Patient safety is the cornerstone of anesthetic practice, and maintaining adequate respiration represents its most critical initial step. In situations where spontaneous breathing cannot be sustained-such as during general anesthesia-the airway must be mechanically secured. While simple face masks may be sufficient in some cases, endotracheal intubation remains the most reliable method for airway control in conditions associated with respiratory depression.
Airway management may be challenging due to various patient-related anatomical factors, including facial and mandibular structure, obesity, limited mouth opening, facial hair, sunken cheeks, wide facial morphology, and a short or muscular neck. These challenges are collectively described as difficult ventilation and difficult intubation (cannot ventilate-cannot intubate), which may occur unexpectedly or be anticipated. A difficult airway is defined as difficulty encountered by a trained anesthesiologist in face mask ventilation, tracheal intubation, or both.
Several predictors of difficult airway are widely accepted, such as thyromental and sternomental distances, neck circumference, Mallampati classification, upper lip bite test, mouth opening, and interincisor distance. Thorough preoperative airway evaluation is mandatory, as difficult mask ventilation and failed intubation remain major contributors to anesthesia-related morbidity and mortality. Although numerous studies have examined these predictors, research focusing on facial morphology and anthropometric indices-particularly the face index-is extremely limited.
Facial morphology varies considerably among individuals and can be evaluated anthropometrically using simple, noninvasive tools such as a digital caliper. Anthropometric analysis is commonly applied in forensic medicine and reconstructive surgery but has rarely been incorporated into airway assessment.
This study aims to introduce face index analysis as a novel predictor of difficult airway alongside conventional methods. By evaluating measurements such as trichion-gnathion distance, total facial index, upper facial index, and nasal index, the study investigates whether airway difficulty can be predicted using a single index value. All measurements are standard, noninvasive, and routinely performed during preoperative assessment.
Adult patients over the age of 18
Patients who received general anesthesia
A prior history of difficult airway
All patients who have undergone facial deformities
All patients who have tracheostomy
All patients who have general anesthesia
Cohort
Prospective
Face index
Other interventionFace index is an anthropometric measurement
1. The facial index: Unit of Measure: Ratio (dimensionless) 2. Upper Face Height: Unit of Measure: mm 3. Total Face Height: Unit of Measure: mm 4. Mallampati: Categorical (Class I-IV) 5. Difficult Airway: Categorical (yes / no)
1. The facial index in will be calculated as the ratio of total face height (nasion-gnathion) to bizygomatic width measured preoperatively. 2. Upper Face Height: Linear distance between subnasale and stomion measured preoperatively. 3. Total Face Height: Linear distance between nasion and gnathion measured preoperatively. 4. Mallampati Categorical (Class I-IV): Airway classification assessed preoperatively. 5. Difficult Airway: Categorical (yes / no): Defined as the presence of difficult mask ventilation and/or difficult intubation.
Face index and face mask ventilation
Facial Anthropometric Measurements: Facial anthropometric measurements, including trichion-gnathion distance, upper face height (subnasale-stomion), total face height (nasion-gnathion), bizygomatic width, and alar width, measured preoperatively and recorded for each participant.
Facial Index and Preoperative Airway Assessment Parameters
Facial index values and preoperative airway assessment parameters, including Mallampati classification, thyromental distance, sternomental distance, mandible length, interincisor gap, Upper Lip Bite Test, and atlanto-occipital joint angle, measured preoperatively and recorded for each participant prior to intubation.
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