Bleeding, Dysphagia, Dysphonia, Dysarthria, Severe Sore Throat, and Possible Recurrent Laryngeal, Hypoglossal, and Lingual Nerve Injury Associated with Routine Laryngeal Mask Airway Management: Where Is the Vigilance?

Dr. Reier’s aggressively titled letter demonstrates a lack of understanding of the aims of our study,1the laryngeal mask concept, and the ProSeal™  laryngeal mask airway (PLMA; Laryngeal Mask Company, Henley-on-Thames, United Kingdom) literature and exposes a deep-rooted, unfounded belief that the endotracheal tube (ETT) and facemask are the undisputed accepted standards for modern airway management. We will respond to each of his many points in turn.

First, Dr. Reier is incorrect in stating that sore throats were excluded if they did not cause constant pain, because most patients with a nonconstant sore throat had pain on swallowing or speaking and were therefore included in these morbidity categories.

Second, the use of terminology such as dysarthria  and dysphonia  is somewhat confusing because there are a variety of conflicting definitions used by researchers. It is essential that these terms are therefore defined when used. We defined dysphonia as difficulty/pain on speaking. Further analysis of our data reveals that all patients with dysphonia had pain on speaking, and none had any impairment of vocal function. Patients with airway morbidity symptoms were all followed up, and none of these symptoms persisted beyond 72 h.

Third, Dr. Reier suggests that patients with normal airways have minimal airway morbidity when treated with the facemask and ETT. Airway morbidity is indeed low for the facemask (although postoperative jaw pain is more common than the LMA-Classic ™[Laryngeal Mask Company, Henley-on-Thames, United Kingdom]2), but this is certainly not the case for the ETT. An analysis of studies comparing the LMA -Classic ™ and laryngoscope-guided tracheal intubation reveals that the incidence of sore throat is much higher for laryngoscope-guided tracheal intubation (39% vs.  17%; P < 0.00001; table 1). An article3and accompanying editorial4in the August 2003 issue of Anesthesiology highlight the dangers of routine tracheal intubation. The incidence of airway morbidity is similar for the PLMA and LMA -Classic ™.5 

Fourth, Dr. Reier considers that the etiology of airway morbidity with the PLMA was related to mucosal injury (abrasions during insertion and ischemia after insertion) and to regurgitation of gastric acid. Dr. Reier is clearly unaware of a study demonstrating that the PLMA exerts pressures against the surrounding mucosa that are lower than perfusion pressure6and that the PLMA protects the patient from regurgitation when correctly positioned.7By default, the most likely cause of airway morbidity with the PLMA is trauma during insertion. An important finding in our study was that trauma was less common with the gum elastic bougie–guided technique.1 

Fifth, Dr. Reier considers that the PLMA has no role in the emergent airway because it is too slow to insert and has an inadequate seal to deal with noncompliant lungs. He also claims, without citing evidence, that the majority of emergent airway patients have noncompliant lungs. We consider that 25–34 s—which was the average time from picking up the PLMA to successfully inserting it into the pharynx, establishing correct positioning, and establishing effective ventilation—is rapid enough for the emergent airway. The PLMA has a seal that is 10 cm H²O higher than that of the LMA -Classic ™,8which is more than adequate to ventilate even morbidly obese patients9and those undergoing laparoscopic surgery.10A recent study showed that digital insertion of the PLMA has a success rate similar to that of the LMA -Classic ™.11The LMA -Classic ™ has been recommended by the American Society of Anesthesiologists for the emergent airway since 1993.12Unlike the ETT, the LMA does not trigger bronchospasm,13so higher tidal volumes are possible for a given peak pressure for the LMA than for the ETT.

Sixth, Dr. Reier suggests that swapping a facemask with an oropharyngeal leak pressure of greater than 40 cm H²O for a PLMA with an oropharyngeal leak pressure of less than 25 cm H²O could prove fatal in the emergent airway. We never suggested making such an exchange in our article. However, to ventilate a patient with a facemask at airway pressures of greater than 40 cm H²O would inevitably lead to massive gastric dilatation (gastric insufflation begins with peak airway pressures of around 20 cm H²O7,14) unless cricoid pressure is simultaneous applied,14in which case insertion of a PLMA and passage of a gastric tube might reduce morbidity and mortality.

Seventh, Dr. Reier presents previously unpublished, non–peer- reviewed data suggesting that the facemask and ETT are superior to the PLMA in terms of success on the first attempt, insertion time, failure rate, visible blood, airway morbidity, and the need for an assistant. It is beyond the scope of this reply to debate all these points; suffice it to say that most of the data presented by Dr. Reier are totally at odds with the plentiful, peer-reviewed published data. For example, the incidence of sore throat for laryngoscope-guided tracheal intubation is more like 40% rather than 0.4% (table 1), and the incidence of sore throat with the facemask is more like 4%2,15than 0.1%. Also, such interstudy comparisons are difficult to interpret scientifically. Meaningful comparisons between the performance of the PLMA versus  the ETT and the facemask will have to await the results of properly conducted clinical trials. The benefits of the LMA -Classic ™ over the facemask and ETT, however, have been well established.16 

Finally, Dr. Reier states than the PLMA has a failure rate of 1.25% and always requires an assistant. In fact, there were no overall failures, because the other techniques succeeded if the primary technique failed. Matioc and Arndt demonstrate how that technique can be easily conducted without an assistant.

Matioc and Arndt’s excellent technique for gum elastic bougie–guided insertion of the PLMA without an assistant extends its range of use to resuscitation and other single-operator situations. We would like to add that the gum elastic bougie–guided technique has an extremely high success rate. The author and colleagues have used it in more than 6,000 patients, with a first-time insertion failure rate of 0.07% (n = 4; failure to position the PLMA in the pharynx), and a first-time ventilation failure rate of 0.5% (n = 28; failure to ventilate once in the pharynx). The etiology of first-time insertion failure was limited mouth opening (n = 3) and unexpected pharyngeal pathology (n = 1). The etiology of first-time ventilatory failure was laryngospasm (which was treated with propofol or muscle relaxation), mechanical compression of the vocal cords (which was treated by applying jaw thrust or removing air from the cuff), infolding of the cuff (which was treated by removing air from the cuff or use of a smaller size), or epiglottic down-folding (which was treated by jaw thrust and reinsertion with maintained laryngoscopy). The overall ventilation failure rate for the technique was 0.08%. There have been no cases of esophageal or pharyngeal injury.

We thank Dr. El-Orbany et al.  for pointing out our incorrect use of the term gum elastic bougie . We were aware of the terminology issue when we wrote the article but decided to use gum elastic bougie  because we considered it the most commonly used and best-understood term. We would like to point out that the Eschmann endotracheal tube introducer/gum elastic bougie is not ideal for use with the PLMA because the distal portion does not have an atraumatic tip. The development of an atraumatic esophageal guide for use with the PLMA and other extraglottic airway devices is currently under way.

* James Cook University, Cairns Base Hospital, The Esplanade, Cairns, Australia. jbrimaco@bigpond.net.au