Can the "Face Index"; an Anthropometric Measurement, Predict Difficult Laryngoscopy and Intubation?

Patient safety is the most critical aspect of anesthetic practice, and the first step in ensuring this safety is the maintenance of adequate respiratory function. Under anesthesia, or in any situation where spontaneous respiration cannot be sustained, the upper and lower airways must be mechanically secured. Airway control can often be achieved using simple face masks; however, in cases of general anesthesia or similar conditions associated with respiratory depression, airway management must be ensured through the more reliable method of endotracheal intubation.

During artificial ventilation, numerous physical characteristics such as facial structure, mandibular anatomy, obesity, limited mouth opening, the presence of a beard, a thin face with sunken cheeks, a wide facial structure, and a short, muscular neck may pose challenges for the anesthesiologist. These situations, defined in the medical literature as "difficult ventilation - difficult intubation" (cannot ventilate - cannot intubate), are not uncommon and may present as either anticipated or unanticipated difficult airways. A difficult airway is defined as a clinical situation in which a trained anesthesiologist experiences difficulty with face mask ventilation, tracheal intubation, or both, due to upper airway conditions (1,2).

Universally accepted predictors of difficult airway among anesthesiologists and the scientific community include physical measurements and classifications such as thyromental distance, sternomental distance, neck circumference, upper lip bite test, Mallampati classification, mandibular length, mouth opening, and interincisor distance (1,3,4). A comprehensive preoperative airway evaluation is both necessary and mandatory during the physical examination of patients scheduled for general anesthesia (5,6). One of the most common-and arguably the most significant-causes of anesthesia-related morbidity and mortality is difficult mask ventilation and failed intubation. In daily anesthetic practice, these classifications are frequently used to reduce the risk of airway difficulty and enhance patient safety, and numerous studies and theses addressing these physical examination criteria are available in the literature.

Despite the abundance of such studies, research evaluating facial morphology and anthropometric measurements-including the "face index"-is almost nonexistent. Facial morphology varies widely among individuals worldwide. It can be analyzed anthropometrically using various measurements and indices, which are currently most commonly applied in fields such as forensic medicine and aesthetic or reconstructive surgery. Anthropometric measurement is a technique that examines metrically definable body characteristics and can be performed easily using a simple measurement tool such as a digital caliper (7).

The primary aim of this study is to introduce a novel perspective on difficult airway assessment by incorporating face index analysis as an additional airway predictor alongside traditional measurement methods that have long been used in anesthesiology. Specifically, the study seeks to determine whether airway difficulty can be predicted using a single index value rather than multiple measurements in patients with different facial morphologies.