To the Editor:

Almost 50 years after its birth in respiratory physiology,1,2 we are seeing a growing interest in the airway-occlusion pressure at 0.1 s (P0.1) parameter as an expression of the mechanical output of the respiratory drive and, therefore, of the inspiratory effort made by the patient. The assessment of P0.1 in patients with acute hypoxemic respiratory failure may help in decision making regarding mechanical ventilation and sedation, with the aim to protect the patient from self-induced lung and diaphragm injury.3,4 The measurement of P0.1 is offered by a few mechanical ventilators according to different technologies: either a short patient-triggered occlusion performed on demand by closure of the ventilator valves or a continuous breath-by-breath analysis of airway pressure during the short interval preceding inspiratory trigger activation.

In turn, continuous P0.1 monitoring is based on two different methods. The mini-occlusion method was designed in the 1990s and is based on the measurement and extrapolation to 100 ms of the maximum slope of the airway-pressure drop …

Correspondence: Giorgio A Iotti MD. E-mail: giorgio.a.iottigmail.com