Left molar approach

The left molar approach is a technique to improve the view at laryngoscopy using a standard macintosh laryngoscope. It was described by Yamamoto1 as follows:

  • insert the blade from the left corner of the mouth at a point above the left molars;
  • the tip of the blade is directed posteromedially along the groove between the tongue and the tonsil until the epiglottis and glottis come into sight;
  • before elevating the epiglottis, the tip of the blade is kept in the midline of the vallecula and the blade is kept above the left molars;
  • the view provided is framed by the flange, the lingual surface of the blade, and the tongue bulged to right of the blade.

The success of this approach in comparison with alternatives has been reproduced by others2. However although Yamamoto and others demonstrated that this improved the laryngoscopic view, actual intubation may still be difficult because of the limited access to the cords, in part caused by the bulging of the tongue.
Physicians from Turkey described a case3 of an unpredicted difficult airway to demonstrate that the use of the gum elastic bougie can facilitate intubation which had otherwise not been successful via the left molar approach.
The take home message for me is that if I have a grade IV view despite my usual first-pass success optimisation manoeuvres such as positioning, reducing or releasing cricoid pressure, and providing external laryngeal manipulation, it is worth trying the left molar approach in combination with a bougie to gain a view of the glottis and to pass the tube.
1. Left-molar Approach Improves the Laryngeal View in Patients with Difficult Laryngoscopy
Anesthesiology. 2000 Jan;92(1):70-4 Full Text
2. Comparative Study Of Molar Approaches Of Laryngoscopy Using Macintosh Versus Flexitip Blade
The Internet Journal of Anesthesiology 2007 : Volume 12 Number 1
3. The use of the left-molar approach for direct laryngoscopy combined with a gum-elastic bougie
European Journal of Emergency Medicine December 2010 ;17(6):355-356

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