[Fiber optic intubation using a modified laryngeal mask. Report of experiences with use in 105 patients]

This study was made to investigate the suitability of a modified laryngeal mask airway as an aid for fibreoptic endotracheal intubation in patients with a difficult airway. We used a laryngeal mask airway split lengthwise on its convex site, the incision going from a point corresponding to the teeth down to the base of the cuff. The cuff remains uncut. By this modification it is possible to ventilate an anaesthetised patient and to pass down a fibreoptic bronchoscope via splitting of the laryngeal mask airway into the trachea at the same time. An endotracheal tube of any diameter already mounted over the bronchoscope is then guided into the trachea. The feasibility of this technique was tested and haemodynamic reactions and changes of the parameters of respiration were recorded.

This technique was used in 105 patients, 68 male and 37 female, mean age 34 years, when difficult intubation was expected or occurred. Blood pressure, pulse rate and peripheral oxygen saturation was recorded on arrival in the anaesthetic room, after induction of anaesthesia, during and after fibreoptic endotracheal intubation. The respiratory minute volume was measured after insertion of the laryngeal mask airway and during the course of fibreoptic intubation. The time needed was recorded.

In all cases endotracheal intubation was successful using this technique. The time needed was between 4 and 16 minutes. There was a statistically significant increase in peripheral oxygen saturation and decrease of the pulse rate after induction of anaesthesia. There were no further significant changes of the recorded haemodynamic parameters and the oxygen saturation during and after fibreoptic intubation compared to the results after induction of anaesthesia.

It could be demonstrated that a fibreoptic intubation is possible in cases of a difficult airway using the technique described here. There is no haemodynamic strain on the patient. This method can be carried out without pressure of time and without to endanger the patient by hypoxia as the patient can be ventilated during the fibreoptic intubation. In cases of impossible intubation and insufficient mask ventilation it can be tried to establish ventilation and to avoid a emergency surgical airway or transtracheal jet ventilation by using this technique.