Airway Skills 8:
Intubating Laryngeal Mask Airway
An intubating laryngeal mask airway (ILMA) (LMA-Fastrach, LMA North America, San Diego, CA) is another method of tracheal intubation that does not require visualization of the glottis. An ILMA is a reusable device that is safe, effective, and relatively gentle. An ILMA does not require neck motion and may be used in awake intubation when used with topical anesthesia. It is especially useful for intubating morbidly obese patients.
Promotional illustration from LMA North America
How to Use
- Select the appropriate size of ILMA. Small adult—size 3;
normal and
larger adult—size 4; large adult—size 5. Select a standard ET
tube
appropriate
for the patient (8.0 or less). Place the ET tube in a basin of
hot
water to soften it.
- Place the ventral surface of the laryngeal mask on a flat surface. With a 20 cc syringe, aspirate the cuff so that it is flattened and tends to bend away from the ventral surface. Lubricate the posterior surface of the mask.
- Hold the ILMA by the metal handle only. Open the patient’s mouth and slide the mask in with its posterior surface on the hard palate. Continue this motion until the mask lodges in the introitus of the esophagus. In this position, its ventral surface will face the glottic opening. Inflate the cuff with just enough air to provide a seal (15 to 40 cc).
- Ventilate the patient with the ILMA. Slight adjustment in position may be necessary. Oxygenate the patient in this manner until ready to endotracheally intubate.
The ILMA does not protect against aspiration of regurgitated gastric contents, so although the patient may be ventilated at this point, there is a need to go on to endotracheal intubation.
- When ready to intubate, select the polyvinyl chloride (PVC) ET tube already warmed in the hot water. Lubricate the tube. Insert the tube through the ILMA so that its normal curvature is reversed as it goes through the ILMA. This helps it round the bend into the trachea. Insert the tube to appropriate depth and inflate its cuff. Resume ventilations. Check for position as usual.
If the ET tube meets excessive resistance, try lifting the ILMA toward the ceiling or try rocking it and try again. If this fails, try inserting the straight end of an ET tube introducer (ETI) through the ILMA. If tracheal rings are felt, the trachea has been cannulated. Deflate the cuff of the ILMA and remove it over the ETI; then intubate over the ETI as usual.
- When ready to remove the ILMA, deflate its cuff. Remove the 15 mm adaptor from the ET tube. An obturator is provided with the ILMA. Use this to keep the ET tube at its correct depth while the ILMA is removed.
The pilot balloon of the ET tube eventually reaches the ILMA. At this point, remove the extender. As soon as it is possible, grasp the ET tube at the mouth. The ILMA may now be removed entirely. Reattach the 15 mm adaptor and resume ventilations.
References
-
Reardon RF, Martel M. The intubating laryngeal mask airway: suggestions for use in the emergency department. Acad Emerg Med. 2001;8:833-838.
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Pollack CV. The laryngeal mask airway: a comprehensive review for the emergency physician. J Emerg Med. 2001;20:53-66.