| Laryngeal Mask Airway |
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The LMA was invented in the 1980s by British anaesthetist, Dr. Archie Brain.
The laryngeal mask airway is a device that sits tightly over the top of the larynx. It avoids tracheal intubation and can be used with spontaneous respiration or artificial ventilation. However, it may not protect the airway from the aspiration of regurgitated material. It has found favour in day case surgery. The cuff of the mask is emptied before insertion and lubricated. The patient is now anaesthetised; alternatively, they may present unconscious. The neck is extended and the mouth opened widely. The apex of the mask, with its open end pointing downwards to the tongue, is pushed backwards towards the uvula. It follows the natural bend of the oropharynx and comes to rest over the pyriform fossa. At this point - gauged by experience - the cuff around the mask is inflated with air to create the seal. Air entry is confirmed by auscultating in the axillae. Comments on the Laryngeal Mask Insertion Technique Presented in the New Advanced Cardiac Life Support Protocol Adrian Matioc, MD; George A. Arndt, MD Department of Medicine, Section of Emergency, Med Flight, University of Wisconsin Hospital and Clinics, Madison, WI, aamatioc@facstaff.wisc.edu To the Editor: The new 2000 guidelines for cardiopulmonary resuscitation and emergency cardiovascular care were published in August 2000.1 The laryngeal mask airway (LMA) was presented as an alternative airway. We would like to comment on the illustration to insert the LMA. The picture depicts several classic mistakes made during the insertion of the LMA. These may lead to LMA malpositioning and inability to achieve an airway and ventilation.2 In the 2000 guidelines, the LMA is depicted with a semi-inflated cuff, held by the shaft with the left hand and introduced straight into the mouth. The correct LMA technique3 is based on a close imitation of the swallowing mechanism. Before attempting insertion, the LMA cuff should be completely deflated and lubricated. The LMA is held with the dominant hand. The hand holds the LMA like a pen, with the index finger placed at the junction of the cuff and the shaft, with the LMA opening oriented over the tongue. The LMA is passed behind the upper incisors, with the shaft parallel to the patient’s chest and the index finger pointing toward the intubator. The lubricated LMA is pushed into position along the palatopharyngeal curve, with the index finger maintaining pressure on the tube. The index finger is used to push the LMA in the final position. This insertion technique is not self-evident for the first-time user but is essential for correct insertion. The LMA was developed by an anesthesiologist, Dr Brain, for operating room use, and it is widely used throughout the world. The LMA is relatively uncommon in the United States in the prehospital setting. However, the LMA is often used in prehospital settings outside the United States. Research has demonstrated that experienced clinicians can easily teach the inexperienced how to insert the LMA correctly.4 Real-life training for Advanced Cardiac Life Support providers will be done by instructors with little or no clinical experience with the LMA. The 2000 guidelines are misleading and may lead to difficulty and failure in using the LMA. References Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2000; 102 (suppl 1): I95–I104. {Link without Title} Asai T, Morris S. The laryngeal mask airway: its features, effects and role. Can J Anesthesiol. 1994; 41: 930–960. {Link without Title} 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. |
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