Preoperative Airway Images for Difficult Airway Prediction

Preoperative airway assessment is important for identifying patients at risk for difficult laryngoscopy or difficult intubation. However, conventional bedside airway predictors have limited accuracy when used alone. Multimodal artificial intelligence models may provide additional image-based information by evaluating visible anatomical features from standardized preoperative airway photographs.

In this prospective observational study, adult patients undergoing elective surgery requiring endotracheal intubation will be enrolled between June and September 2026. Each participant will undergo standardized eight-view airway photography during the pre-anesthetic evaluation. The image set will include frontal facial, lateral profile, maximal mouth opening, modified Mallampati, neck extension, and anterior neck views. Images will be anonymized before assessment.

The same image sets will be independently evaluated by multimodal AI models, including ChatGPT, Gemini, and Grok, using an identical structured prompt. The AI models will provide categorical and binary predictions for difficult laryngoscopy and difficult intubation based only on visible image-based anatomical features. No intraoperative outcome data, expert predictions, or conventional airway assessment results will be provided to the AI models.

AI-generated predictions will be compared with expert anesthesiologist image-based assessments, conventional airway evaluation parameters, and prospectively recorded intraoperative reference outcomes. Difficult laryngoscopy will be defined as Cormack-Lehane grade III or IV. Difficult intubation will be defined using objective intraoperative criteria, including more than one intubation attempt, need for bougie or stylet assistance, rescue use of video laryngoscopy or supraglottic airway device, intubation time exceeding 60 seconds, or Intubation Difficulty Scale score greater than 5.

The study will assess the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, receiver operating characteristic performance, and agreement between AI models and expert anesthesiologist assessments. The findings may help clarify whether multimodal AI can serve as a clinician-supervised adjunct for preoperative difficult airway risk stratification.

Inclusion criteria

• Age 18 years or older
• Scheduled for elective surgery requiring endotracheal intubation
• Able to cooperate with the standardized preoperative airway photography protocol
• Able to provide written informed consent

Exclusion criteria

• Age younger than 18 years
• Emergency surgery
• Refusal or inability to provide informed consent
• Inability to cooperate with the standardized photographic protocol
• Known craniofacial or cervical deformity
• History of major head and neck surgery or radiotherapy
• Obstruction of key anatomical landmarks by facial hair, dressings, cervical collars, or other external devices
• Incomplete or poor-quality image sets despite repeated acquisition
• Missing clinical airway assessment data
• No endotracheal intubation performed
• Airway difficulty could not be reliably evaluated
• Planned awake fiberoptic intubation or other preplanned advanced airway technique because of known difficult airway