[Endotracheal intubation using the Airtraq optical laryngoscope when the glottis is off-center of the viewfinder: are the options of optimization exhausted?].

The leading cause of anesthesia-related injury is the inability to intubate the trachea and secure the airway.1 Improvements in video and optical laryngoscopy have allowed to obtain an indirect view of the glottis in a more simple way but sometimes this advantage occurs together with a difficult or impossible endotracheal tube (ETT) insertion.2 This is because indirect techniques do not require the alignment of the oral, pharyngeal, and tracheal axes. In this sense the optical laryngoscope Airtraq® (Prodol Meditec S.A., Vizcaya, Spain) provides an improved indirect view of the upper airway. However, successful intubation requires optimal positioning of the glottis in the middle of the viewfinder. There are maneuvers of optimization when the glottis is off-center. They can be classified into two groups.3--5 (1) Adjustment of the distal position of device involving external laryngeal manipulation or withdrawal the Airtraq laryngoscope, and (2) adjustment of the distal position or the output of the ETT respect the Airtraq using a intubating stylet, the Endoflex ETT (Merlyn Associates, Tustin, CA, USA) or a flexible fiberoptic bronchoscope. However, occasionally, these maneuvers are not sufficient. We report the successful tracheal intubation with the Airtraq laryngoscope in six adult patients whose glottis was off-center of the viewfinder after initial failure in spite of using the described optimization maneuvers. All of them gave written informed consent for the publication of this article. Tracheal intubation with a styletted standard polyvinyl chloride or standard wire-reinforced ETT was attempted using the regular Airtraq as the first line approach. The vocal cords were visualized off-center of the viewfinder. Attempts to raise the tip of the ETT aligning the center of the visual field by twisting clockwise or anticlockwise and external laryngeal manipulation were unsuccessful, as was tracheal intubation. We then used a preconfigured IS (Rüsch, Intubation Stylet, Rüsch, Vienna, Austria), a Frova intubating introducer (Cook® Medical, Bloomington, USA) or FOB adjusting the output of the ETT through the guiding channel of the Airtraq. However the arytenoids or subglottic structures inhibited advancement of the ETT into the trachea being impossible tracheal intubation. We then used a LMATM ETT (LMA North America, San Diego, CA, USA) with previous maneuvers. When the ETT tip went toward the vocal cords the ETT was then advanced into the trachea on the first attempt without difficulty. There were no oxygen desaturations, airway trauma, hemodynamic instability or other complications. The location of the glottis off-center of the Airtraq viewfinder is predictive of obstruction during advancement of the ETT. Thus, the tip of the standard ETT is often impinged at the level of the epiglottis, arytenoid cartilages or subglottic structures inhibiting its advancement. Different maneuvers can approximate the glottis in the center but the ETT may still encountered resistance. Repeated attempts at passage of the tube through the glottis may lead to laryngeal trauma or bleeding and airway control may be difficult. Our experience suggests that this problem is common in patients with narrow upper airway, large epiglottis or subglottic tumors. The use of the LMATM ETT with the Airtraq as a method of rescue when this problem arises has several advantages. Its hemispherical bevel with the leading edge in the midline helps to reduce the incidence of failure of advancement. Likewise, the bevel of this tube is made from silicone rubber and is softer than the standard polyvinyl chloride design with the leading edge in the midline. It prevents laryngeal injury. Likewise this ETT is less stiff. This improved flexibility allows changing direction more easily and thereby leading to easier intubation. This case series illustrates that LMATM ETT is a useful adjunct to Airtraq optical laryngoscope intubation when a standard polyvinyl chloride or wire-reinforced ETT proves to be difficult to pass on the first attempt. It even could be considered as a first choice for difficult tracheal intubation with this device but this requires formal evaluation.