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Inter-observer reliability of ten tests used for predicting difficult tracheal intubation


Purpose — To determine inter-observer reliability of ten preoperative airway assessment tests used for predicting difficult tracheal intubation. 

Method — We prospectively assessed 59 patients undergoing elective surgery requiring tracheal intubation at a large metropolitan teaching hospital. Two experienced observers independently conducted the airway assessment tests on the same group of patients. Inter-observer reliability was examined using Kappa (K) and intraclass correlation coefficient (ICC). 

Results — Two tests — mouth opening (ICC = 0.93) and chin protrusion (ICC = 0.89) — had excellent inter-observer reliability. Seven tests — thyromental distance (thyromental distance (ICC = 0.74), subluxation (K = 0.66), atlanto-occipital extension distance (ICC = 0.67) and angle (K = 0.66), profile classification (K = 0.58), ramus length (ICC = 0.53), oropharyngeal best view (K = 0.49) — were moderately reliable. One test — Mallampati technique of assessing oropharyngeal view (K = 0.31) — had poor reliability.

Conclusion — Many of the preoperative airway tests have only moderate inter-observer reliability. This may provide some insight into why previous research has failed to show that the tests accurately predict difficult tracheal intubation.



Karkouti K, Rose DK, Ferris LE, Wigglesworth DF, Meisami-Fard T, Lee H. Can J Anaesth. 1996; 43(6):554-9.

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