Perioperative challenges: does smoking compromise high-flow nasal oxygen efficacy in obese Men? A randomised controlled trial

Background Obesity poses a risk of airway-related incidents during anaesthesia. Perioperative pre-oxygenation in obese patients often involves high-flow nasal oxygen to reduce the risk of airway complications. Nevertheless, few studies have investigated the effect of smoking habits on apnoeic oxygenation with high-flow nasal cannula in obese men. Objective This study aimed to explore the effects of smoking on the safe apnoea duration in obese males. Design Prospective, randomised, controlled study. Setting University-affiliated hospital from September 2024 to May 2025. Patients Sixty obese males who underwent abdominal (non-thoracic) surgery, aged between 18 and 65 years. Interventions Patients were categorised into two groups according to their smoking habits: smokers (Group S) and never smokers (Group NS). Smokers were defined as current smokers consuming at least 10 cigarettes daily for over 2 years, and had continued smoking up to at least 14 days prior to surgery, while non-smokers had no history of smoking. All patients underwent intravenous anaesthesia induction and received 5 min of high-flow nasal oxygen (60 L/min) before induction. Following anaesthesia induction, patients remained apnoeic until their peripheral oxygen saturation dropped to 92%. Main outcome measures The primary outcome was the comparison of safe apnoea duration between the two groups after receiving 5-minute pre-oxygenation with high-flow nasal oxygen. Results Sixty patients were enrolled (30 smokers and 30 non-smokers). Never smokers had a significantly longer safe apnoea duration than smokers, with median [IQR] values of 373.5 (106.25) vs. 262.5 (138.5) seconds, P = 0.012. However, the incidence of postoperative nausea and vomiting was slightly higher in never smokers than in smokers, with values of 6 (20.0%) vs. 1 (3.3%), P = 0.044. Conclusion Smoking may reduce the efficacy of apnoeic oxygenation with high-flow nasal cannula in obese males and diminish effective pulmonary reserve. Smoking cessation should be recommended, and patients should be advised not to smoke during the peri-procedural period. Trial registration Registered at [ ClinicalTrials.gov ], [NCT06562660, principal investigator: Chao Chen].