Abstract: Objective To investigate the degree of difficult intubations for patients with ankylosing spondylitis (AS) and to predict the related factors influencing the selection of intubation methods. Methods A total of 347 patients(276 males, 71 females), aged 15-77 years, ASA Ⅰ-Ⅲwith AS underwent surgical procedure from January 2008 to January 2017 were included. During general anesthesia induction, patients were divided into two groups according to the application of non-visual devices (179 cases) and visual devices (168 cases). Patient data were collected, including gender, age, kyphosis, degree of mouth opening, Mallampatti classification, neck mobility and the duration of the AS. Multivariate regression analysis of variables was conducted to find the relevant predictors of intubations method selection in AS patients with difficult endotracheal airway. Results The older patients, kyphosis, limited mouth opening, limited neck range of motion, and longer duration of AS, the utilization rate of the visual group was significantly higher than that of the non-visual group (P＜0.05). Multi-factor Logistic regression analysis suggested that moderate limitation of neck range of motion(OR=5.41,95% CI: 2.32-13.10,P＜0.001)and severe limitation of neck range of motion (OR=9.22,95% CI: 4.37-20.25,P＜0.001) were related factors for tracheal intubation with visual devices in patients with difficult airway. Conclusions Neck mobility has a great influence on whether or not to use visual intubation tools. When neck mobility decreases, anesthesiologists are more likely to use visual devices such as video laryngoscope, McCoy laryngoscope, visual rigid and fiberoptic bronchoscope.

Key words: ankylosing spondylitis, difficult airway, general anesthesia and intubation, related factors, visible devices