Ultrasonography: A Novel and Noninvasive Tool for Airway Assessment

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Ultrasonography: A Novel and Noninvasive Tool for Airway Assessment

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Context: Securing the airway to ensure alveolar ventilation and prevent pulmonary aspiration constitutes a crucial component in the practice of clinical anesthesia. Unanticipated difficult intubation still occur despite adoption of various clinical predictors. Ultrasound imagimg technique has emerged as new tool for various aspects in anesthesia practice. Aims: We have evaluated the feasibility of ultrasonography as an imaging tool in identifying important airway anatomical structures on the anterior aspect of the neck and correlated the ultrasound-guided measurements of the airway parameters with the modified Cormack-Lehane grading of the direct laryngoscopy for prediction of the difficult airway. Settings and Design: For this prospective observational study, 100 patients above the age of 18, ASA I to III grades, scheduled for elective surgery, requiring general anesthesia and endotracheal intubation were included. Methods and Materials: Modified Mallampati score, Body Mass Index, distance between the anterior commissure to epiglottis (DACE) and distance from epiglottis to midpoint of maximum distance between vocal cords (DEM) using the USG machine followed by MCLS grade on laryngoscopy were noted. Statistical analysis used: Software named Statistical package for the social sciences (SPSS version 21.0, IBM Corporation, USA) for MS Windows. Results: On data analysis mean of DACE in Easy MCLS group was 0.46 ± 0.19 while in Difficult MCLS group was 0.91 ± 0.23 and the difference was statistically significant. Similarly mean of DEM in Easy MCLS group was 0.66 ± 0.21 while in Difficult MCLS group was 0.59 ± 0.23. The Mean of Ratio of DACE to DEM in Easy MCLS group was 0.71 ± 0.19 while in Difficult MCLS group was 1.67 ± 0.23 and this difference was also statistically significant. From Receiver operating characteristic (ROC) analyses distribution of area under the curve for DACE/DEM ratio was 0.96 which was significantly higher for prediction of difficult laryngoscopy. Conclusions: We as anesthesiologists can use USG as a clinical tool for assessing airway in order to rule out difficult airway and prepare the anesthesia workstation for the benefit of the patient.

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