To the Editor:
We read with great interest the editorial in which Edmond Cohen1 extensively reviews the use of endobronchial blockers (BBs) versus double-lumen tubes. We support his message that the anesthesiologist should be familiar with alternative devices for a double-lumen tube. However, some of his comments on our work2 on the EZ-blocker (EZB) deserve our attention.
First, Cohen points out that the most important limitation of the EZB is its inability to remove secretions through this blocker or to apply any effective suction. Indeed, the central lumen of the EZB is narrower than that of other BBs. It is, however, doubtful whether thick slimy secretions can be successfully removed through any of the BBs. All BBs are also in a fixed position and cannot be moved forth and back in search of a collection of secretions. Therefore, one needs a larger suction catheter or a flexible bronchoscope that can be used only with a double-lumen tube.
There is no immediate need to aspirate air from the lung with our technique of acquiring lung collapse, i.e., 3-min preoxygenation, followed by disconnection of the single-lumen tube from the ventilator for 60 s (starting just before the surgeon opens the pleural space), then insufflation of the cuff of the EZB. In our study, the quality of lung collapse with an EZB was comparable to that with a double-lumen tube, and it was not necessary to aspirate residual air. In cases outside our study, it proved to be possible to remove residual air through the lumen of the EZB by intermittent suction. This practice must be performed with caution because of the risk of negative pressure edema. Oxygen can be administered through the lumen of the EZB to the collapsed lung with a continuous positive airway pressure system because of a low flow suffices, e.g., when hypoxemia occurs during one-lung ventilation.
Second, there seems to be confusion about some properties of the EZB versus those of other BBs. As reported,1 BBs such as the Arndt blocker, the Cohen blocker, or the Uniblocker have low-pressure, high-volume cuffs. This does certainly not apply to the EZB, which often needs cuff pressures2 of more than 110 cm H20. Another difference is that the pilot balloons at the proximal end of the EZB are larger. A substantial amount of the volume that is insufflated remains in the pilot balloon and does not contribute to the volume of the distal cuff. Thus, the cuffs of the EZB should rather be classified as high pressure and low volume.