Hemodynamic and fluid optimization during perioperative period can reduce postoperative morbidity. The assessment of preload and determination of whether the patient is fluid responsive is still challenging. Static preload indices such as central venous pressure are not accurate to assess fluid responsiveness contrary to dynamic preload indices such as pulse pressure variation (PPV) and stroke volume (SV) variation. However, such indices suffer from several limitations and should be used under strict conditions. Alternative dynamic methods such as lung recruitment maneuvers (LRM) have been developed LRM can be used to reopen or prevent collapsed lung under mechanical ventilation so as to decrease respiratory complications. LRM induces a transient increase in intra-thoracic pressure and decreases in venous return, leading to a decrease in left ventricular end-diastolic area and stroke volume. Several studies have shown that the PEEP-induced decrease in stroke volume is related to pre-existing preload responsiveness. Few studies have also shown that LRM can represent a functional test to predict fluid responsiveness. However, monitoring stroke volume during LRM to assess fluid responsiveness is costly, and cardiac output devices may not be reliable. In this context, central venous pressure (CVP) or systemic arterial parameters monitoring are easily accessible and inexpensive during major surgery.

The aims of the current study were

1. to assess the ability of a LRM with a stepwise increase of PEEP to predict fluid responsiveness in mechanically ventilated patients,
2. to identify the best criteria for fluid responsiveness prediction between variations of systolic aortic pressure (SAP), mean arterial pressure (MAP), diastolic aortic pressure (DAP), pulse pressure (PP) and central venous pressure (CVP),
3. to compare the ability of these criteria with pulse pressure variation (PPV) to predict fluid responsiveness

Inclusion Criteria:

• needing invasive arterial blood pressure and pulse contour analysis (PICCO system) for cardiac output measurement,
• central venous pressure monitoring,
• using of protective mechanical ventilation
• Indication for fluid expansion
• Admitted in the intensive care unit of CHU of St ETienne

Exclusion Criteria:

• right ventricular dysfunction
• significant valvulopathy,
• ejection fraction less than 50%,
• arrhythmia
• contraindication to LRMs

Patients admited in the intensive care unit of the University Hospital of Saint-Etienne