Is ultrasonic investigation of transverse tracheal air shadow diameter reasonable for evaluation of difficult airway in pregnant women: A prospective comparative study

Objective: The aim of this study was to compare clinical screening tests (modified Mallampati score, Cormack-Lehane score, thyromental distance, and sternomental distance) with ultrasonic measurements of the upper airway in predicting difficult intubation in pregnant women whose Body Mass Index (BMI) is higher and lower than 30 kg m-2. Methods: This study was designed as a prospective observational trial, and consisted of 40 pregnant women of American Society of Anesthesiologists (ASA) 1-2 groups. Patients with a BMI lower than 30 kg m-2 were included in Group 1 (n=20), and patients with a BMI higher than 30 kg m-2 were included in Group 2 (n=20). In the supine position with head in mild extension, the diameter of the transverse tracheal air shadow in the subglottic area of the front neck was measured using ultrasonography. Modified Mallampati score, Cormack-Lehane score, thyromental distance and sternomental distance measurements were recorded. Results: No statistically significant difference was detected between groups regarding mean age, mean number of pregnancy, ASA scores and comorbid disease. Mean body weight (p=0.0001) and mean pre-pregnancy weight (p=0.0001) were significantly higher in Group 2. There was no statistically significant difference between groups regarding mean modified Mallampati score, thyromental distance, sternomental distance measurements, Cormack-Lehane score, and mean ultrasonic measurements. Conclusion: It was found that BMI higher or lower than 30 kg m-2 has no effect on ultrasonic measurements and clinical airway tests. We thought that ultrasonic measurement could not give us valuable information in obese or non-obese pregnant women.