Respiratory support applied
No invasive mechanical ventilation (NIV): BIPAP Vision V60® (Respironics Philips) with full face or oronasal mask. Modalities: continuous positive pressure (CPAP) and bi-level positive pressure (BiPAP). Initially, the CPAP was started at 5-6 cmH2O. In case of BiPAP, the Inspiratory Positive Airway Pressure was set at beginning at 8-10 cmH2O and the End-positive Airway Pressure at 5-6 cmH2O. Inspiratory and expiratory pressure was titrated in increments of 2 cmH2O based on tidal volume, continuous pulse oximetry, work of breathing, respiratory rate and subject-ventilator synchrony. The fraction of inspired oxygen (FIO2) was titrated to maintain a SpO2> 92%.
High flow nasal cannula (HFNC): Fisher-Paykel high flow nasal cannula® and Vapotherm® were applied. A cannula of suitable size, an appropriate circuit, humidifier and air/oxygen. Cannula size was selected based on subject weight Flow rates were initiated at 0,5-1 L/kg/min. The fraction of inspired oxygen (FIO2) was titrated to maintain a SpO2> 92%.