Study: NCT01784146

Intervention type: OTHER
Group type: PLACEBO_COMPARATOR
Intervention: Oxygen
Description: For inhalation of oxygen, we used a noninvasive delivery system, semi - closed (Figure 3) consisting of a non-toxic face mask with two unidirectional valves - inspiratory and expiratory branch - connected to the~nebulizer (Airlife Misty Neb, Baxter; Valencia, CA, USA). In the inspiratory branch, a reservoir bag (Hudson RCI, USA) with capacity of 2.5 L was connected, in order to avoid dilution of the gas. This skin was fixed to the patient's face to prevent leakage and to maintain adequate pressurization and improved patient compliance to the PEEP. The nebulizer was fed by a flow of 8 l / min of oxygen.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Oxygen
Description: For inhalation of oxygen, we used a noninvasive delivery system, semi - closed (Figure 3) consisting of a non-toxic face mask with two unidirectional valves - inspiratory and expiratory branch - connected to the~nebulizer (Airlife Misty Neb, Baxter; Valencia, CA, USA). In the inspiratory branch, a reservoir bag (Hudson RCI, USA) with capacity of 2.5 L was connected, in order to avoid dilution of the gas. This skin was fixed to the patient's face to prevent leakage and to maintain adequate pressurization and improved patient compliance to the PEEP. The nebulizer was fed by a flow of 8 l / min of oxygen.

Intervention type: OTHER
Group type: ACTIVE_COMPARATOR
Intervention: Heliox
Description: For inhalation of heliox, we used a noninvasive delivery system, semi - closed consisting of a non-toxic face mask with two unidirectional valves - inspiratory and expiratory branch - connected to the~nebulizer (Airlife Misty Neb, Baxter; Valencia, CA, USA). In the inspiratory branch, a reservoir bag (Hudson RCI, USA) with capacity of 2.5 L was connected, in order to avoid dilution of the gas. This skin was fixed to the patient's face to prevent leakage and to maintain adequate pressurization and improved patient compliance to the PEEP. The nebulizer was fed by a 11 l / min of heliox for the heliox group in accordance with a protocol of Hess et al.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Heliox
Description: For inhalation of heliox, we used a noninvasive delivery system, semi - closed consisting of a non-toxic face mask with two unidirectional valves - inspiratory and expiratory branch - connected to the~nebulizer (Airlife Misty Neb, Baxter; Valencia, CA, USA). In the inspiratory branch, a reservoir bag (Hudson RCI, USA) with capacity of 2.5 L was connected, in order to avoid dilution of the gas. This skin was fixed to the patient's face to prevent leakage and to maintain adequate pressurization and improved patient compliance to the PEEP. The nebulizer was fed by a 11 l / min of heliox for the heliox group in accordance with a protocol of Hess et al.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: PEEP
Description: PEEP supplied was 10 cm H2O through valve (Vital Signs,Totowa, USA) attached to the expiratory branch.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: PEEP
Description: PEEP supplied was 10 cm H2O through valve (Vital Signs,Totowa, USA) attached to the expiratory branch.