Assessment of N-acetylcysteine as a therapy for phosgene-induced acute lung injury.

The toxic industrial chemical (TIC1) phosgene remains an important chemical intermediate in many industrial processes. Inhalation of phosgene can cause an acute lung injury (ALI) which, in severe cases may result in death. There are currently no effective pharmacological therapies or evidence-based treatment guidelines for managing exposed individuals. N-acetylcysteine (NAC) is a commercially available drug licensed in the UK and elsewhere for the treatment of paracetamol (acetaminophen) overdose. It has a number of mechanisms of action which may provide therapeutic benefit for the treatment of phosgene-induced ALI. It has previously been shown to provide therapeutic efficacy against the lung damaging effects of sulfur mustard vapour exposure, when given by the inhaled route, in the pig (Jugg et al., 2013). Our research objective was to determine whether inhaled NAC might also be therapeutic for other chemicals, in this case, phosgene. This study has demonstrated that multiple nebulised doses, administered from 30 min after exposure of terminally anaesthetised pigs to phosgene, is not an effective therapy when administered at the times and doses employed in this study. There remains no pharmacological treatment for phosgene-induced lung injury.

Continuous positive airway pressure: An early intervention to prevent phosgene-induced acute lung injury.

Exposure to toxic industrial chemicals such as phosgene may occur through accidental or deliberate release. Inhalation may result in an acute lung injury which manifests as hypoxaemia with insufficient oxygen being delivered to the tissues resulting in hypoxia, respiratory failure and death. No effective pharmacological therapy currently exists and treatment remains supportive, often requiring intensive care facilities. In a mass casualty scenario the logistical burden of managing exposed individuals would rapidly overwhelm healthcare systems. This highlights the need to develop post exposure therapeutic strategies to minimise injury severity and increase survival in individuals exposed to toxic chemicals. Our research objective was to investigate a commercial off the shelf (COTS) therapy; ambient air continuous positive airway pressure (CPAP) support, initiated 1h post exposure to explore the concept that early intervention with positive airway pressure would reduce or ameliorate lung injury following exposure to phosgene. This study has demonstrated that CPAP, initiated before overt signs of exposure become manifest, significantly improved survival as well as improving some clinically relevant physiological measures of phosgene-induced acute lung injury over 24h.