I appreciate the suggestion of Dr. Karzai of an alternative method to facilitate lung collapse while using a wire-guided endobronchial blocker (WEB®; Cook, Bloomington, IN). The various methods I discussed in my article 1for facilitating and/or expediting lung collapse when the WEB® is in use include: (1) Removal of the wire loop after the patient is turned to a lateral decubitus position and fiberoptic confirmation demonstrate that the WEB® is correctly placed in the optimal position, so that air can be evacuated spontaneously along with the absorption atelectasis in the nondependent lung. (2) Use of the low-suction–assisted method, which basically consists of connecting the barrel of a 3-ml syringe to the wire loop site (after the wire loop has been removed) then attaching it to a low-suction device after the cuff of the blocker has been fully inflated. I do not recommend continuous suction through this channel, because of the risk of developing negative pressure pulmonary edema reported with the Univent® endotracheal tube (Vitaid, Lewiston, NY). 2
Regardless of the method used to facilitate or expedite lung collapse, variability among time to lung collapse exists when using double-lumen endotracheal tubes (DLT) or bronchial blockers (Univent® and WEB®). In a recent study, 3when comparing the DLT versus Univent® and WEB®, it was found that the majority of patients assigned to the WEB® group required assisted suction and took longer to achieve complete lung collapse when compared to the DLT or Univent® groups (by an average of 7 min). The method proposed by Dr. Karzai raises some concerns How long do we need to stop ventilating the patient until complete collapse is achieved? Has this method been tested in a prospective, randomized, and scientific fashion? I will assume that some patients with severe chronic obstructive pulmonary disease may not tolerate prolonged periods of apnea. Until Dr. Karzai's method to expedite lung collapse is tested in a scientific fashion defining length of time and oxygenation/saturation measurements, I would not propose using it clinically.
Another important issue that Dr. Karzai mentioned relates to maintaining the wire loop through the operation as long as is needed. In a recent study 3when comparing the left-sided DLT with the Univent® and WEB®, we reported nine total malpositions in 32 patients in the WEB® group. The first six malpositions occurred while changing from the supine to the lateral decubitus position. The wire loop was kept until the WEB® was confirmed to be in its optimal position with the fiberoptic bronchoscope after the blocker cuff was fully inflated. The other three malpositions occurred during one-lung ventilation, after the wire loop was already removed. The WEB® was repositioned under fiberoptic bronchoscopy with no difficulty and was placed in its optimal position. In addition, removing the wire loop allows the opening channel to apply continuous positive airway pressure ventilation or intermittent inflation, if required. Maintaining the wire loop in the WEB® during the operation may potentially damage the membranous airway, or the airway may accidentally be stapled into the bronchial closure, as reported when the bronchial blocker of the Univent® was stapled during a right upper lobectomy. 4
I appreciate the comments by Dr. Arndt and would like to address the issue he has raised. I agree with the importance of comparing the inner and outer diameters of the DLT, Univent®, and single-lumen endotracheal tubes. As mentioned in his letter, one of the advantages of the WEB® is the ability to preserve the inner diameter of a single-lumen endotracheal tube while using the WEB®. However, one must consider that a reduction of the cross-sectional area occurs when a WEB® is placed inside a single-lumen endotracheal tube. I would speculate that the presence of the WEB® may also affect air-flow resistance, which at the present time has not been tested scientifically, as opposed to DLT, Univent®, and single-lumen endotracheal tubes. 5
I also appreciate the comments by Munir et al. and would like to address the alternative method for using the Fogarty® embolectomy balloon catheter (Edwards Lifesciences, Irvine, CA) through the vocal cords alongside the single-lumen endotracheal tube under direct laryngoscopy. This method of placement has been previously reported in the pediatric literature and is commonplace in some practices. 6I disagree with Munir et al . that a fiberoptic bronchoscope may not be needed for guidance while advancing the Fogarty catheter. I believe it would not be a safe practice to omit the use of the bronchoscope. If a Fogarty catheter is advanced with its stylet in place, there is the potential for tracheobronchial laceration, as previously reported. 7Regarding the cost, Fogarty catheters are cheap, $4.20, when compared to the DLT (the University of Iowa acquisition cost for a left-sided DLT is $79.20, a Univent® is $137, a WEB® is $107 plus $1 for a single-lumen endotracheal tube, and a Fogarty catheter No. 8/14 F is $75). One of the advantages that the Fogarty catheter may offer over the DLT is its balloon durability when compared with DLTs in which the tracheal cuff is more prone to tears in some cases. 8
I believe that the use of the fiberoptic bronchoscope suction port to facilitate and expedite lung collapse is justified while using a bronchial blocker. It is doubtful that the negative pressure and flow characteristics used would be sufficient to collapse the cartilage-supported bronchi and bronchioles. Finally, to advance a Fogarty catheter independently alongside the single-lumen endotracheal tube in a patient who is critically ill and mechanically ventilated, as suggested by Munir et al. (usually these patients are intubated for days and have severe edema in the vocal cords), would be difficult because the upper airway would likely be edematous.