Association Between Preoperative Oronasal Breathing Patterns and Endotracheal Tube Intolerance During Emergence From General Anesthesia: A Prospective Nested Case-Control Study

This is a case-control study designed to enroll 224 patients who will undergo tracheal intubation for general anesthesia in the operating rooms of Peking University People's Hospital between July 20, 2026, and October 31, 2026. The case group will consist of patients who develop coughing before extubation (N=112), while the control group will comprise those without coughing before extubation (N=112).

Data to be collected include general demographic characteristics, smoking and smoking cessation history, comorbid conditions (with particular attention to snoring during sleep and sleep apnea-hypopnea syndrome [SAHS]), history of pulmonary diseases, mode of spontaneous breathing, surgical and anesthetic data, as well as blood pressure and heart rate before, during, and after extubation, pain scores, and sedation levels.

Continuous variables will be presented as mean ± standard deviation (for normally distributed data) or median with interquartile range (IQR) (for non-normally distributed data). Categorical variables will be described using frequencies and percentages (e.g., sex, smoking history). Baseline differences between the case and control groups will be compared using the chi-square test (for categorical variables), Student's t-test (for normally distributed continuous variables), or the Mann-Whitney U test (for non-normally distributed continuous variables). Multivariable logistic regression analysis will be employed to evaluate the independent association between the mode of spontaneous breathing and coughing before extubation, with adjustment for potential confounding factors, and odds ratios (ORs) with their 95% confidence intervals (95%CI) will be calculated. All statistical analyses will be performed using SPSS or R software.