Using electronic cigarettes, or vaping, has become increasingly popular within the past several years. Within the past few months, an outbreak of vaping-associated pulmonary injury (VAPI) has been recognized in locations across the United States. The number of patients involved has rapidly increased to the hundreds, and several deaths have been reported.

This is currently an area of active investigation about which little is known for certain.

Here’s what we do know.

Quick Tips: Diagnosis and Treatment

Available evidence suggests that the predominant form of lung injury is lipoid pneumonia. This may relate largely to the vaping of tetrahydrocannabinol (marijuana-like) products, which are diluted using vitamin E acetate. However, not all patients report a history of vaping with tetrahydrocannabinol, so other products may be involved as well.

The clinical presentation of VAPI usually begins gradually over several days with gastrointestinal and pulmonary symptoms. Early on, patients may appear to have a viral gastroenteritis or mild pneumonia. Eventually hypoxemic respiratory compromise worsens, with the development of bilateral pulmonary infiltrates. Additional symptoms may include fever, chest pain, and weight loss. CT scans typically show bilateral diffuse ground-glass opacification. Steroid administration may be associated with clinical improvement, although this remains unproven and speculative. Severity is variable, with some patients requiring intubation or even extracorporeal membrane oxygenation.

The optimal approach to investigation and treatment of this disorder remains unknown. Evaluation is primarily driven toward exclusion of alternative likely possibilities (especially various types of infectious pneumonia). Whether every patient requires a bronchoscopy is debatable. For critically ill patients at risk of deterioration, the safest approach could be to provide empiric therapy for both pneumonia and VAPI (current approaches are a combination of antibiotics and a steroid).

This is a rapidly evolving topic, and approaches are likely to evolve even as this goes to print. The most important aspect is to be aware that VAPI exists. This awareness should prompt us to take a detailed vaping history among patients with respiratory or gastrointestinal symptoms, especially in otherwise healthy patients not expected to develop acute respiratory illnesses. In suspected cases, specialty consultation may be advisable (most often pulmonology), and local health departments should be notified as they can provide updated clinical guidance and assist in tracking cases.

The Devil We Don’t Know

Vaping’s popularity has been, in part, driven by the medical community, which has viewed the habit as a safer alternative to smoking cigarettes. Unfortunately, the use of vaping as a smoking cessation strategy is scientifically a bit dodgy. Our understanding of the toxicity of cigarettes emerged very slowly. This toxicity wasn’t recognized for decades, until long-term epidemiological evidence implicated smoking in lung cancer. Since vaping hasn’t been around that long, it’s simply impossible to know what its long-term effects will be. Thus, it’s impossible to be sure that the long-term effects of vaping will be less severe than those of smoking. Nonetheless, passion to eliminate smoking has promoted this transition away from the devil we know toward a devil we don’t yet understand.

Once commercialized, vaping has rapidly expanded to new markets. Companies have aggressively promoted vaping to adolescents, using advertisement campaigns on Instagram and products of various flavors, including fruit and candy flavors. Consequently, vaping has become common among adolescents, who have been led to believe that vaping is a safer alternative to smoking. Currently, more than a third of high school seniors report some use of vaping.

Trouble Brewing

The gastrointestinal tract has evolved to take in widely heterogeneous material, absorb nutrients, and excrete the remainder. Overall, the gut is astonishingly successful at coping with foreign materials while remaining healthy. In comparison, the lungs are not well-designed to deal with foreign material. Vaping exposes the lungs to a dizzying array of chemicals (some of which are known to cause lung disease). This is a recipe for potential disaster.

About a dozen case reports over the last several years have described various forms of lung disease that may result from vaping. The most fulminant form is acute eosinophilic pneumonia, a form of respiratory failure, which may also be caused by smoking cigarettes. Other forms of lung disease associated with vaping include lipoid pneumonia and cryptogenic organizing pneumonia. These are more gradual but may nonetheless progress to ventilator-dependent respiratory failure. To simplify matters, these various forms of VAPI share similar features—they cause bilateral pulmonary infiltrates, which generally respond to steroids.

Despite some early signals of harm, most practitioners have remained blissfully unaware of vaping risks, so it is not a part of medical culture to think about it. Vaping wasn’t taught to us as something to ask about during a medical history the way other substance use was. It’s possible that some cases of VAPI weren’t diagnosed simply because we didn’t know enough to ask about it.

Public Health Considerations

The current epidemic has cast a harsh light on the lack of regulation of vaping products. Vaping is now a billion-dollar industry in the United States and may already be influenced by substantial political contributions. The U.S. Food and Drug Administration (FDA) was given authority to oversee vaping in 2016. However, companies have been given until 2022 before they must submit products for review. Overall, the industry has remained largely unregulated.

Vaping itself may turn out to be safer than smoking, as it takes oncogenic tobacco and smoke out of the equation. In fact, the current epidemic of VAPI most likely relates to adulterants (eg, vitamin E acetate), which, once discovered and banned from e-cigarettes, will likely render VAPI a rare entity. However, this outbreak is doubtless facilitated by the use of vaping products that are designed to be modifiable. And so one of e-cigarettes’ appeals—the diversity in product it can deliver—may be a setup for other hazards we have yet to discover.

Given a lack of regulation from the federal government, some local governments have stepped in. Gov. Gretchen Whitmer recently outlawed the sale of flavored electronic cigarettes in Michigan (see “Vaping & Public Health Policy” sidebar below). This announcement was lauded by officials from the American Heart Association and the American Thoracic Society. In Vermont, a state law was recently passed increasing the age required to buy e-cigarettes to 21.

Harm Avoidance

Aside from identifying patients with VAPI, we can begin to educate patients about the potential harms from vaping. If patients are unwilling or unable to abstain from vaping, they should avoid using adulterated vaping liquid or products containing tetrahydrocannabinol. For patients seeking to stop smoking, vaping should not be viewed as an aid; cessation strategies that have definitively been proven to be less dangerous should be tried first.

Dr. Farkas is assistant professor of pulmonary and critical care medicine at the University of Vermont in Burlington.