Background and aims Difficult endotracheal intubation is one of the most challenging operations in anesthesia. How to better predict difficult airway and make corresponding preparations to reduce the occurrence of accidents is a difficult task faced by anesthesiologists every day. This study decide to evaluate the value of the Upper Lip Bite Test (ULBT) and the Modified Mallampati Test (MMT) in predicting difficult intubation under direct laryngoscopy and find out the most intuitive and simple method to predict difficult intubation under direct laryngoscopy in apparently normal patients. Patients and methods This descriptive-analytical study was performed on 450 patients for elective surgery under general anesthesia requiring endotracheal intubation. The ULBT and MMT grading were evaluated preoperatively and Cormack and Lehane’s (CL) classification was recorded on the day of surgery during intubation under direct laryngoscopy. The accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR), Youden index and area under ROC curve of ULBT and MMT respectively and in combination were calculated and compared. And the consistency between the total scores of ULBT and MMT combined in different ways and CL grading was counted. Results Of the 450 patients, 69 (15.3%) were classified as difficult cases of direct laryngoscopy. The accuracy, sensitivity, specificity, PPV and NPV of ULBT were 81.33, 11.59, 93.96, 25.81, 85.44%; and those the corresponding values for MMT were 66.22, 62.32, 69.29, 26.88 and 91.03%. A combination of ULBT and MMT did not improve the sensitivity in the sample tested. The combined total scores of ULBT and MMT in both ways were less consistent with CL grading in predicting difficult intubation under direct laryngoscopy. Conclusion Based on findings of current study, we conclude that ULBT and MMT for difficult intubation have only poor to moderate discriminative power when used alone. The combination of the two tests in fractional form is also not a good predictor of difficult intubation under direct laryngoscopy. Trial registration Chinese Clinical Trial Registry, ChiCTR2100052987, Registered 07 November 2021, http://www.chictr.org.cn

Introduction Postoperative delirium(POD) is a common postoperative complication and is associated with numerous adverse outcomes. Advanced age and hip surgery are high risk factors for POD. Both remimazolam tosilate for injection and sevoflurane can be used as sedatives for the maintenance of general anesthesia, but the comparison of their impacts on the incidence of POD has not been reported. This study aims to compare the effect of remimazolam tosilate vernussevoflurane on the incidence of POD in elderly patients undergoing total hip arthroplasty. Methods and Analysis This is a two-arm, parallel, prospective, multicenter, randomized controlled trial. A total of 456 elderly patients at six clinical trial centers in China will be randomly assigned in a 1:1 ratio to receive general anesthesia with remimazolam tosilate or sevoflurane as sedative. The primary outcome measure is the prevalence of POD during the first 4 postoperative days. Secondary outcomes include cognitive function [Mini-Mental State Examination (MMSE)], perioperative pain degree [Visual Analogue Scale (VAS)], postoperative nausea and vomiting (PONV) within 4 days after surgery, recovery time after drug withdrawal, the amount of vasoactive drugs used during operation, length of hospital stay, and in-hospital complications. Ethics and Dissemination The Research Ethics Committee of Qilu Hospital of Shandong University has approved the study protocol (REF: KYLL-202206-25), which is applicable to all research centers. Participant recruitment begins in August 2022. Written informed consent will be obtained from each patient before randomization. The findings will be published in an international peer-reviewed medical journal. Trial Registration The trial has been registered at the Chinese Clinical Trial Registry: ChiCTR2200062455; date of registration: 2022-08-08.