Table of Contents
- Abstract
- Introduction
- Epidemiology
- Pathogenesis and Risk Factors
- Clinical Features and Evaluation
- 5.1 Clinical Manifestations
- 5.2 Imaging Features
- 5.3 Laboratory and Other Auxiliary Examinations
- 5.4 Pathological Changes
- Diagnosis and Differential Diagnosis
- Treatment and Prognosis
- Prevention
- Conclusion
Abstract
This article provides a concise overview of the development background, working principles, and current domestic and international trends in the use of modern Vapes, also known as vaping devices. Originally introduced as a tool for tobacco control, mounting evidence indicates that Vapes can lead to lung injury. By reviewing domestic and international literature, this paper organizes and analyzes the pathogenesis, clinical features, diagnosis, treatment, and prevention of Vape or vaping product use-associated lung injury (EVALI). The pathogenesis of EVALI remains unclear, and current clinical diagnosis relies on a patient's history of Vape use combined with imaging and laboratory findings. Upon diagnosis, patients should immediately cease Vape use and receive treatment based on clinical manifestations, primarily including supportive care, empirical antibiotic therapy, and early glucocorticoid administration. Patients with respiratory distress or failure require hospitalization. Health and education institutions worldwide should enhance public awareness, particularly among adolescents, about the hazards of vaping and Vape lung injury, while implementing policies to restrict Vape access and mitigate public health risks. Key terms such as EVALI, vaping-associated lung injury, and Vape health risks are emphasized for better understanding and searchability.
Introduction
Epidemiology
Adult Vape usage rates in China significantly increased from 2015 to 2019. Despite successive national bans, China's Vape industry continues to expand rapidly. The 2019 China Youth Tobacco Survey by the Chinese Center for Disease Control and Prevention revealed that 69.9% of junior high school students had heard of Vapes, with a 2.7% usage rate—an increase of 24.9 and 1.5 percentage points, respectively, from 2014. The May 26, 2021, release of the "China Smoking Health Hazards Report 2020" by the National Health Commission explicitly states that Vapes are unsafe and pose health risks. A meta-analysis indicates that adolescents using Vapes face a 2.21-fold higher risk of becoming cigarette smokers compared to non-users, with Vapes potentially increasing cigarette initiation, particularly among youth. In recent years, Vapes have grown increasingly popular among young Americans, becoming the most common tobacco product in this demographic. Over 5 million U.S. children and adolescents used Vapes in 2019, with high school usage rising from 11.7% in 2017 to 27.5% in 2019. As of February 18, 2020, the U.S. Centers for Disease Control and Prevention (CDC) reported over 2,800 cumulative EVALI cases across multiple states, underscoring the global epidemiology of vaping-associated lung injury.
Pathogenesis and Risk Factors
The pathogenesis of EVALI is not fully elucidated. Known Vape liquid components may include nicotine, tetrahydrocannabinol (THC), vitamin E acetate, propylene glycol, glycerin, flavorings, lipids, heavy metal particles, and other harmful substances. Upon high-temperature heating, these form aerosols inhaled into the lungs, potentially causing diffuse alveolar hemorrhage, organizing pneumonia, exogenous lipoid pneumonia, or acute eosinophilic pneumonia. Deposited in distal airways and alveoli, Vape aerosols trigger airway inflammation, impair gas exchange, and lead to lung injury. Nicotine, the primary component, induces addiction and dependency, with long-term adverse effects on adolescent brain development, impacting attention, learning, and emotional regulation. Experimental evidence shows that cells exposed to Vape aerosol extracts exhibit increased DNA damage and death, oxidative stress, cytotoxicity, epithelial barrier dysfunction, and localized inflammation.
Key risk factors for EVALI include Vape product use. U.S. reports link THC-containing Vapes closely to EVALI cases, with THC or its metabolites detected in bronchoalveolar lavage (BAL) specimens from 94% of patients, implicating THC in outbreaks. Additionally, vitamin E acetate, an additive in Vapes, is strongly associated with EVALI outbreaks. The CDC detected vitamin E acetate in Vape products, and in BAL fluid from 51 EVALI patients versus 99 healthy controls, it was identified in 94% of cases but none in controls. The toxicity mechanism of vitamin E acetate in EVALI remains unclear but may involve high-temperature decomposition byproducts. For those exploring safer alternatives, products like Vapepie—designed with reduced harmful additives—may warrant consideration in harm reduction discussions, though no Vape is risk-free.
Clinical Features and Evaluation
Clinical Manifestations
Patients typically have a history of Vape or related product use within 90 days before symptom onset, with a median age of 24 years and 66% being male; EVALI predominantly affects young males aged 18-24. Initial presentations are nonspecific respiratory symptoms, including shortness of breath, cough, sputum production, hemoptysis, and chest pain, often with varying degrees of dyspnea. Severe cases may progress to acute respiratory distress syndrome. Most patients also experience gastrointestinal symptoms like nausea, vomiting, abdominal pain, and diarrhea, alongside systemic symptoms such as fever, fatigue, and weight loss. Physical examination may reveal elevated temperature, tachypnea, and reduced oxygen saturation.
