With the spike in cases of e-cigarette or vaping product use associated lung injury (EVALI) during 2019, much still remains to be seen in long-term studies. One of the results of EVALI studies that seems to remain unknown is if improvement in diffusion capacity (DLCO) will occur.
Starting as early as 2017 and spiking in 2019, e-cigarette and vaping injuries began to become problematic to America. Reports from February 2020 have indicated that over 2800 cases have been reported in the USA. Of those, 86 have proven fatal. About 15% of the reported cases have been in patients under the age of 18, as reported in Emergency Radiology in 2020.
The Struggle is Real
Part of the struggle with EVALI is that there is no specific test for diagnosis. EVALI tends to present similarly to influenza and COVID-19. In order to diagnose EVALI, there is a need to rule out other diagnoses. The cases reported reveal that the lung injury is not from infectious causes, but rather a direct injury.
The THC and Vitamin E Acetate Factor
One of the largest contributing factors so far shows that there is a prevalence of tetrahydrocannabinol (THC) products used by patients. The Center for Disease Control and Prevention (CDC) reports 82% of patients diagnosed with EVALI have reported using THC. To add to the problem we are facing with vaping/e-cigarette use, 25% of adolescent vapers admit to using THC, per a study out of Children’s Hospital of Philadelphia. The CDC also reports that one other unique factor about these patients is that all EVALI cases have found Vitamin E acetate in the lung fluid of patients, but not in non-EVALI patients.
Radiographic imaging and pulmonary function testing are often used to help understand the disease. Radiographic imaging reveals interstitial changes in the lungs. And CT scans similarly reveal bilateral ground glass opacities and interstitial opacities in nearly all patients. On follow-up testing, these changes have resolved.
Pulmonary function testing performed on these patients focused on spirometry and diffusing capacity for carbon monoxide (DLCO). Spirometry results have shown either normal test results, or mildly reduced airflow obstruction. In a study published in Emergency Radiology in 2020, the mean FEV1 during hospitalization to outpatient follow-up improved from 81% to 99% predicted. The DLCO tends to be mildly decreased. On repeat testing post discharge, spirometry is normal. The DLCO however remains mildly decreased. Interestingly, in a few reports, the DLCO actually decreased more post-discharge from the hospital.
DLCO measures the ability of carbon monoxide to pass from the lungs into the blood from inhaled air, similarly to the path oxygen takes, but with a greater affinity for hemoglobin. A decrease in the surface area or an increase in the alveolar capillary membrane will lead to decreases in the DLCO. A low DLCO, but normal spirometry can be seen in mild interstitial lung disease, pulmonary vascular diseases, smoking, anemia, and certain medications.
Treatments for EVALI have largely consisted of supplemental oxygen and corticosteroids. Oxygen use appears to be discontinued before discharge as patients begin to become asymptomatic. As this continues to be an evolving disease, there has not been much research into corticosteroid use as a treatment. Their use has shown a rapid improvement in patients receiving them. This, according to the CDC, has also been evidenced in patients who discontinue e-cigarette/vaping altogether.
There is much still to learn about this disease. And one of those areas will definitely be the long-term effects on the DLCO in these patients. While other initial results seem to resolve post-hospital discharge, the DLCO does not. It will be interesting to see if with time these patients do recover, or if the damage done to the blood-gas membrane will be permanent. In order to accomplish this, the patients will need to follow-up regularly with their pulmonologist and consistent testing.
- Corcoran, A., Carl, J. C., & Rezaee, F. (2020). The importance of anti-vaping vigilance-EVALI in seven adolescent pediatric patients in Northeast Ohio. Pediatric pulmonology, 55(7), 1719–1724. https://doi.org/10.1002/ppul.24872
- Ahmad, M., Aftab, G., Rehman, S., & Frenia, D. (2020). Long-term Impact of E-cigarette and Vaping Product Use-associated Lung Injury on Diffusing Capacity for Carbon Monoxide Values: A Case Series. Cureus, 12(2), e7002. https://doi.org/10.7759/cureus.7002
- Chatham-Stephens, K. R., VP. Krishnasamy, B. D. H., S. Ellington, P. P. S., KF. Trivers, E. P., BC. Blount, M. P. K., S. Kligerman, C. R., … AM. Foust, G. S. P. (2020, May 28). Clinical and radiological characteristics of e-cigarette or vaping product use associated lung injury. Emergency Radiology. https://link.springer.com/article/10.1007/s10140-020-01796-z.
- Centers for Disease Control and Prevention. (2020, March 17). For Healthcare Providers. Centers for Disease Control and Prevention. https://www.cdc.gov/tobacco/basic_information/e-cigarettes/severe-lung-disease/healthcare-providers/index.html.
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