• Date of ICU admission, mode of mechanical ventilation, date of initiation of mechanical ventilation, demographic dates (age, gender, reason to start mechanical ventilation, severity score at admission, weight, and height), arterial blood gas at the beginning of mechanical ventilation, daily ventilator parameters (applied positive end expiratory pressure [PEEP], volume tidal, peak pressure, plateau pressure), mode of NIV, duration of NIV (failure and success), monitoring during NIV (respiratory rate, sedation scale [Richmond Agitation Sedation Scale, RASS], arterial blood gas during NIV [at the beginning, every 2 hours of NIV if tolerated, and if it failed]), date of the starting of withdrawal of mechanical ventilation, method for weaning in the first attempt, mode of spontaneous breathing trial (SBT), reason for failure of SBT, date of extubation, date of reintubation, arterial blood gas at the time for extubation, reason for reintubation, development of complications during mechanical ventilation (organ failures [cardiovascular, hematological, hepatic or renal failures], barotrauma, ARDS, sepsis, ventilator-associated pneumonia, ICUAW), tracheostomy if needed, date of tracheostomy, type of tracheostomy, date of ICU discharge and status of ICU discharge, reason of ICU mortality, status at hospital discharge, length of ICU and hospital stays.