E-cigarette use alters respiration but does not impair lung function, according to new findings

A recent study published in npj Primary Care Respiratory Medicine indicated that although vaping increases airway resistance, it does not impact lung function.

Background

In recent years, electronic cigarette use (or vaping)––which was regarded as a safer alternative to traditional cigarettes––has had a huge impact on the tobacco industry. However, evidence depicts the harmful effects of vaping on the respiratory system.

In e-cigarettes, nicotine combustion is replaced by the electronic heating of a liquid. Some manufacturers claim that e-cigarettes have fewer adverse effects on the respiratory system than smoking tobacco.

E-cigarettes have been tried as an alternative to smoking tobacco for addiction treatment – as an aid to quitting tobacco smoking. Previously believed to be less hazardous to health than traditional cigarettes, the negative impact of vaping on the lungs is now common knowledge.

The emergence of E-Cigarette and Vaping-Associated Lung Illness (EVALI) has raised concerns about the short-term respiratory effects of vaping, particularly when cannabis or tetrahydrocannabinol (THC)-containing products are used in e-cigarettes. Considering this evidence, the safety of e-cigarette use and its efficacy remain disputed. Therefore, an extensive study was undertaken to investigate the effects of vaping on lung function.

The study

This systematic review entailed a comprehensive analysis of how vaping affects pulmonary function. The goal of this review was to obtain information regarding the short-term effects of vaping and Vaping-Associated Lung Illness (EVALI) – to determine the safety of vaping on short- and long-term use.

A study protocol was prepared and recorded in the PROSPERO database of systematic reviews. The systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations.

Using Ovid, Cochrane, Web of Science Core, and the CENTRAL database, the researchers searched EMBASE, PsycINFO, and MEDLINE from 2004-2021 – to identify 8,856 potentially relevant studies.

Overall, 273 participants were included in the eight selected studies. Seven studies examined the immediate effects of vaping, while only one examined the long-term impact.

The findings

According to the literature review, only eight small-scale studies addressed this topic; among these, one study examined the long-span outcomes (3.5 years). These studies revealed that vaping was not associated with any acute health-related changes.

On the other hand, two studies disclosed that e-cigarettes might accentuate airway resistance and conductance across diverse demographic subgroups. Due to the limited number of studies available on this topic and because most focus on the acute effects of vaping, these findings are suggestive but not conclusive, and further research is necessary.

There were a few other limitations to the interpretability of the results – three of the included studies had an unknown risk of bias, four had a moderate risk of bias, and one had a high bias risk.

Additionally, due to the data heterogeneity, this review did not undertake subgroup analyses or a meta-analysis. This search incorporated only a small number of studies owing to the differences amongst study designs, definitions of e-cigarettes, and the participants’ smoking status.

According to some studies, the term “non-vapers” includes both traditional smokers and non-smokers – this led to inconsistent data and non-differentiation of the participants based on their conventional smoking status.

The results depicted no effect of vaping on the forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the FEV1/FVC ratio.

Some studies also employed a mock vaping session in which either an e-cigarette without e-liquid or second-hand smoke was used. Of note, most of the studies were conducted on smokers alone, without a comparison group of nonsmokers.

It would be beneficial to conduct future research on subgroups based on the level of smoking or vaping to enable a more accurate quantitative analysis.

• Honeycutt, L., Huerne, K., Miller, A., et al. (2022). A systematic review of the effects of e-cigarette use on lung function. npj Primary Care Respiratory Medicine. doi: 10.1038/s41533-022-00311-w https://www.nature.com/articles/s41533-022-00311-w