Aug 23, 2021 Why spirometry is not enough: Vaping (#1 in a series)
Vaping and pulmonary injury
Vaping associated pulmonary injury (VAPI), also called e-cigarette or vaping product use associated lung injury (EVALI), is a relatively new respiratory illness affecting both youth and adults.
The first cases of EVALI in the US were reported in March 2019 when a cluster of patients developed lung injury associated with the use of e-cigarettes. As of February 2020, a total of 2700 cases and 68 deaths were reported in the US. While the number of cases has since dropped due to widespread banning of e-cigarettes, 24% of US youth, or 3.5M teenagers, still use them, according to a study conducted in early 2021. 
The exact cause of EVALI has not been established, but the most suspected agent is Vitamin E acetate, which started to be used for thickening in tetrahydrocannabinol (THC)-containing e-cigarette and vaping products in early 2019, coinciding with the EVALI outbreak. [2,3]
Diagnosis and management
Since it is a relatively recent disease, the long-lasting effects of EVALI are not yet known. However, the diagnosis and management of EVALI-associated lung injury have been discussed in a number of case studies.
With respiratory symptoms like cough, chest pain, and/or shortness of breath, EVALI can present like other lung disorders. Therefore, the goal is to rule out other possible causes of lung injury such as pneumonia and any ongoing chronic inflammatory process that might affect the lungs. The severity of symptoms guide as to whether the patient needs a hospital admission or can be managed on an outpatient basis.
DLCO and spirometry for the full picture
In a number of reports, follow-up PFTs were taken in patients post-hospitalization to evaluate ongoing lung function. [4, 5, 6] Testing performed on these patients focused primarily on spirometry and diffusing capacity for carbon monoxide (DLCO). In a study with 114 patients, the most common abnormalities were obstruction only, DLCO reduction only, and obstruction with DLCO reduction.  One study of 3 cases reported variable spirometry results, but consistently reduced, IC, RV and DLCO with elevated ERV, which were consistent with diffuse alveolar disease visualized on chest CTs. 
Recommendations for follow-up
Clinicians should be aware of the possibility of chronic effects of EVALI on lung function. According to the experts, it’s important that the follow-up of patients with EVALI include pulmonary function testing, particularly spirometry and DLCO, even if radiographic abnormalities and symptoms have resolved. 
Zulfiqar H, Rahman O. Vaping Associated Pulmonary Injury. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK560656/
Ahmad M, Aftab G, Rehman S, Frenia D. Long-term Impact of E-cigarette and Vaping Product Use-associated Lung Injury on Diffusing Capacity for Carbon Monoxide Values: A Case Series. Cureus 2020; 12(2): e7002. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7077067/
Anderson B, Harris D, Rea S, Guidry D, et al. Short-term pulmonary function test characteristics in patients diagnosed with e-cigarette- or vaping-associated lung injury. CHEST 2020. 158(4): A2377. https://journal.chestnet.org/article/S0012-3692(20)34204-5/fulltext
- Corcoran A, Carl JC, Rezaee F. The importance of anti-vaping vigilance—EVALI in seven adolescent pediatric patients in Northeast Ohio. Pediatric Pulmonology 2020; 55 (7):1719-1724. https://onlinelibrary.wiley.com/doi/full/10.1002/ppul.24872
- Tsirilakis K, Sather E. Pulmonary Function Testing in Vaping Associated Lung Injury. Am J Respir Crit Care Med 2020;201:A7684. https://www.atsjournals.org/doi/pdf/10.1164/ajrccm-conference.2020.201.1_MeetingAbstracts.A7684