Abstract

Recent case clusters of a respiratory syndrome associated with e-cigarette use (vaping) have been identified. We describe clinical features of six cases in Utah that help characterize this nascent syndrome. We present the most severe case in our series here; A previously healthy 21-year-old man who had been vaping nicotine and tetrahydrocannabinol (THC) daily presented with 1 week of dyspnea, cough, abdominal pain, nausea, and vomiting. He had bilateral interstitial opacities on chest radiography and was empirically treated for bacterial pneumonia. His condition deteriorated, and he was intubated for acute respiratory distress syndrome. Chest computed tomography (CT) showed diffuse consolidative opacities (Fig. S1 in the Supplementary Appendix). Laboratory studies were notable for negative HIV testing and a markedly elevated level of C-reactive protein (30.7 mg per deciliter). Bronchoalveolar lavage (BAL) fluid showed neutrophilic predominance (49%) and more than 50% lipid-laden macrophages by oil red O staining. Testing of this fluid by culture and polymerase-chain-reaction assay for bacterial, fungal, and viral pathogens did not reveal any evidence of infection. Methylprednisolone (1 mg per kilogram of body weight) was administered, but refractory hypoxemia developed, and the patient was treated with venovenous extracorporeal membrane oxygenation (ECMO). During the next 7 days, his condition improved, with resolution of radiographic opacities, and he was extubated and weaned from ECMO. He was discharged home without supplemental oxygen 2 weeks after initial presentation.

A notable and consistent feature of the cases we report is the presence of lipid-laden macrophages seen with oil red O staining in BAL samples that are not attributable to aspiration of exogenous lipoid material. In addition, the diffuse parenchymal opacities seen on CT scans did not have low attenuation (in Hounsfield units) consistent with classic lipoid pneumonia.Although the pathophysiological significance of these lipid-laden macrophages and their relation to the cause of this syndrome are not yet known, we posit that they may be a useful marker of this disease.3-5 Further work is needed to characterize the sensitivity and specificity of lipid-laden macrophages for vaping-related lung injury, and at this stage they cannot be used to confirm or exclude this syndrome. However, when vaping-related lung injury is suspected and infectious causes have been excluded, the presence of lipid-laden macrophages in BAL fluid may suggest vaping-related lung injury as a provisional diagnosis.

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