Objective:To observe the effects of esketamine combined with butorphanol in endotracheal intubation guided by fiberoptic bronchoscopy with spontaneous breathing.Methods:Forty patients suspected of having difficult airways during elective general anesthesia operations in Hunan Provincial People′s Hospital were prospectively selected and divided into control group and observation group by random number table. Propofol plus sufentanil, esketamine plus butorphanol were used for intravenous general anesthesia respectively. At the same time, they were assisted with cricothyroid puncture and surface anesthesia of nasopharynx and larynx, and then trachea intubation with spontaneous breathing was performed through the nose under the guidance of fiberoptic bronchoscope. The changes of heart rate (HR), mean arterial pressure (MAP), arterial partial pressure of oxygen (PaO 2), and the levels of serum cortisol, norepinephrine and adrenaline before and after endotracheal intubation were compared between the two groups. The number of body motions and coughing at the completion of endotracheal intubation was compared between the two groups. Results:In the control group, the HR and MAP at the completion of intubation were higher than those before intubation, and the PaO 2 was lower than those before intubation (all P<0.05); In the observation group, there was no significant difference in HR, MAP and PaO 2 at the completion of intubation and before intubation (all P>0.05). The HR and MAP at the end of intubation in the observation group were lower than those in the control group, and the PaO 2 was higher than that in the control group (all P<0.05). The number of body motion and coughing in the observation group was significantly less than that in the control group at the completion of endotracheal intubation (all P<0.01). At the end of endotracheal intubation, the serum cortisol, norepinephrine and epinephrine level in the observation group were significantly lower than those in the control group (all P<0.01). Conclusions:Esketamine combined with butorphanol has advantages over propofol combined with sufentanil in the application of fiberoptic bronchoscopy guided tracheal intubation in difficult airways that retain spontaneous breathing, and can better control the stress response caused by tracheal intubation.