Letters to the Editor: Letters & Announcements
I would like to thank Drs. Brodsky and Lohser for their interest in our recent report of tracheobronchial injury secondary to left double-lumen tube (DLT) placement. What is clear from various reports is that tracheobronchial injury is far more common with the use of DLTs than single-lumen tubes, that women are more likely to sustain the injury, and that the injury is usually localized in the membranous portion of the trachea near the carina (1–4). In every case the conventional blind technique involving a 90°–120° counterclockwise turn was utilized for the insertion of the left DLT. The authors have, at best, speculated as to what could have possibly gone wrong (2).
In our technique, the bronchial tip is advanced through the majority of the tracheal length in relation to cartilaginous trachea. To achieve this goal, the left DLT is first advanced further down the trachea (until the tracheal cuff at the vocal cords) before attempting counterclockwise rotation between 70° to 90°. This, we believe, and as suggested by the authors, is expected to reduce the incidence of tracheobronchial injury.
We concur with the view that the efficacy of this technique must be assessed in a prospective study. Multiple reports have confirmed the poor efficacy of conventional left DLT placement technique with a very high first pass failure rate (23%–25%) (5). One would agree that our technique of delaying the rotation further down the trachea and reducing the angle of rotation to less than 90° achieves an effect equivalent to the one employed by Brodsky and Lemmens (5) to accomplish rescue intubation in the event of inadvertent right bronchial intubation (failed first-pass intubation). Because our technique achieves the same effect that is achieved with withdrawing the left DLT into the trachea just above the carina and turning the head to the right before advancing the tube in the event of inadvertent right endobronchial intubation, we believe, and as suggested by the authors, that it is possible that using this technique form the outset may improve the first pass left DLT placement rate (5).
I understand the authors’ point of view but do not believe that selection of smaller left DLT sizes has any bearing on the incidence of tracheobronchial injury, as the measured total linear effective width of the left DLT at its distal end as shown in Figure 1 is essentially the same (approximately 3 cm) in all adult left DLT irrespective of their size (35–41F). It is noteworthy that accommodating a 35F tube in the female trachea with an average width of 1.5 cm is significantly tighter than placing a 41F left DLT into a male trachea with a tracheal width of 2.4 cm. If, what the authors are suggesting were true, then the incidence of tracheobronchial injury secondary to left DLT should have been much greater among male patients. Because the trachea is a tube with differential wall strength, a posteriorly pointing tip of the left DLT in a smaller trachea is more likely to retain its shape and impinge at a greater angle of incidence on the membranous wall. It is also noteworthy that the posterior membranous portion of the trachea is easily deformable and is devoid of any significant extramural tissue support as we push closer to the carina, where it is related to the right lung and its posterior pleural reflections.
According to accepted guidelines, an optimal left DLT size for a particular patient is defined as the largest tube that will fit in the left bronchus while allowing for a small air leak when the cuff is deflated. The tracheal and bronchial widths on computed tomography or radiograph of the chest have been recommended to calculate appropriate DLT size for a given patient (6–8). The currently recommended and used sizing principle does not take into account the fact that the relatively stiff curved tip has to be advanced safely through the whole length of the trachea. The sizing principle may work for most men because the discrepancy between the curved distal bronchial element and the tracheal width is smaller than for women. Interestingly, none of the studies evaluating the approach to choosing the size of left DLT based on tracheal or bronchial diameter has the statistical power or design to comment on their safety with regard to tracheobronchial injury (6–8).
Govind R. Rajan, MD
Department of Anesthesiology
Saint Louis University
St. Louis, MO
1. Liu H, Jahr JS, Sullivan E, Waters PF. Tracheobronchial rupture after double-lumen endotracheal intubation. J Cardiothorac Vasc Anesth 2004;18:228–33.
2. Fitzmaurice BG, Brodsky JB. Airway rupture from double-lumen tubes. J Cardiothorac Vasc Anesth 1999;13:322–9.
3. Wagner DL, Gammage GW, Wong ML. Tracheal rupture following the insertion of a disposable double-lumen endotracheal tube. Anesthesiology 1985;63:698–700.
4. Rajan GR. Tracheal perforation with modified Broncho-Cath: is it the tube or the technique? Anesth Analg 2005;100:291.
5. Brodsky JB, Lemmens HJ. Left double-lumen tubes: clinical experience with 1,170 patients. J Cardiothorac Vasc Anesth 2003;17:289–98.
6. Hannallah M, Bennumof JL, Silverman PM, et al. Evaluation of an approach to choosing a left double-lumen tube size based on chest computed tomographic scan measurement of left mainstem bronchial diameter. J Cardiothorac Vasc Anesth 1997;11:168–71.
7. Brodsky JB, Macario A, Mark JBD. Tracheal diameter predicts double lumen size: a method of selecting left double lumen tubes. Anesth Anal 1996;82:861–4.
8. Brodsky JB. Estimating the diameter of the left main bronchus is a clinically useful method for selecting left double-lumen tubes. Anaesth Intensive Care. 2001;29:304–5.