Association between factors predicting and assessing the airway and use of intubating laryngeal mask airway.

BACKGROUND AND OBJECTIVE: The Intubating Laryngeal Mask Airway FastrachTM (ILMA) has been used with success in difficult intubation cases. The purpose of this study is to evaluate the effect of mouth opening, Mallampati classification, thyromental distance and Cormack-Lehane Grade, on the ease of ILMA use.

METHODS: Eighty one patients ASA I-II, were assessed preoperatively for mouth opening, Mallampati classification and thyromental distance. After induction with propofol and rocuronium, the first investigator recorded Cormack-Lehane Grade by direct laryngoscopy. Subsequently an appropriate size ILMAwas inserted by the second investigator and correct placement was confirmed by adequate ventilation and normal capnogram. A maximum of three ILMA insertion attempts were allowed and the number was recorded. Then blind intubation was attempted and classified as follows, according to Intubation Difficulty Grade (IDG): IDG-1: intubation succeeded: at first attempt requiring no or minor ILMA manipulations. IDG-2: intubation succeeded at second attempt requiring major ILMA manipulations or size change. IDG-3: intubation failed after the second attempt or oesophageal intubation occurred at either attempt. In failure of the technique direct laryngoscopy was the alternative approach.

RESULTS: Success rates in insertion of ILMA and in blind intubation were 100% and 92.6% respectively. No difference was found between Cormack-Lehane Grade I-II and II-IV or Mallampati classification and number of ILMA insertion attempts or IDG. There was also no correlation between mouth opening, or thyromental distance and number of ILMA insertion attempts or IDG. It is concluded that easiness of ILMA use is irrelevant to mouth opening, thyromental distance, Mallampati classification or Cormack-Lehane Grade.