NCT07461792

New Method for Evaluation of Difficult Intubation in Adults

Evaluation of Height/Thyromental Distance Ratio Combined With Obstruction and Neck Mobility for Predicting Difficult Endotracheal Intubation in Adults : A Prospective Observational Study

• Status: Active Not Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 350 (estimated)
• Sponsor: Sohag University · Academic / Other
• Sex: All
• Age: 15 Years – 60 Years
• Healthy volunteers: Accepted

Summary

There are multiple scores used for airway assesment ,the commonest one is LEMON score. LEMON is an airway assessment score that measures factors associated with difficult intubation such as obesity, head and neck movement, jaw movement , receding mandible, long upper incisors, Mallampatti scores, maxillary incisor characteristics, decreased mouth opening ,shorten thyromental distance and short neck. The Height-to-Thyromental Distance ratio (H/TMD) has emerged as a simple, objective, and reproducible anatomical predictor of difficult laryngoscopy, as it normalizes mandibular space to patient height. However, airway difficulty is not purely anatomical; functional factors such as airway obstruction and cervical spine mobility significantly affect intubation success. Therefore, combining H/TMD with two highly predictive functional elements from the LEMON score - Obstruction (O) and Neck Mobility (N) - may provide a more accurate, simplified, and clinically applicable model for predicting difficult airway. This combination is referred to as the HON Model (Height/TMD + Obstruction + Neck mobility).

Conditions

• Difficult Airway Intubation

Interventions

Type	Name	Description
OTHER	evaluation of difficult intubation	The Height-to-Thyromental Distance ratio (H/TMD) has emerged as a simple, objective, and reproducible anatomical predictor of difficult laryngoscopy, as it normalizes mandibular space to patient height. However, airway difficulty is not purely anatomical; functional factors such as airway obstruction and cervical spine mobility significantly affect intubation success. Therefore, combining H/TMD with two highly predictive functional elements from the LEMON score - Obstruction (O) and Neck Mobility (N) - may provide a more accurate, simplified, and clinically applicable model for predicting difficult airway. This combination is referred to as the HON Model (Height/TMD + Obstruction + Neck mobility).

Timeline

• Start date: 2026-01-05
• Primary completion: 2026-06-15
• Completion: 2026-07-15
• First posted: 2026-03-10
• Last updated: 2026-04-17

Locations

1 site across 1 country: Egypt