Acute Respiratory Distress: from syndrome to disease

The acute respiratory distress syndrome (ARDS) is currently one of the most important critical entities given its high incidence, rate of mortality, long-term sequelae and non-specific pharmacological treatment. The histological hallmark of ARDS is diffuse alveolar damage (DAD). Approximately 50% of ARDS patients present DAD, the rest is made up of a heterogeneous group of histological patterns, many of which correspond to a well-recognized disease. For that reason, if these patterns could be diagnosed, patients could benefit from a treatment. Recently, the effect of DAD in clinical and analytical evolution of ARDS has been demonstrated, so the classical approach to ARDS as an entity defined solely by clinical, radiological and gasometrical variables should be reconsidered. This narrative review aims to examine the need to evolve from the concept of ARDS as a syndrome to ARDS as a specific disease. So we have raised 4 critical questions: a) What is a disease?; b) what is DAD?; c) how is DAD considered according to ARDS definition?, and d) what is the relationship between ARDS and DAD?