Double lumen endotracheal tubes (DLTs) are considered the gold standard for lung isolation – a procedure where we selectively ventilate a single lung or lobe. This is necessary to “protect” healthy lung tissue from hemorrhage or infection, isolate a bronchopleural fistula, perform unilateral lung lavage, or facilitate video-assisted thoracoscopic surgeries.
Although bronchial blockers are another option for lung isolation (especially for selective lobe isolation), anecdotally, they tend to move and do not allow suctioning beyond the blocker’s cuff. In contrast, DLTs permit small catheters to suction distal to the area of isolation which promotes lung collapse, secretion sampling, lavage, etc. In my practice, these are what I use the most for complete, unilateral lung isolation.
DLTs come in two flavors: left-sided and right-sided. The laterality refers to where the tube’s bronchial cuff resides (left mainstem or right mainstem). Although these tubes are initially advanced into the airway with laryngoscopy, their final position is confirmed with bronchoscopy. Therefore, one must consider airway anatomy to ensure appropriate positioning. In particular, the right upper lobe’s (RUL) takeoff originates very proximal in the right mainstem. If the right-sided DLT was not specially designed, its bronchial cuff could potentially occlude this RUL takeoff. Instead, the right-sided DLT has a special RUL lumen that needs to be appropriately positioned facing the RUL takeoff.
Similar to a conventional single lumen endotracheal tube (SLT), the tracheal cuff and tracheal lumen are both situated within the trachea proximal to the carina and allow airflow in both lungs. When the bronchial cuff (which resides in either the right or left mainstem) is inflated, airflow out of the tracheal lumen will “hit” the bronchial cuff. At that point, the bronchial lumen will be responsible for ventilating that lung while the tracheal lumen ventilates the other. By applying a clamp on the DLT adapter outside of the patient, we can control whether airflow is going down the bronchial lumen, tracheal lumen, or both lumens thereby facilitating lung isolation.
So if we can isolate the left and right lung separately with either a left-sided or right-sided DLT, why do we pick one over the other? From time to time, if we’re doing a left-sided total pneumonectomy for reasons related to trauma, malignancy, or transplantation, it’s ideal not to have anything (like a bronchial cuff) down in the left mainstem as this could potentially be incorporated into the left mainstem bronchus staple line as the left lung is removed. In these situations, a right-sided DLT is often placed (again, making sure the RUL lumen is appropriately positioned with bronchoscopy).