High-flow nasal oxygenation versus standard face mask preoxygenation in patients with class 3 obesity: a prospective comparative study

Purpose The purpose of this study was to compare the effectiveness of high-flow nasal oxygenation (HFNO) with standard face-mask preoxygenation in patients with class 3 obesity undergoing induction of general anesthesia. We aimed to determine whether HFNO reduces the frequency of minor airway adverse events, improves oxygenation stability, prolongs safe apnea time, and decreases the need for airway adjuncts. Secondary objectives included evaluating minimal SpO₂, EtCO₂ changes, desaturation time, and identifying patient-related predictors of peri-intubation complications. The study sought to clarify the clinical value of HFNO for airway safety in this high-risk population. Methods: This prospective study included 40 adult patients with BMI > 40 kg/m² undergoing elective general surgery under general anesthesia. Patients were randomized into two equal groups: standard face mask preoxygenation (10–12 L/min, FiO₂ 1.0) or high-flow nasal oxygenation (60 L/min, FiO₂ 1.0). Preoxygenation time was standardized to 3 minutes. SpO₂ and EtCO₂ were measured before induction, during intubation, and after endotracheal tube placement. Primary endpoint: composite frequency of minor adverse events (desaturation < 92%, hypercapnia > 40 mmHg, adjunct device use, inadequate mask ventilation). Secondary endpoints included minimal SpO₂, time to desaturation < 92%, and correlations with anthropometric parameters. Results: Critical incidents occurred in 75% of patients. HFNO significantly reduced minor adverse events frequency (50% vs 100%, p = 0.002). Hypercapnia was the most common component (70% overall), more frequent in control (85%) than HFNO (55%, p = 0.021). HFNO improved minimal SpO₂ (91.2% ± 1.0 vs 87.5% ± 1.8, p = 0.034) and extended time to desaturation < 92% (189.4 ± 32.1 s vs 121.6 ± 27.8 s, p < 0.001). Requirement for airway adjuncts was higher in the control group (40% vs 10%, p = 0.041). Mallampati ≥ III and induction time > 150 s were independent predictors of incidents. Conclusions: HFNO significantly improves oxygenation stability, reduces minor events frequency, and prolongs safe apnea time in patients with class 3 obesity. It may be recommended as a preferred preoxygenation technique in this high-risk population.