• Oxygenation index (FiO 2 × Pāw/PaO 2 ) • PaO 2 /FiO 2 ratio • Ventilatory index (Peak -end expiratory pressure) × respiratory rate × PaCO 2 /1000 (if conventional ventilation is provided) • Alveolar ventilation estimate during high frequency oscillatory ventilation (DCO 2 = frequency * (tidal volume) 2 ], if a specific flow sensor is available) [58] Moreover, the following data will be recorded: