Objectives: To investigate whether respiratory variations of inferior vena cava diameters (cIVC) predict fluid responsiveness in spontaneously breathing patients with septic acute circulatory failure and irregular heartbeats.

Design: Prospective, bicentric study, intensive care units.

Patients and measures: Spontaneously breathing patients with sepsis and clinical signs of acute circulatory failure are included. A positive response to fluid loading (FL) is defined as an increase of the stroke volume (SV) >10%. The investigators measured the minimum inspiratory and maximum expiratory diameters of the IVC (idIVC and edIVC) during standardized (st) and unstandardized (ns) breathing. The investigators calculated cIVCst and cIVCns before a 500ml-colloid FL.

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