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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
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT07461792
Acronym
intubation
Enrollment
350
Registered
2026-03-10
Start date
2026-01-05
Completion date
2026-07-15
Last updated
2026-04-17

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Difficult Airway Intubation

Brief 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).

Interventions

OTHERevaluation 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).

Sponsors

Sohag University
Lead SponsorOTHER

Study design

Observational model
COHORT
Time perspective
PROSPECTIVE

Eligibility

Sex/Gender
ALL
Age
15 Years to 60 Years
Healthy volunteers
Yes

Inclusion criteria

* Adult patients from 15- 60 yrs old * Patients who require endotracheal intubation for surgery under general anesthesia. * Patients with ASA I - II * Patients who provide informed consent

Exclusion criteria

* Patients with history of previous difficult intubation. * Patients with inability to sit/stand, heamodinamiclly unstable and need for rapid sequence induction .

Design outcomes

Primary

MeasureTime frame
The primary outcome evaluate using Ratio of Patient's Height to Thyromental Distance Combined with Obstruction and Neck Mobility (HON Model) as a new practical scoring system in predicting Difficult Laryngoscopy .30 minutes

Countries

Egypt

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Apr 18, 2026