Relationship Between Upper Airway Ultrasound Parameters and Degree of Difficult Laryngoscopy for Endotracheal Intubation

Background Limited research has been conducted on the role of ultrasound in predicting difficult laryngoscopy (DL). This study aimed to evaluate the predictive values of upper airway ultrasound parameters for the degree of DL during intubation. Methods and Materials This observational-prospective study was performed on 120 patients requiring intubation during elective surgery. Initially, the degree of DL was assessed by the Mallampati Scale. The patients' neck circumference was then measured and recorded.  Ultrasound was used to determine the Hyomental distance in the neutral position (HMDN) and in the head extension (HMDE), as well as tongue width (TW), tongue thickness (TT), oral cavity height ratio (OCH), the amount of soft tissue (ST), and the Tongue thickness-to-oral cavity height ratio (TT/OCH) was used. Afterward, the patients underwent general anesthesia and were intubated. The degree of difficult intubation was measured based on the Cormack-Lehane classification system, according to which the patients were divided into easy and difficult laryngoscopy groups. Finally, the effectiveness of the two methods of ultrasound and intubation was compared. Results The Cormack score and Mallampati class recorded intubation difficulty as 28.3% and 30.8%, respectively. According to the Cormack score, only the neck circumference was significantly associated with intubation difficulty (P = 0.002). In terms of Mallampati class, the neck circumference and HMDN, HMDE, TT, OCH, and ST were significantly associated with the degree of DL (P <0.05). The predictive value of ultrasound parameters for the degree of DL was low based on both of the criteria (AUC <0.7). Conclusion The results showed that although Mallampati class lacked the desirable accuracy, it provided a better predictive measure for the degree of DL during intubation compared to the Cormack score