1.3 Specialty Endotracheal & Endobronchial Tubes

Specialty Endotracheal & Endobronchial Tubes

Standard polyvinyl chloride (PVC) endotracheal tubes are suitable for most mechanically ventilated patients. However, specialized clinical scenarios—such as surgeries requiring patient positioning, the need for long-term ventilation, or the necessity of isolating one lung from the other—require the selection and management of specialty airway tubes.

Wire-Reinforced (Armored) Endotracheal Tubes

Wire-reinforced tubes contain a spiral metal wire coil embedded within the wall of the silicone or PVC tube. This structural reinforcement prevents the tube from kinking or collapsing when bent.

• Key Indications: Head and neck surgeries, neurosurgery (where the patient's head is flexed or rotated), and prone positioning.
• Hazards & Troubleshooting: If a patient bites down on a wire-reinforced tube, the metal coil can become permanently deformed. Unlike standard PVC tubes, which re-expand when the pressure is released, a kinked armored tube may remain permanently obstructed. Therefore, a bite block must always be placed. Additionally, wire-reinforced tubes cannot be cut to shorten them, as doing so will expose and unravel the wire coil.

Subglottic Suctioning ETTs (CASS)

Continuous Aspiration of Subglottic Secretions (CASS) tubes are designed with an additional, small-bore lumen that runs along the dorsal aspect of the tube and terminates in a suction port located just above the cuff.

• Clinical Rationale: In standard ETTs, oral and gastric secretions pool in the subglottic space above the inflated cuff. Over time, these contaminated secretions leak past the cuff (microaspiration) into the lower respiratory tract, leading to Ventilator-Associated Pneumonia (VAP).
• Suction Protocol: The subglottic port is connected to low continuous suction (20 to 30 mmHg) or intermittent suction (100 to 150 mmHg).
• Troubleshooting Blockage: If secretions stop clearing, the port is likely obstructed by thick mucus or mucosal tissue. First, check the suction regulator. If it is functioning, gently flush the port with 5 to 10 mL of air or a small volume of sterile water. Never apply high continuous suction, as this can draw the tracheal mucosa into the port, causing localized mucosal necrosis and bleeding.

Double-Lumen Endobronchial Tubes (DLT)

Double-lumen tubes allow for independent ventilation of each lung, a process known as lung isolation. A DLT contains two separate lumens (one tracheal, one bronchial) and two cuffs (a clear/white tracheal cuff and a blue bronchial cuff).

Left-Sided vs. Right-Sided DLTs

Left-sided DLTs are preferred and utilized in the vast majority of clinical scenarios, even for left-sided lung surgeries. Right-sided DLTs are technically difficult to position and rarely used.

• Anatomy: The right mainstem bronchus is short, and the right upper lobe bronchus branches off approximately 1.5 to 2.0 cm from the carina. A right-sided DLT has a ventilation slot (Murphy eye) designed to line up with the right upper lobe bronchus. If the tube rotates slightly, it will occlude the upper lobe, leading to atelectasis. In contrast, the left mainstem bronchus is longer (approx. 5 cm) and lacks early branching, making a left-sided DLT far more stable and safer to position.

Indications for Lung Isolation

• Lung Protection: Preventing contamination of a healthy lung from a diseased contralateral lung (e.g., massive unilateral hemoptysis, unilateral pulmonary abscess, or whole-lung lavage).
• Control of Ventilation: Managing severe air leaks from a bronchopleural fistula or giant unilateral cyst.
• Surgical Exposure: Collapsing one lung during thoracic surgeries (e.g., lobectomy, pneumonectomy, thoracic aortic aneurysm repair) to provide a quiet surgical field.

Management and Placement

• Sizing Selection: DLT sizing is based on the patient's gender and height. For females, a 35 Fr is used if height is < 160 cm, and 37 Fr if >= 160 cm. For males, a 39 Fr is used if height is < 170 cm, and 41 Fr if >= 170 cm.
• Cuff Inflation: The tracheal cuff requires 5 to 10 mL of air. The bronchial (blue) cuff must be inflated with only 1 to 2 mL of air. Over-inflation of the bronchial cuff can easily rupture the bronchus.
• Confirmation: Fiberoptic bronchoscopy is the gold standard for verifying correct DLT placement. The clinician must visualize the blue bronchial cuff sitting just below the carina, without herniating back into the trachea.
• Troubleshooting Malposition: If peak airway pressures rise suddenly or unilateral breath sounds disappear, the DLT has likely migrated. Re-confirm positioning immediately with a pediatric fiberoptic bronchoscope.

Bronchial Blockers

A bronchial blocker is a single-lumen catheter with an inflatable balloon at the distal tip. It is inserted through a standard endotracheal tube using a specialized multi-port airway adapter.

• Indications: When a double-lumen tube is indicated but cannot be safely placed. This includes patients with a known difficult airway (where navigating a bulky DLT is risky), pediatric patients, patients with an existing tracheostomy, or when postoperative mechanical ventilation is anticipated (avoiding the need to exchange a DLT back to a single-lumen tube).
• Mechanism: The blocker is advanced under fiberoptic guidance into the mainstem bronchus of the lung to be isolated. The balloon is inflated, blocking gas flow to that lung while the contralateral lung is ventilated via the standard ETT.

ACCS Exam Traps

• Trap 1: Choosing a right-sided DLT for a left lung surgery. Unless the left mainstem bronchus itself is diseased or surgically resected, a left-sided DLT is the correct choice.
• Trap 2: Managing a blocked CASS port by increasing the suction pressure. This will damage the tracheal mucosa; instead, choose to flush the port with air or saline.