Effect of acute cigarette smoking on gastric contents in regular smoker volunteers. A prospective randomized cross-over study.

BACKGROUND The authors sought to assess the effect of acute smoking on gastric contents in regular smoker volunteers. The primary endpoint was the variation in antral area during the 120-min study period after cigarette smoking. METHODS Regular smoker volunteers were included in this prospective randomized single blind cross-over study. Volunteers attended two separate study sessions: Control and Smoking sessions. The study started with an initial ultrasound measurement of the antral area, immediately followed by a 30-min periods of waiting (Control session) or of two-cigarettes smoking (Smoking session). Ultrasound measurements of the antral area were then performed 30, 60, 90 and 120 min after the initial ultrasonography, allowing for the calculations of the variation rates in antral area during the periods 0-30, 0-60, 0-90 and 0-120 min in both sessions. RESULTS The variation in antral area during the period 0-120 min was equivalent in both sessions, as the difference in the variation rates between both sessions was -1.2%, with 90% confidence interval of the difference including 0 and lying entirely within the range of equivalence of -10% to 10%. No equivalence was found for the periods 0-30, 0-60 and 0-90 min, because of a non-significant decrease in antral area in the Smoking sessions during these periods. CONCLUSIONS Preoperative acute smoking did not affect the variation in the gastric volume in regular smoker volunteers during the study period. These results allow for the suggestion that acute preoperative smoking does not probably change the risk of pulmonary aspiration of gastric contents in healthy regular smokers. CLINICAL TRIAL REGISTRATION NCT 02080598.