Analysis of cigarette smoking mechanism by real time video-endoscopic documentation.

Objective: To view, document and analyze the smoking mechanism as seen via video-endoscopic examination during the action of cigarette smoking.

Study Design: Observational study.

Methods: Twenty-two healthy smoking volunteers were examined with a trans-nasal video-laryngoscope while breathing, sniffing and cigarette smoking. Smoking a whole cigarette was recorded in each participant. The different stages of smoking were defined and their duration was measured. The glottic opening angle was calculated during breathing, sniffing and smoking.

Results: A smoking cycle with four distinct stages was recognized. The stages included an oral smoke accumulation, pharyngo-laryngeal jet inhalation, infralaryngeal spread, and finally humidified exhalation stage. The stages' mean duration was 1.93(±1.21), 0.39(±0.31), 2.00(±1.12) and 4.5(±2.70) seconds, respectively. The glottic opening angle during smoke inhalation was wider in 16% (p = 0.02) compared to normal inhalation during breathing. The glottic opening during smoke exhalation was comparable to what was observed during normal exhalation. The reduction in the glottic opening was more significant during the action of smoking compared with normal breathing (p = 0.042).

Conclusions: Smoking follows a consistent sequence of events, defined by specific anatomic configuration and relatively persistent duration. The fast turbulent flow of the smoke over the narrow glottic aperture and at the areas of bifurcation at the trachea and bronchi may have a role in the high relative risk for carcinoma in these areas.