Brazilian Journal of Anesthesiology
Brazilian Journal of Anesthesiology
Original Investigation

Upper airway angle and glottic height: a prospective cohort to evaluate two new features for airway prediction

Clístenes Crístian de Carvalho, Danielle Melo da Silva, Marina Sampaio Leite, Lívia Barboza de Andrade

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Predicting difficult direct laryngoscopies remains challenging and improvements are needed in preoperative airway assessment. We conceived two new tests (the upper airway angle and the glottic height) and assessed their association with difficult direct laryngoscopies as well as their predictive performance.

A prospective cohort was conducted with 211 patients undergoing general anesthesia for surgical procedures. We assessed the association between difficult laryngoscopies and modified Mallampati Test (MMT), Upper Lip Bite Test (ULBT), Mandibular Length (ML), Neck Circumference (NC), Mouth Opening (MO), Sternomental Distance (SMD), Thyromental Distance (TMD), Upper Airway Angle (UAA), and Glottic Height (GH). We also estimated their predictive values.

Difficult laryngoscopy was presented by 12 patients (5.7%). Six tests were significantly associated with difficult laryngoscopies and their area under the ROC curve, and 95% CIs were as follows: UAA = 88.82 (81.86–95.78); GH = 86.43 (72.67–100); ML = 83.75 (72.77–94.74); NC = 79.17 (64.98–93.36); MO = 65.58 (45.13–86.02); and MMT = 77.89 (68.37–87.41).

We have found two new features (the UAA and the GH) to be significantly associated with the occurrence of difficult direct laryngoscopies. They also presented the best predictive performance amongst the nine evaluated tests in our cohort of patients. We cannot ensure, however, these tests to be superior to other regularly used bedside tests based on our estimated 95% CIs.


Airway management;  Laryngoscopy;  Predictive values of tests;  Sensitivity and specificity


1 TM Cook, N Woodall, J Harper, J Benger, Fourth National Audit Project Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia Br J Anaesth, 106 (2011), pp. 617-631

2 T Tikka, OJ. Hilmi Upper airway tract complications of endotracheal intubation Br J of Hosp Med, 80 (2019), pp. 441-447

3 EU Umobong, PH. Mayo Critical Care Airway Management Critl Care Clin, 34 (2018), pp. 313-324

4 A Vannucci, LF. Cavallone Bedside predictors of difficult intubation : a systematic review Minerva Anestesiol, 82 (2016), pp. 69-83

5 P. Baker Assessment Before Airway Management Anesthesiol Clin, 33 (2015), pp. 257-278

6 SM. Yentis Predicting difficult intubation–worthwhile exercise or pointless ritual? Anaesthesia, 57 (2002), pp. 105-109

7 JJ Pandit, T. Heidegger Putting the “point” back into the ritual: a binary approach to difficult airway prediction Anaesthesia, 72 (2017), pp. 283-288

8 T Shiga, Z Wajima, T Inoue, A. Sakamoto Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance Anesthesiology, 103 (2005), pp. 429-437

9 AK Nørskov, CV Rosenstock, J Wetterslev, G Astrup, A Afshari, LH. Lundstrøm Diagnostic accuracy of anaesthesiologists’ prediction of difficult airway management in daily clinical practice: A cohort study of 188 064 patients registered in the Danish Anaesthesia Database Anaesthesia., 70 (2015), pp. 272-281

10 WH Teoh, MS. Kristensen Prediction in airway management: what is worthwhile, what is a waste of time and what about the future? Br J Anaesth, 117 (2016), pp. 1-3

11 CC de Carvalho, DM da Silva, AD de Carvalho Junior, et al. Pre-operative voice evaluation as a hypothetical predictor of difficult laryngoscopy Anaesthesia, 74 (2019), pp. 1147-1152

12 JL Apfelbaum, CA Hagberg, RA Caplan, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway Anesthesiology, 118 (2013), pp. 251-270

13 C Frerk, VS Mitchell, AF McNarry, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults Br J Anaesth, 115 (2015), pp. 827-848

14 A Higgs, BA McGrath, C Goddard, et al. Guidelines for the management of tracheal intubation in critically ill adults Br J Anaesth, 120 (2018), pp. 23-52

15 JA Law, LV Duggan, M Asselin, et al. Canadian Airway Focus Group updated consensus – based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway Can J Anaesth, 68 (2021), pp. 1405-1436

16 TM. Cook A new practical classification of laryngeal view Anaesthesia, 55 (2000), pp. 274-279

17 K Gupta, PK. Gupta Assessment of difficult laryngoscopy by electronically measured maxillo-pharyngeal angle on lateral cervical radiograph: A prospective study Saudi J Anaesth, 4 (2010), pp. 158-162

18 M Naguib, T Malabarey, RA Alsatli, Damegh S Al, AH Samarkandi Predictive models for difficult laryngoscopy and intubation. A clinical, radiologic and three-dimensional computer imaging study Can J Anaesth, 46 (1999), pp. 748-759

19 CC Carvalho, JM Santos Neto, FA de Orange Predictive performance of thyromental height for difficult laryngoscopies in adults: a systematic review and meta-analysis Braz J Anesthesiol (2021), 10.1016/j.bjane.2021.06.015 Online ahead of print

20 F Etezadi, A Ahangari, H Shokri, et al. Thyromental height: A new clinical test for prediction of difficult laryngoscopy Anesth Analg, 117 (2013), pp. 1347-1351

21 RS Cormack, J. Lehane Difficult tracheal intubation in obstetrics Anaesthesia, 39 (1984), pp. 1105-1111

22 YOUNG JRB SAMSOON GLT Difficult tracheal intubation: a retrospective study Anaesthesia, 42 (1987), pp. 487-490

23 I Schindelin j, Arganda-Carreras, E Frise, et al. Fiji: na open-source platform for biological-image analysis Nat Methods, 9 (2012), pp. 676-682

24 R Core Team R: A language and environment for statistical computing R Foundation for Statistical Computing, Vienna, Austria (2019) URL (accessed 08/12/2019)

25 Dean AG, Sullivan KM, Soe MM. OpenEpi: Open-Source Epidemiologic Statistics for Public Health, 2013. (accessed 09/15/2019).

26 D Roth, NL Pace, A Lee, et al. Bedside tests for predicting difficult airways: an abridged Cochrane diagnostic test accuracy systematic review Anaesthesia, 74 (2019), pp. 915-928

27 MA Bujang, TH. Adnan Requirements for Minimum Sample Size for Sensitivity and Specificity Analysis J Clin Diagn Res, 10 (2016), pp. YE01-YE06

28 C Carvalho, D da Silva, M. Leite Dataset from a Cohort study assessing the association between difficult laryngoscopies and two new features (the Upper Airway Angle and the Glottic Height Mendeley Data (2021), 10.17632/vvkx4hjmp3.1

29 ME Detsky, N Jivraj, NK Adhikari, et al. Will This Patient Be Difficult to Intubate?: The Rational Clinical Examination Systematic Review JAMA, 32 (2019), pp. 493-503

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