Comparison of Supine to Prone Position During Major Spinal Surgery

During mechanical ventilation, the alveolar recruitment maneuver (ARM) is to apply a positive end-expiratory pressure (PEEP) (generally 30 cm H2O) for a period of at least 30 seconds. The realization of MRA is one of three main elements of mechanical ventilation called "protective". This ventilatory strategy, originally described for the ventilation of acute respiratory distress syndrome (ARDS), and pulmonary and during abdominal surgery is based on a decrease tidal volumes, optimization of PEEP and the realization of MRA. Protective ventilation limit the occurrence of atelectasis, the surdistentions and, ultimately, significantly decreases postoperative complications.

The MRA is currently recommended in the "major" surgery. Most spine surgery (eg transpedicular fixation) used in this definition, the MRA are indicated and now commonly used. This type of surgery requires further positioning the patient in the prone position (DV). The DV modifies the compliance of the chest respiratory characteristics and changes (increase in insufflation pressure) and hemodynamic (decreased venous return) of the patient.

Respiratory and haemodynamic effects of MRA made VIS at major spine surgery are not known. The aim of this observational study, non-interventional, is to compare the hemodynamic and respiratory effects of MRA performed in DV to those of MRA performed in the prone position (DD).

The investigators hypothesis is that the respiratory and hemodynamic consequences of MRA performed in DV is different from those conducted in DD. A better understanding of hemodynamic and respiratory characteristics of MRA performed in DV would provide a more tailored to this type of surgery respiratory optimization strategy and reduce respiratory complications of this surgery.