Evaluation of airway ultrasound parameters in predicting difficult airway: A Prospective observational study

Airway assessment plays a key role during pre-anaesthetic assessment. Identifying difficult airway beforehand can help us in adequate preparation, selection of  equipments , and participation of skilled persons during intubation. Airway assessment is usually done using different clinical parameters such as Body Mass Index (BMI), circumference of neck , Mallampati score, interincisior gap, sternomental distance, thyromental distance and neck mobility. These parameters are often used in combination so as to overcome their low sensitivity in predicting difficult airway. Incidence of unanticipated difficult airway stands at 1%-8% in spite of using multiple screening tools. Moreover, in case of unconscious and uncooperative patients, clinical tools have limited use. To overcome the above limitations of clinical airway assessment tools, there is a need to develop an accurate airway assessment tool.

 Ultrasonography, being simple, portable, bed-side, non-invasive and non-ionizing tool, has been proposed recently as an aid for airway assessment and predicting difficult laryngoscopy. Various ultrasonographic measurements i.e. distance between skin and hyoid bone, distance from skin to thyrohyoid membrane, skin to epiglottis distance , distance from skin to vocal cord have been used for this purpose.

 To the best of our knowledge the data from previous studies are inconclusive, also the data from Indian population is not so robust. Therefore, we are planning to conduct the current study while including a novel ultrasonographic parameter i.e. tongue thickness to oral height ratio in assessing difficult airway.