How is correct positioning of the double-lumen endobronchial tube assessed?
Correct placement of the endobronchial tube must be confirmed immediately after intubation and after turning the patient into the lateral decubitus position. The patient’s lungs are initially ventilated through both lumens with the tracheal cuff inflated. Bilateral breath sounds, bilateral chest excursion, and bilateral fogging of endobronchial tube lumens should be present. Gas should not leak around the cuff. The capnogram should be examined for excretion of CO2. Successful response to these maneuvers ensures that the distal end of the tracheal lumen is in the trachea and is above the carina. Unilateral breath sounds and chest movement indicate that the tube has been inserted too far, and the tracheal lumen is in the bronchus, ipsilateral to the side on which breath sounds are present. In this case, the tracheal cuff should be deflated and the tube withdrawn until bilateral ventilation is established.
Next, the bronchial balloon is inflated with less than 2 mL of air (Figure 15.1). The tracheal lumen is clamped and the access cap opened. Ventilation should result in chest movement and breath sounds on the endobronchial side. The presence of bilateral breath sounds and chest movement indicates that the bronchial lumen’s orifice is proximal to the carina (Figure 15.2). Unilateral breath sounds and chest movement of the side opposite the bronchus intended for intubation indicate that the tube has been placed in the wrong side (Figure 15.3). If this has happened, both cuffs should be deflated and the tube with-drawn to a point where the distal end of the endobronchial tube is in the trachea. The tube is then rotated and advanced again until there is resistance to further movement. An alternative method is to insert a fiberscope through the bronchial lumen, visualize the carina, pass the fiberscope down the bronchus intended for intubation, and then slide the tube distally using the fiberscope as a guide until resist-ance is met. If the trachea was easy to intubate, instead of remanipulating the tube within the patient, the tube can be removed from the patient entirely, and the procedure repeated. A right-sided tube will almost always go to the right side, but a left-sided tube will sometimes pass to the right side. A left-sided tube should not be allowed to remain in the right side, because there is no opening for the right upper lobe bronchus on a left-sided tube. Rotating the patient’s head to the right, as is performed for left endobronchial rigid bronchoscopy, may facilitate passage of the tube to the left side.
Ventilation of the lung while the endobronchial lumen is clamped should provide breath sounds and chest move-ment only on the side opposite the bronchus intended for intubation, provided the tube has been placed in the appropriate bronchus (Figure 15.4). Inability to ventilate during this maneuver indicates that the tube has been malpositioned and is either too deep in the bronchus or too shallow in the trachea. Deflation of the endobronchial cuff while keeping the endobronchial lumen clamped will allow ventilation of only one lung if the tube is too deep in the bronchus (Figures 15.5 and 15.6), or bilateral lung ventilation if the tube is too shallow in the trachea (Figures 15.7 and 15.8). Ventilation of the lung contralateral to the position of the endobronchial lumen and only the upper lobe of the side ipsilateral to endobronchial tube placement indicates that the cuff of the endobronchial tube is distal to the upper lobe bronchus and that the tube needs to be withdrawn.
The precise positioning of the tube can be evaluated with the use of a flexible fiberoptic bronchoscope. Passage down the tracheal lumen should reveal the carina and just the proximal tip of the blue cuff of the bronchial lumen at the entrance to the mainstem bronchus.
Visualization of the tube passing into the bronchus beyond the carina without observation of the blue bronchial cuff indicates that the tube is positioned too deep into the bronchus. Inspection via the bronchial side should reveal a patent bronchial lumen that is not occluded internally by the cuff. If the tube’s distal opening opposes the bronchial wall, ventilation of that lung becomes difficult because double-lumen tubes lack Murphy eyes. Visualization of the bronchial carina indicates that the tube is not placed too deeply. If the tube is right-sided, visualization through the side opening should allow proper alignment with the right upper lobe bronchus. If, after placing a fiberscope through the tracheal lumen, the carina is not visualized, the tube is probably too shallow, too deep, or located in the unintended bronchus. If the tube is too shallow, then defla-tion of the bronchial balloon should provide a view of the carina. If the tube is down the contralateral bronchus, then deflation of the bronchial cuff will not demonstrate tracheal carina, but opposite side anatomy will be observed. For example, if a left-sided tube lodges in the right bronchus, then deflation of the bronchial cuff will demonstrate bronchus intermedius (right upper lobe, right middle lobe, and right lower lobe bronchi).