Supraglottic airway

(Redirected from LMA)


  • Need for positive pressure ventilation (PPV)
    • Primary or rescue airway[1]
    • Conduit/guide for elective or rescue fiberoptic intubation[2]
    • Intubating LMA may be used to guide placement of an endotracheal tube
  • Field intubation by paramedics, especially in pediatric patients[3][4]



  • Spontaneous respirations
  • Gag reflex


  • Significant facial trauma

Difficult Supraglottic Device (RODS)

  • Restricted mouth opening
  • Obstruction
  • Distorted airway
  • Stiff lungs (chronic pulmonary disease, obesity) or neck (C-spine collar, limited neck extension)

Equipment Needed

  • Supraglottic Airway (SGA) device (many options exist, see below)
  • Appropriate sedation/paralytic agents, if indicated

LMA Sizes[5]

Mask Size Weight (kg) Age (yr) LMA Length (cm) LMA Cuff Vol (mL) Largest ETT^ (mm)
1 <5 <0.5 10 4 3.5
1.5 5-10 <1 10 5-7 4
2 6.5-20 1-5 11.5 7-10 4.5
2.5 20-30 5-10 12.5 14 5
3 30-60 10-15 19 15-20 6
4 60-80 >15 19 25-30 6.5
5 >80 >15 19 30-40 7

^Largest ETT that can pass thorough "Intubating LMA" (ILMA)

iGel Sizes

igel size patient size weight (kg)
1 neonate 2-5
1.5 infant 5-12
2 smal pediatric 10-25
2.5 large pediatric 25-35
3 small adult 30-60
4 medium adult 50-90
5 large adult 90+


Due to variety of devices and placement techniques, impossible to give exact universal procedure

  1. Prepare patient as for intubation
  2. If patient is awake, provide topical anesthetic
  3. Place supraglottic airway device by one of the following techniques:
    • Use thumb or index finger to guide device along midline of hard palate with cuff deflated or partially inflated and advance until seated
    • Insert device with cuff facing hard palate, then rotate 180 degrees while advancing (similar to OPA insertion)
    • Insert laterally 45 degrees against tongue, advance and rotate to midline
  4. Inflate cuff (if applicable)
  5. Confirm placement as with endotracheal tube

Intubating LMA[6]

  1. Prepare patient as for intubation
  2. Partially deflate the cuff of the iLMA and lubricate
  3. Holding iLMA by metal handle only, insert into patient's mouth with the posterior surface of the iLMA against the hard palate
  4. Advance the iLMA until it is seated
  5. Inflate the iLMA cuff
  6. Ventilate patient and confirm placement as usual
  7. Lubricate endotracheal tube
  8. Insert ETT into the aperture on the iLMA
  9. Slide ETT to appropriate depth
  10. Inflate ETT cuff and confirm placement as usual
  11. Disconnect adaptor from ETT
  12. Deflate iLMA cuff
  13. Use obturator to push against ETT while slowly removing iLMA
  14. Grasp ETT in the oral cavity as soon as able
  15. When iLMA is fully removed, reattach ETT adaptor
  16. Ventilate patient and confirm placement as usual


  • Bronchospasm
  • Hoarseness
  • Laryngeal nerve injury
  • Hypoglossal nerve injury
  • Pharyngeal edema
  • Dysphagia

Special Considerations

  • There are 2 generations of supraglottic airway devices[7][2]
    • 1st Gen = classic LMA, other standard LMAs
    • 2nd Gen = iGel, LMA Supreme, Pro-Seal LMA (PLMA)
  • Second generation devices achieve improved esophageal and pharyngeal seal (causes ↑ oropharyngeal leak pressure), incorporate a "drain tube" that allows access to the esophagus and stomach, and usually have an incorporated bite block.
  • Oropharyngeal leak pressure = the applied pressure at which the seal between the device and the larynx begins to leak.
    • Peak inspiratory pressure needs to be less than the oropharyngeal leak pressure for effective ventilation and to prevent gastric insufflation.[8]
  • Higher failure rate with obese patients, inappropriate patient position (e.g. trendelenberg), and placement by inexperienced provider[2]

See Also

Airway Pages

External Links



  1. 1.0 1.1 Apfelbaum JL, et al.; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2013 Feb;118(2):251-70
  2. 2.0 2.1 2.2 Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Cook TM, Woodall N, Frerk C; Fourth National Audit Project. Br J Anaesth. 2011 May;106(5)
  3. Zhu X-Y, Lin B-C, Zhang Q-S, Ye H-M, Yu R-J. A prospective evaluation of the efficacy of the laryngeal mask airway during neonatal resuscitation. Resuscitation. 2011;82(11):1405–1409. doi:10.1016/j.resuscitation.2011.06.010
  4. Calkins MD, Robinson TD. Combat trauma airway management: endotracheal intubation versus laryngeal mask airway versus combitube use by Navy SEAL and Reconnaissance combat corpsmen. J Trauma. 1999;46(5):927–932
  5. Tarascon Adult Emergency Pocketbook
  7. Timmermann, A. Supraglottic airways in difficult airway management: successes, failures, use and misuse. Anaesthesia, 2011, 66(Suppl. 2), pages 45–56.
  8. Patel B., Bingham R. Laryngeal mask airway and other supraglottic airway devices in paediatric practice. Contin Educ Anaesth Crit Care Pain (2009) 9 (1): 6-9.