The Berlin definition of ARDS versus pathological evidence of diffuse alveolar damage.

have a very short duration of illness and have excellent outcomes, but our ability to clearly define this group of patients at the outset remains limited. If we cannot be sure in whom to intervene, any economic benefit from successful therapy quickly deteriorates due to massive overtreatment. Finally we have to consider what downstream adverse effects there may be from intervening. Both glucocorticoids and anti– tumor necrosis factor therapies offered promise, but ultimately failed to show benefit both in bacterial and viral pneumonia in part due to excess side effects such as secondary infections (10). Although shutting down pulmonary inflammation may provide acute benefits, it may increase the risk of downstream complications. There is evidence that patients with ARDS are now older and have more comorbidities (11, 12). Another interesting issue is the possibility of genetic modification to secrete a specific protein that plays an important role in the control and pathogenesis of ALI/ARDS (13, 14). Will reducing the severity of ARDS, without affecting the underlying disease(s) responsible, produce real mortality and economic benefits, or will we be just keep some patients alive a little longer at great expense? Overall Lee and colleagues are to be commended for their very detailed study and their new findings. KGF, given that it could be easily produced in large quantities and can be given systemically, avoiding the need to start mechanical ventilation preemptively, shows some promise. We should, however, recognize the severe limitations this and other experimental models of ARDS have and continue to try and produce data that answer the key questions: What is the window of opportunity to give the intervention? How long does the intervention continue to depress the immune response? What subgroup(s) of patients at risk for ARDS does this truly benefit? The increasing participation of large pharmaceutical companies in stem cell therapies and strong funding from research foundations and governmental agencies (15) is likely to expand new clinical trials in this field.