What are the risks of popcorn lung associated with vaping?

Popcorn Lung and Vaping: Understanding the Risk

"Popcorn lung" (bronchiolitis obliterans) is a real but rare risk associated with vaping, caused by inhalation of flavoring chemicals like diacetyl and 2,3-pentanedione found in e-liquids, though the more common and severe vaping-related lung injury is EVALI (E-cigarette or Vaping product use-Associated Lung Injury), which presents differently and requires immediate discontinuation of all vaping products. 1, 2

What is "Popcorn Lung"?

Bronchiolitis obliterans is a severe, irreversible form of fixed airway obstruction characterized by fibrotic scarring of the small airways. 3 The term "popcorn lung" originated from cases in microwave popcorn factory workers exposed to butter-flavoring vapors containing diacetyl. 4, 5

Key Causative Agents in Vaping Products

• Diacetyl and 2,3-pentanedione are α-dicarbonyl flavoring compounds present in many flavored nicotine e-liquids used in electronic nicotine delivery systems. 1
• These chemicals cause airway epithelial necrosis, damage biological molecules, and with chronic exposure produce airway fibrosis resembling bronchiolitis obliterans. 3
• Diacetyl substitutes (like 2,3-pentanedione) cause similar peri-bronchiolar fibrotic lesions and may pose equivalent risk. 1, 3

Clinical Presentation of Vaping-Associated Bronchiolitis Obliterans

The presentation differs from the more common EVALI syndrome:

• Progressive dyspnea and intractable cough developing over weeks to months of intensive vaping. 2
• Fixed airflow obstruction with gas trapping on pulmonary function testing. 2
• CT findings showing diffuse centrilobular "tree-in-bud" nodularity consistent with bronchiolitis. 2
• Persistent symptoms even months after cessation, with limited exercise tolerance. 2

Documented Case Evidence

A 17-year-old previously healthy Canadian youth developed life-threatening bronchiolitis requiring ECMO after intensive vaping of flavored e-liquids, with persistent fixed airflow obstruction months after recovery—representing possible vaping-associated bronchiolitis obliterans. 2 This pattern appears distinct from the alveolar injury predominantly seen in EVALI cases. 2

EVALI: The More Common Vaping-Related Lung Injury

EVALI is the predominant acute lung injury syndrome associated with vaping and requires different clinical management than bronchiolitis obliterans. 6

Clinical Recognition of EVALI

Patients present with:

• Respiratory symptoms: shortness of breath, cough, chest pain. 6
• Systemic symptoms: fever, fatigue, muscle aches, nausea, vomiting. 6
• Hypoxemia and respiratory distress in severe cases. 6

Initial Assessment Algorithm

For any patient presenting with respiratory symptoms who vapes:

1. Measure vital signs and pulse oximetry to assess oxygen saturation and hemodynamic stability. 6
2. Obtain focused history specifically asking about e-cigarette or vaping product use. 6
3. Rule out infectious etiologies including influenza and community-acquired pneumonia. 6

Hospitalization Criteria

Admit to hospital if ANY of the following:

• Oxygen saturation <95% on room air. 6
• Respiratory distress present. 6
• Comorbidities that compromise cardiopulmonary reserve. 6
• Inability to discontinue vaping products or adhere to outpatient treatment. 6
• Lack of reliable access to care or social support systems. 6

Inpatient Management Protocol

Diagnostic workup:

• Obtain chest X-ray and strongly consider CT scan even if CXR is normal. 6
• Perform urine toxicology and influenza testing. 6
• Consider bronchoalveolar lavage or lung biopsy if clinically indicated, in consultation with pulmonary specialists. 6

Treatment approach:

• Immediately discontinue all e-cigarette or vaping products—this is the single most critical intervention. 6
• Offer cessation services to all patients and facilitate connection. 6
• Consider empiric antimicrobials according to community-acquired pneumonia guidelines. 6
• Consider corticosteroids with caution as they may worsen respiratory infections. 6
• Administer annual influenza vaccination if not previously received. 6

Discharge Planning Requirements

Before discharge, ensure:

• Clinical stability for 24-48 hours. 6
• Screen for mental health, substance use disorders, and social care needs. 6
• Inpatient pharmacist counseling regarding medication reconciliation, particularly for patients on corticosteroid taper. 6
• Educate about adrenal insufficiency symptoms (fatigue, decreased appetite, GI distress, myalgia, joint pain, salt craving, dizziness, postural hypotension) if prolonged corticosteroid course. 6
• Schedule outpatient follow-up within 48 hours before discharge. 6
• Arrange pulmonology follow-up within 2-4 weeks. 6

Outpatient Management for Mild Cases

Candidates for outpatient management must meet ALL criteria:

• O2 saturation ≥95% on room air. 6
• No respiratory distress. 6
• No comorbidities compromising cardiopulmonary reserve. 6
• Reliable access to care and strong social support. 6

Outpatient treatment:

• Advise discontinuation of all e-cigarette or vaping products. 6
• Consider chest X-ray if chest pain or dyspnea present. 6
• Use corticosteroids with extreme caution due to risk of worsening occult respiratory infections. 6
• Early initiation of antivirals if influenza suspected. 6

Critical Distinctions and Clinical Pitfalls

Bronchiolitis Obliterans vs. EVALI

Bronchiolitis obliterans from flavoring exposure:

• Develops over weeks to months of chronic exposure. 2
• Presents with progressive fixed airflow obstruction. 2
• Shows centrilobular nodularity on CT. 2
• Results in permanent lung damage. 2, 4

EVALI:

• Presents acutely over days to weeks. 6
• Shows alveolar injury pattern. 2
• May improve with cessation and corticosteroids. 6

Exposure Risk Context

Consumer exposure levels to diacetyl from microwave popcorn have been documented to cause bronchiolitis obliterans at levels comparable to those that caused disease in manufacturing workers. 4 This underscores that even consumer-level exposures to flavoring chemicals can cause severe lung disease. 4

Mortality Risk

Workers at microwave popcorn facilities exposed to diacetyl experienced 4-fold higher rates of COPD-associated mortality (SMR = 4.10; CI: 1.12-10.49), particularly among those employed before exposure reduction interventions. 5 This demonstrates the serious long-term mortality implications of flavoring chemical exposure. 5

Post-Discharge Follow-Up Strategy

Initial follow-up within 48 hours is critical to prevent rehospitalization and death. 6

Follow-up should include:

• Assessment of vital signs, physical exam, and symptom resolution. 6
• Verification of adherence to corticosteroid taper if prescribed. 6
• Reinforcement of complete abstinence from all vaping products. 6
• Pulmonology evaluation at 2-4 weeks with spirometry and DLCO testing. 6

Care transition best practices:

• Schedule appointments before discharge and assign patient navigators for those with barriers to care. 6
• Conduct telephone or text check-ins. 6
• Facilitate home visits by community health workers for vulnerable patients. 6

Bottom Line for Clinical Practice

The primary intervention for both suspected bronchiolitis obliterans and EVALI is immediate and permanent discontinuation of all vaping products. 6 While true bronchiolitis obliterans from vaping appears rare, EVALI is a well-documented syndrome requiring aggressive supportive care and close follow-up. 6 The presence of diacetyl and similar α-dicarbonyl compounds in e-liquids creates a theoretical risk for chronic bronchiolitis obliterans with long-term use, though EVALI remains the more immediate clinical concern. 1, 2