“…The reasons for this may be the result of greater variation in the population, a higher likelihood of misdiagnosis, a larger range in illness severity, and that NIV may be started in the ED (and even by prehospital emergency medical systems -EMS-) and are often removed in the ED itself due to the fact that NIV can improve AHF patient's clinical status in a few hours [6][7][8]. Moreover, the inclusion and exclusion criteria that a RCT imposes on the final sample of patients selected for analysis excludes a large portion of patients, often surpassing 80% [8]. Therefore, although there is no doubt that for patients able to tolerate NIV the improvement of symptoms is greater and faster, the effects of NIV on short-term mortality are still controversial when it is used in the ED setting in real world conditions.…”