The use of double-lumen endotracheal tubes (DLTs) is standard practice for thoracic and other surgical procedures requiring one-lung ventilation, as well as in life-threatening conditions requiring lung isolation, such as hemoptysis. Although the techniques for accurate placement and ventilation with DLTs are more complex than for placement of a standard endotracheal tube, practitioners should be no more intimidated by them than by any other (slightly advanced) airway procedure. The trick to the placement and use of a DLT is to take it step by step. Remember that appropriate caution in placing DLTs is always warranted (never force “the square peg in a round hole”), but no more than in any other area of anesthetic practice.

DLTs are designed to ventilate one lung while isolating the contralateral side. There are design differences depending on the manufacturer, but all DLTs consist of a tracheal lumen and endobronchial lumen. Sizes of DLTs vary from 26 to 41 French (one French equals 1/3 mm and is a measurement of diameter). A 39 F DLT is equivalent to a 9.5-mm-internal-diameter endotracheal tube. Choosing the “proper size” has been a topic of many investigations, including the use of chest radiographs and computerized tomography (CT) scans to measure tracheal and bronchial diameter. No one method has proven an absolute predictor of the “optimal” size of DLT or, in other words, the size DLT that results in the fewest minor and major complications for any given patient but that still functions reliably in the intraoperative period. Traumatic airway injuries are common with double-lumen endotracheal tubes, with a high incidence of hoarseness and sore throat, and presumably an oversized tube will contribute to this unnecessarily. However, undersizing a DLT could lead to distal migration and possible pneumothorax.

The typical method of placing a left DLT is to use direct laryngoscopy to pass the bronchial tip through the vocal cords, remove the stylet, and then advance the tube until the “double” portion passes through the larynx. At this point, for proper placement in the left bronchus, a “blind” or fiberoptic technique may be used. In the “blind” technique, the tracheal cuff is placed past the vocal cords, the tube is rotated counterclockwise, and the
tube is advanced until it meets resistance (approximately 28 to 30 cm at the teeth). Using the fiber-optic method, the bronchial tip is placed past the vocal cords, the scope is placed through the bronchial lumen and driven into the left mainstem bronchus, and the tube is advanced over the scope into the left side.

There are advantages and disadvantages to each technique for initial placement of DLTs. The fiber-optic scope technique is favored by some senior practitioners and is often described as the technique of choice. However, a fiber-optic scope may not be available or may not be helpful in situations of significant hemorrhage or secretions, and one must rely on clinical skills for proper positioning.

The “blind” technique allows for rapid placement without the need for excess equipment other than a stethoscope for auscultation to confirm correct placement. Unfortunately, malposition requiring further manipulation has been reported as from 30% to 78%. Leaving the stylet in place for the entire “blind” placement has demonstrated improved success, although the potential risk for airway trauma may outweigh this benefit. An additional technique reported increased success by insufflating 2 mL of air into the bronchial cuff after placement, withdrawing while holding the pilot balloon until it collapsed, deflating the bronchial cuff, and advancing 1.5 cm. Proper placement occurred in 26 of 29 left-sided DLT attempts. One major disadvantage with the “blind” method beyond lower success rates is the inability to visualize anatomic problems. An example is thoracic aortic aneurysms, which can compress the left main bronchus, impairing placement and potentially leading to aneurysm rupture by “blind” DLT placement.

Left-sided double-lumen placement can be confirmed by auscultation or by fiber-optic visualization. With proper technique, clinical confirmation can be performed successfully with a stethoscope. First, inflate the tracheal cuff and listen for bilateral breath sounds. Clamp the tracheal side, open the tracheal vent, and listen for a leak on the tracheal side. Inflate the bronchial cuff until the leak disappears, usually less than 2 mL and never more than 3 mL. Isolation is confirmed by the loss of breath sounds on the tracheal side and preserved sounds on the bronchial side. Bilateral breath sounds should return after the clamp is removed and the vent is closed.