Cigarette smoke inhibits pulmonary perfusion while nicotine-delivering vapors from e-cigarettes do the opposite, actually increasing blood flow in the lungs, according to a functional MRI-based study conducted in Switzerland and published in the July print edition of Radiology.
Corresponding author Sylvia Nyilas, PhD, of Bern University Hospital and colleagues sent 44 healthy adults for unenhanced lung fMRI and functional lung tests—first to establish baseline and again to observe changes after the participants smoked or vaped according to established habit.
Regular users of electronic nicotine delivery systems (ENDS) numbered 13 of the 44, while 12 were active smokers, 9 former smokers and 10 non-users comprised a control cohort.
Upon reading the imaging, radiologists found the current and past tobacco users experienced a significant localized decrease in lung perfusion after smoking vs. baseline. Meanwhile the e-cig users whose products delivered nicotine saw an increase in lung perfusion after vaping.
The healthy controls had no significant change between before and after scans, and a subgroup of e-cig users inhaling vapors absent of nicotine showed the same.
Throughout their study report, the authors stress the close connection between blood flow and airflow through the lungs, i.e., perfusion and ventilation.
They cite several prior studies suggesting lung fMRI could be a “sensitive marker” of changes to functional tissue within the lungs, illuminating early signs of changes in ventilation and perfusion too fine to detect in traditional imaging exams and clinical tests.
Those studies guided the formulation of the hypothesis Nyilas and colleagues pursued. Based on the findings of their small study, the team concludes that fMRI can indeed sensitively detect short-term perfusion changes brought on by both smoking and electronic nicotine delivery systems.
Further noting that lung ventilation evidenced no changes after nicotine intake, the authors comment that visible perfusion impairment nevertheless correlated with ventilation inhomogeneity (lung clearance index) and was altered after tobacco smoking.
“These preliminary results suggest that MRI indexes may be considered as a noninvasive test to complement pulmonary function testing in this setting,” Nyilas et al. write.
In accompanying commentary, Seth Kligerman, MD, division chief of cardiothoracic radiology at UC-San Diego, notes the small patient sample and other limitations in Nyilas and colleagues’ study design.
Still, he writes, the study “is an important addition to the literature. It not only confirms the increase in pulmonary perfusion after vaping but also shows a decrease in perfusion after smoking”.
Although both cigarettes and vape pens can each serve as a nicotine delivery system, their mechanics and physiologic effects are unique, indicating the need for continued research. … [A]lthough we are only beginning to understand the short-term effects of vaping, the long-term effects are yet to be uncovered. It is important to recall that before the 20th century and the widespread introduction of cigarettes, lung cancer was considered an uncommon disease.”
Dave Pearson – Business Intelligence – 2022-07-11