190821 vaping
The vaporisation process can transform the molecules into toxic substances. Image Credit: Pixabay

New York: Smoking e-cigarettes, also called vaping, can be harmful to the blood vessels even when the vapour is entirely nicotine-free, a new study suggests.

For the study published in the journal Radiology, the researchers performed MRI exams on 31 healthy, non-smoking adults before and after vaping a nicotine-free e-cigarette.

Comparing the pre- and post-MRI data, the single episode of vaping resulted in reduced blood flow and impaired endothelial function in the large artery that supplies blood to the thigh and leg.

The endothelium, which lines the inside surface of blood vessels, is essential to proper blood circulation. Once the endothelium is damaged, arteries thicken and blood flow to the heart and the brain can be cut off, resulting in heart attack or stroke.

"While e-cigarette liquid may be relatively harmless, the vaporisation process can transform the molecules -- primarily propylene glycol and glycerol -- into toxic substances," said Felix W. Wehrli, Professor at the University of Pennsylvania in the US.

"Beyond the harmful effects of nicotine, we have shown that vaping has a sudden, immediate effect on the body's vascular function, and could potentially lead to long-term harmful consequences," Wehrli said.

In this study, the research team examined the impact of an e-cigarette that contained propylene glycol and glycerol with tobacco flavouring, but no nicotine.

Using a multi-parametric MRI procedure, researchers scanned the large artery and vein in the leg before and after each vaping episode to see how vascular function changed.

The researchers then performed a statistical analysis to determine group differences in vascular function before and after vaping. They observed, on average, a 34 per cent reduction in the femoral artery's dilation.

E-cigarette exposure also led to a 17.5 per cent reduction in peak blood flow, a 20 per cent reduction in venous oxygen, and a 25.8 per cent reduction in blood acceleration after the cuff release -- the speed at which the blood returned to the normal flow after being constricted.

These findings suggest that vaping can cause significant changes to the inner lining of blood vessels.