Abstract

Unanticipated difficult intubation remains a prima¬ry concern for anaesthesiologists. Theoretically, accurate pre¬operative airway evaluation can reduce or avoid unanticipated difficult intubation. Aim: To determine the utility of sonographic measurements of anterior neck soft tissue thickness (at the level of hyoid bone, thyrohyoid membrane and anterior commissure) neck circumference and BMI in distinguishing easy and difficult intubation. Methods: 60 obese patients with BMI (30kg/m-2) and ASA Grade II and III both sexes, aged between 18 and 70 years, scheduled for different surgeries under general anaesthesia were included in this prospective observational study conducted at the SMHS Hospital which is one of the associated hospitals of Government Medical College Srinagar. Patients selected for surgery were admitted at least 24 hours prior to surgery. The attending anaesthetist evaluate the following variables pre operatively: history of snoring and OSAS, Modified Mallampati score (MMS), loose or protruding upper teeth or partially missing upper incisors or canines; thyromental distance, TM joint mobility, neck mobility, body mass index, neck circumference at the level of thyroid cartilage and USG measurements of anterior neck soft tissue thickness was obtained at three levels. Results: Mean weight of 66.40±8.15kg in the patients with difficult intubation while as mean weight of 60.50±9.25 among the patients with easy intubation with statistically significant difference among the study population (p=0.001). Mean Body Mass of 40.60±4.8 among the patients with a difficult intubation while as the body mass index of 36.55±3.5 among the patients with an easy intubation with statistically significant difference among the study population (p=0.004). The mean of neck circumference of 45±4.8 among the patients with a difficult intubation and mean of 38±3.2 among the patients with Easy intubation.The statistical difference between the patients was statically significant with a p value= 0.002. The distance between skin and hyoid bone ranged from 1-4 with a mean of 1.91±0.30 and 1-3 with a mean of 1.38± 0.20 among the patients with easy intubation. The statistical difference between the patients was statically significant with a p value= 0.0002. Conclusion: Anterior neck soft tissue thicknesses measured by US at hyoid bone, thyrohyoid membrane, and anterior com¬missure levels are independent predictors of difficult laryngoscopy. Combinations of those screening tests or risk factors with US measurements might increase the ability to predict difficult laryngoscopy.

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