Purpose of review: To review the implications of recent literature for clinical trial design in acute lung injury/acute respiratory distress syndrome (ARDS).
Recent findings: Refinement of acute lung injury/acute respiratory distress syndrome diagnostic criteria and study enrollment criteria, greater efforts to define usual care appropriately, and balancing of efficacy and effectiveness design principles will be key components of future trials.
Summary: Clinical trial design in acute lung injury/acute respiratory distress syndrome faces many challenges. Although we have learned much from past trials, persistent design dilemmas must be addressed for future trials.