N-acetylcysteine attenuates lung injury in a rodent model of fracture

Background: Neutrophil-mediated lung injury is a cause of significant morbidity and mortality in patients with multiple injuries. We have shown previously that fracture hematoma can activate neutrophils and is thus a putative mediator of the systemic inflammatory response syndrome (SIRS), acute respiratory distress syndrome (ARDS) and multiple organ failure (MOF) in those patients with severe skeletal trauma. Our aim was to establish a rodent model of fracture which caused lung injury and subsequently to administer a drug following fracture to attenuate the lung injury. The drug we chose was N-acetylcysteine, a potent antioxidant Animals and methods: Adult Sprague-Dawley rats were assigned to 4 groups: (1) general anesthetic only, (2) general anesthetic with bilateral femur fractures and nailing, (3) general anesthetic and N-acetylcysteine, (4) general anesthetic with bilateral femur fractures and nailing and N-acetylcysteine after the injury (n = 6 in each group). The dose of N-acetylcysteine was 0.5 mg/kg which was given intraperitoneally after injury to the treated groups. The rats were killed 24 hours after injury and some parameters of lung injury were evaluated - i.e., bronchoalveolar lavage (BAL), lung tissue myeloperoxidase levels (MPO) and wet/dry ratios of lung tissue. The results were analyzed, using one-way analysis of variance. Results: Bilateral femur fracture produced a significant lung injury, measured by increases in MPO (25-43 μg/g tissue) and BAL protein (460-605 μg/mL). This effect was attenuated by treatment with N-acetylcysteine (MPO 43-9 μg/mL, BAL protein 605-198 μg/mL). Interpretation: N-acetyl cysteine, if given after skeletal trauma, is of potential therapeutic benefit, in preventing SIRS, ARDS and MOF.