NIV success or failure is closely related to the tolerance of NIV treatment, which is tightly correlated to patient-ventilator synchrony. As severe asynchronies frequently occurs during NIV (namely in more than 40% of patients) and as the occurence of asynchronies is related to the use of high pressure support levels, to the presence of leaks and/or to non optimal expiratory trigger settings, very frequent ventilator settings adaptations should allow reducing patient-ventilator asynchronies but require the presence of an experienced clinician at the bedside during NIV treatment.