Characterization of the response to primary blast injury.

Lung injuries, predominantly arising from blast exposure, are a clinical problem in a significant minority of current military casualties. This special feature consists of a series of articles on lung injury. This first article examines the mechanism of the response to blast lung (primary blast injury to the lung). Subsequent articles examine the incidence of blast lung, clinical consequences and current concepts of treatment, computer (in silico) modelling of lung injury and finally chemical injuries to the lungs. Blast lung is caused by a shock wave generated by an explosion causing widespread damage in the lungs, leading to intrapulmonary haemorrhage. This, and the ensuing inflammatory response in the lung, leads to a compromise in pulmonary gas exchange and hypoxia that can worsen over several hours. There is also a characteristic cardio-respiratory effect mediated via an autonomic reflex causing apnoea (or rapid shallow breathing), bradycardia and hypotension (the latter possibly also due to the release of nitric oxide). An understanding of this response, and the way it modifies other reflexes, can help the development of new treatment strategies for this condition and for the way it influences the patient's response to concomitant injuries.