In Reply:—
We thank Drs. Ng and Neustein for their interest in our research.1Addressing Dr. Ng’s letter, we fully agree with his comments that more attention should be given while training residents or staff anesthesiologists in lung isolation techniques, with particular emphasis on tracheobronchial anatomy and skills in fiberoptic bronchoscopy. In fact, after we published our study,1we designed a second study based on the lessons that we learned previously. Because the previous study did not demonstrate any advantage between the left-sided double-lumen endotracheal tubes and bronchial blockers (Univent®[Vitaid Ltd., Lewiston, NY] and Arndt®[Cook Critical Care, Bloomington, IN] blocker) and because the most common device used for lung isolation is the left-sided double-lumen endotracheal tube, we are currently conducting a new study, involving the use of left-sided double-lumen endotracheal tubes among anesthesiologists with limited experience in thoracic anesthesia (i.e. , less than two lung isolation device cases per month). In this randomized study, one group of anesthesiologists has been assigned to a tutorial in the simulator facility at The University of Iowa (Iowa City, Iowa), providing a tutorial demonstration and hands-on practice in proper placement of a double-lumen endotracheal tube with the aid of flexible fiberoptic bronchoscopy techniques on a mannequin model. The second group has been assigned to self-training using a DVD that was made by one of the authors (J.H.C.) that includes placement of left-sided double-lumen endotracheal tubes along with a detailed description of fiberoptic bronchoscopy techniques. It is our hope to have a definitive answer to determine which method (simulator training vs. DVD self-training) facilitates placement of double-lumen endotracheal tubes for anesthesiologists with limited thoracic anesthesia experience.
Our study has shown that one of the limitations of anesthesiologists with limited experience in thoracic anesthesia is unfamiliarity with bronchial anatomy.1In principle, every anesthesiologist resident or staff member should know the anatomical distances pertaining to the airway; for example, in an average subject, the distance from the incisors to the vocal cords is 15 cm, and the distance from the vocal cords to the tracheal carina is approximately 12 cm. The distance from the tracheal carina to the takeoff of the right upper lobe bronchus is an average of 1.5 cm in females and 2 cm in males. The distances from the carina to the takeoff of the left upper and left lower bronchus are an average of 4.5 and 5.0 cm, respectively.
Furthermore, when looking through the fiberoptic bronchoscope, the only early structure in the right mainstem bronchus that has three orifices is the right upper lobe bronchus: These are the apical, the anterior and the posterior bronchi. If every anesthesiologist recognized this anatomical structure, fewer problems would be encountered when inserting lung isolation devices. Adding a shared demonstration through a video-bronchoscopy might enhance training. Unfortunately, it has not been scientifically tested.
In response to Dr. Neustein’s comments regarding the Cohen endobronchial blocker,2when the original manuscript was submitted, this blocker was mentioned as one of the lung isolation devices. However, one of the reviewers stated that this blocker should be deleted from the manuscript because this device was not tested in our study, and we complied. We have used the Cohen endobronchial blocker when lung isolation is required for either a left- or a right-sided surgical procedure with excellent results but have not identified an advantage over the Arndt® wire-guided endobronchial blocker.
As we previously stated, every trainee must be familiar with (1) the devices for lung isolation, (2) fiberoptic bronchoscopy techniques, and (3) the complete knowledge of tracheobronchial anatomy to be able to properly position and use these devices. This should be a high priority in resident training during thoracic anesthesia rotations and should be the case with every anesthesiologist who is involved on an occasional basis with lung isolation cases.
Regarding the question of which views were included in the tutorial, a graphic display of fiberoptic bronchoscopy images was shown in color in real time, showing step-by-step the correct fiberoptic bronchoscopy findings of the right or left bronchus and its secondary bronchus with special attention to the takeoff of the right upper bronchus, including a view of the apical, anterior, and posterior bronchus. Also, as we stated in our study, a pictorial review of the fiberoptic views that constituted proper positioning of the three devices was shown to each participant before the study.
Regarding the workshops given in major meetings, there is no study available to demonstrate the efficacy of this method. Personally, we do not believe it is the solution to the problem. Perhaps a simulator or self-teaching instruction with a professional DVD made by an expert in the field could make a difference. Our next study should provide an answer to this question.
Regarding the choice of lung isolation techniques, Dr. Neustein stated in his letter that bronchial blockers placed on the right side are more easily dislodged than a double-lumen endotracheal tube. We absolutely disagree with his statement. In a previous report by our group,3when we compared right-sided double-lumen endotracheal tubes with bronchial blockers (Univent® bronchial blocker), there were three malpositions in the right-sided double-lumen endotracheal tube group versus five malpositions in the right-sided Univent® bronchial blocker group. In both groups, there was only one instance in which a right-sided double-lumen endotracheal tube and a bronchial blocker dislodged; the other malpositions were related to the cuff needing more air or the tube being too far in. Overall in that study, the number of malpositions was quite low for both tube types and did not differ between the groups. Therefore, the choice of device for lung isolation in the right mainstem bronchus does not matter when a cardiothoracic anesthesiologist places these devices. This concept might not apply to anesthesiologists with limited experience in thoracic anesthesia, but to our knowledge, this has not been tested scientifically.
*The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa. javier-campos@uiowa.edu
