Abstract

Background: Electronic cigarettes represent a new phenomenon in the fight against smoking. While they continue to be marketed both as safer than traditional cigarettes and as potential smoking cessation tools, little is known about their potential physiological effects.
Objectives: The purpose of this systematic review was to provide an analysis of the physiological effects of e-cigarettes in humans.
Methods: A search was conducted by two independent authors using PubMed, SCOPUS, Web of Science and the Cochrane Library electronic databases (until July 24, 2017 ). Inclusion criteria consisted of: English and French language peer-reviewed articles; studies including human participants; objective measurements of physiological responses to active e-cigarette smoking; physiological measures obtained during or post-smoking and compared to baseline measures.
Results: Of the 3101 studies investigated, fourteen studies met the inclusion criteria. These studies indicated that the short-term (4-20 minutes) use of e-cigarettes resulted in decreases in measures of respiratory function such as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory flow (FEF) and exhaled carbon monoxide (eCO); as well as increases in cardiovascular measures such as heart rate and blood pressure. Exposure to e-cigarettes was found to be less harmful than exposure to combustible cigarettes, though not entirely benign.
Conclusions: Based on the current literature, e-cigarettes do not appear to be as harmful as traditional cigarettes. As these devices have only recently become available, it has been impossible to conduct any long-term studies into their repercussions. Further studies are needed to gain an understanding of potential long-term effects.