This is a double crossover study where all patients are randomly allocated to one of two treatment sequences associated with endotracheal aspiration.The first treatment (A) uses two suctioning methods for each patient: one involving hyperoxygenation with administration of 100% oxygen 1 minute before and after suction (intervention I), and the other hyperoxygenation with oxygen supply to 20% above basal offer (Intervention II) in the same way.The second treatment (B) uses a technique of hyperinflation with the mechanical ventilator (PEEP-ZEEP) associated with hyperoxygenation. The intervention I, uses PEEP-ZEEP offering 20% above basal oxygenation and intervention II uses the PEEP-ZEEP with basal oxygen supply in the same way.

All subjects were randomly allocated using sealed envelopes to a treatment sequence A or B on Day 1. Patients received two treatments, at least four hours apart. The first treatment is in the morning and the alternate treatment is performed in the afternoon. On Day 2 the order of the treatments was reversed using the same patient position sequence.The interventions I and II are performed at least 4 hours apart to minimize any carryover effect.

Endotracheal suction must be carried out only through precise indication, because it is associated with undesirable effects on the hemodynamic parameters, ventilation, oxygenation and respiratory mechanics.

The hyperoxygenation is one of the methods of prevention of hypoxemia induced by tracheal suction procedure and have been proposed for its efficiency. Another method is the hyperinflation with the mechanical ventilator. Ventilator hyperinflation improves oxygenation, mobilizes the bronchial secretion excess and re-expand the lung collapsed areas.

The PEEP-ZEEP is a ventilator hyperinflation technique, described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to ZEEP (0 centimeters of water (cmH2O)).

Inclusion Criteria:

• Mechanical ventilation for more than 12h
• Hemodynamic stability
• Presence of indication criteria of endotracheal aspiration procedure

Exclusion Criteria:

• High doses of vasopressor amines amines and/or severe arrhythmias
• Hemoglobin < 7 g/dL
• FiO2 ≥ 0.6
• PEEP ≥ 10 cmH2O
• Conditions: rib fractures, chest drain, severe bronchospasm, pneumothorax not drained and tracheostomy
• Contraindications of ventilator hyperinflation(PEEP-ZEEP): intracranial pressure > 10 mmHg, bleeding disorders, accented degrees of gastroesophageal reflux and bullous lung disease.