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Three Part Question

In [adults with an unsecured airway requiring an emergent laryngeal mask airway] should [bite guards be used] to [prevent airway loss during awakening]?

Clinical Scenario

A 54-year-old man has suffered an out-of-hospital cardiac arrest. The Paramedic Emergency Service have instituted ALS—administering a defibrillatory shock and managing his airway by insertion of a laryngeal mask airway device. Spontaneous circulation has returned but the patient still required airway and breathing support. The resuscitation team leader is just having a conversation with the anaesthetist about securing the airway with an endotracheal tube when the patient has what appears to be a fit. During the tonic phase of the fit, he clenches his teeth and occludes the laryngeal mask airway device. His airway is obstructed, and he subsequently develops pulmonary oedema. You wonder whether these complications could have been prevented with a bite guard.

Search Strategy

Medline using the PubMed interface date of searching 1 December 2014: ("laryngeal masks"[MeSH Terms] OR ("laryngeal"[All Fields] AND "masks"[All Fields]) OR "laryngeal masks"[All Fields] OR ("laryngeal"[All Fields] AND "mask"[All Fields]) OR "laryngeal mask"[All Fields]) AND "bite block"[All Fields] OR LMA[All Fields] AND "bite block"[All Fields]

The Cochrane Library Issue 12 of 12, 2014: “bite block” ti, ab, kw 3 records 0 relevance.

Search Outcome

Altogether 18 papers were found in Medline and 3 were found in the Cochrane Library. A further eight relevant papers were found by scanning the references of relevant papers. All relevant papers are summarised in the table

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Chang et al 2007 Taiwan	One patient undergoing general anaesthesia with an LMA without a bite block Bit through tube during recovery	Case Report	Complications	Airway obstruction
Banchereau et al 2001 France	One adult patient who underwent general anaesthesia with an LMA and bite block Inhalation of the bite block during recovery	Case report	Complications	Inhalation of the bite block
Shameem et al 2004 Pakistan	One adult patient undergoing anaesthesia with an LMA without a bite block	Case report	Complications	Pulmonary oedema
Petrou et al 2003 Greece	Case report - one adult patient undergoing general anaesthesia with a LMA and no bite block.	One adult patient undergoing general anaesthesia with an LMA and no bite block Bit tube during recovery	Complications	Pulmonary oedema
Devys et al 2000 Canada	One adult patient undergoing anaesthesia with an LMA with no bite block Bit tube during recovery	Case report - one patient	Complications	Pulmonary oedema
Vandse et al 2012 USA	One patient undergoing general anaesthesia with an LMA without a bite block Bit tube during recovery	Case report	Complications	Pulmonary oedema
Sullivan M 1999 Australia	One adult patient undergoing anaesthesia with a laryngeal mask airway (LMA) without a bite block Bit tube during positioning causing obstruction	Case report	Complications	Pulmonary oedema
Sickmann et al 2005 Germany	One patient undergoing general anaesthesia with an LMA without a bite block Bit tube during recovery	Case report - one patient	Complications	Pulmonary oedema	Only one patient discussed in the broader context of LMA use and complications.
Blackurn et al May 2003 UK	Anaesthetists in teaching and non-teaching units across the UK 42% of 451 replied	Postal survey	Biting causing obstruction experienced by respondents	7.3% of flexible LMA users and 18.1% of standard LMA users	Abstract only published Low response rate
Quinlan J 2002	One adult patient undergoing anaesthesia with an LMA with no bite block Bit through tube during recovery	Case report	Complications	Airway obstruction

Comment(s)

The vast majority of the papers found are case reports, though a single survey suggests that biting of an unguarded laryngeal mask airway (LMA) is not an uncommon event. Complications of biting include airway obstruction and the development of negative pressure pulmonary oedema, neither of which would be welcome events in the resuscitation area. It should be noted that the use of bite guards is not without risk—and a single case report records airway obstruction secondary to inhalation of the guard itself. The riskiest time seems to be during recovery.

Clinical Bottom Line

Bite guards should be used when laryngeal mask airways are employed in the emergency department.

References

1. Chang WL, Hseu SS, Wang CC et al. Successful management of severe upper airway obstruction during emergence of anesthesia in consequence of fracture of deflated laryngeal mask airway due to biting--a case report. ACTA Anaesthesiologica Taiwanica 2007;45:39–42.
2. Banchereau F, Marié S, Pez H et al. Acute pulmonary edema from inhalation of the bite-block after anesthesia with a laryngeal mask. Ann Fr Anesth Reanim 2001;20:865–8.
3. Shameem A, Malak AM, Rahmani JA Postobstructive pulmonary edema associated with biting a laryngeal mask airway. J Coll Physicians Surg Pak 2004;14:564–5.
4. Petrou A, Valmas K, Svarna E et al. Negative Pressure Pulmonary Oedema in a Patient Ventilated with a Laryngeal Mask. Greek E J Perioper Med 2003;1:69–73.
5. Devys JM, Balleau C, Jayr C et al. Biting the laryngeal mask: an unusual cause of negative pressure pulmonary edema. Can J of Anaesth 2000;47:176–8.
6. Vandse R, Kothari DS, Tripath RS et al. Negative pressure pulmonary edema with laryngeal mask airway use: Recognition, pathophysiology and treatment modalities. Int J Cri Illn Inj Sci 2012; 98-103.
7. Sullivan M. Unilateral negative pressure pulmonary edema during anesthesia with a laryngeal mask airway. Can J Anaesth 1999;46:1053–6.
8. Sickmann K, Seider R, Dahm M, et al. Negative pressure pulmonary edema. Post-obstructive lung edema after use of a laryngeal mask Der Anaesthetist 2005;54:1197–200.
9. Blackurn JP, Con A, Moore C A national survey of the use of bite guards and critical incidents involving the laryngeal mask airway. Anaesthesia 2003;58:506–7.
10. Quinlan J. Reinforced laryngeal mask severed by biting. Anaesthesia 2002;55:186.