Anatomic Features of the Neck and Preoperative Tests as Predictive Markers of Difficult Laryngoscopy
- Conditions
- Airway ManagementPredictive Value of Tests
- Registration Number
- NCT02957084
- Lead Sponsor
- National and Kapodistrian University of Athens
- Brief Summary
In this prospective, open cohort study the diagnostic value of tests based on neck anatomy in predicting difficult laryngoscopy was assessed.
The anatomic features of the neck measured were head extension, mouth opening, upper lip bite, Mallampati class, thyromental distance, sternomental distance, ratio of height to thyromental, neck circumference, thyrosternal distance, hyomental distance at full head extension (FHE) and at neutral position (NP), ratio of neck circumference to thyromental distance and ratio of hyomental distance FHE to hyomental distance NP.
- Detailed Description
Difficult airway assessment is based on various anatomic parameters of upper airway, much of it being concentrated on oral cavity and the pharyngeal structures. The diagnostic value of tests based on neck anatomy in predicting difficult laryngoscopy was assessed in this study .
The sample consisted of adult patients scheduled to receive general anaesthesia. Anatomic features of the neck were measured pre-operatively.
The anatomic features of the neck measured were thyromental distance, sternomental distance, ratio of height to thyromental, neck circumference, thyrosternal distance, hyomental distance at full head extension (FHE) and at neutral position (NP), ratio of neck circumference to thyromental distance and ratio of hyomental distance FHE to hyomental distance NP. The commonly used predictive tests head extension, mouth opening, upper lip bite test and Mallampati class were also measured.
The laryngoscopic view was classified according to the Cormack-Lehane Grade (1-4). Difficult laryngoscopy was defined as Cormack-Lehane Grade 3 or 4. Years of experience of the anaesthesiologists were recorded, as well as the number of tries needed to intubate the patient.
The optimal cut-off points for each predictive tests were identified by using receiver operating characteristic analysis. Sensitivity, specificity and positive predictive value and negative predictive value (NPV) were calculated for each test. Multivariate analysis with logistic regression, including all variables, was used to create a predictive model. Comparisons between genders were also performed to explore possible differences in diagnostic value and cut-off points. Finally, the years of experience of the clinician and the number of tries needed to intubate the patient were compared to assess risk of bias.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 1142
- Adult patients
- BMI less than 35 kg/m2
- No known neck or airway pathology
- Scheduled for surgical procedures under general anaesthesia with tracheal intubation
- Age less than 18 years
- BMI higher than 35 kg/m2
- Obvious airway malformations
- Need for rapid sequence induction/intubation under cricoid pressure
- Awake intubation
- Cervical spine pathology requiring specific manipulation
- Obstetric cases
Study & Design
- Study Type
- OBSERVATIONAL
- Study Design
- Not specified
- Primary Outcome Measures
Name Time Method Difficult laryngoscopy classification using Cormack-Lehane Grade immediate Assessment of difficult laryngoscopy at the time of the airway management procedure. Classified as Grade I - visualization of entire laryngeal aperture, grade II - visualization of only posterior commissure of laryngeal aperture, grade III - visualization of only epiglottis, grade IV - visualization of just the soft palate.
- Secondary Outcome Measures
Name Time Method Thyromental distance measured in cm with a measuring tape immediate The distance from the mentum to the thyroid notch while the patient's neck is fully extended and the mouth closed
Thyrosternal distance calculated in cm immediate Calculated from the subtraction: sternomental (cm) minus thyromental (cm)
Upper lip bite test immediate Classified as class I - lower incisors can bite the upper lip above the vermilion line, class II - lower incisors can bite the upper lip below the vermilion line and class III - lower incisors cannot bite the upper lip.
Head extension measured in degrees with goniometer immediate The patient was asked to hold head erect, facing directly to the front, then asked to extend the head maximally and the examiner estimated the angle traversed by the occlusal surface of upper teeth using a goniometer.
Ratio of neck circumference to thyromental distance immediate Calculated ratio of the neck circumference to the aforementioned thyromental distance
Hyomental distance at full head extension (FHE) measured in cm with a measuring tape immediate The distance from the mentum to the hyoid bone while the patient's neck is fully extended and the mouth closed
Hyomental distance at neutral position (NP) measured in cm with a measuring tape immediate The distance from the mentum to the hyoid bone while the patient's neck is in neutral position and the mouth closed
Ratio of hyomental distance at FHE to hyomental distance at NP immediate Calculated ratio of the aforementioned variables
Mallampati class immediate Classified as class I - soft palate, fauces, uvula, and pillars seen, class II - soft palate, fauces, and uvula seen, class III - soft palate and base of uvula seen and class IV - soft palate not visible.
Neck circumference measured in cm with a measuring tape immediate Measurement at the level of the cricoid cartilage while the patient's neck is in neutral position
Mouth opening measured in cm with a measuring tape immediate The distance between the upper and lower incisors with the mouth fully open
Sternomental distance measured in cm with a measuring tape immediate The distance from the suprasternal notch to the mentum while the patient's neck is fully extended and the mouth closed
Ratio of height to thyromental distance immediate Calculated ratio of the height in cm to the aforementioned thyromental distance