Cerebral Blood Flow Regulation Following Inhalation of Nicotine via Electronic Cigarettes

Background: The use of electronic cigarettes (e-cigarettes) is growing rapidly but the physiologic effects of vaporized nicotine are relatively unknown. We hypothesized that acute inhalation of vaporized nicotine via e-cigarettes would impair regulation of cerebral blood flow (CBF) in response to variations in arterial pressure (cerebral autoregulation, CA). Methods: 13 subjects (6 F; 7 M) inhaled vapor from an 18 mg nicotine (nicotine) or a 0 mg nicotine (placebo) e-cigarette on separate days (randomized). Heart rate (HR), mean arterial pressure (MAP), mean middle cerebral artery velocity (MCAv), and cerebral oxygen saturation (SCO2) were measured non-invasively. Oscillatory lower body negative pressure (OLBNP) between 0 and -60 mmHg was applied for 20 cycles at 0.05 Hz and 0.10 Hz. Results: Between placebo and nicotine conditions, baseline MAP, MCAv, SCO2, and HR were similar (P≥0.21). MAP and ScO2 very low frequency (VLF; 0.04-0.07 Hz) power with 0.05 Hz OLBNP, and low frequency (LF; 0.07-0.2 Hz) power with 0.1 Hz OLBNP were higher under the placebo condition (P≤0.03-0.06). Cross-spectral analysis in the LF (with 0.1 Hz OLBNP) and VLF (with 0.05 Hz OLBNP) revealed that gain between MAP-MCAv was similar between conditions (P≥0.128). MCAv-ScO2 and MAP-ScO2 coherences wereConclusion: These data suggest that nicotine, when acutely inhaled via e-cigarettes, does not impair the cerebral pressure-flow relationship.