E-Cigarette or Vaping-Associated Lung Injury

E-cigarette or vaping associated lung injury is an acute lung illness linked to inhalation of aerosols from e-cigarette or vaping devices. Most cases involve tetrahydrocannabinol containing cartridges with vitamin E acetate as an additive, but injury has been reported with nicotine products and other contaminants.

It is mainly a disease of adolescents and young adults, with a male predominance, and cases peaked in 2019 with thousands of hospitalisations and dozens of deaths. It remains a diagnosis of exclusion, and cases still occur.

Pathophysiology. Inhaled chemicals, solvents, oils and heated flavouring agents damage the airway and alveolar epithelium, causing diffuse alveolar damage, acute fibrinous organising pneumonia or organising pneumonia, often with foamy macrophages and a bronchiolocentric pattern. Vitamin E acetate is found in lavage fluid from many patients.

Over days to weeks: cough, dyspnoea, pleuritic chest pain, fever, chills and weight loss, with gastrointestinal symptoms (nausea, vomiting, diarrhoea, abdominal pain) in most. Examination shows tachypnoea, tachycardia and hypoxaemia, with crackles in some. Respiratory failure requiring ventilation occurs in about a quarter.

Hypoxaemia (saturation below 92%), respiratory distress or a need for oxygen needs urgent hospital assessment.

• Use of e-cigarette or vaping products in the preceding 90 days, pulmonary infiltrates on chest radiograph or CT, absence of pulmonary infection on initial workup, and no alternative explanation.
• Chest radiograph: bilateral hazy or patchy opacities. CT: bilateral ground glass opacity with subpleural sparing, or consolidation, and sometimes pneumomediastinum.
• Laboratory tests: leucocytosis with neutrophilia, raised C-reactive protein and erythrocyte sedimentation rate, and raised transaminases in some.
• Infection workup: respiratory viral panel (including influenza and SARS-CoV-2), blood and sputum cultures, urinary antigens, and Pneumocystis testing when immunosuppressed.
• Bronchoscopy with lavage is not required but may show lipid laden macrophages (oil red O stain) and neutrophilia, and excludes infection.
• Urine drug screen and ask directly about cannabis products, source (informal market products carry the highest risk) and frequency.

Differential diagnosis.

• Community acquired pneumonia and influenza
• COVID-19
• Acute eosinophilic pneumonia (especially new vaping or smoking)
• Hypersensitivity pneumonitis
• Aspiration pneumonia
• Acute respiratory distress syndrome of another cause
• Opportunistic infection

• Admit patients with hypoxaemia (saturation below 95% on air), respiratory distress or comorbidity. Oxygen titrated to a saturation of 92 to 96%, with high flow oxygen, non-invasive ventilation or invasive ventilation as needed, using lung protective settings.
• Empirical treatment for community acquired pneumonia until infection is excluded: ceftriaxone 2 g intravenously daily with azithromycin 500 mg daily (or doxycycline 100 mg twice daily), and oseltamivir 75 mg twice daily for 5 days in influenza season until tests are negative.
• Corticosteroid: methylprednisolone 0.5 to 1 mg/kg daily intravenously (or prednisolone 40 to 60 mg daily orally) for moderate to severe disease, once infection is reasonably excluded, with improvement commonly within 24 to 48 hours. Taper over 5 to 10 days up to 4 weeks, with a longer course for relapse. Pulse methylprednisolone 500 to 1000 mg daily is used in severe disease. Evidence comes from case series.
• Stop all vaping and cannabis aerosol use permanently, and offer cessation support: nicotine replacement (patch 21 mg daily for those using nicotine) or varenicline (0.5 mg days 1 to 3, 0.5 mg twice daily days 4 to 7, then 1 mg twice daily for 12 weeks), and behavioural support.
• Vaccination against influenza and COVID-19 before discharge. Counsel on avoiding informal market products.
• Extracorporeal membrane oxygenation in refractory respiratory failure.

Complications and prognosis. Most recover fully, but some have a persisting restrictive or obstructive defect, reduced DLCO, or symptoms for months. Mortality in hospitalised patients is about 2 to 3%. Relapse on resuming vaping occurs.

Monitoring. Review within 48 hours of discharge, follow up at 1 to 2 weeks and 1 to 2 months with spirometry, DLCO and chest radiograph (CT if abnormal), and repeat at 3 to 6 months until normal.

Referral and escalation. Refer to a respiratory physician after discharge, and to intensive care for respiratory failure. Refer to substance use services if needed.