How to Choose the Double-Lumen Tube Size and Side
Highlights
- Tracheal diameter should be measured at the level of the clavicles on the posterior–anterior chest radiograph (View Highlight)
- The bronchial diameter should be measured on the computed tomography scan within 1 to 2 mm of carina,5, 7 because the left mainstem is not clearly visible on the chest radiograph in 50% to 70% of cases (View Highlight)
- Although measuring radiograph films has a theoretical scientific background, it may not be practical. Moreover, this approach may work for most white patients, but it does not seem to be as effective in the Asian population, especially if female (View Highlight)
- The supporters of using a small DLT (35F or 37F catheter) advocate the use of this size based on the assumption that it is easy to place, fits all patients, and does not seem to be associated with an increased incidence of airway damage.10 In case of difficult airway or for small patients, a small device may be easier to use (View Highlight)
- The proponents of a bigger size (39F and 41F catheter) argue that if the DLT is too small, it will cause airway injury because of (1) the need to use high pressures in the bronchial cuff to achieve lung isolation; (2) a higher incidence of dislodgment, causing either failure to isolate the lung or ventilator-induced lung injury; (3) the inability to suction secretions; and (4) an increased resistance during mechanical ventilation, which could lead to auto positive end-expiratory pressure (View Highlight)
- Small-size DLTs required more volume in the cuff to have an underwater seal, generating higher pressures than bigger size tubes. However, the highest pressures needed to achieve a seal to 25 mm Hg pressure ranged from 12 to 24 mm Hg. This was lower than the accepted threshold for mucosal ischemia of 30 mm Hg. (View Highlight)
- Big DLTs may have the advantage of allowing better suctioning of secretions, faster lung collapse, and cause less work of breathing when patients resume spontaneous ventilation at the end of the case (View Highlight)
- Small DLTs may work better for Asian females; difficult airways with cervical or carinal compression or stenosis; when an awake fiber optic (FOB) intubation is needed; or in the presence of a fresh tracheostomy (<7 days) or laryngoplasty or vocal cord medialization. (View Highlight)
- Because of the length of the left mainstem bronchus (4.4–4.9 cm), left-sided DLTs are thought to have a larger margin of safety for positioning and quality of lung isolation (View Highlight)
- The presence of a porcine bronchus, which takes off above the carina, represents the only absolute contraindication for a right-sided DLT placement. (View Highlight)
- Indications for mainstem intubation include pediatric airway (below the limits of commercially available DLT size); critical airway in patients already intubated (where changing the DLT would be problematic, such as unstable neck or difficult airway); and in case of distorted or damaged trachea (View Highlight)