Double-lumen endotracheal (tracheobronchial) tubes (DLTs) are used in surgeries in which lung isolation is essential. This includes situations in which it is essential to prevent secretions and blood from one lung contaminating the other and when one-lung ventilation (OLV) is desired. Among the techniques used in OLV, which include bronchial blockers (BBs) and single-lumen endotracheal tubes (ETTs)/endobronchial tubes, DLT are the most popular.

The first DLT was the Carlens tube, developed and first used in 1950. The feat ures of this tube included a small internal diameter and a carinal hook, designed to prevent distal migration of the tube (Fig. 45-1). The major disadvantages of the Carlens tube are the small internal diameter of the tube, which produced high resistance to gas flow and precluded effective suctioning, and also the carinal hook, which made it difficult to place through the glottic opening. Robertshaw introduced a red rubber DLT in the 1960s, which lacked the carinal hook and had a larger lumen. Both the Carlens tube and the Robertshaw design were made in both right- and left-sided versions.

The DLTs in current use are made primarily of polyvinyl chloride and are disposable. The DLT consists essentially of one long endobronchial tube fused to a shorter ETT. The distal end of the DLT has two high-volume, lowpressure cuffs in order to facilitate lung isolation. When the tube is properly placed, one cuff is located in the trachea while the other is positioned in either the right or left mainstem bronchus. The endobronchial cuff is blue in color for better visualization during fiberoptic bronchoscopy. These tubes are curved to facilitate guidance into either the right or left mainstem bronchus. The available types of DLTs are manufactured by Covidien, Mansfiled, MA, USA (Mallinckrodt), Smiths Medical, Dublin, OH, USA (Portex), and Teleflex Medical, Research Triangle Park, NC, USA (Rusch and Sheridan) (Fig. 45-2).

Based on the different anatomy of the right and left lungs, both right and left DLT are available. The left main bronchus has a smaller diameter, diverges from the trachea at an angle of 45°, and divides to form upper and lower lobe branches. On the other hand, the right mainstem bronchus branches off the trachea at a less acute angle, is wider than the left bronchus, and forms three lobes (upper, middle, lower). The left bronchus divides into upper and middle lobes approximately 5 to 6 cm away from the carina in women and between 6 and 8 cm in men. The takeoff of the upper lobe of the right lung, however, averages approximately 1 to 2 cm below the carina, necessitating specialized right double-lumen tubes that allow the right upper lobe (RUL) to be ventilated.¹ The endobronchial cuff is uniquely designed on right-sided double-lumen tubes in order to prevent obstruction of the RUL. The design of the endobronchial cuff for these right-sided DLTs, which provides isolation with a “slot” in order to ventilate the RUL, varies among manufacturers (Fig. 45-3). Some right-sided DLT also have a radiographic white marker, which facilitates placement with a fiberoptic bronchoscope (FOB).

Placement of the DLT can be challenging. Alliaume et al studied the number of DLTs that required repositioning with FOB after being inserted blindly in 24 patients. Blind insertion resulted in 78% malpositioning of left-sided DLTs and 83% of right-sided DLTs, such that FOB was necessary to adjust the position of the tube.² Klein et al³ showed that of 200 DLTs that were placed blindly, 35% were not correctly positioned when fiberoptic bronchoscopy was used to confirm placement. A study by Boucek et al4 showed that when comparing the blind technique with the direct vision technique for left-sided DLT insertion, both methods were successful, but more time was required using fiberoptic bronchoscopy compared with the blind technique (88 vs 181 seconds, respectively).

When comparing DLTs with the other methods of lung separation and OLV, DLTs have several distinct advantages and are considered the best tool for absolute lung isolation. Either lung can be isolated and ventilated independently without having to move either a right- or left-sided DLT. The DLTs have an internal diameter that is able to accommodate either an FOB or suction catheter through both the tracheal and bronchial lumens, which facilitates visualization and suctioning of each lung.

A study by Narayanaswamy et al compared DLTs with BBs during thoracic surgery, measuring the time it took each to isolate the left lung, the number of times each had to be repositioned, and the mean peak airway pressures generated by each device.⁵ The time for lung isolation was significantly less for DLTs versus BBs (93 ± 62 vs 203 ± 132 seconds). Also, double-lumen tubes had to be repositioned far fewer times than the BBs (2 vs 35). With regard to peak airway pressures, not only did DLTs have lower mean values (16 cm H₂O vs 19 cm H₂O), but patients being ventilated with BBs had a lower pH and higher PaCO₂ compared with DLTs.

Double-lumen tubes are the better choice in cases where lung separation is absolutely necessary, as well as for sleeve pneumonectomies. BBs are more advantageous when a patient presents with an anticipated difficult airway, if nasal intubation is necessary, if the patient has an established ETT and is too unstable to change to a DLT, and also when the patient will require postoperative mechanical ventilation-especially with a right-sided DLT.⁶

Double-lumen endobronchial tubes have also been shown to cause more trauma to the airway, increasing the incidence of postoperative hoarseness and throat pain. A review of DLTs over 25 years was conducted by Fitzmaurice et al,⁷ who found that airway injuries were more common with undersized DLTs, and bronchial rupture was more common with disposable, polyvinylchloride DLTs. Heike studied the incidence of postoperative hoarseness and sore throat, as well as using bronchoscopy immediately following the surgery in order to objectively assess vocal cord and bronchial injuries in a population undergoing thoracic surgery. Patients experienced significantly more hoarseness in the DLT group compared with the bronchial blocker group (44% vs 17%). Postoperative vocal cord lesions were also increased in patients in the DLT group (44% vs 17%), whereas the incidence of bronchial lesions were similar between the two groups.⁸

Some controversy exists in comparing the use of right-and left-sided DLTs. Due to the narrow margin for error when inserting a right-sided DLT and during repositioning of the patient (due to obstruction of the RUL bronchus), opponents of these devices state that the only situations in which right-sided DLTs should be used in clinical practice are when there is an intrinsic or extrinsic left mediastinal, thoracic, or bronchial mass that prevents the insertion of a left-sided DLT, and for teaching purposes. Cohen⁹ has noted that there is a steep learning curve when training to use the right-sided DLTs because there are different shapes and locations of the endobronchial cuffs and different sizes among the ventilation slots between manufacturers. Fiberoptic bronchoscopy is essential when using a right-sided DLT, both during insertion and throughout the case because the margin of error is only 1 to 8 mm for right-sided DLT compared with 4 to 6 cm when using a left-sided DLT.¹ Campos et al¹⁰ found that the time required for correct placement was almost double than the left-sided DLT. Finally, if postoperative mechanical ventilation is required, a right-sided DLT must be exchanged for a single-lumen ETT because the intensive care unit staff does not have the training to manage a right-sided DLT if it should become improperly positioned. Of concern, when exchanging ETTs, the dependent lung may
become exposed to blood and secretions, or a difficult reintubation may be encountered because of the postoperative edema, blood, and secretions.⁹

The only contraindication in the use of the right-sided DLT is an anomalous takeoff of the RUL bronchus directly from the trachea, which occurs in approximately 1 in 250 patients.¹¹ With recent improvement in the design of right-sided double-lumen tubes and in the techniques used for placement, there are several investigations that have shown that right-sided DLTs have similar efficacy and safety when compared with BBs and left-sided DLTs.¹⁰,¹²