Neutrophil elastase activity in acute lung injury and respiratory distress syndrome

Background and objective: Neutrophil elastase (NE) may play a key role in the development of acute lung injury (ALI) or ARDS. NE activity (NEA) was measured in patients with ALI treated with a selective NE inhibitor. Methods: NEA and NE‐α1‐antitrypsin (NE‐AT) complex were measured in plasma before, during and after the administration of the selective NE inhibitor, sivelestat, in 32 patients with a diagnosis of ALI or ARDS. NEA index (NEAI) was calculated as NEA/NE‐AT. The sequential organ failure assessment (SOFA) score and the ratio PaO 2 /fraction of inspired oxygen (FiO 2 ) were measured. Results: NEA and NE‐AT was raised in all patients. Sivelestat reduced NEAI and NEA ( P < 0.01 for both) but not NE‐AT and NEA, and NEAI returned to pretreatment levels. NEA correlated closely with NE‐AT before, but not after treatment. No relationship was observed between these indices and SOFA score or PaO 2 /FiO 2 ratio. Conclusions: Sivelestat reduced NEA and NEAI in patients with ALI or ARDS suggesting NE inhibition. A larger study is needed to determine the relationship of NEA, NE‐AT and NEAI with the outcome of ALI/ARDS.