To the Editor:—
Impaction of the distal cuff with the glottic inlet is a well-recognized complication of laryngeal mask airway insertion, but it is rarely reported because it is frequently mistaken for and/or associated with reflex glottic closure and requires fiberoptic assessment for confirmation.1There is little information about the incidence, with one study reporting that it occurred in 4% of anesthetized patients2and another reporting that it occurred in 2% of sedated patients.3In principle, it is more likely to occur if the distal cuff follows an anterior path, the larynx is posteriorly placed, or the cuff presents a broad leading edge. We describe three cases of airway obstruction after laryngeal mask insertion where rapid fiberoptic assessment differentiated between impaction and glottic closure and facilitated prompt and appropriate treatment.
The first patient was a 34-yr-old man with an American Society of Anesthesiologists physical status of I who was undergoing minor general surgery with no anticipated airway problems. Induction was with 3 mg/kg propofol and 1 μg/kg fentanyl. A size 5 disposable LMA-Unique ™ (Laryngeal Mask Company, Ltd., Mahe, Seychelles) was easily inserted by a skilled user using the standard technique, and the cuff was inflated to an intracuff pressure of 60 cm H2O. Ventilation was impossible, with airway obstruction and an audible oropharyngeal air leak at high airway pressures. There was no coughing or bucking. Fiberoptic inspection was completed within 30 s and showed that the distal cuff had impacted with the glottic inlet and the vocal cords were open (fig. 1). The LMA-Unique ™ was removed and reinserted, and a clear airway was obtained. Repeat fiberoptic assessment showed that the distal cuff was sitting in its correct position in the hypopharynx (fig. 1). There were no other complications, and the minimal oxygen saturation measured by pulse oximetry (Spo2) was 95%.
The second patient was a 41-yr-old man undergoing minor urologic surgery. Induction, insertion technique, and cuff inflation and type/size of the laryngeal mask airway were identical to the first case, but in addition, the patient coughed during insertion. Ventilation was impossible with an audible oropharyngeal leak at low airway pressures. The fiberoptic finding, management, and outcome were identical to the first case.
The third patient was a 56-yr-old woman with an American Society of Anesthesiologists physical status of II who was undergoing minor orthopaedic surgery with no anticipated airway problems. Induction was with 2.5 mg/kg propofol and 10 μg/kg alfentanil. A size 4 LMA-Classic ™ (Laryngeal Mask Company, Ltd.) was easily inserted by a skilled user using the standard recommended technique, and the cuff was inflated with 15 ml air. Ventilation was impossible, with airway obstruction and an audible oropharyngeal air leak at high airway pressures. There was no coughing or bucking, but there was a slight movement of the foot during insertion. Fiberoptic inspection was completed within 20 s and showed that the distal cuff was sitting in its correct position in the hypopharynx but the vocal cords were closed. An additional 100 mg propofol was administered, continuous positive airway pressure was applied, and the airway obstruction was relieved within a minute. There were no other complications, and the minimal Spo2was 98%.
We strongly recommend the rapid use of the fiberoptic scope to assess the etiology of airway obstruction after the insertion of a laryngeal mask, because the treatment for impaction is reinsertion and the treatment for reflex glottic closure is to deepen anesthesia or give a muscle relaxant, unless associated with a transient swallow, in which case, the glottis will spontaneously reopen within 20–30 s. On occasion, impaction will also lead to reflex glottic closure, in which case both treatments may be required. If reinsertion using a different approach does not correct the problem of glottic impaction, the simplest solution is to place a guide in the esophagus and railroad the LMA-ProSeal ™ (Laryngeal Mask Company Ltd., Nicosia, Cyprus) into position along its drain tube.4,5
*Catharina Hospital–Brabant Medical School, Eindhoven, The Netherlands. email@example.com