Prediction of Response to Recruitment Maneuvers in Patients With Acute Respiratory Failure

Prediction of Response to Recruitment Maneuvers in Patients With Acute Respiratory Failure

The study will explore the possibility to predict potential for recruitment in acute hypoxemic respiratory failure patients by electrical impedance tomography (EIT) Swisstom BB2 (Swisstom, Landquart, Switzerland) during stepwise increase in positive end-expiratory pressure (PEEP) followed by recruitment maneuver (RM). It will compare data obtained by EIT to those obtained by pressure-volume (P-V) curves on respiratory system mechanics and data on pulmonary gas exchange.

The investigators will monitor lung ventilation by EIT during the whole protocol and perform P-V curves and arterial blood gas analysis at every step of the protocol.

Participants will be sedated and paralyzed, ventilated in volume-controlled with protective ventilation (tidal volume=6-8 mL/Kg of predicted body weight and respiratory rate set to obtain normal pH) then the protocol will follow 5 steps each lasting 20 minutes to obtain clinical stability:

1. PEEP 5 centimeter of water (cmH2O)
2. PEEP 10 cmH2O
3. Recruitment maneuver followed by PEEP 15 cmH2O
4. PEEP 10 cmH2O
5. PEEP 5 cmH2O

Inclusion Criteria:

• Patients with acute hypoxemic respiratory failure defined by recent known clinical insult or worsening of respiratory symptoms and arterial pressure of oxygen to inspired fraction of oxygen ratio (PaO2/FiO2) ≤300 mmHg
• Patient on invasive mechanical ventilation
• Age ≥18 years
• Written informed consent

Exclusion Criteria:

• Pregnancy
• Unstable hemodynamic condition requiring blood transfusion or adjustment of inotropics more often than every hour
• FiO2 ≥80% or clinical suspicion of pulmonary embolism
• Pneumothorax
• Chronic obstructive pulmonary disease (COPD) with clinical symptoms of lung emphysema as evidenced by chest radiography or computed tomography or autoPEEP > 5 cmH2O
• Intracranial hypertension
• Impossibility to correctly position the EIT belt (e.g., dressings, chest drainage, etc.)
• Contraindications to EIT (e.g., implantable cardiac defibrillator, pacemaker, instable spinal lesions)