Definition and epidemiology of acute respiratory distress syndrome

Abstract

Fifty years ago, Ashbaugh and colleagues defined for the first time the acute respiratory distress syndrome (ARDS), one among the most challenging clinical condition of the critical care medicine. The scientific community worked over the years to generate a unified definition of ARDS, which saw its revisited version in the Berlin definition, in 2014. Epidemiologic information about ARDS is limited in the era of the new Berlin definition, and wide differences are reported among countries all over the world. Despite decades of study in the field of lung injury, ARDS is still so far under-recognized, with 2 out of 5 cases missed by clinicians. Furthermore, although advances of ventilator strategies in the management of ARDS associated with outcome improvements-such as protective mechanical ventilation, lower driving pressure, higher PEEP levels and prone positioning-ARDS appears to be undertreated and mortality remains elevated up to 40%. In this review, we cover the history that led to the current worldwide accepted Berlin definition of ARDS and we summarize the recent data regarding ARDS epidemiology.

Keywords: Acute respiratory distress syndrome (ARDS); definition; epidemiology.

Figure 1

Hospital mortality reported in the main epidemiological studies after AECC ARDS definition in all ARDS categories (mild, moderate and severe) (A) and in the subgroups of moderate-severe ARDS (B). On the X-axis, the studies are chronologically ordered based on the study period. In panel (B), moderate–severe ARDS hospital mortality in the study by Li et al. [2011] is reported in two different years of study, 2001 and 2008 (88). The studies are reported as first author et al., year of publication (41,55,81,83,84,87-89). AECC, American-European Consensus Conference; ARDS, acute respiratory distress syndrome.