultrasonographic evidence of pulmonary edema due to heart failure * pregnancy * abdominal compartment syndrome * regular cardiac rhythm