How do you know that the tube is in the correct position?
Answer:
Recommended insertion techniques for a DLT include direct laryngoscopy followed by fiberoptic guidance in the appropriate mainstem. Blind insertion may cause the potential of airway injury. Auscultation alone is unreliable to confirm the position of a DLT especially in the presence of a baseline decrease in breath sounds, such as in case of COPD. The position of the device should be reconfirmed once the patient is in the lateral decubitus prior to lung collapse.
During bronchoscopy, the tracheal cartilaginous rings are anterior and the tracheal membrane is posterior. Therefore, right versus left can be discerned by the relationship of the mainstem bronchi to the anterior cartilaginous rings and the posterior membrane (Fig. 2.1A). In addition, the right upper lobe takeoff (which usually arises from the lateral aspect of the right mainstem bronchus, just below the tracheal carina) is a useful landmark when the airway anatomy has been obscured by bleeding, edema, or radiation-induced changes or has been distorted by extrinsic compression. Left DLT position and depth are confirmed by inserting the fiberoptic bronchoscope in the tracheal lumen. The entire right mainstem bronchus should be visible, and the tracheal lumen orifice of the DLT should be 1 to 2 cm above the tracheal carina. When properly positioned, the upper part of the blue endobronchial cuff is visualized just below the tracheal carina in the left mainstem bronchus (Fig. 2.1B). If a right DLT is used, correct positioning is confirmed by visualization of the bronchial cuff in the right mainstem bronchus (Fig. 2.1C) and visualization of the right upper lobe orifice through a slot on the lateral surface of the DLT (Fig. 2.1D). For both left- and right-sided tubes, the bronchoscope should also be inserted in the bronchial lumen to evaluate the distance between the tip of the tube and the distal bifurcation of the bronchus. DLT position should be reconfirmed after the patient is positioned laterally, before inflating the blue cuff and isolating the lung.
When the VivaSight® (Ambu Inc, Columbia, MD) tube is used, placement and repositioning can be facilitated by the high-resolution built-in camera. The main advantage for its use is during robotic cases because of the difficult access to the patient being potentially far away from the anesthesiologist and the robotic arms very close to the patient head, making any adjustments to the DLT position a challenge. The main disadvantage is the fogging of the camera by secretions, especially during right-sided procedures, and the bigger outer diameter, which may cause airway injury during the placement. The lack of a camera on the bronchial side still requires the use of a fiberoptic bronchoscope to assess secondary carina.