Airway Ultrasound as Predictor of Difficult Direct Laryngoscopy

Mismanaging the airway can cause a lot of harm and death, and an unanticipated difficult intubation could be fatal during anaesthesia. In clinical practise, several bedside screening tests are used to identify patients at risk of having a difficult airway. Despite the fact that their accuracy and utility have been well established in the literature and in clinical practise, a small proportion of patients classified as having an easy airway may present an unexpected difficulty. Predicting a "difficult airway" in all patients is not a simple process. 1–7: Numerous structures and functional units contribute to the pathogenesis of a difficult airway, which is a dynamic process that is highly dependent on the operator's experience. For many years, ultrasounds have been used in conjunction with other diagnostic tools to predict difficulty with airway management, both qualitatively and quantitatively. Recently published systematic review and meta-analysis tried to determine whether preoperative upper airway ultrasound (UA-US) can accurately predict difficult airway in adult patients undergoing elective surgery under general anaesthesia who do not have obvious anatomic evidence of a difficult airway on standard clinical examination..

From their beginning through December 2020, the authors searched Medline, Scopus, and Web of Science databases. Adults who needed tracheal intubation for elective surgery under general anaesthesia without obvious anatomic anomalies indicating difficult laryngoscopy were included in the study sample. For the quantitative analysis of summary receiver operating characteristic data, fifteen studies were analysed (SROC). Sensitivity values for the distance between the skin and the epiglottis (DSE), the distance between the skin and the hyoid bone (DSHB), and the distance between the skin and the vocal cords (DSVC) were 0.82 (0.74–0.87), 0.71 (0.58–0.82), and 0.75 (0.62–0.84, respectively. DSE, DSHB, and DSVC had a specificity of 0.79 (0.70–0.87), 0.71 (0.57–0.82), and 0.72 (0.45–0.89), respectively. The area under the curve (AUC) values for DSE, DSHB, DSVC, and the ratio of the depth of the pre-epiglottic space to the distance between the epiglottis and the vocal cords (Pre-E/E-VC) were 0.87 (0.84–0.90), 0.77 (0.73–0.81), 0.78 (0.74–0.81), and 0.71 (0.67–0.75, respectively. Patients undergoing difficult direct laryngoscopy have significantly higher DSE, DSVC, and DSHB values than patients undergoing easy direct laryngoscopy, with a mean difference of 0.38 cm (95 percent confidence interval [CI], 0.17–0.58 cm; P =.0004), 0.18 cm (95 percent CI, 0.01–0.35 cm; P =.04), and 0.23 cm (95 percent CI, 0.08–0.39 cm; P =.00.