A study to predict difficult airway by Ultrasonography and conventional indices in Obese and Non-Obese population

Abstract

Background: A “difficult airway” is defined as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both. The purpose of undertaking airway assessment is to diagnose the potential for difficult airway for optimal patient preparation, proper selection of equipment and technique and participation of personnel experienced in the difficult airway management. This study aims at proper airway assessment using conventional methods and ultrasound and then comparing it with the result obtained by laryngoscopy using proper statistical tests to prove the usefulness of USG for difficult airway prediction.

Material and Methods: This was a prospective comparative study done in the department of anesthesia and critical care in Sarojini Naidu Medical college, Agra. It involved a total of 120 patients divided into 2 groups of 60 patients each based on their BMI value who were found to be eligible for the study after meeting the inclusion criteria. Its objective was to compare the effectiveness of ultrasonography over conventional methods in prediction of difficult airway in obese and non-obese population. The study was conducted over a period of 18 months. The outcomes studied were Mallampati score, hyomental distance ratio obtained clinically, neck circumference, mouth opening, and neck mobility for conventional indices while hyomental distance ratio obtained using ultrasonography, hyoid bone visualization, distance from skin to epiglottis and anterior neck soft tissue at the level of vocal cord. The level of significance was set at <0.05.

Results: On the basis of all the conventional indices combined, 15 patients in non-obese group while 53 patients in obese group were found to be having difficult airway. On the basis of all the USG indices combined, 10 patients in non-obese group while 42 patients in obese group were found to be having difficult airway. Upon laryngoscopy, 10 patients in non-obese and 39 patients in obese group were found to be having difficult airway. All the groups were compared and the result was found to be statistically significant.

Conclusion: The above results clearly show the superiority of USG over conventional methods as a tool for prediction of difficult airway in both obese and non-obese population. Ultrasound of the upper airway shows promise in being an effective method for airway management.