He was recently hospitalized because of subcutaneous emphysema, with signs of acute respiratory failure from RSV infection. Because of an increased need for oxygen, he was intubated and ventilated with an FiO 2 of 100%, and PEEP was 3. A chest X-ray did not show pneumothorax that could be drained. Tracheal aspirate was positive for RSV and Hemophilus influenzae. A few days later, because of emergence of an alveolar syndrome associated with persistence of subcutaneous emphysema, he was transferred to our unit for possible extracorporeal membrane oxygenation (ECMO). Upon arrival, he had an oxygenation saturation index of 9.4 as well as with the other criteria for ARDS (bilateral infiltrates on a chest radiograph and no evidence of left atrial hypertension). Respiratory parameters were an SIMV with a VT of 85 ml (6 ml/kg), the rate was 25/ min, PEEP was 6 cm H 2 O, and FiO 2 was 70%. SpO2 was 89%, mean airway pressure was 12 cm H 2 O, peak inspiratory pressure was 28 cm H 2 O, and minute volume was 2 l/min. Venous blood gas showed a pH of 7.32, and a PvCO 2 of 53 Torr (7.1 kPa). Because of a slight improvement, the child was not treated by ECMO. He underwent fibroscopy to eliminate the diagnosis of foreign body inhalation, which would have explained the subcutaneous emphysema. Forty-eight hours later, because of an increase in cough, cutaneous emphysema worsened and became diffuse (cervico-thoraco-abdominal) despite the reduction in PEEP to 4 cm H 2 O (FiO 2 60%). We decided to use NAVA to improve the synchronization of mechanical ventilation with the child's spontaneous breathing. Sedation was reduced, midazolam was decreased to 80 μg/kg/h and sufentanil to 0.3 μg/kg/h. The child became alert. Initial NAVA settings were a PEEP of 5 cm H 2 O, NAVA level was 1.2 cm H 2 O/μV, and FiO 2 was 60%.