The relevance of clinical and radiological measurements in predicting difficulties in fibreoptic orotracheal intubation in adults

Resistance to the passage of the tracheal tube has been reported to occur i n up to 36% of patients subjected to orotracheal fibreoptic intubation. In this prospective study we assessed five radiological measurements of the up per airway in an attempt to find anatomical causes of obstruction to passag e of the tube. Forty-nine patients undergoing fibreoptic orotracheal intuba tion under general anaesthesia mere studied. Pre-operatively, the Mallampat i grade and the thyromental distance were assessed. The plain films, CT sca ns or MR images of the cervical spine were used for measurement of the posi tion of the vocal cords, the length of the epiglottis and the size of the t ongue. The resistance to the passage of the tube was graded as none, mild, moderate or severe. The length of the epiglottis and the size of the tongue , but not the position of the vocal cords, had positive correlations with t he severity of impingement. The pre-operative bedside tests did not correla te with difficulties in fibreoptic intubation.