Fatal Pulmonary Edema After Acute Occupational Exposure to Nitric Acid

Background: Nitric acid (HNO3) is a solution of nitrogen dioxide (NO2) in water commonly used as an industrial chemical and cleaner. Oxides of nitrogen liberated as nitric acid interact with the environment to cause inhalation injuries. The coexistence of HNO3 with varying oxides of nitrogen likely results in the large continuum of symptoms related to HNO3 exposure and varying times of onset—acute, subacute, and delayed. Furthermore, dyspnea and evidence of acute lung injury may not occur for several hours after exposure and can lead to rapidly progressive acute respiratory distress syndrome (ARDS). Objectives: This case illustrates to physicians and occupational health personnel that HNO3 inhalation may initially appear benign and that onset of severe effects may be delayed. Case Report: A 66-year-old man developed delayed-onset pulmonary edema, ARDS, and fatal circulatory collapse 53 h after occupational exposure to HNO3. Conclusion: This case serves to increase awareness among emergency physicians, as well as occupational health personnel, that patients exposed to HNO3 may initially be asymptomatic. Patients should be evaluated and observed regardless of the severity or benign nature of symptoms, which occur immediately after exposure, as the most severe symptoms are often delayed in onset and rapidly progressive.