Airway exchange catheters

What it is / how it works

• A long, semi-rigid, hollow catheter placed through an existing tracheal tube (or supraglottic device in some techniques) into the trachea to maintain access for re-intubation during extubation or tube exchange.
  • Functions: guide for re-intubation, conduit for oxygen insufflation (and in some devices jet ventilation), and a depth marker to reduce loss of airway.
• Common devices: Cook Airway Exchange Catheter (adult/pediatric sizes), Frova intubating introducer (shorter; not a true AEC but used similarly for tube exchange), Aintree intubation catheter (designed for fibreoptic-guided intubation via an LMA).

When to use (clinical scenarios)

• Planned extubation of a patient at high risk of difficult re-intubation (e.g., head & neck surgery, airway oedema, cervical spine pathology, morbid obesity, known difficult laryngoscopy).
• Tracheal tube exchange: change size/type (e.g., DLT to single-lumen, cuff leak, damaged tube, need for reinforced tube, change from oral to nasal tube).
• Bridge during extubation in ICU/ED where re-intubation may be hazardous and resources may be limited.
• Adjunct to extubation strategy in accordance with Difficult Airway Society (DAS) extubation principles: risk stratify, plan, and consider an airway exchange catheter as an ‘advanced technique’ for at-risk extubations.

Contraindications / situations to avoid

• Uncooperative patient without adequate topicalisation/sedation where coughing/biting may displace catheter or cause trauma.
• Severe airway pathology where catheter placement may worsen obstruction or cause bleeding (e.g., friable tumour, severe subglottic stenosis) unless benefits outweigh risks and skilled help available.
• Do not use jet ventilation through an AEC unless trained and with appropriate equipment/monitoring; high risk of barotrauma especially with upper airway obstruction or closed mouth/glottis.

Step-by-step technique (safe use)

• Preparation: explain plan, ensure skilled assistance, difficult airway trolley available, suction, capnography, oxygen, airway rescue plan (including front-of-neck access).
• Choose size: AEC must fit through existing tracheal tube while allowing some gas flow around it; larger AEC improves railroading but increases resistance to ventilation around it.
• Insertion depth: advance under control to a pre-defined depth; aim for mid-trachea and avoid endobronchial placement.
  • Typical adult depth guides (vary by manufacturer/patient): oral placement often ~20–24 cm at lips; nasal often deeper. Avoid advancing beyond ~26–30 cm at lips unless specifically indicated and confirmed.
  • Confirm position: continuous waveform capnography via AEC lumen if possible, or clinical signs; fibreoptic confirmation if uncertainty.
• Extubation over AEC: deflate cuff, withdraw tracheal tube while stabilising AEC; maintain oxygenation (facemask/THRIVE) and monitor for obstruction/stridor.
• Re-intubation over AEC: lubricate, consider smaller tube, use laryngoscopy to open the airway and reduce impingement; railroad gently while stabilising AEC.
  • If hang-up occurs at arytenoids/vocal cords: rotate tube 90° anticlockwise, withdraw slightly and re-advance, use a softer/armoured tube, or use videolaryngoscopy/fibreoptic guidance.
• Oxygen via AEC: prefer low-flow oxygen insufflation with continuous egress path (open mouth, patent upper airway). Use capnography and avoid high pressures.
• Duration in situ: keep only as long as needed; reassess regularly; secure and clearly label to avoid accidental removal or misinterpretation as NG tube/line.

Equipment features and sizing (practical points)

• Key features: atraumatic tip, depth markings, hollow lumen (oxygen/CO2 sampling), connectors/adaptors (e.g., 15 mm, Luer) depending on device.
• Sizing considerations: must pass through the existing tracheal tube internal diameter; ensure adequate clearance to allow gas escape around catheter during oxygen insufflation.
• Not all introducers are AECs: bougies are solid and not suitable for oxygen insufflation; Frova has a lumen and can be used for exchange but is shorter and primarily an introducer.

Physiology and risks of oxygenation/ventilation through an AEC

• Oxygen insufflation can improve oxygenation but does not guarantee ventilation; CO2 clearance may be poor, especially with small lumen and obstructed upper airway.
• Jet ventilation risks: high driving pressures + limited expiratory egress (closed glottis, laryngospasm, upper airway obstruction) can cause air trapping, barotrauma, pneumothorax, pneumomediastinum, and cardiovascular collapse.
• Capnography via AEC lumen (when feasible) helps confirm tracheal position and detect hypoventilation/apnoea early.

Complications

• Malposition: oesophageal placement, endobronchial placement, or displacement during extubation/re-intubation.
• Trauma: mucosal injury, bleeding, vocal cord/arytenoid injury, tracheobronchial perforation (rare but catastrophic).
• Barotrauma from oxygen insufflation/jet ventilation: pneumothorax, pneumomediastinum, subcutaneous emphysema, gastric insufflation/aspiration risk.
• Failure to railroad tube: impingement at larynx; kinking; tube catching on epiglottis/arytenoids; catheter too flexible or too deep.
• Patient intolerance: coughing, laryngospasm, agitation; may worsen airway oedema or precipitate obstruction.

Troubleshooting (high-yield)

• If oxygenation worsens after extubation with AEC in place: treat as airway obstruction until proven otherwise (jaw thrust, airway adjuncts, CPAP, suction, consider laryngospasm management).
• If capnography absent via AEC: check connections, ensure lumen not blocked with secretions, reassess position (withdraw slightly), consider fibreoptic confirmation; do not assume tracheal placement.
• If railroading fails: use laryngoscopy/videolaryngoscopy to align glottis, rotate tube, use smaller tube, consider fibreoptic over/alongside AEC, or abandon and re-intubate by alternative plan.
• If using oxygen insufflation: keep flows low, ensure upper airway patency and egress, monitor chest movement and capnography, stop immediately if resistance or swelling/crepitus develops.

Integration into extubation planning

• Risk stratify extubation: airway swelling/bleeding risk, difficulty of re-intubation, physiological reserve, location/time of day, availability of skilled help.
• AEC is one component: also consider cuff leak test (limited predictive value), steroids when appropriate, head-up positioning, high-flow nasal oxygen, and post-extubation monitoring in appropriate area.