The aim of this multicenter, randomized controlled trial is to evaluate the weaning time from mechanical ventilation comparing non-variable PSV, variable PSV, and Smart CareTM.

This study is a multicenter randomized controlled open trial comparing variable, non-variable pressure support ventilation and Smart CareTM in patients receiving mechanical ventilation for more than 24 hours who are able to be weaned.

The aim of the study is to determine the duration of weaning from mechanical ventilation for each one of the above mentioned weaning methods

Inclusion Criteria:

• age≥18 years
• duration of controlled mechanical ventilation≥ 24 h
• temperature≤ 39°C
• hemoglobin≥ 6 g/dl
• ratio of arterial partial pressure of oxygen to inspiratory oxygen fraction - PaO2/FiO2≥150mmHg with positive end-expiratory pressure (PEEP)≤ 16 cmH2O
• ability of the patient to breathe spontaneously
• informed consent

Exclusion Criteria:

• patient participated in another interventional trial within the last four weeks before enrollment
• peripheral neurological disease associated with impairment of the respiratory pump
• muscular disease associated with impairment of the respiratory pump
• unstable thorax with paradoxical chest wall movement
• planned surgery under general anesthesia within 72 hours
• difficult airway or intubation
• existing tracheotomy at ICU admission
• expected survival<72 hours
• home mechanical ventilation or on chronic oxygen therapy
• suspected or confirmed pregnancy