Q & A on Endobrochial Blockers
Q: What are the indications of a wire-guided endobronchial blocker?
A: While wire-guided endobronchial blockers can be used in almost any patient requiring one-lung ventilation, there are several situations where they may be distinctly preferable to the use of a double-lumen endotracheal tube. Wire-guided endobronchial blockers are indicated for patients requiring one-lung ventilation but optimally managed with conventional single-lumen tubes or when a double-lumen endotracheal tube is contraindicated. Examples of these indications include patients requiring one-lung ventilation where continued postoperative intubation and ventilation is anticipated, patients with a known difficult airway, the tracheotomized patient needing one-lung ventilation, emergent thoracic trauma, critical care patients and small adults or pediatric patients.
Q: What are the advantages of a wire-guided endobronchial blocker over other endobronchial blocker systems?
A: The wire-guided endobronchial blocker is placed coaxially through a conventional single-lumen endotracheal tube. The requirement for one-lung ventilation is separated from primary airway management issues. The wire-guided endobronchial blocker is placed through a special manifold built to allow simultaneous ventilation, fiberoptic bronchoscopy and airway instrumentation. The wire-guided endobronchial blocker allows one-lung ventilation independent of placing a specific device into the airway. The wire-guided endobronchial is removed, leaving the patient intubated with a conventional single-lumen tube following one-lung ventilation.
Q: What are the advantages of wire-guided endobronchial blockers over conventional double-lumen tubes?
A: The wire-guided endobronchial blocker allows conservation of cross-sectional area. A small single-lumen endotracheal tube has the same internal cross-sectional area as a much larger double-lumen endotracheal tube. The wire-guided endobronchial blocker does not require re-intubation at the conclusion of surgery as with a double-lumen endotracheal tube. Double-lumen endotracheal tubes are technically more challenging to insert and position. In addition, trauma to the airway may be greater than with single-lumen endotracheal tube placement. Tearing of the double-lumen tube cuff often occurs during placement, necessitating replacement at additional cost and inconvenience.
Q: What size bronchoscope should be used with the wire-guided endobronchial blocker?
A: The adult 9 Fr blocker is optimally placed with a pediatric bronchoscope with an outer diameter (OD) of 3.0 to 3.5 mm. An endotracheal tube with an inner diameter (ID) of 8.0 to 8.5 mm is optimal, although it may be placed through a tube with as small an ID of 6.5 mm, but not without significant technical challenge. The 5 Fr pediatric blocker is optimally placed with a 1.8 to 2.0 mm OD bronchoscope through a 4.5 to 5.0 mm ID endotracheal tube.
Q: What volume of air does the endobronchial blocker balloon require to occlude the bronchus?
A: The high-volume, low-pressure balloon is designed to accommodate up to 15 mL of air. How much is required to occlude the bronchus varies amongst individuals, but typically 5 to 8 mL is required.
Q: Are there any contraindications to its use?
A: The unavailability of or unfamiliarity with fiberoptic bronchoscopy should contraindicate its use. Fiberoptic bronchoscopy is essential to the safe and effective use of the wire-guided endobronchial blocker. A relative contraindication might be the patient in whom bilateral thoracic procedures are planned, thereby requiring sequential one-lung ventilation. While the blocker can be repositioned, it requires keeping the wire loop within the central lumen of the blocker, which may hamper lung deflation somewhat.
Q: Can continuous positive airway pressure (CPAP) be used if needed to treat hypoxemia during one-lung ventilation?
A: CPAP can be applied through the central lumen of the blocker using an adapter included in the blocker kit. Any conventional CPAP circuit can then be utilized.
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