Difficulties with placement of disposable laryngeal mask airways

We write to describe our recent experiences with the disposable laryngeal mask airway, a batch of which were recently purchased to provide an additional means of securing an airway in the maternity unit should a failed intubation arise. We used this for the first time under a controlled situation when one of us (A.M.H) was asked to anaesthetise a patient for evacuation of retained products of conception in maternity theatres. As she was fully starved, slim and of 12 weeks gestation, she did not require tracheal intubation. We found that, despite an adequate dose of fentanyl and propofol, a size 3 disposable laryngeal mask airway would not pass beyond the upper part of the pharynx and the stiffness of the material did not allow any adjustment of its position once at this point. The procedure was completed uneventfully using mask ventilation. M.K.W later tried to use the disposable laryngeal mask airway on two patients presenting for elective surgery. The first had no outward signs suggestive of potential airway problems; however, laryngeal mask airway insertion was unexpectedly difficult and was only accomplished when it was placed upside down and rotated through 180°. The second patient had a potential difficult airway (hypoplastic mandible, thyromental distance of 3 cm) and in this case the laryngeal mask airway could not be passed beyond the hard palate. Its use was abandoned and a conventional laryngeal mask airway was then placed easily in this patient. Because of these experiences we have replaced all the disposable laryngeal mask airways in our maternity theatre with the re-usable ones with which we are all familiar. We feel that disposable laryngeal mask airways are more difficult to insert, primarily due to the additional stiffness of the device, and that their use in the emergency situation in our unit is unhelpful to trainees and consultants alike. Of particular concern was the contrast between the ease of use of the re-useable vs. the disposable laryngeal mask airway in the last patient. We would be interested to hear from other anaesthetists who have used this device.