Neutrophil Elastase as a Predicting Factor for Development of Acute Lung Injury

Objective To determine whether the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) associated with systemic inflammatory response syndrome (SIRS) can be predicted by the plasma neutrophil elastase level. Patients and Methods Patients were sequentially enrolled after obtaining informed consent. Twenty-three adult patients with SIRS were classified into the following groups; SIRS alone (5 patients), Group A of ALI/ARDS with SIRS (9 patients) that did not require mechanical ventilation, and Group B of ALI/ARDS with SIRS (9 patients) that required mechanical ventilation. Blood samples were obtained after the diagnosis of SIRS, and the sequential sampling was performed. Results The plasma neutrophil elastase level was significantly elevated in all patient groups as compared with healthy controls (43.7±5.4 ng/ml). The elastase levels in SIRS alone, Group A of ALI/ARDS, and Group B of ALI/ARDS were 126.9±11.0 ng/ml, 316.2±68.9 ng/ml, and 458.4±132.8 ng/ml, respectively. The elastase level in ALI/ARDS with SIRS was significantly greater than that in SIRS alone. The maximal level in 13 of 18 patients with ALI/ARDS with SIRS was more than 220 ng/ml. The level in all patients with SIRS alone was consistently less than 220 ng/ml over the study period. The serum levels of inflammatory cytokines were elevated in these patients, but no statistical significance was detected among the groups. Conclusion The critical level of plasma neutrophil elastase is 220 ng/ml, and the SIRS patients with more than 220 ng/ml neutrophil elastase are highly likely to develop ALI/ARDS.