The ProSeal™ laryngeal mask airway (PLMA) insertion using a gum-elastic bougie placed in the oesophagus as a guide has a high first-attempt success rate (>99%) and a potential role in difficult airway management . On those occasions when it fails, the aetiology is usually laryngospasm, severe epiglottic downfolding, glottic/supraglottic compression or cuff infolding . Most of these problems can be identified and rectified by following an algorithm that we recently proposed . We present a case illustrating another cause of failure.
An obese 57-yr-old male (height 165 cm, weight 106 kg) with a history of failed laryngoscope-guided tracheal intubation but easy face mask ventilation presented for elective intra-abdominal surgery. He refused awake tracheal intubation. The airway management plan was to perform optimal laryngoscopy and to insert a tracheal tube if the vocal cords were seen, or a ProSeal LMA if not seen. The patient was pre-oxygenated until the end-tidal O2 was >90%. Induction was with midazolam 2 mg, alfentanil 1 mg and propofol 2.5 mg kg−1. Face mask ventilation was easy but required a Guedel airway. Muscle relaxation was with atracurium 50 mg. At laryngoscopy, the epiglottis/glottis/hypopharynx could not be seen and the straight end of the gum-elastic bougie was directed blindly and without resistance along the right posterior pharyngeal wall until the distal portion was 10 cm beyond the laryngopharynx. A size 5 ProSeal LMA was railroaded into position along its drain tube and the cuff inflated with 20 mL of air. Ventilation, however, was impossible with high airway pressures and airway obstruction. The proposed algorithm was followed, but the mechanical obstruction tests and recommended manoeuvres failed to solve the problem. Remembering that ‘whatever remains, however improbable, must be the truth’, the gum-elastic bougie was advanced and resistance was encountered after approximately 10 cm, indicating tracheal placement. The ProSeal LMA was rapidly exchanged for a tracheal tube, which passed easily along the bougie and provided unobstructed ventilation once the bougie was removed. The lowest SPO2 was 94% and there were no other problems.
An alternative solution would have been to reinsert the bougie along the left posterior pharyngeal wall to reposition it in the oesophagus. Based on an audit of our experience with the gum-elastic bougie-guided technique during routine use, we estimate that the frequency of inadvertent tracheal placement is around 1: 5000. In principle, inadvertent tracheal placement is more likely in the difficult airway scenario, as the hypopharynx may not been seen at laryngoscopy. The proposed algorithm has been modified to accommodate this rare but important scenario (Fig.).
1Department of Anaesthesia and Intensive Care, James Cook University, Cairns Base Hospital, Cairns, Australia
2Department of Anaesthesia and Intensive Care Medicine, Medical University Innsbruck, Innsbruck, Austria
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