Evaluation of the relationship between ultrasonographic and anthropometric measurements of the anatomical structures in the neck and difficult airway

Background: The incidence of difficult laryngoscopy or intubation varies between 1.5% and 13%. Unsuccessful intubation is one of the causes of anesthesia-related death and permanent brain damage. In this study, we primarily evaluated the predictive potential (specificity and sensitivity) of difficult airway and difficult laryngoscopy procedure with ultrasonographic measurements. Secondly, the measurements of elective surgery patients with difficult airway were compared with those without difficult airway. Material and Methods: The study was carried out with the approval of Duzce University Faculty of Medicine Non-Interventional Health Research Ethics Committee dated 21.06.2021 and numbered 2021/160. In the ASA I-III group, 170 patients between the ages of 18-65 years who will undergo endotracheal intubation under general anesthesia with an indication for elective surgery were included in the study. 170 patients were recruited. In the preoperative evaluation, anthropometric measurements and ultrasonographic measurements of the patients were taken by the first anesthetist. The patients were intubated using the same induction anesthetic agents by a second anesthetist with at least 3 years of experience who did not know the results of the preoperative evaluation. Using Macintosh 3 or 4 blades, Cormack-Lehane classification was determined according to the laryngoscopic appearance in the first trial and without any maneuver. It was stated that intubation could be performed in the first attempt. Difficult mask ventilation, difficult intubation, easy and difficult laryngoscopy were evaluated. Results: : In comparisons in terms of demographic and clinical characteristics, a significant difference was found between easy intubation (n=142) and difficult intubation (n=28) in terms of height, weight and neck circumference (p values 0.017; 0.002; <0.001, respectively). It was determined that the number of difficult intubations was less in females and more in males (p=0.001). Grade IV was found to be significantly higher, with Mallampati being the highest in grade III (p <0.001). A significant difference was found between easy and difficult intubation, especially in tongue thickness, and in the distances between neck structures and skin. According to v the results of ROC curve analysis for ultrasound measurements, it was observed that the measurements with the highest sensitivity and specificity were tongue thickness and distance between skin and epiglottis (Cut-off values ≥59.85; ≥28.40, respectively). Conclusion: It was observed that ultrasonographic measurements had moderate to weak sensitivity and specificity in terms of measurement parameters other than tongue thickness and epiglottis skin thickness in predicting difficult intubation. Keywords: laryngoscopy, difficult airway, ultrasonography