SESSION TITLE: Pneumonia and Pneumonitis
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Sunday, October 27, 2013 at 04:15 PM - 05:15 PM
INTRODUCTION: Nitrogen dioxide (NO2) is a noxious gas often produced in silos and as a byproduct of industrial processes. Its inhalation is a cause of acute respiratory distress syndrome (ARDS) known as Silo Filler’s disease. We present the case of a 54 year old male who developed ARDS from acute N02 intoxication.
CASE PRESENTATION: A 54 year old, otherwise healthy farmer was leveling out a silo for 1 hour when he started feeling short of breath. This was despite the usual precautions: wearing protective gear and having air pumped into the silo to displace the NO2. Despite coming off the Silo he become progressively more short of breath and presented to our facility for further evaluation. At presentation he was hypoxic requiring 15 Liters of oxygen by non-re-breather mask to maintain an oxygen saturation of 91%. Chest radiography revealed bilateral patchy opacities. Patient was emergently intubated and placed on protective ventilation strategy to manage his ARDS. He was started on high dose-steroids to attenuate the inflammatory response. He was also empirically started on broad spectrum antibiotics which were discontinued once it became clear that there was no infectious component. The patient made steady progress and was successfully extubated on hospital day-5 and was eventually discharged home on a prolonged steroid taper over 8 weeks.
DISCUSSION: Our patient had silo filler’s disease, an acute lung injury caused be inhalation of toxic gasses that build up over silage. Chief among these gasses and the one responsible for most of the injury is NO2. Other potential sources of NO2 inhalation include motor vehicle exhaust and industrial processes such as power generation and nitric acid production. Once inhaled, nitrogen dioxide undergoes the following reaction in the lungs: 3 NO2 + H2O = 2 HNO3 + NO The nitric acid has powerful corrosive properties often responsible for acute lung injury characterized by acute pulmonary edema, airway denudation and subsequent proliferation and possible fibrosis. Furthermore, Nitrous oxide generation plays a role both enhancing the inflammatory response and contributing to hemodynamic instability in affected patients. There is no specific treatment for NO2 inhalation other than supportive measures and steroids. Farmers are advised to wear protective masks and adhere to practices aimed at reducing NO2 production, maintain blowers to remove NO2 and to have blowers work continuously for at least 30 minutes before entering the silo.
CONCLUSIONS: Silo Fillers disease is a rare cause of ARDS caused by inhalation of NO2 usually from silage. Treatment is mainly supportive. High dose steroids with prolonged taper over 8 weeks have been reported to improve outcome. Early recognition and prompt treatment is associated with good outcome.
Reference #1: Persinger RL et al. Molecular mechanisms of nitrogen dioxide induced epithelial injury in the lung. Mol Cell Biochem. 2002 May-Jun;234-235(1-2):71-80.
DISCLOSURE: The following authors have nothing to disclose: Narendranath Epperla, Salah Sabbagh, Natalia Usoltseva, Martin Reriani
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