Respiratory Variations for Predicting Fluid Responsiveness

Hypovolemia and acute circulatory failure affects more than 60% of patients hospitalized in intensive care or resuscitation. The volume expansion (VE) by fluid replacement therapy is the first treatment improve circulatory function. However, too much VE can be harmful. So, the use of dynamic predictive indicators of fluid responsiveness is recommended in patients with sepsis.In patients with spontaneous ventilation, few studies have evaluated these parameters. In mechanical ventilation, indices based on the respiratory variation of the diameters of vena cava have been studied and validated to predict the response to VE. However there is no similar study in spontaneously breathing patients without ventilatory support. The investigators hypothesize that the respiratory variations in the IVC diameters and femoral artery flow during standardized respiratory cycles are predictive factors of fluid responsiveness in spontaneously breathing patients with sepsis, acute circulatory failure, and regular cardiac rhythm.