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Inserting the Laryngeal Mask Airway

 

Table 4. Preparation of the Laryngeal Mask Airway for clinical use.
  • Ensure laryngeal mask airway has been previously sterilized.
  • Check cuff and valve.
  • Lubricate the LMA with KY jelly or other sterile surgical lubricant, specifically avoiding the bowl of the LMA so that lubricant cannot get into the LMA aperture.
  • Evacuate all air from cuff, preferably using the LMA deflator.
Table 5. Laryngeal Mask Airway sizes.
Size Weight Maximum
Air in Cuff
1 under 5 kg 4 ml
1.5 5 to 10 kg 7 ml
2 10 to 20 kg 10 ml
2.5 20 to 30 kg 14 ml
3 30 kg to small adult 20 ml
4 adult 50-70 kg 30 ml
5 big adult 70 - 100 kg 40 ml
6 adult over 100 kg 50 ml

While the standard LMA can be inserted by trial and error with relative ease, following Dr. Brain's recommended insertion technique transforms the process into a slick maneuver with minimal respiratory or hemodynamic consequences. Moreover, insertion of the reinforced LMA is very much less forgiving to deviations in insertion technique. Preparation for insertion of the LMA is given in Table 4. The LMA may be deflated with an ordinary syringe, but a special device is also available to help with optimal deflation (Figure 10). The deflated, lubricated LMA is best inserted under propofol anaesthesia (deep vapor will also suffice) with the head and neck positioned as for normal intubation. With an assistant temporarily holding the mouth open until the widest part of the mask is past the teeth, or using the third finger of the inserting hand, the tip of the LMA is inserted into the mouth, pressing the LMA tip against the hard palate as it is advanced cephalad into the pharynx with the right hand. Then, with the index finger positioned at the cuff/tube interface, the LMA is inserted as far as possible into the hypopharynx (see illustrations).

Before removing the index finger, bring the other hand up to the connector and press gently but firmly in the cephalad direction. When resistance is felt, the tip of the cuff is positioned at the upper esophageal sphincter. After assuring that the black line on the LMA is facing the upper lip, the cuff is inflated (Table 5). The images below Tables 4 and 5 illustrate the technique graphically.

 

Step #1:

Deflate LMA using syringe and optional cuff deflation device.

Figure 10. Insertion step 1. Use the above device to remove all air from the LMA cuff prior to insertion.		 LMA insertion step #1 - Cuff deflating device

Step #2:

Press mask tip upwards against the hard palate to flatten it out and advance the mask into the pharynx using the index finger. (CAUTION: Be sure to carefully "fit" the deflated LMA tip into the convexity of the hard palate as this is the KEY to successful insertion.)

Figure 11. Insertion step 2. Press mask tip upwards against the hard palate to flatten it out and advance the mask into the pharynx using the index finger.		 LMA insertion step #2

Step #3:

With neck flexed and head extended, press the laryngeal mask airway into the posterior pharyngeal wall using the index finger.

Figure 12. Insertion step 3. With neck flexed and head extended, press the laryngeal mask airway into the posterior pharyngeal wall using the index finger.		 LMA insertion step #3

Step #4:

Complete the insertion by exerting cephalad pressure by the nondominant hand prior to removing the index finger.

Figure 13. Insertion step 4. Complete the insertion by exerting cephalad pressure by the nondominant hand prior to removing the index finger.		 LMA insertion step #4

Step #5:

Inflate laryngeal mask airway (see Table 5 for details) and secure in place with tape.

Figure 14. Insertion step 5. Inflate laryngeal mask airway (see Table 6 for details) and secure in place with tape.		 LMA insertion step #5

 

Synopsis of Insertion Technique

  1. Check that the LMA is properly prepared.
  2. Keep the neck flexed and the head extended with nondominant hand during the insertion procedure.
  3. Using the index finger to maintain a continuous cephalad pressure, slide the LMA over the hard palate and soft palate into the hypopharynx until definite resistance is felt.
  4. Complete the insertion by exerting cephalad pressure by the nondominant hand prior to removing the index finger.
  5. Inflate mask with air without holding the tube (short outward movement is normal) (see Table 5 for details).
  6. Secure LMA and bite-block with tape.

NOTE: The LMA is also available in a flexible version that resists kinking in a manner similar to an armoured.

 

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