Hakim R, et al. - Researchers investigated the definitions of acute respiratory failure, the characteristics of recruited patients, and the criteria for intubation used in randomized trials. Searching MEDLINE, they assessed 53 trials of noninvasive respiratory support modalities in patients with de novo respiratory failure; 7,225 patients were enrolled in these trials. The design and reporting of randomized trials were identified to have deficiencies, some of which can be remedied by investigators. The use of variables varied widely for defining acute respiratory failure. In these trials, a rare measurement of dyspnea and poor definition of an increase in breathing effort were evident. The characteristics of patients enrolled in trials varied over time and changed by the cause of respiratory failure. Poor characterization of intubation was reported. Higher variability was observed in the criteria for intubation vs the criteria for respiratory failure. These findings can allow a clinician to recognize patients at the right moment to benefit from the examined interventions and investigators in generating criteria for enrollment in future trials.