We were interested in the recent article by Bozdogan et al.  regarding the use of left molar laryngoscopy to make difficult intubation easier. The authors rightly mentioned that the improved laryngeal view achieved with left molar laryngoscopy does not necessarily mean an improved success rate of tracheal intubation. This is attributable to the tongue being displaced to the right resulting in little space in the oral cavity to negotiate the tracheal tube into the glottic opening [1,2].
We have been using this technique and would like to suggest a few measures to increase the success rate of intubation while using left molar laryngoscopy. First, wherever feasible, a smaller size tracheal tube, size 6.5 for women and 7 for men, should be used as this can be negotiated more easily into the trachea. Further, it is always preferable to mount the tracheal tube on a malleable stylet. This tube with an internal stylet is passed from the centre or the right corner of the mouth with its concavity facing to the right side and advanced towards the glottic. This avoids an inadvertent misdirection of the tube tip that is liable to occur when the tube contacts the walls of the narrow oropharyngeal passage created using left molar laryngoscopy. Further, when introduced from the right corner of the mouth, the tip of the tube faces towards the right and this results in a better view of the larynx . In some cases, one may need to bend the stylet like a hockey stick to achieve the goal [3,4].
Alternatively or if use of the stylet does not succeed, use of a gum elastic bougie increases the success rate of negotiating the tracheal tube into the trachea. The use of a gum elastic bougie with an angled tip has been found to be especially useful when the operator recognizes some anatomical landmarks, but cannot direct the tip of the tracheal tube into the laryngeal inlet [4,5]. Once the gum elastic bougie is negotiated into the glottic aperture, the laryngoscope is left in position and the desired tube, preferably a flexometallic tube with a hemispherical bevel, is railroaded over the gum elastic bougie with a rotary motion. Use of a tube that minimizes the gap between the leading edge and the gum elastic bougie is known to facilitate insertion of the tracheal tube into the trachea . Alternatively, after advancing the bougie in a left molar approach to a maximum of 45 cm , one can shift over to a conventional midline approach and negotiate the tracheal tube over the bougie in this position.
1 Bozdogan N, Sener M, Bilen A, et al
. Does left molar approach to laryngoscopy make difficult intubation easier than the conventional midline approach? Eur J Anaesthesiol 2008; 25:681–684.
2 Yamamoto K, Tsubokawa T, Ohmura S, et al
. Left-molar approach improves the laryngeal view in patients with difficult laryngoscopy. Anesthesiology 2000; 92:70–74.
3 Smith M, Buist RJ, Mansour NY. A simple method to facilitate difficult intubation. Can J Anaesth 1990; 37:144–145.
4 Dorsch JA, Dorsch SE. Tracheal tubes. In: Dorsch JA, Dorsch SE, editors. Understanding anesthesia equipment. Baltimore: Williams & Wilkins; 1999. pp. 557–578.
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6 Makino H, Katoh T, Kobayashi S, et al
. The effects of tracheal tube tip design and tube thickness on laryngeal pass ability during oral tube exchange with an introducer. Anesth Analg 2003; 97:285–288.
7 Henderson JJ, Popat MT, Latto IP, Pearce AC, Difficult Airway Society. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004; 59:675–694.