Use of the laryngeal mask during emergence from anaesthesia

Sir: Stimulatory effects of the presence of a tracheal tube during emergence from anaesthesia can be minimized when the trachea is extubated while the patient is still anaesthetized. However, supraglottic airway obstruction may frequently occur after extubation. Several authors have suggested that removal of the tracheal tube and subsequent insertion of a laryngeal mask, while the patient is still deeply anaesthetized, might minimize the stress response, while providing a patent airway during emergence from anaesthesia [1-4]. However, after tracheal extubation, insertion of the laryngeal mask might fail. This can be avoided by a simple method - insertion of the laryngeal mask before tracheal extubation (Fig. 1). Because the distal part of the laryngeal mask is inserted into the hypopharynx [5], the presence of a tracheal tube in theory does not prevent the insertion of the mask. With this method, even if insertion of the mask has failed, a patent airway will not be lost; the attempt at insertion of the mask may be repeated or abandoned.Fig. 1: Use of the laryngeal mask during emergence from anaesthesia. At the end of surgery, the laryngeal mask is inserted while a tracheal tube is still in place. The tracheal tube is then removed, the cuff of the laryngeal mask inflated and the breathing system is connected to the laryngeal mask.I used this method in 10 patients. At the end of surgery, nitrous oxide was discontinued but isoflurane was maintained at 2-3%. The laryngeal mask was always inserted without difficulty at the first attempt while a tracheal tube was still in place. The tracheal tube was then removed while the laryngeal mask was held in position, and the cuff of the mask was inflated. After tracheal extubation, it was always easy to ventilate the lungs through the laryngeal mask. In no patient did any respiratory complication, such as straining or laryngospasm, occur during this period. Neuromuscular blockade was then antagonized. When sufficient spontaneous breathing had returned, oxygen was given through a T-piece and the laryngeal mask, and the patient was transferred to the recovery room. No airway obstruction occurred during transport. When the patient had regained consciousness and responded to verbal command, the mask was removed, which did not cause any respiratory problems, including coughing. In conclusion, I feel that it is practical to insert the laryngeal mask before tracheal extubation and use the laryngeal mask during emergence from anaesthesia. The use of the laryngeal mask after tracheal extubation may be particularly useful for patients in whom stress responses can be detrimental, such as those who have undergone eye surgery. T. ASAI Department of Anesthesiology, Kansai Medical University, Moriguchi City, Osaka, Japan