Intra-alveolar urinary trypsin inhibitor cannot inhibit polymorphonuclear elastase activity in the lung in postsurgical patients with acute respiratory distress syndrome.

The aim of this study was to evaluate the concentrative relationship between polymorphonuclear elastase (PMNE) and urinary trypsin inhibitor (UTI) in the bronchoalveolar lavage fluid (BALF) of patients with acute respiratory distress syndrome (ARDS). A total of eight patients who developed ARDS after gastroenterological surgery and eight patients with normal respiratory function during general anesthesia using tracheal intubation were the subjects of this study. BALF was collected from the right middle lobe using saline, and the PMNE and UTI concentrations were measured. The PMNE concentrations were 1277 +/- 1589 ng/ml and 38 +/- 26 ng/ml in the patients with ARDS and those with normal lung function, respectively, and the UTI concentrations were 225 +/- 175 mU/ml and 81 +/- 40 mU/ml, respectively, expressed as mean +/- SD. Based on the UTI concentration which can inhibit PMNE activity, the PMNE concentration in the ARDS patients was not entirely inhibited by UTI. Since only UTI can inhibit PMNE activity in the inflammatory tissues, PMNE in the BALF may induce and aggravate lung injury in ARDS. Thus, we conclude that PMNE released from activated neutrophils in the lung is associated with the development of ARDS.