The ten diseases that look like ARDS

Excerpt

Five decades ago, Ashbaugh and colleagues first used the term “syndrome of acute respiratory distress” (ARDS) to describe 12 patients with respiratory failure [1]. The hallmarks of the syndrome were hypoxemia refractory to supplemental oxygen, diffuse radiographic opacities, and histologic evidence of diffuse alveolar damage (DAD) in most but not all fatal cases. Over three decades later, the widely adopted American–European Consensus Conference (AECC) definition of ARDS facilitated research and aided cross-study comparison and translation of research findings to clinical practice [2]. The new Berlin definition refined the AECC definition by explicitly defining acute onset. Since the majority of patients destined to develop ARDS do so within the first 72 h after recognition of a clinical risk factor, with the rest progressing within a week, the Berlin definition explicitly defined “acute onset” as 7 days [3]. It defined mild, moderate, and severe ARDS with explicit ranges of PaO₂/FiO₂. It also attempted to improve the poor interobserver agreement on the AECC radiographic criteria by explicitly describing qualifying opacities and providing example radiographs [4, 5]. As left atrial hypertension and ARDS may coexist, the Berlin definition abandoned the pulmonary artery occlusion pressures exclusion [6]. Finally, the Berlin definition added the requirement for a known clinical risk factor (e.g., pneumonia, sepsis, trauma, etc.), and if none is apparent then additional testing is recommended to exclude congestive heart failure. Both the AECC and the Berlin definition retain the central elements of Ashbaugh’s original description. However, both the definitions have only moderate sensitivity and specificity for identifying patients who have DAD on post mortem examination, even in the severe subgroup of the Berlin definition [7, 8]. Moreover, lung biopsy findings in patients with what is assumed to be unresolving ARDS frequently show a number of pathologic entities other than DAD. From our clinical experience, we discuss ten of these clinical entities that may be mistaken for ARDS. …