Prediction of Difficult Laryngoscopy in Obese Patients by Ultrasound of Tongue Thickness: A Prospective Observational Study
Abstract
Objective: Tongue thickness, measured by ultrasonography, has been used to predict difficult tracheal intubation in normal-weight patients. This study investigated the predictive value of tongue thickness for difficult laryngoscopy in obese Thai patients.
Material and Methods: Eighty-five obese adult patients (body mass index [BMI] ≥30 kg/m2) who underwent elective general anesthesia with tracheal intubation were enrolled in the study between January and May 2019. Tongue thickness was measured preoperatively using submental ultrasonography in the median sagittal plane, both in the closed- and open-mouth supine positions. The primary outcome was a difficult laryngoscopy, defined as a laryngoscopic view of grade 3 or 4 on the Cormack-Lehane scale. Multivariate logistic regression and receiver operating characteristic curve were used for the statistical analysis.
Results: The mean BMI of the 85 patients was 38.68 kg/m² (range: 30.00–64.96 kg/m²). The incidence of difficult laryngoscopy was 17.65% (15/85 patients). Univariate analysis showed that a tongue thickness greater than 58 mm in the closed-mouth position was an independent predictor of difficult laryngoscopy, with a sensitivity of 0.73 and specificity of 0.63. Multiple logistic regression analysis revealed that age 45 years or older and an inter-incisor gap less than 45 mm were also predictors for difficult laryngoscopy. The combination of these three factors improved the prediction of difficult laryngoscopy, yielding a sensitivity of 0.87 and specificity of 0.67.
Conclusion: Tongue thickness greater than 58 mm, measured in the closed-mouth position by ultrasonography, can predict difficult laryngoscopy in obese Thai patients.
Keywords
Full Text:
PDFReferences
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;103:429–37.
Horner RL, Mohiaddin RH, Lowell DG, Shea SA, Burman ED, Longmore DB, et al. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J 1989;2:613-22.
Javaherforoosh F, Safaii S. Comparison of the sensitivity and specificity of different tests to determine difficult intubation. WJPR 2015;13:203-10.
Kristensen MS, Teoh WH, Graumann O, Laursen CB. Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae. Insights Imaging 2014;5:253-79.
Kundra P, Mishra SK, Ramesh A. Ultrasound of the airway. Indian J Anaesth 2011;55:456- 62.
Ezri T, Gewurtz G, Sessler DI, Medalion B, Szmuk P, Hagberg, et al. Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue. Anaesthesia 2003;58:1111-4.
Wojtczak JA. Submandibular sonography: assessment of hyomental distances and ratio, tongue size, and floor of the mouth musculature using portable sonography. J Ultrasound Med 2012;31:523–8.
Koay CK. Difficult tracheal intubation–analysis and management in 37 cases. Singapore Med J 1998;39:112–4.
Ovassapian A, Glassenberg R, Randel GI, Klock A, Mesnick PS, Klafta JM. The unexpected difficult airway and lingual tonsil hyperplasia: a case series and a review of the literature. Anesthesiology 2002;97:124–32.
Yao W, Wang B. Can tongue thickness measured by ultrasonography predict difficult tracheal intubation? BJA 2017;118:601-9.
Mallampati SR, Gatt SP, Gugino LD, Desai SP, Waraksa B, Freiberger D, et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 1985;32:429–34.
Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105-11.
Apfelbaum JL, Hagberg CA, Caplan RA, Biltt CD, Connis RT, Nickinovich DG, 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 2013;118:251-70.
Lundstrøm LH, Møller AM, Rosenstock C, Astrup G, Wetterslev J. High body mass index is a weak predictor for difficult and failed tracheal Intubation: a cohort study of 91,332 consecutive patients scheduled for direct laryngoscopy registered in the Danish Anesthesia Database. Anesthesiology 2009;110:266–74.
Lundstrøm LH, Vester-Andersen M, Møller AM, Charuluxananan S, L’Hermite J, Wetterslev J. Poor prognostic value of the modified Mallampati score: a meta-analysis involving 177 088 patients. BJA 2011;107:659-67.
Budde AO, Desciak M, Reddy V, Falcucci OA, Vaida SJ, Pott LM. The prediction of difficult intubation in obese patients using mirror indirect laryngoscopy: a prospective pilot study. J Anaesthesiol Clin Pharmacol 2013;29:183-6.
Rastogi A, Singh AK, Srivastava D, Kannaujia AK, Singh TK, Mishra P. Evaluation of ultrasound measured tongue thickness, tongue thickness-thyromental distance ratio, and skin to epiglottis distance in predicting unanticipated difficult laryngoscopy. J Anaesthesiol Clin Pharmacol 2025;41:151-7.
Sajitha NS, Kachru N, Yadav U, Yadav R. Evaluation of ultrasound guided measurement of tongue thickness in predicting difficult tracheal intubation in patients undergoing elective surgery: a cross sectional study. AACC 2023;9:201-5.
Furia JS, Nadkarni MM. Ultraound based assessment of tongue thickness for prediction of difficult laryngscopy and intubation J Anaesthesiol Clin Pharmacol 2024;40:235-41.
Refbacks
- There are currently no refbacks.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.