Difficult tracheal intubation--analysis and management in 37 cases.Singapore Med J. 1998 Mar; 39(3):112-4.SM
To analyse the anatomical features of difficult airways encountered during general anaesthesia and study how difficult intubation was circumvented during anaesthesia in our local population.
Difficult intubation was defined as failure to visualise the larynx during laryngoscopy after neck flexion and external cricoid pressure was applied. All cases of difficult intubation collected over 1 1/2 years during general anaesthesia were recorded prospectively and analysed.
Thirty-seven cases of difficult intubation were identified among 5,379 cases of general anaesthesia requiring endotracheal intubation. 40.5% of the cases were not expected to be difficult pre-operatively. 5.4% of the cases were Lehane II, 91.9% Lehane III and 2.7% Lehane IV. The anatomical features encountered included receding chin, limited mouth opening, limited neck extension, abnormal dentition, short thyromental distance, large tongue, supraglottic mass and floppy epiglottis. Gum elastic bougie was commonly used to overcome the intubation difficulties. Laryngeal mask, blind nasal tracheal intubation, fiberoptic bronchoscopic intubation and sometimes an alternative anaesthetic technique, such as regional anaesthesia, were resorted to.
Assessment of multiple anatomical features would improve prediction of difficult intubation. Assessment of receding chin, neck extension, mouth opening, teeth, tongue size, thyromental distance might pick up 81% of difficult airways. Unexpected problems with epiglottis and glottic inlet are the potential sources of danger that are difficult to predict pre-operatively.