Advanced respiratory monitoring in acute respiratory failure. These technologies can be used from the early stage of the disease, with patient in spontaneous breath or noninvasive respiratory support, and during invasive mechanical ventilation in passive and active conditions. In these contexts, advanced respiratory monitoring provides useful information on the cause of acute respiratory failure and the characterization of lung involvement. Also, these tools allow the assessment of intratidal gas distribution and lung aeration in terms of overdistention and collapse as well as pulmonary perfusion and ventilation–perfusion matching. In recovering from acute respiratory failure, advanced respiratory monitoring technologies offer an in-depth evaluation of patient–ventilator interaction in terms of inspiratory effort and respiratory muscles activation, respiratory drive, and patient–ventilator synchrony.