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Predicting difficult direct laryngoscopies remains challenging and improvements are needed in preoperative airway assessment. We conceived two new tests (the upper airway angle and the glottic height) and assessed their association with difficult direct laryngoscopies as well as their predictive performance.A prospective cohort was conducted with 211 patients undergoing general anesthesia for surgical procedures. We assessed the association between difficult laryngoscopies and modified Mallampati Test (MMT), Upper Lip Bite Test (ULBT), Mandibular Length (ML), Neck Circumference (NC), Mouth Opening (MO), Sternomental Distance (SMD), Thyromental Distance (TMD), Upper Airway Angle (UAA), and Glottic Height (GH). We also estimated their predictive values.Difficult laryngoscopy was presented by 12 patients (5.7%). Six tests were significantly associated with difficult laryngoscopies and their area under the ROC curve, and 95% CIs were as follows: UAA = 88.82 (81.86-95.78); GH = 86.43 (72.67-100); ML = 83.75 (72.77-94.74); NC = 79.17 (64.98-93.36); MO = 65.58 (45.13-86.02); and MMT = 77.89 (68.37-87.41).We have found two new features (the UAA and the GH) to be significantly associated with the occurrence of difficult direct laryngoscopies. They also presented the best predictive performance amongst the nine evaluated tests in our cohort of patients. We cannot ensure, however, these tests to be superior to other regularly used bedside tests based on our estimated 95% CIs.

Background There is currently some discussion over the actual usefulness of performing preoperative upper airway assessment to predict difficult airways. In this field, modified Mallampati test (MMT) is a widespread tool used for prediction of difficult airways showing only a feeble predictive performance as a diagnostic test. We therefore aimed at evaluating if MMT test would perform better when used as a screening test rather than diagnostic. Methods An accuracy prospective study was conducted with 570 patients undergoing general anesthesia for surgical procedures. We collected preoperatively data on sex, age, weight, height, body mass index (BMI), ASA physical status, and MMT. The main outcome was difficult laryngoscopy defined as Cormack and Lahane classes 3 or 4. Bivariate analyses were performed to build three different predictive models with their ROC curves. Results Difficult laryngoscopy was reported in 36 patients (6.32%). Sex, ASA physical status, and MMT were associated with difficult laryngoscopy, while body mass index (BMI) was not. The MMT cut-off with the highest odds ratio was the class II, which also presented significantly higher sensitivity (94.44%). The balanced accuracy was 67.11% (95% CI: 62.78–71.44%) for the cut-off of class II and 71.68% (95% CI: 63.83–79.54) for the class III. Conclusion MMT seems to be more clinically useful when the class II is employed as the threshold for possible difficult laryngoscopies. At this cut-off, MMT shows the considerable highest sensitivity plus the highest odds ratio, prioritizing thus the anticipation of difficult laryngoscopies.