Background: The current global situation of COVID-19 epidemic is serious. Routine preoperative methods to assess airway such as the interincisor distance(IID), Mallampati classification, and the upper lip bite test(ULBT) have a certain risk of upper respiratory tract exposure and virus spread. The condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and the assessment method does not require the patient to expose the upper respiratory tract, but its value in predicting

more »

... ult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic.Methods: We enrolled adult patients who underwent general anesthesia and tracheal intubation. The IID, Mallampati test result, ULBT result, and the C-TMD of each patient were evaluated prior to the initiation of anesthesia. The primary outcome were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 , the number of intubation attempts and intubation time.Results: A total of 304 patients were successfully included in the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD >1 finger group 46.8±7.3s, compared with the C-TMD <1 finger group 50.8±8.6s (p<0.01).First attempt success rate was higher in the C-TMD >1 finger group than in the C-TMD <1 finger group (P<0.01).The correlation between the C-TMD and Cormack-Lehane Level was 0.317(Spearman correlation coefficient, P<0.001), and the area under the ROC curve was 0.699(P<0.01). The C-TMD <1 finger width was the most consistent with difficult laryngoscopy (κ=0.485;95%CI: 0.286-0.612) and its OR value was 10.09(95%CI: 4.19-24.28), sensitivity was 0.469(95%CI: 0.325-0.617), specificity was 0.929(95%CI: 0.877-0.964), positive predictive value was 0.676 (95%CI: 0.484-0.745), negative predictive value was 0.847(95%CI :0.825-0.865).Conclusion: Compared with the IID , Mallampati classification and ULBT, the C-TMD has higher value in predicting difficult laryngoscopy, which can become a more favorable airway assessment method during the epidemic of COVID-19.Trial registration: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry (ChiCTR1900026775).