Ultrasound-based airway assessment in obese patients as a valuable tool for predicting difficult airway: an observational study

Background

Difficult airway, characterized by difficult mask ventilation and intubation, is common in obese patients undergoing surgery. The purpose of this study was to evaluate and compare the prognostic efficiency of ultrasound-measured anterior cervical soft tissue parameters as an indicator of difficult airway during anesthesia induction in obese patients.

Methods

This prospective, double-blind, observational study was conducted at Balikesir University Faculty of Medicine Hospital between March 2020 and March 2022. A total of 157 patients age ≥ 18 (BMI ≥ 30 kg.m^-2), without previous head and neck surgery were included in the study. Anterior cervical soft tissue measurements were performed at three levels; minimum distance between the hyoid bone and skin at the level of the hyoid bone; (DSHB), distance between the midpoint of the epiglottis and skin at the level of the thyrohyoid membrane; (DSE), distance between the anterior commissure of vocal cords and skin at the vocal cord level; (DSV). The Han scale was used to assess difficult mask ventilation and the Cormack-Lehane scale was used to assess difficult laryngoscopy.

Results

In the difficult laryngoscopy group, the mean values of DSHB, DSE and DSV were 18.5 ± 3.5, 18.3 ± 3.8, and 18.6 ± 3.4, respectively. The AUC values for DSHB, DSE, and DSV were 0.845, 0.827, and 0.850, respectively. Anterior cervical measurements showed a better predictive value for difficult laryngoscopy compared to difficult mask ventilation.

Conclusion

Ultrasonographic measurements were predictive for difficult laryngoscopy and ventilation with better correlation in laryngoscopy.