Laryngeal Mask Airway (LMA)

OVERVIEW

  • LMA is an acronym for Laryngeal Mask Airway
  • a type of extraglottic airway device aka supraglottic airway device (SAD)

USES

  • rescue airway in a failed intubation
  • facilitate blind insertion of bougie or ETT into trachea
  • facilitate blind insertion of bronchscopic assisted airway control
  • improve oxygenation as part of rapid sequence airway approach
  • ventilation during elective anaesthesia to fasted patients with low risks of regurgitation

DESCRIPTION

Parts:

  • shaft (tube)
  • proximal 15 mm connector
  • distal end with broad elliptical inflatable cuff — upper smooth surface to prevent pharyngeal secretions entering the larynx and an under surface with an orifice with linear bars that sits over the larynx to create a seal
  • pilot balloon

Types:

  • Reusable (silicon)
  • Intubating LMA with endotracheal tube (e.g. FastTrackTM) (disposable)
  • LMA with gastric suction channel (e.g. ProSealTM) (disposable)

Sizes:

  • 0 (infant) to 6 (large adult)
  • size 3 (females) or 4 (males) commonly used in adults
Mask
Size
Weight
(kg)
Age
(yr)
LMA length
(cm)
LMA Cuff Vol
(mL)
Largest ETT^
(mm)
1<5<0.51043.5
1.55-10<1105-74
26.5-201-511.57-104.5
2.520-305-1012.5145
330-6010-151915-206
460-80>151925-306.5
5>80>151930-407

METHOD OF INSERTION/ USE

  • blindly inserted to form a low pressure seal over the laryngeal inlet

LMA

  • sniffing position
  • partially inflated cuff
  • lubricate mask surface
  • aperture facing towards laryngeal inlet or posteriorly with a 180 degrees twist once behind tongue
  • inflate cuff with 20-40mL of air

Standard LMA insertion

ILMA

  • insert with aperture facing laryngeal inlet
  • test ventilate
  • feed ETT through inlet followed by obturator
  • slide LMA while ensuring ETT stays in trachea
  • confirm position with ETCO2
  • LMA can either be left in situ stabilising the ETT, or can be removed leaving just the ETT in situ

CONTRAINDICATIONS

  • poor mouth opening
  • potential pharyngeal/laryngeal pathology
  • poor pulmonary compliance
  • high airway resistance

RODS predicts difficulty with extra-glottic airway use

  • Restricted mouth opening
  • Obstruction
  • Distorted airway
  • Stiff lungs or c-spine

COMPLICATIONS

  • inability to achieve a seal and ventilate (can be assisted by deepening the level of anaesthesia, inserting under direct vision with a laryngoscope, partially inflating the cuff, flexing the lower spine with chin lift)
  • regurgitation and aspiration
  • gas insufflation
  • partial airway obstruction (mask misplacement)
  • shaft kinking
  • malposition
  • dislodgement
  • laryngospasm
  • cough
  • trauma to the upper airway (e.g. bleeding, dislodgement of teeth)

OTHER INFORMATION

  • Invented by Dr Archie Brain, a British Anaesthetist in 1983
  • LMA works best with an under-inflated mask

Advantages

  • provide rapid protection of airway in the field
  • technically easier to insert than ETT
  • some models provide a gastric port

Disadvantages

  • non-definitive airway protection and patency
  • difficult ventilation if high airway pressures

References and Links

Journal articles

  • Cook T, Howes B. Supraglottic airway devices: recent advances. Continuing Education in Anaesthesia, Critical Care & Pain. 11(2):56-61. 2010. [free full text]
  • Ramaiah R, Das D, Bhananker SM, Joffe AM. Extraglottic airway devices: A review. Int J Crit Illn Inj Sci [serial online] 2014 [cited 2014 Apr 19];4:77-87. Available from: http://www.ijciis.org/text.asp?2014/4/1/77/128019

FOAM and web resources


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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