By Stan Deresinski, MD, FACP, FIDSA

Clinical Professor of Medicine, Stanford University

Dr. Deresinski reports no financial relationships relevant to this field of study.

SYNOPSIS: As of Oct. 1, 2019, 1,080 cases of lung injury possibly related to vaping have been reported to the CDC. Evidence to date suggests the illness is a form of acute lipoid pneumonia likely related to inhalation of lipid materials.

SOURCES: Davidson K, Brancato A, Heetderks P, et al. Outbreak of electronic-cigarette-associated acute lipoid pneumonia - North Carolina, July-August 2019. MMWR Morb Mortal Wkly Rep 2019;68:784-786.

Schier JG, Meiman JG, Layden J, et al. Severe pulmonary disease associated with electronic-cigarette–product use - interim guidance. MMWR Morb Mortal Wkly Rep 2019;68:787-790.

Five patients presented to two North Carolina hospitals in July and August 2019 with severe pneumonitis that progressed to hypoxemic respiratory failure. Each had been “vaping,” using vaping pens and/or e-cigarettes with refillable chambers or interchangeable cartridges filled with tetrahydrocannabinol concentrates or oil that had been purchased “on the street.”

The patients complained of worsening dyspnea, nausea, vomiting, abdominal discomfort, and fever, and all exhibited peripheral blood neutrophil-predominant leukocytosis. They received empiric antibiotics recommended for treatment of community-acquired pneumonia, but tests for microbiological etiologies proved negative. Chest CT revealed infiltrates that were mostly basilar with ground glass opacities and tree-in-bud patterns. While no microbial etiology was identified on evaluation of bronchoalveolar lavage fluid, staining of cytological specimens with Oil Red O allowed visualization of lipid-laden macrophages. Rapid clinical improvement occurred after administration of methylprednisolone, and only one patient required intubation and mechanical ventilation. All five survived.

These cases are among the wave of reported cases of severe pulmonary disease associated with electronic cigarette product use in the United States; more than 1,000 cases were reported by 48 states and one U.S. territory as of Oct. 1, 2019. The clinical presentation and course of these cases appear to be generally compatible with that of the five North Carolina cases described earlier. Lipid-laden macrophages from cytological specimens also have been identified in several (but not all) of these cases, contributing to the belief that the illness represents a form of exogenous lipoid pneumonia. In addition, many patients appear to have responded similarly to corticosteroid therapy.

COMMENTARY

Electronic cigarette devices produce an aerosol that may contain a variety of chemicals depending on what is placed in the chamber, such as nicotine or THC and associated oils, but also other substances. The finding of lipid-laden macrophages on cytological specimens from the respiratory tract of several cases, together with an inability to identify an infectious etiology, is compatible with a diagnosis of lipoid pneumonia resulting from inhalation of lipids.

Most cases of exogenous lipoid pneumonia, which, at least in its chronic form is considered to result from a foreign body reaction to fat, have an insidious onset and chronic course, unlike that seen in the cases discussed here. However, the potential for massive inhalation with the use of vaping devices could account for the more acute presentations of the current cases. The inhaled lipid possibly responsible for this illness remains uncertain, but one, vitamin E acetate, has been identified in many, but not all vaping samples from cases tested so far. The CDC warns that until the definitive cause of these illnesses is determined, no one should use e-cigarettes or vaping products that contain THC. Further, independent of this continuing investigation, e-cigarette users should not acquire these products off the street and should not modify or add substances not intended by the manufacturer to any product. For more information, please visit this resource: http://bit.ly/2IuVgPR.