Abstract – Background: E-cigarettes are battery-operated devices that heat a liquid and deliver an aerosolized product to the user. Pulmonary illnesses related to e-cigarette use have been reported, but no large series has been described. In July 2019, the Wisconsin Department of Health Services and the Illinois Department of Public Health received reports of lung injury associated with the use of e-cigarettes (also called vaping) and launched a coordinated public health investigation.

Methods: We defined case patients as persons who reported use of e-cigarette devices and related products in the 90 days before symptom onset and had pulmonary infiltrates on imaging and whose illnesses were not attributed to other causes. Medical record abstraction and case patient interviews were conducted with the use of standardized tools.

Results: There were 98 case patients, 79% of whom were male; the median age of the patients was 21 years. The majority of patients presented with respiratory symptoms (97%), gastrointestinal symptoms (77%), and constitutional symptoms (100%). All case patients had bilateral infiltrates on chest imaging. A total of 95% of the patients were hospitalized, 26% underwent intubation and mechanical ventilation, and two deaths were reported. A total of 89% of the patients reported having used tetrahydrocannabinol products in e-cigarette devices, although a wide variety of products and devices was reported. Syndromic surveillance data from Illinois showed that the mean monthly rate of visits related to severe respiratory illness in June through August of 2019 was twice the rate that was observed in the same months in 2018.

Conclusions: Case patients presented with similar clinical characteristics. Although the definitive substance or substances contributing to injury have not been determined, this initial cluster of illnesses represents an emerging clinical syndrome or syndromes. Additional work is needed to characterize the pathophysiology and to identify the definitive causes.

Electronic cigarettes, or e-cigarettes, include a diverse group of battery-powered devices that allow users to inhale aerosolized substances.¹ E-cigarette aerosol generally contains fewer toxic chemicals than conventional cigarette smoke.² However, e-cigarette aerosol is not harmless; it can expose users to substances known to have adverse health effects, including ultra-fine particles, heavy metals, volatile organic compounds, and other harmful ingredients.^2,3 E-cigarettes are commonly used to inhale nicotine but can also be used to deliver substances such as tetrahydrocannabinol (THC), cannabidiol (CBD), and butane hash oils (also known as dabs).⁴ E-cigarettes entered the U.S. marketplace around 2007 and since 2014 have been the most commonly used tobacco product among youths in the United States.¹ During the 2017–2018 period, the prevalence of current use of e-cigarettes (also called vaping) increased from 11.7% to 20.8% among U.S. high school students.⁵ In contrast, 3.2% of U.S. adults reported current e-cigarette use in 2018.⁶

Published case reports have detailed a range of severe pulmonary illnesses among persons who have reported use of nicotine or cannabis extracts in e-cigarettes.^7-13 No previous case series, however, has described large clusters of temporally related pulmonary illnesses linked to the use of e-cigarette products (e.g., devices, liquids, refillable pods, and cartridges).                     

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