Laryngeal mask airway

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Invention and development

The first laryngeal mask airway was invented in 1983 by a British anaesthetist, Dr. Archie Brain.

Use

Laryngeal masks are used in anaesthesia and in emergency medicine for airway management.   They consist of a tube with an inflatable cuff that is inserted into the pharynx. They cause less pain and coughing than an endotracheal tube, and are much easier to insert. However, a standard laryngeal mask airway does not protect the lungs from aspiration, making them unsuitable for anybody at risk for this complication.

The device is useful in situations where a patient is trapped in a sitting position, suspected of trauma to the cervical spine (where tilting the head to maintain an open airway is contraindicated), or when intubation is unsuccessful. It is not inserted as far as an endotracheal tube (it sits tightly over the top of the larynx, and thus does not need to be inserted into the trachea), and supports both spontaneous and artificial ventilation. It is popular in day case surgery.

However, unlike an endotracheal tube, a laryngeal mask cannot protect the airway or lungs from aspiration of regurgitated material, and deep (subglottic) suctioning cannot be performed through the mask.

Guide to use

Laryngeal mask airways come in a variety of sizes. The cuff of the mask is deflated before insertion and lubricated. The patient is anaesthetized if conscious, and their neck is extended and their mouth opened widely. The apex of the mask, with its open end pointing downwards toward the tongue, is pushed backwards towards the uvula. It follows the natural bend of the oropharynx and comes to rest over the pyriform fossa. Once placed, the cuff around the mask is inflated with air to create a tight seal. Air entry is confirmed by listening for air entry into the lungs with a stethoscope, or by presence of end tidal carbon dioxide.

References

Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2000; 102 (suppl 1): I95–I104.[Medline]

Asai T, Morris S. The laryngeal mask airway: its features, effects and role. Can J Anesthesiol. 1994; 41: 930–960.[Abstract]

Brain A, Denman WT, Goudsouzian NG. Laryngeal Mask Airway Instruction Manual. San Diego, Calif: LMA North America Inc; 1999.

Brimacombe R, Brain AIJ, Berry A. Nonanesthetic uses. In: The Laryngeal Mask Airway: A Review and Practice Guide. Philadelphia, Pa: Saunders; 1997: 216–277.

Rothrock J. Alexander's - Care of the Patient. Missouri; Saunders; 2003; 236.

Complications: p316-7 http://medind.nic.in/iad/t05/i4/iadt05i4p308.pdf