Smoking Linked to Reduced Benefit of High-Flow Nasal Oxygen during Anesthesia Induction in Obese Men

Dr Atulya Atreja, Department of Pulmonology and Critical Care, Aarogyam Hospital, Karnal

Obese male smokers desaturated sooner after anesthesia induction than never smokers, even with high-flow nasal oxygen for pre-oxygenation.

Obesity raises the risk of airway-related incidents during anesthesia. Reduced functional residual capacity, higher oxygen consumption, and increased intrapulmonary shunt all leave obese patients with a shorter period of apnoeic oxygenation than people of normal weight.

The apnoea that follows induction can lead quickly to dangerous hypoxemia. High-flow nasal oxygen is widely used for pre-oxygenation in this group, yet few studies have examined whether smoking alters its benefit.

A prospective, randomized, controlled study set out to answer this question between September 2024 and May 2025. It enrolled 60 obese men aged 18–65 years who were undergoing abdominal (non-thoracic) surgery.

A total of 30 were smokers, defined as men who had smoked at least 10 cigarettes daily for more than 2 years and continued until at least 14 days before surgery. The other 30 had never smoked.

Each patient received high-flow nasal oxygen at 60 L/min for 5 minutes before intravenous induction. Patients then remained apnoeic until peripheral oxygen saturation (SpO₂) fell to 92%. This interval was recorded as the safe apnoea duration.

Non-smokers maintained oxygenation considerably longer, with a median safe apnoea duration of 373.5 seconds against 262.5 seconds in smokers (P = 0.012). However, postoperative nausea and vomiting occurred more often in non-smokers (20.0% vs. 3.3%; P = 0.044).

The authors concluded that smoking may reduce the efficacy of apnoeic oxygenation with a high-flow nasal cannula in obese men and diminish effective pulmonary reserve. They recommend smoking cessation and advise that patients should not smoke during the peri-procedural period.

(Reference: Wang, H., Zhang, C., Li, L., Tian, Y., & Chen, C. (2026). Perioperative challenges: Does smoking compromise high-flow nasal oxygen efficacy in obese Men? A randomised controlled trial. Frontiers in Anesthesiology, 5, 1915310. https://doi.org/10.3389/fanes.2026.1915310)