Free
Correspondence  |   May 2007
A New Twist in Approaching Difficult Tracheal Intubation. Description of an Economic, Easy, and Effective Way: The Σ Way
Author Affiliations & Notes
  • Luca La Colla, M.S.
    *
  • *IRCCS San Raffaele, Milan, Italy.
Article Information
Correspondence
Correspondence   |   May 2007
A New Twist in Approaching Difficult Tracheal Intubation. Description of an Economic, Easy, and Effective Way: The Σ Way
Anesthesiology 5 2007, Vol.106, 1069-1070. doi:10.1097/01.anes.0000265181.00029.97
Anesthesiology 5 2007, Vol.106, 1069-1070. doi:10.1097/01.anes.0000265181.00029.97
To the Editor:—
After direct laryngoscopy, tracheal intubation has been reported to be awkward in 2.5% and difficult in 1.8% of cases.1 Change of blade type or length, the backward upward rightward pressure (BURP) maneuver,2 and optimal external laryngeal manipulation3 have shown to significantly improve the degree of visualization of the larynx. However, there are some cases in which intubation remains difficult. In these cases, a semirigid stylet can be used to alter the curvature of the tube to facilitate intubation. Anesthesiologists usually employ the so-called hockey stick configuration to direct the tube toward the airway when the larynx is not readily visible (e.g.  , Cormack and Lehane grade 3 or 4). However, although withdrawal of the stylet causes the tip of the endotracheal tube to move anteriorly, thus facilitating intubation,4 there are still some cases in which intubation is impossible. This could be due not only to a particularly reduced interincisor distance or a particularly marked prognathism or retrognathism, but also to the impossibility to flex the cervical spine or extend the atlanto-occipital joint completely up to the sniffing position. In many of the aforesaid situations, alignment of the mouth, larynx and pharynx axes could be almost impossible. In such cases, even if partial insertion of the tube is achieved by means of hockey stick configuration of the tube, its rectilinear part may hit the superior dental arch, thus preventing the anesthesiologist from directing and finally advancing its distal tip through the vocal cords.
In all of these cases, and generally in every situation where intubation is difficult, we have found a new way of shaping the tube with the stylet (fig. 1) that is particularly easy and effective. The tube is shaped in a way that resembles the Greek letter Σ, with two curves, the distal one being more pronounced. The difference with the traditional hockey stick configuration is evident: With this new method, the endotracheal tube is shaped according to three main axes (a, b, and c), whereas in the traditional way, there are only two axes. In addition, with this new configuration, the tube can safely be shaped in such a way that its distal part (axis c) can be even longer compared with the traditional way, because it is almost impossible for its proximal part to hit the superior dental arch (see next paragraph).
Fig. 1. The traditional “hockey stick” configuration  (left  ) compared with the new way of shaping the tube  (right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
Fig. 1. The traditional “hockey stick” configuration 
	(left  ) compared with the new way of shaping the tube 
	(right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
Fig. 1. The traditional “hockey stick” configuration  (left  ) compared with the new way of shaping the tube  (right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
×
Correct placement of the endotracheal tube is possible after only four simple phases. Under direct laryngoscopy, the tube is initially inserted into the patient’s oral cavity with axis a parallel to his body surface (phase I). At the end of this phase, the distal part of the tube follows the tongue profile, and axis c coincides with the mouth axis. The tube is then rotated backward (in the sagittal plane) by 45°–60° (phase II). The tube now fits perfectly to the profile of tongue and laryngopharynx: In fact, axis c is now aligned with the pharynx axis, whereas axis b coincides with the mouth axis. Finally, there should be a combined movement of further backward rotation (10°–15°) and an advance of the endotracheal tube (phase III). This last phase is allowed by the proximal curve of the tube, which prevents it from hitting the superior dental arch. Moreover, the combined movement of rotation–advance not only aligns axis c with the larynx axis, but also permits the distal tip of the tube to pass through the vocal cords.
At this time, the tube is almost in the right position. It is sufficient to hold it firmly in place while an assistant (or the anesthesiologist) removes the stylet (phase IV). A minimum, further advance of the tube may be necessary. One possible question the reader might ask is whether it is easy or difficult to remove the stylet. In our experience, if medical gel or spray lubricant is used, the force that must be applied to remove the stylet is comparable to the force applied when a traditional tube configuration is used.
This technique has many peculiarities and advantages over other commonly used extraglottic and supraglottic devices: Not only does it allow anesthesiologists to intubate blindly when there is a poor laryngeal view (e.g.  , Cormack and Lehane grade 3 or 4, blood/secretions in the pharynx), thus securing the airway, but it is also adjustable to different patients, because the anesthesiologist can decide to shape and angle the tube as preferred, according to his or her needs. In addition, this technique allows us to intubate patients who otherwise could not be intubated with the traditional hockey stick configuration, and, in our experience, systematic use of this simple method could result in minimal use of more complex and more expensive devices.
We started using this technique more than 20 yr ago, when many of the modern devices for the management of difficult airways had not been invented. It is therefore an old technique, but it may still be the first choice when a fiberoptic bronchoscope or any other airway management device is not immediately available, and a life-saving option when a particular contingent situation (e.g.  , in the emergency room) does not allow the anesthesiologist to take time to deal with more complex instrumentation and techniques.
*IRCCS San Raffaele, Milan, Italy.
References
Rose DK, Cohen MM: The airway: Problems and predictions in 18,500 patients. Can J Anesth 1994; 41:372–83Rose, DK Cohen, MM
Takahata O, Kubota M, Mamiya K, Akama Y, Nozaka T, Matsumoto H, Ogawa H: The efficacy of the “BURP” maneuver during a difficult laryngoscopy. Anesth Analg 1997; 84:419–21Takahata, O Kubota, M Mamiya, K Akama, Y Nozaka, T Matsumoto, H Ogawa, H
Benumof JL, Cooper SD: Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. J Clin Anesth 1996; 8:136–40Benumof, JL Cooper, SD
Stix MS, Mancini E: How a rigid stylet can make an endotracheal tube move (letter). Anesth Analg 2000; 90:1008Stix, MS Mancini, E
Fig. 1. The traditional “hockey stick” configuration  (left  ) compared with the new way of shaping the tube  (right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
Fig. 1. The traditional “hockey stick” configuration 
	(left  ) compared with the new way of shaping the tube 
	(right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
Fig. 1. The traditional “hockey stick” configuration  (left  ) compared with the new way of shaping the tube  (right  ). The difference between these two configurations is evident: Whereas the first tube is shaped according to two main axes, the second one takes advantage of three different axes. 
×