[The laryngeal mask airway in the difficult intubation. The results of a prospective study]

The laryngeal mask airway (LMA) was prospectively used in patients who were difficult to intubate to evaluate whether it improves ventilation compared to a face mask, facilitates fibreoptic intubation, and how often blind intubation would be possible.

In a university hospital, 30 patients who were difficult to intubate (35 operative procedures) and 50 normal subjects were investigated; 23 patients had had radical resection of a facial tumor with irradiation at a previous time and 7 could not be intubated conventionally (grade 3 and 4 visibility of the larynx according to Cormack [14]). Blind intubation was attempted with a bent bougie, a 6.0-mm uncuffed tube, or a straight bougie.

Insertion of the LMA was possible in all except 1 patient with a mouth opening of 1 cm. Ventilation via the LMA was always excellent and, for tumor patients, superior to a face mask. In tumor patients, leak pressure was higher than in patients with normal cervical anatomy either with or without difficult intubation conditions (25.2 +/- 7.9, P < 0.05, vs. 20.8 +/- 4.4 vs. 20.6 +/- 4.9 cmH2O; n.s.; Fig. 2). Fibreoptic intubation through the LMA was successful in all cases and easier than via a nasal or oral route. Blind intubation was successful in 22% of difficult to intubate patients and 19% of normals, mainly using a 6.0 mm uncuffed endotracheal tube. Substitution of an uncuffed oral tube inserted via the LMA by a nasal endotrachel tube using a reinforced stomach tube is described (Fig. 4).

The LMA improves ventilation, facilitates fibreoptic intubation, and offers the possibility for blind endotracheal intubation in difficult to intubate patients. Blind intubation though the LMA has to be practised extensively to have a high success rate. The LMA represents an additional aid for the anaesthetic management of patients who are difficult to intubate.