Acute lung injury: clinical concept and experimental approaches to pathogenesis

Acute lung injury (ALI) was defined recently as a syndrome of inflammation and increased permeability of the lungs that is associated with clinical radiologic, and physiologic abnormalities that can not be explained by left atrial hypertension. ALI has the same clinical spectrum, although in a milder form, as acute respiratory distress syndrome (ARDS). The risk factors, incidence, and prognosis of ALI are described based on the medical literature and data collected at Keio University Hospital. We estimate that 20,000 to 40,000 cases of ALI, half of which also have ARDS, occur annually in Japan. Despite the new diagnostic criteria, the clinical entity of ALI remains to be clarified both physiologically and biochemically because of the lack of direct diagnostic methods. I briefly review the central mediator(s) and their role in the inflammatory cascade of ALI. Experimental studies and pharmacological interventions from our laboratory are also described.