Vaping-Associated Lung Injury: A Review

Abstract

Since commercial development in 2003, the usage of modern electronic cigarette (e-cigarette) continues to increase amongst people who have never smoked, ex-smokers who have switched to e-cigarettes, and dual-users of both conventional cigarettes and e-cigarettes. With such an increase in use, knowledge of the irritative, toxic and potential carcinogenic effects on the lungs is increasing. This review article will discuss the background of e-cigarettes, vaping devices and explore their popularity. We will further summarise the available literature describing the mechanism of lung injury caused by e-cigarette or vaping use.

Keywords: EVALI; Oil Red O stain; e-cigarette; foamy macrophages; vaping.

Figure 1

E-cigarette or vaping device.

Figure 2

Images show electronic cigarette or vaping product use–associated lung injury in an 18-year-old male who attended our institution. Axial CT chest imaging (A–C) demonstrates extensive bilateral centrilobular and peri-bronchial ground glass opacification with subpleural sparing, slightly more confluent in the lower zones.

Figure 3

(A,B) Bronchoalveolar lavage (BAL) cytology from a patient diagnosed with EVALI in our institution, stained with Oil-Red-O × 400 magnification showing positive red intracytoplasmic droplets in the alveolar macrophages, consistent with excess neutral lipid.

Figure 4

Proposed mechanism of action by which e-cigarettes cause lung injury. Many e-cigarettes that contain tetrahydrocannabinol (THC) have been shown to have higher levels of vitamin E acetate, commonly used as a thickening agent. It is possible that increased exposure of the lungs to Vitamin E (naturally occurring at low levels in surfactant) or Vitamin E acetate could affect the physical structure and phase behaviour of surfactant, impairing its ability to maintain surface tension leading to respiratory distress. Dysfunctional surfactant might lead to excess lipid accumulation within alveolar macrophages and that reverse cholesterol transport or cholesterol efflux might be implicated. Secondly, a known product of vaporised vitamin E acetate is ketene which is believed to be a lung irritant.