Measurement of Neck Circumference, Tongue thickness and Skin to Epiglottis Distance as Predictors of Difficult Intubation: A Prospective Study

Abstract

Airway Assessment is essential in pre anesthetic assessment. Anticipating and preparing for difficulty in airway management is crucial to avoid airway catastrophes. Routine pre operative airway examination usually includes mouth opening and dentition, Mallampati classification, thyromental distance and neck movements. Neck circumference is a quick bedside test to determine difficult laryngoscopy. Increased tongue thickness and skin to epiglottis distance affects performance of laryngoscopy and tracheal intubation increasing the risk of difficult airway. Presently there is a search for non-invasive and accurate tools to overcome limitations of clinical airway assessment tests. Ultrasonography has been evolving as a useful device for airway assessment especially soft tissue structures in anterior surface of neck. Here we studied the measurement of neck circumference and ultrasound measurement of tonguethickness and skin to epiglottis distance as predictors for difficult intubation. The Aim of the study is to predict difficulty in intubation by measuring neck circumference, thickness of tongue and thickness of skin to epiglottis. Prospective observational study, 120 patients posted for surgery under general anesthesia, Department of anesthesia, Meenakshi medical college, Kanchipuram. After institutional Human ethical committee clearance, 120 Patients were screened during preoperative assessment for undergoing procedures under general anaesthesia. Neck circumference and other airway parameters were measured with measuring tape and distance between Skin to epiglottis and tongue thickness were measured with ultrasound linear probe. Patients were grouped into Group E( Easy Intubation) whose Cormack-lehane grade was 1 and 2 and Group D ( Difficult intubation) whose Cormack-lehane grade was 3 and 4. SPSS version 16 was used for statistical analysis. There was no statistical significance seen between age, sex, height among easy and difficult intubation but significance was seen with weight (p <0.05), Thyromental distance(p<0.05) and Sterno-mental distance(p<0.05). High significance was seen in Distance between skin to epiglottis distance(p<0.001), Tongue thickness(p<0.001) and Neck Circumference(p<0.001) in difficult intubation cases. Neck circumference and ultrasonographic measurement of tongue thickness and skin to epiglottis can avoid unanticipated difficult intubation.