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Completed

NCT Number: NCT07077317

Examining the Effects of Anthropometric Measurements on Difficult Airway Prediction

Airway-related complications are among the leading causes of anesthesia-associated morbidity and mortality. Therefore, the ability to predict difficult mask ventilation, laryngoscopy, and intubation before induction is essential to ensure proper preparation in patients at risk and avoid unnecessary airway manipulations in low-risk individuals. While numerous studies have focused on predicting difficult intubation, most have limited sample sizes and do not consider postoperative critical respiratory events.

In this prospective observational clinical study, we aim to investigate the relationship between commonly used preoperative airway assessment tools-including anthropometric measurements, Mallampati score, and the STOP-Bang questionnaire for obstructive sleep apnea-and the incidence of difficult mask ventilation, difficult laryngoscopy (Cormack-Lehane grading), difficult intubation, and critical respiratory events in the postoperative period.

The study will include adult patients (≥18 years) classified as ASA I-IV undergoing surgery under general anesthesia with endotracheal intubation. Data will be collected preoperatively, intraoperatively, and in the post-anesthesia care unit (PACU) by experienced anesthesia personnel. Postoperative critical respiratory events are defined as unexpected hypoxemia, hypoventilation, reintubation, or interventions required for upper/lower airway obstruction.

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Key information

Conditions

Difficult Airway Airway Management Difficult Airway Intubation

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Department of Anesthesiology, KUTAHYA CITY HOSPITAL

Kütahya, 43020, Turkey (Türkiye)

About this study

Difficult airway management remains one of the most significant challenges in clinical anesthesia, often leading to severe complications such as hypoxemia, aspiration, and even cardiac arrest. Despite various clinical predictors, no single assessment method reliably identifies all patients at risk. This prospective, observational study aims to comprehensively evaluate the association between preoperative airway assessment parameters and both intraoperative airway difficulty and postoperative critical respiratory events.

The preoperative assessment will include demographic characteristics, comorbidities, ASA classification, Mallampati score, and detailed anthropometric airway measurements (neck circumference, thyromental distance, sternomental distance, interincisor gap, head dimensions, presence of beard/dentition, and neck mobility). Additionally, the STOP-Bang questionnaire will be administered to assess the risk of obstructive sleep apnea (OSA).

During induction and airway management, mask ventilation difficulty will be graded, Cormack-Lehane score during laryngoscopy will be recorded, and intubation will be evaluated in terms of the number of attempts and need for adjunctive devices (stylet, bougie, fiberoptic bronchoscope, videolaryngoscope, etc.).

In the postoperative phase, patients will be monitored for critical respiratory events including unexpected hypoxemia (SpO₂ <90%), hypoventilation (RR <8/min or PaCO₂ >50 mmHg), reintubation, and any interventions (e.g., airway support, bronchodilators, cold mist, etc.) required for upper or lower airway obstruction.

The outcomes of this study may help refine preoperative screening protocols and contribute to the development of risk-based airway management strategies aimed at improving patient safety.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18 years,
  • ASA Physical Status I, II, III or IV,
  • Undergoing elective surgery under general anesthesia with endotracheal intubation,
  • Written informed consent provided

Exclusion criteria

  • History of head and neck surgery or trauma causing anatomical deformity,
  • Known congenital or acquired airway abnormality,
  • Cervical spine surgery or instability,
  • Age < 18 years

Treatment and study plan

Airway Assessment Using Standard Clinical Tools

Other

Preoperative airway evaluation using routine physical measurements (e.g., Mallampati score, neck circumference, STOP-Bang questionnaire), and intraoperative/postoperative observation of airway-related parameters.

Primary outcomes

  1. Incidence of Difficult Mask Ventilation

    Time frame: Intraoperative (during anesthesia induction)

    Evaluation of mask ventilation using a standard difficulty grading scale.

    • Mask Ventilation Successful
    • Mask Ventilation Requires Oral Airway
    • Mask Ventilation Requires Oral Airway And Assistant (Two Hands)
    • Mask Ventilation Failure

  2. Incidence of Difficult Laryngoscopy

    Time frame: Intraoperative (during laryngoscopy)

    Cormack-Lehane grade III-IV views considered difficult laryngoscopy.

  3. Incidence of Difficult Intubation

    Time frame: Intraoperative (during intubation)

    Defined as more than two attempts, or the requirement of adjuncts such as bougie, videolaryngoscope, or fiberoptic bronchoscope.

  4. Occurrence of Postoperative Critical Respiratory Events

    Time frame: Within the first 2 hours postoperatively (in PACU)

    Events include unexpected hypoxemia (SpO₂ < 90%), hypoventilation (RR < 8/min or PaCO₂ > 50 mmHg), reintubation, and active interventions for airway obstruction.

Secondary outcomes

  1. Correlation Between STOP-Bang Score and Difficult Airway Incidence

    Time frame: Preoperative through intraoperative period

    Evaluate predictive value of high STOP-Bang scores (≥3) for difficult mask ventilation, laryngoscopy, and intubation.

  2. Correlation Between Anthropometric Measurements and Critical Respiratory Events

    Time frame: Preoperative to postoperative period

    Investigate associations between variables such as neck circumference, interincisor gap, or sternomental distance with postoperative respiratory complications.

  3. Correlation Between Anthropometric Measurements and Difficult Airway Management

    Time frame: Preoperative to intraoperative (induction period of anesthesia)

    Investigate associations between variables such as neck circumference, interincisor gap, or sternomental distance, head dimensions, with difficult mask ventilation or difficult intubation.

Sponsors and collaborators

Lead sponsor

Kutahya Health Sciences University

Other

Registry information

Official study title

Examining the Effects of the Stop-Bang Scoring Model, Anthropometric Measurements, and Head Dimensions on Difficult Airway Prediction

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jul 22, 2025
Registry last updated
Nov 25, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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