Leane was 28 days old (3 kg) and was born at term. She had a 2-year-old brother with bronchiolitis. After an episode of rhinorrhea, she presented with feeding difficulties and was referred to the emergency room of a local hospital. Four hours later, she progressively presented with low oxygen saturation, tachypnea, and chest retraction. She was placed under nasal CPAP with 30% FiO 2 , and then transferred to our unit for severe RSV bronchiolitis. She was intubated on arrival because of clinical signs of respiratory distress and collapse. Although we suspected concomitant bacterial pneumonia because of a major inflammatory syndrome, we did not have bacteriological confirmation. Her respiratory status deteriorated rapidly. The OSI was 6.8 (with other diagnosis criteria for acute lung injury). Her need for oxygen increased rapidly with bilateral infiltrates on a chest radiograph. We chose to use NAVA after a short period of decreased sedation (morphine was decreased to 8 μg/kg/h). Initial NAVA settings were a PEEP of 5 cm H 2 O, NAVA level was 1 cm H 2 O/μV, and FiO 2 was initially 60% and was then adjusted by a nurse for a SpO 2 > 90% and < 98%. Six hours later, FiO 2 was 35%, while ventilatory pressures were lower than before starting NAVA ( Table 3) . As in the 2 other cases, ventilatory parameters were highly variable (Figure 4) , while chest movements of the child were smooth as if the child was not mechanically ventilated. Twenty-four hours after starting NAVA, FiO 2 was 21%. The modified COMFORT scale ranged between 7 and 13.