E-cigarettes, or vapes, are punted as being less harmful than cigarettes, however, a new, small study has found that vaping, even without nicotine, has immediate impacts on vascular function.
Findings from the ongoing study were recently presented at the annual meeting of the Radiological Society of North America (RSNA), reports SciTechDaily.
“E-cigarettes have long been marketed as a safer alternative to regular tobacco smoking,” said study lead author Marianne Nabbout, M.D., a radiology resident at the University of Arkansas for Medical Sciences. “Some believe that e-cigarettes don’t contain any of the harmful products, such as free radicals, found in regular tobacco cigarettes, because no combustion is involved.”
In the study conducted at the University of Pennsylvania, Nabbout and colleagues sought to identify the acute effects on vascular function of cigarette smoking and the immediate effects of e-cigarette vaping, with and without nicotine.
A total of 31 healthy smokers and vapers ranging in age from 21 to 49 years have been included to date. In three separate sessions, study participants underwent two MRI exams, one before and one after each of the following smoking/vaping episodes: tobacco cigarette, e-cigarette aerosol with nicotine and e-cigarette aerosol without nicotine.
A cuff was placed on the upper thigh to restrict blood flow. Once deflated, femoral artery flow velocity (a measure of the speed of blood flow in the femoral artery) and venous oxygen saturation (a measure of the amount of oxygen in the blood that returns to the heart after supplying oxygen to the body’s tissues) were evaluated.
Cerebrovascular (blood flow in the brain) reactivity was measured with a special type of MRI called phase-contrast MRI.
Significant Decreases in Vascular Function
The data of the smokers and vapers was then compared to the baseline scans of 10 non-smokers and non-vapers ranging from 21 to 33-years-old.
Following inhalation of each type of vaping or smoking, there was a significant decrease in the resting blood flow velocity in the superficial femoral artery. This artery runs along the thigh and supplies oxygenated blood to the entire lower body.
The decrease in vascular function was most pronounced after inhalation of e-cigarettes containing nicotine, followed by e-cigarettes without nicotine.
Decreased venous oxygen saturation was also present in vapers, whether or not the e-cigarettes contained nicotine. This suggests an immediate decrease in the uptake of oxygen by the lungs after vaping.
“This study serves to highlight the acute effects smoking and vaping can have on a multitude of vascular beds in the human body,” Nabbout said. “If the acute consumption of an e-cigarette can have an effect that is immediately manifested at the level of the vessels, it is conceivable that the chronic use can cause vascular disease.”
According to Nabbout, the take-home message for the public is that vaping may not be free of harm. “Ultimately, we are relying on science to help guide the regulation of such products in favour of public health,” she said. “Refraining from smoking and vaping is always recommended.”
Study Details
Acute Effects of Smoking and Vaping on Markers of Vascular Function via Quantitative MRI, An Expanded Cohort
Purpose
This work aims to evaluate the acute effects of tobacco smoking, nicotinised- and non-nicotinised e-cigarette vaping challenges on vascular function in healthy smokers and vapers via quantitative MRI. Pre-inhalation challenge markers are compared to baseline data from non-smokers/non-vapers.
Methods
Participants undergo three study visits involving two suites of MRI scans separated by inhalation challenges:
(1) tobacco cigarette smoke, (2) nicotinised e-cigarette aerosol, (3) non-nicotinised e-cigarette aerosol.
Thirty-one healthy smokers and vapers (17 males), ages 21-49 years, have been studied to date. Twenty-two participants completed all three visits, eight participants completed one visit, and one participant completed two visits. Ten non-smokers/non-vapers (two males), ages 21-33 years, also underwent a baseline scan protocol only. Most elements of the protocol have been described in previous literature published by our laboratory. In brief, a cuff occlusion was applied at the proximal thigh to assess flow-mediated dilation (FMD). Following deflation, femoral artery flow velocity and venous oxygen saturation (SvO2) were quantified. Aortic arch pulse wave velocity was evaluated with complex difference signals from velocityencoded projections. Phase-contrast MR at the superior sagittal sinus (SSS) during a breath-hold challenge yielded a measure of cerebrovascular reactivity. Cerebral metabolic rate of oxygen was derived from the SSS flow velocity and SvO2. Finally, neurovascular compliance of the brain’s arterial tree was measured from time-resolved carotid flow rates. Pre- versus post-inhalation markers from each of the three interventions were then compared using unpaired t-tests.
Results
The study is ongoing and double-blinded. Therefore, data from all three interventions were combined. Following inhalation there were significant decreases in the superficial femoral artery baseline velocity and
time of forward flow, suggesting impaired vascular reactivity (both p<0.05). At the femoral vein, baseline SvO2 was reduced (p = 0.01). The comparison of biomarkers from smokers/vapers pre-inhalation to nonsmokers/non-vapers (no inhalation) showed NVC was greater (+37%; p<0.005) and FMD lower (-42%; p<0.05) in smokers/vapers.
Conclusions
This MRI protocol was able to detect acute effects of smoking and vaping on markers of vascular function.
SciTechDaily – Vaping Isn’t Safe: Scientists Uncover Alarming Vascular Risks
Press Release – Radiological Society of North America