Tube Exchanger (Airway Exchange Catheter) 

Definition 

A tube exchanger, more precisely called an Airway Exchange Catheter (AEC), is a long, thin, hollow, semi-rigid catheter used to:

  • Exchange an endotracheal tube (ETT) without losing airway access
  • Provide oxygenation (apneic oxygenation / jet ventilation)
  • Act as a guide for reintubation in difficult airway

 Design & Structure

1. Physical Characteristics

  • Length: 45–83 cm (longer than ETT)
  • Diameter: Measured in French (Fr)
    • Adults: 11–19 Fr
    • Pediatrics: smaller sizes
  • Material: Semi-rigid plastic (flexible but maintains shape)

2. Key Components

a. Central Lumen

  • Allows:
    • Oxygen insufflation
    • Capnography
    • Jet ventilation

b. Depth Markings

  • Crucial for safe placement
  • Prevents:
    • Endobronchial insertion
    • Esophageal misplacement

c. Adapters

  • Connectors for:
    • Oxygen source
    • Jet ventilator
    • Capnograph

Indications 

1. Endotracheal Tube Exchange

  • Replace:
    • Blocked ETT
    • Small → larger ETT
    • Damaged cuff

2. Difficult Airway (Bridge Device)

  • Leave AEC in situ after extubation
  • Allows rapid reintubation

3. Oxygenation in Apneic Patient

  • Insufflation or jet ventilation

4. Airway Access Maintenance

  • Especially in:
    • Anticipated difficult reintubation
    • ICU high-risk extubation

Physiological Principle

Apneic Oxygenation

  • Oxygen delivered via AEC diffuses into alveoli despite apnea
  • Driven by oxygen consumption gradient (~250 mL/min)

 Complications

1. Barotrauma (MOST IMPORTANT) from jet ventilation

  • Pneumothorax
  • Pneumomediastinum
  • Subcutaneous emphysema

 Risk increases with:

  • Jet ventilation
  • Distal placement
  • Obstructed airway

2. Esophageal Placement

  • Leads to:
    • Ineffective ventilation
    • Gastric insufflation

3. Airway Trauma

  • Tracheal perforation
  • Bleeding

4. Kinking / Misplacement

  • Loss of airway access

“NEVER FORCE OXYGEN THROUGH AEC”

  • Always confirm tracheal position
  • Use low flow first
  • Avoid jet ventilation unless expert setup

Depth Guidelines (Adults)

Landmark

Depth

Teeth/Lips

20–25 cm

Carina safety

Avoid >25 cm

 Confirmation of Placement

  • Capnography (best)
  • Aspiration of air
  • Chest movement
  • Fiberoptic visualization (gold standard)

Comparison with Other Airway Devices

Device

Function

Oxygenation

Tube Exchanger (AEC)

Exchange + oxygen

YES

Bougie

Guide only

NO

Stylet

Shape ETT

NO

Guidelines & Evidence 

Difficult Airway Society (DAS) & ASA:

  • Recommend AEC for:
    • Difficult extubation strategy
    • Airway “safety bridge