Humidified hydrogen peroxide associated pneumonitis: A cautionary tale

Hydrogen peroxide is a chemical commonly used as a household antiseptic for cleaning and disinfecting. Chronic inhalation of hydrogen peroxide is described in case reports as causing interstitial lung disease with radiographic images demonstrating septal line thickening, honeycombing, and traction bronchiectasis with associated ground glass opacification. In a literature review, no cases of acute hydrogen peroxide inhalation induced lung injury have been previously described. This is a case of acute hydrogen peroxide induced pneumonitis initially masquerading as Covid-19 pneumonia. An 82-year-old male with a pertinent history of diastolic heart failure, obstructive sleep apnea, and chronic obstructive pulmonary disease presented with worsening dyspnea and morning hemoptysis. He endorsed a COVID-19 exposure two weeks previously. Upon initial evaluation, he was afebrile and hemodynamically normal, with tachypnea and requiring 6 liters of supplemental oxygen to maintain spo2> 88%. Pulmonary auscultation revealed clear breath sounds and no signs of fluid overload were evident on the remainder of the physical exam. The initial chest x-ray and CT imaging demonstrated multifocal, bilateral, hazy consolidations with increased interstitial markings concerning for COVID-19 pneumonia. Pertinent lab results revealed negative COVID-19 and viral respiratory PCR results, and respiratory cultures with no growth of pathogenic bacteria. An echocardiogram revealed new systolic dysfunction with a reduced ejection fraction of 35-40%. The patient continued to have severe dyspnea and hypoxemia despite treatment for heart failure, COPD, and bacterial pneumonia consisting of diuretics, bronchodilators, and antibiotics. On further interview the patient recounted mixing hydrogen peroxide in his CPAP humidifier for the previous week before admission, based on a friend's advice in preventing COVID-19. The patient was subsequently initiated on systemic glucocorticoid therapy and had significant improvement in hypoxemia and dyspnea and oxygen requirements decreased from 6L to 2L nasal cannula at time of discharge. In light of the recent influential media attention and fear, cleaning products such as bleach have received disproportionate attention in the killing of the COVID-19 virus. Similarly, hydrogen peroxide is used as a disinfectant, which was intentionally inhaled in large amounts and over a one-week duration in this case. Prior case reports describe environmental and occupational exposure over 3-5 years developing into a non-specific interstitial pneumonia pattern. This case demonstrates a rare acute pneumonitis after the recent use of hydrogen peroxide in a CPAP humidifier. Inhalation of hydrogen peroxide may produce an acute pneumonitis distinct from what has been described previously with chronic inhalation.