Quick Facts

• The Laryngeal Mask Airway (LMA) is a supraglottic airway device designed to sit above the glottis, providing a seal around the laryngeal inlet.

• It is less invasive than endotracheal intubation, avoids laryngoscopy, and can be inserted blindly in most patients.

• LMAs are commonly used in elective surgeries, rescue airways during difficult intubation, and emergency settings when bag-mask ventilation is inadequate.

• Contraindications include patients at high aspiration risk (e.g., full stomach, pregnancy, trauma), poor pulmonary compliance requiring high airway pressures, or pathology causing airway obstruction below the glottis.

Procedure

Preparation

• Position the patient in the “sniffing” position unless contraindicated (e.g., suspected cervical spine injury).
• Select the appropriate LMA size based on the patient’s weight (size 3 for small adults, size 4 for average adults, size 5 for large adults).
• Inspect the cuff for tears and check for leaks by inflating then deflating fully.
• Apply a water-based lubricant to the posterior surface of the cuff (avoid excess, especially on the anterior side)
• Ensure adequate depth of anesthesia to suppress airway reflexes before insertion.

Insertion (there are variations in technique)

1. Hold the LMA like a pen, with the index finger at the junction of the tube and cuff. The cuff may be fully deflated (Brain’s technique), inflated partially, or inflated fully. It is usually provider dependent.
2. Open the patient’s mouth and gently advance the cuff along the hard palate, maintaining midline orientation.
3. Advance until resistance is felt, usually at the hypopharynx when the cuff seats around the laryngeal inlet.
4. Inflate the cuff with the recommended volume of air (do not overinflate—excess pressure can cause mucosal ischemia or sore throat).
5. Connect the LMA to the breathing circuit and begin gentle ventilation to verify placement (bilateral chest rise, breath sounds, and end tidal CO2).

Troubleshooting

• If there is a poor seal or leak, consider repositioning, adjusting cuff volume, or replacing with a different size.
• If ventilation remains inadequate, consider alternative supraglottic airway or endotracheal intubation.
• Be cautious of gastric insufflation with high airway pressures; the LMA is best suited when peak inspiratory pressures are < 20 cmH₂O.

Confirmation Steps

• Observe for adequate chest rise and fall with each ventilation.
• Listen for bilateral breath sounds and absence of gurgling over the stomach.
• Use capnography to confirm effective ventilation and airway placement.
• Check for minimal or no leak at peak inspiratory pressures during positive pressure ventilation.

Documentation Requirements

• Record the LMA size and type (e.g., classic, ProSeal, i-gel).
• Note the number of insertion attempts and whether troubleshooting measures were needed.
• Document patient response, adequacy of ventilation, and any complications such as sore throat, blood on the cuff, or regurgitation.

Scope Guide

References

1. Merck Manual Professional Version. How To Insert a Laryngeal Mask Airway. https://www.merckmanuals.com/professional/critical-care-medicine/how-to-do-other-airway-procedures/how-to-insert-a-laryngeal-mask-airway
2. Wikipedia. Laryngeal mask airway. https://en.wikipedia.org/wiki/Laryngeal_mask_airway
3. Cook TM, Kelly FE. A national survey of the use of the laryngeal mask airway in the United Kingdom. Br J Anaesth. 2005;95(5):633–639.