Nasopharyngeal airway oxygenation enhances safe apnea time in patients at moderately high altitude: a randomized clinical trial

This study evaluated the safe apnea time in patients at moderate high altitude and the effect of combining a nasopharyngeal airway. Thirty-six patients were randomly assigned to either a preoxygenation group (Group P) or a nasopharyngeal airway group (Group N).P Group: Standard facemask preoxygenation was followed by intravenous induction with maintenance guided by bispectral index (BIS) monitoring (40-60);N Group: Building upon the P group protocol, a nasopharyngeal airway delivering 12 L/min pure oxygen for apneic oxygenation was inserted prior to laryngoscopy The primary outcome was the safe apnea time in both groups. Secondary outcomes included the maximum PetCO₂ after resumption of ventilation, hemodynamic parameters, and others.The results demonstrated that the safe apnea time in Group P was 506 (399-613) s, whereas in Group N it was prolonged to 732 (492-900) s. No significant hemodynamic differences were observed between the groups. Following resumption of ventilation, Group N exhibited a lower PetCO₂ and higher PaO₂ on arterial blood gas analysis at T3.Preoxygenation combined with apneic oxygenation via a nasopharyngeal airway extends the safeapnea time without causing adverse hemodynamic effects, offering a clinically feasible strategy.