Th e defi nition of IPF exacerbations 'after excluding identi fi able causes of lung injury' implies that in 'idiopathic' pulmonary fi brosis, 'idiopathic' exacerbations occur [3, 4, 6] . However, in clinical practice, when such a patient is referred to the emergency department (ED), the attending clinician has to face one of three clinical scenarios [38] (Figure 1 ). Th e fi rst scenario is the case in which the physical evolution of IPF comes to the fi nal end in which spontaneous breathing becomes unsup portable [39] (Figures 1a and 2) . In this scenario, the exclusion of 'identifi able-treatable causes of lung deterior ation' is demanding, but the only option attainable is palliation. Th e second scenario refers to 'true' IPF exacerbation that brings the patient to the ED (Figures 1b and  3 ). In this case, after admission to the hospital ward, the patient usually becomes unable to maintain spontaneous breathing within hours or very few days, often not enough time for the extensive work-up required to identify treatable factors of deterioration, and needs ventilatory support and ICU transfer [5, 7, 8] . Th e third scenario refers to the admission to the hospital ward of an IPF-deteriorated patient because of reversible causes either aff ecting the lung or not; in this case, early identifi cation of the precipitating factor(s) and their prompt treatment are imperative (Figures 1c and 4) . Nevertheless, borders between the above scenarios are unclear in routine clinical practice since exacerbations occur as a spectrum rather than a clearly defi nable event.