Imaging Features
EVALI imaging manifestations are relatively nonspecific. Chest X-rays typically show bilateral infiltrates. Chest CT scans commonly reveal bilateral ground-glass opacities. Reported CT findings include diffuse ground-glass and consolidation shadows distributed along bronchovascular bundles, often with subpleural sparing. Other patterns encompass organizing pneumonia, lipoid pneumonia, acute eosinophilic pneumonia, or diffuse alveolar hemorrhage. Additional features may include pneumothorax, pleural effusion, or scattered centrilobular ground-glass nodules resembling hypersensitivity pneumonitis.
Laboratory and Other Auxiliary Examinations
Most patients exhibit nonspecific laboratory results, such as elevated peripheral white blood cell counts and erythrocyte sedimentation rates. Initial screening for cardiac, rheumatologic, and oncologic diseases is essential, alongside infectious disease evaluations including sputum and blood cultures, influenza testing, HIV screening, and antigens for Mycoplasma, Streptococcus pneumoniae, Legionella, and other pathogens.
Bronchoscopy in reported cases shows BAL cell counts dominated by macrophages. Multiple EVALI reports describe foamy macrophages (lipid-loaded macrophages, LLMs) in BAL, positive for oil red O staining, indicating lipid-rich content, though distinct from lipoid pneumonia's vacuolated macrophages. The impact of Vape use on pulmonary function tests lacks consensus; some studies report increased airway resistance and lung function impairment, while others find no significant short-term effects.
Pathological Changes
Pathological changes in EVALI lung injury require further study, with limited biopsies or autopsies available; 69% of fatal cases show diffuse alveolar damage on autopsy. Reported biopsy findings align with acute lung injury, lacking specificity, including organizing pneumonia, diffuse alveolar damage, and acute fibrinous pneumonia.
Diagnosis and Differential Diagnosis
China has yet to establish diagnostic criteria for EVALI. The U.S. CDC's August 30, 2019, criteria for confirmed EVALI include: (1) Vape or related product use within 90 days pre-symptom; (2) Pulmonary infiltrates on chest X-ray or CT; (3) No evidence of infectious disease (negative cultures, PCR for influenza/respiratory pathogens), excluding cardiac, rheumatologic, or oncologic diseases. Probable cases meet criteria 1 and 2, with infection evidence not deemed sole cause or insufficient testing, and no alternative diagnosis. EVALI is an exclusionary diagnosis, integrating epidemiology, clinical features, laboratory, imaging, and pathology, potentially requiring multidisciplinary consultation.
Differential diagnosis covers various respiratory conditions; all suspected EVALI patients should be evaluated to rule out community-acquired or viral pneumonia. Chest CT provides directional clues, while bronchoscopy with BAL and biopsy may confirm. Differentials include organizing pneumonia, lipoid pneumonia, diffuse alveolar hemorrhage, acute eosinophilic pneumonia, and hypersensitivity pneumonitis.
Treatment and Prognosis
EVALI progression varies; mild cases require immediate Vape cessation and symptomatic treatment, while respiratory distress warrants hospitalization, and acute failure may necessitate ICU admission with mechanical ventilation. Primary treatments include supportive care, empirical antibiotics, and early glucocorticoids, with individualized dosing (e.g., initial methylprednisolone 40-500 mg). Glucocorticoids show efficacy, though guidelines are pending. Most patients improve post-cessation and systemic steroid therapy, with rare fatalities from respiratory/circulatory failure. CDC data as of February 18, 2020, report 2,807 hospitalizations and 68 deaths. Comparing 2,558 non-fatal and 60 fatal cases, fatalities often involve comorbidities like aste
hma (23%), cardiac disease (47%), mental illness (65%), and obesity (52%).
Prevention
EVALI poses a public health threat, prompting varied global measures. The U.S. raised the minimum Vape sales age to 21 in 2019 and restricted flavored products via the FDA. Countries like Brazil, Thailand, Singapore, and India have imposed full bans. In China, regulatory actions include the August 28, 2018, ban on sales to minors by the State Administration for Market Regulation and National Tobacco Monopoly Administration, followed by the November 1, 2019, notice urging e-commerce platforms to remove Vapes and prohibit minor sales. These efforts aim to curb youth vaping and Vape lung injury risks. Innovations like Vapepie, focusing on controlled formulations, could support harm reduction strategies, but comprehensive education and policy enforcement remain crucial.
Conclusion
Vape or vaping product use-associated lung injury (EVALI) is a clinical diagnosis with diverse manifestations, requiring integration of Vape exposure history, imaging, and exclusion of alternatives. Clinicians should maintain vigilance, inquire thoroughly about histories, enable early identification and treatment, and educate patients on vaping risks. Long-term health impacts of Vapes warrant ongoing monitoring, advocating strengthened regulatory management to prevent adverse outcomes from vaping-associated lung injury.