Short-term respiratory effects of e-cigarettes in healthy individuals and smokers with asthma

Background and objectiveThis study investigated the duration of immediate respiratory effects of e-cigarette smoking (ECS) and tested the hypothesis that ECS has more prominent effects in asthmatics compared with healthy smokers (HS). MethodsFifty-four smokers, 27 healthy (HS group) and 27 with intermittent asthma (mild asthma (MA) group) underwent a control session (no liquid, no resistor coil inside e-cigarette cartridge) and an experimental session of ECS using standardized puffing settings. Impulse oscillometry impedance (Z), resistance (R), reactance (X) and fractional exhaled nitric oxide (FeNO) were measured before and 0, 15 and 30min after control and experimental sessions. ResultsControl session revealed no significant changes. In the experimental session, immediately post-ECS, both groups exhibited a significant increase in respiratory system total impedance at 5Hz (Z5) (P<0.001), respiratory system resistance at 5Hz (R5) (P<0.001), respiratory system resistance at 10Hz (R10) (P<0.001), respiratory system resistance at 20Hz (R20) (P<0.05), resonant frequency (P<0.001) and reactance area (P<0.05). MA exhibited higher baseline values and a more prominent effect immediately after ECS compared with HS for Z5 (P=0.022), R5 (P=0.010) and R10 (P=0.013). FeNO decreased significantly in both groups (P<0.001); HS returned to baseline values in 15min while the MA maintained significantly lower values for an additional 15min (P<0.05) and returned to baseline values at 30min post-ECS. ConclusionA single session of ECS had respiratory mechanical and inflammatory effects, which were more prominent in smokers with asthma.