Blast lung injury from an explosion on a civilian bus

Objective: To assess clinical signs and management of primary blast lung in jury (BLI) from explosions in an enclosed space and to propose a BLI severi ty scoring system. Design: Retrospective analysis, Patients: Fifteen patients with primary BLI resulting from explosions on tw o civilian buses in 1996, Results: Ten patients were extremely hypoxemic on admission (PaO2 < 65 mm H g with oxygen supplementation), Four patients remained severely hypoxemic ( PaO2/fraction of inspired oxygen (FIO2) ratio of < 60 mm Hg) after mechanic al ventilation was established and pneumothoraces were drained. Initial che st radiographs revealed bilateral lung opacities of various sizes in 12 pat ients (80%). Seven patients (47%) had bilateral pneumothoraces and two pati ents had a unilateral pneumothorax. Five (33%) had clinically significant b ronchopleural fistulae, After clinical and laboratory data were collected, a BLI severity score was defined based on hypoxemia (PaO2/FIO2 ratio), ches t radiographic abnormalities, and barotrauma, Severe BLI was defined as a P aO2/FIO2 ratio of < 60 mm Hg, bilateral lung infiltrates, and bronchopleura l fistula; moderate BLI as a PaO2/FIO2 ratio of 60 to 200 mm Hg and diffuse (bilateral/unilateral) lung infiltrates with or without pneumothorax; and mild BLI as a PaO2/FIO2 ratio of > 200, localized lung infiltrates, and no pneumothorax, Five patients developed ARDS with Murray scores > 2.5. Respir atory management included positive pressure ventilation in the majority of the patients and unconventional methods (ie, high-frequency jet ventilation , independent lung ventilation, nitric oxide, and extracorporeal membrane o xygenation) in patients with severe BLI, Of the four patients who had sever e BLI, three died, All six patients with moderate BLI survived, and four of five with mild BLI survived (one with head injury died). Conclusions: BLI can cause severe hypoxemia, which can be improved signific antly with aggressive treatment,The lung damage may be accurately estimated in the early hours after injury. The BLI severity score may be helpful in determining patient management and prediction of final outcome.