Clinical Laboratory Evaluation of Electronic Cigarettes: Methodological Challenges

Abstract

Objective Evaluating electronic cigarettes (ECIGs) in the clinical laboratory is critical to understanding their effects. However, laboratory evaluation of ECIGs can be challenging, as they are a novel, varied, and evolving class of products. The objective of this paper is to describe some methodological challenges to the clinical laboratory evaluation of ECIGs. Methods The authors gathered information about challenges involved in the laboratory evaluation of ECIGs. Challenges were categorized and solutions provided when possible. Results Methods used to study combustible cigarettes may need to be adapted to account for ECIG novelty and differences within the class. Challenges to ECIG evaluation can include issues related to 1) identification of ECIG devices and liquids, 2) determination of short -term ECIG abstinence, 3) measurement of use behavior, and 4) assessment of dependence. These challenges are discussed, and some suggestions to inform ECIG evaluation using clinical laboratory methods are provided. Conclusions Awareness of challenges and developing, validating, and reporting methods used to address them aids interpretation of results and replication efforts, thus enhancing the rigor of science used to protect public health through appropriate, empirically-based, ECIG regulation.

Electronic cigarette user plasma nicotine concentration, puff topography, heart rate, and subjective effects: Influence of liquid nicotine concentration and user experience.

“…Third, although the use of a single cartomizer may not be representative of the cartomizers and tanks typically used by experienced ECIG-users, standardization of the cartomizer was necessary to accommodate the topography mouthpiece used and ensures accurate measurement of puff topography; there is an increasing need for topography measurement tools that can be used with advanced-generation ECIGs. Fourth, some participants likely did not comply with protocol-mandated ≥ 12 hours nicotine/ tobacco abstinence prior to the onset of the study session, highlighting the challenge of studying non-combustible tobacco products for which short-term abstinence cannot be verified immediately prior to the start of the study session (Blank, Breland, Cobb, Spindle, Ramôa, & Eissenberg, 2016). Future clinical laboratory research addressing the acute effects of ECIGs and other non-combustible tobacco products will continue to meet such challenges until a reliable and cost-effective method for verifying abstinence from non-combustible tobacco products is discovered.…”

Effects of electronic cigarette liquid solvents propylene glycol and vegetable glycerin on user nicotine delivery, heart rate, subjective effects, and puff topography

“…Due to noncompliance with abstinence requirements by ECIG users in other studies (e.g., Hiler et al, 2017), the present study also required all participants to undergo a one-hour observation period prior to the onset of each study session during which they were not permitted to use any nicotine/tobacco product. Because nicotine has a relatively short half-life of 1-2 hours (Benowitz, 2008), this additional hour likely increased the chances that a participant who was not abstinent for the full 12 hours would still be experiencing nicotine-abstinence symptoms when the session commenced and served to further decrease participants' baseline plasma nicotine concentration (Blank, Breland, Cobb, Spindle, Ramôa, & Eissenberg, 2016).…”

“Essentially, All Models Are Wrong, but Some Are Useful”: A Preliminary Conceptual Model of Co-occurring E-cig and Alcohol Use

“…While these are straightforward measures, they are dichotomous and limit the field’s understanding of variability in e-cig use. At the same time, e-cig use does not lend itself well to being measured continuously and there are unique challenges in assessing e-cig use behaviors [60]. Whereas individuals can report how many cigarettes they smoke in a day, quantifying e-cig use to generalize across individuals is not as straightforward.…”