Letter to the Editor: In Response
In the above two letters, Dr. Ball and Drs. Kessell and Gray both emphasize that the laryngeal mask airway (LMA) is well tolerated in the airway during emergence from anesthesia. Accordingly, when the LMA has been used as a conduit for placement of the endotracheal tube (ETT) in patients presenting with a difficult airway, they recommend that the LMA not be removed during surgery to avoid inadvertant dislodgement of the ETT. Then the LMA can be removed with the ETT at the time of awake tracheal extubation.
While leaving the LMA in situ with the ETT may be appropriate for shorter surgeries, what should be done during longer surgical procedures and/or the situation of planned postoperative intubation (e.g., need for prolonged airway protection or mechanical ventilatory support in the intensive care unit)? There are several concerns with prolonged LMA use. First, presence of the LMA in the supraglottic pharynx has potential for pressure injury to soft tissue structures. In particular, there have been several reports of injury to the hypoglossal nerve [1,2] and the lingual nerve  attributed to pressure injury from the LMA. Conceivably, the concurrent presence of the ETT through the LMA could exacerbate these pressure injuries. Certainly, if the LMA is to be left in situ, the cuff of the LMA should be deflated because it serves no purpose. Second, the LMA may predispose to gastroesophageal reflux even after removal of the LMA , although pharyngeal regurgitation does not seem to be present [5,6]. Third, the presence of the LMA complicates placement of the oro- or nasogastric tube. Finally, at least in American intensive care units, nurses are unfamiliar with use of the LMA, which may predispose to adverse events such as device malposition or overinflation of the cuff. Oral hygiene (including suctioning) is also more difficult.
I maintain that simple and relatively safe techniques are available to remove the LMA conduit and retain ETT position, including the use of another tracheal tube to buttress and hold the ETT steady as the LMA is withdrawn over it , the use of a split LMA, which can be peeled off the ETT , and the short-shaft, large-bore LMA [8,9], which allows grasping and steadying of the ETT in the pharynx as the LMA is removed. The short-shaft, large-bore LMA also permits tracheal intubation with a larger ETT. Accordingly, when the LMA has been used as a conduit for placement of the ETT in the difficult airway and conditions for prolonged positioning of the LMA exist, I believe that the LMA (along with its potential risks) should be removed, given the minimal chance of ETT dislodgement.
Peter H. Breen, MD, FRCPC
Department of Anesthesiology; University of California, Irvine; Orange, CA 92868
1. King C, Street MK. Twelfth cranial nerve paralysis following use of a laryngeal mask airway. Anaesthesia 1994;49:786-7.
2. Nagai K, Sakuramoto C, Goto F. Unilateral hypglossal nerve paralysis following the use of the laryngeal mask airway. Anaesthesia 1994;49:603-4.
3. Laxton CH. Lingual nerve paralysis following the use of the laryngeal mask airway. Anaesthesia 1996;51:869-70.
4. Owens TM, Robertson P, Twomey C, et al. The incidence of gastroesophageal reflux with the laryngeal mask: a comparison with the face mask using esophageal lumen pH electrodes. Anesth Analg 1995;80:980-4.
5. Brimacombe JR. Gastroesophageal reflux with the laryngeal mask [letter]. Anesth Analg 1996;82:215.
6. Joshi GP, Morrison SG, Okonkwo NA, White PF. Continuous hypopharyngeal pH measurements in spontaneously breathing anesthetized outpatients: laryngeal mask airway versus tracheal intubation. Anesth Analg 1996;82:254-7.
7. Breen PH. Simple technique to remove laryngeal mask airway "guide" after endotracheal intubation [letter]. Anesth Analg 1996;82:1302.
8. Brimacombe J. The split laryngeal mask and the difficult airway [letter]. Acta Anaesthesiol Scand 1994;38:744.
9. Kapila A, Addy EV, Verghese C, Brain AIJ. Intubating laryngeal mask airway: a preliminary assessment of performance [abstract]. Br J Anaesth 1995;75:228-9P.