Ultrasound Predictors of Difficult Airway in Adults

Investigation of Ultrasonographic Predictors of Difficult Intubation and Difficult Mask Ventilation in Adult Patients

Difficult airway management is a major cause of perioperative complications. Standard bedside airway assessment tests may have limited ability to predict difficult intubation and difficult mask ventilation. This prospective observational study aims to evaluate whether preoperative ultrasound measurements of airway structures (such as skin-to-epiglottis distance, tongue thickness, and pre-epiglottic space) can predict difficult intubation and difficult mask ventilation in adult patients undergoing surgery under general anesthesia.

Study Overview

• Status: Completed
• Conditions: Difficult Intubation; Difficult Airway; Difficult Mask Ventilation

Detailed Description

This prospective observational cohort study was conducted to evaluate the predictive value of preoperative ultrasonographic airway measurements for difficult intubation and difficult mask ventilation in adult patients undergoing elective surgery under general anesthesia. A total of 400 patients aged 18-70 years with ASA physical status I-III were included. Before induction of anesthesia, standard clinical airway assessment tests were recorded, and ultrasound measurements were performed to assess airway-related anatomical structures. Ultrasonographic parameters included skin-to-epiglottis distance, skin-to-thyroid cartilage distance, thyroid cartilage-to-epiglottis distance, pre-epiglottic space depth, tongue thickness, and hyomental distance measurements.

Intraoperatively, mask ventilation and intubation conditions were documented. Difficult intubation was defined as requiring two or more intubation attempts. Difficult mask ventilation was defined as the need for two-handed mask ventilation or inability to ventilate adequately using a face mask. The primary objective was to determine the association between ultrasonographic measurements and difficult intubation

• Study Type: Observational
• Enrollment (Actual): 400

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Kütahya
    • Kütahya, Kütahya, Turkey (Türkiye), 3100
      • Kütahya Health Sciences University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Adult patients aged 18-70 years (ASA I-III) scheduled for elective surgery under general anesthesia requiring orotracheal intubation

Description

Inclusion Criteria:

• Age 18-70 years

ASA physical status I-III

Elective surgery under general anesthesia requiring orotracheal intubation

Written informed consent

Exclusion Criteria:

• Refusal to participate

Emergency surgery

Pregnancy

Known upper airway pathology or previous airway surgery

Restricted mouth opening (<3 cm)

Cervical spine instability or significant limitation of neck mobility

Morbid obesity (BMI ≥40 kg/m²)

Obstructive upper airway masses (e.g., head and neck tumors)

Prior neck radiotherapy

Clinically relevant neck masses

Major facial/mandibular trauma or craniofacial anomalies

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Cohort 1: Adult patients undergoing surgery under general anesthesia; Adult patients (18-70 years, ASA I-III) scheduled for elective surgery under general anesthesia requiring orotracheal intubation. Preoperative clinical airway assessment and ultrasonographic airway measurements were recorded, and intraoperative intubation and mask ventilation outcomes were evaluated

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants with Difficult Intubation	Difficult intubation was defined as requiring two or more intubation attempts (≥2 attempts) during induction of general anesthesia.	During induction of anesthesia (intraoperative)
Number of Participants with Difficult Mask Ventilation	Difficult mask ventilation was defined as the need for two-handed mask ventilation or inability to ventilate adequately using a face mask	During induction of anesthesia (intraoperative)

Collaborators and Investigators

• Sponsor: Kutahya Health Sciences University
• Investigators: Principal Investigator: Serkan Telli, MD, Kütahya Health Sciences University

Publications and helpful links

General Publications

• 1. Cook TM, MacDougall-Davis SR. Complications and failure of airway management. Br J Anaesth. 2012;109 Suppl 1(suppl 1):i68-i85. 2. Apfelbaum JL, Hagberg CA, Connis RT, Abdelmalak BB, Agarkar M, Dutton RP, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136(1):31-81. 3. Roth D, Pace NL, Lee A, Hovhannisyan K, Warenits AM, Arrich J, et al. Airway physical examination tests for detection of difficult airway management in apparently normal adult patients. Cochrane Database Syst Rev. 2018;5(5):CD008874. 4. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005;103(2):429-37. 5. Detsky ME, Jivraj N, Adhikari NK, Friedrich JO, Pinto R, Simel DL, et al. Will This Patient Be Difficult to Intubate?: The Rational Clinical Examination Systematic Review. JAMA. 2019;321(5):493-503. 6. Singh M, Chin KJ, Chan VW, Wong DT, Prasad GA, Yu E. Use of sonography for airway assessment: an observational study. J Ultrasound Med. 2010;29(1):79-85. 7. Kundra P, Mishra SK, Ramesh A. Ultrasound of the airway. Indian J Anaesth. 2011;55(5):456-62. 8. Marchis IF, Negrut MF, Blebea CM, Crihan M, Alexa AL, Breazu CM. Trends in Preoperative Airway Assessment. Diagnostics (Basel). 2024;14(6). 9. Yao W, Wang B. Can tongue thickness measured by ultrasonography predict difficult tracheal intubation? Br J Anaesth. 2017;118(4):601-9. 10. Daggupati H, Maurya I, Singh RD, Ravishankar M. Development of a scoring system for predicting difficult intubation using ultrasonography. Indian J Anaesth. 2020;64(3):187-92. 11. Sotoodehnia M, Khodayar M, Jalali A, Momeni M, Safaie A, Abdollahi A. Prediction of difficult laryngoscopy / difficult intubation cases using upper airway ultrasound measurements in emergency department: a prospective observational study. BMC Emerg Med. 2023;23(1):78

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2023
• Primary Completion (Actual): October 1, 2024
• Study Completion (Actual): October 1, 2024

Study Registration Dates

• First Submitted: January 26, 2026
• First Submitted That Met QC Criteria: January 26, 2026
• First Posted (Actual): February 3, 2026

Study Record Updates

• Last Update Posted (Actual): February 5, 2026
• Last Update Submitted That Met QC Criteria: February 3, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Ultrasound; Anesthesia; Airway Ultrasonography; Difficult Airway Prediction
• Other Study ID Numbers: 2023/10-19

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared due to institutional policies and to protect participant privacy and confidentiality.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No