Acute chemical pulmonary edema with inhaled nitrogen dioxide intoxication

Abstract

Nitrogen dioxide is released by the interaction of some metals with nitric acid. Inhalation intoxication with nitrogen dioxide leads to chemical pulmonary edema. This study presents the case of a patient who had acute inhalation exposure to an unidentified brown gaseous substance (presumably nitrogen dioxide) when he etched a metal product with nitric acid. Twenty-four hours after contact with the gas, he manifested signs of intoxication, such as chest pain, tachypnea, and decreased saturation. Laboratory tests revealed hemoconcentration, hyperfermentemia, and arterial hypoxemia. The X-ray image of the entire lung surface revealed a sharp increase and deformation of the pulmonary pattern due to the vascular component. The diagnosis was T65, i.e., toxic effect of other and unspecified substances. With treatment, the patients condition improved. On day 4 after therapeutic exposure, with decreased oxygen fraction in the inhaled gas mixture to 0.3, the saturation increased to 98%, and tachypnea disappeared. On day 6, with ongoing treatment (oxygen therapy, use of antioxidants, antihypoxants, anti-inflammatory, and antibacterial drugs), the inflammatory reaction stopped, the rheological properties of the blood improved, and the gas composition of arterial blood normalized, i.e., the oxygenation index was 436, which indicated the disappearance of arterial blood oxygenation disorders. During the radiological examination, the normal radiological picture of the lungs was determined. Thus, on day 6 after the start of therapy, signs of intoxication were completely stopped. Specific changes in the lungs during radiation research techniques, hemoconcentration, inflammation, and hypoxemia during laboratory blood tests should be considered prognostic signs of chemical pulmonary edema. As a pathogenetic therapy, treatment must be supplemented with drugs that stop the cascade of free radical oxidation reactions (acetylcysteine and sodium thiosulfate). Individuals exposed to nitrogen dioxide should be considered a high-risk group for lung damage and hospitalized for dynamic observation for at least 2 days. Taking into account the genotoxic effects of nitrogen dioxide, affected patients should be classified as at risk of developing neoplasms and undergo further dynamic monitoring.