What are the guidelines for blind insertion of a Laryngeal Mask Airway (LMA) in patients with an Endotracheal Tube (ETT) just before extubation?

Blind Insertion of LMA Before Extubation

The Difficult Airway Society guidelines do not recommend blind insertion of an LMA in patients with an endotracheal tube just before extubation; instead, they recommend using an airway exchange catheter (AEC) for at-risk extubations, or the Bailey maneuver (LMA exchange technique) under direct vision with adequate anesthetic depth. 1, 2

The Recommended Approach: Airway Exchange Catheter

For patients requiring a safety device during at-risk extubation, insert an AEC through the ETT before removing the tube, not an LMA. 1

AEC Insertion Protocol:

• Confirm the ETT tip position relative to the carina with fiberoptic bronchoscopy if uncertain, and never insert the AEC beyond 25 cm in adults 1
• Insert the lubricated AEC through the ETT to predetermined depth when ready for extubation, never advancing against resistance 1
• Perform pharyngeal suction before removing the ETT 1
• Remove the ETT over the AEC while maintaining AEC position without advancing it 1
• Secure the AEC to cheek or forehead, record depth, verify leak around AEC, and clearly label to prevent confusion with nasogastric tube 1
• Nurse patient in high dependency or critical care unit, keep nil by mouth, and remove AEC when airway no longer at risk (can be tolerated up to 72 hours) 1

AEC Advantages:

• Complications including hypoxia, bradycardia, hypotension, and esophageal intubation are less common when reintubation is performed using an AEC compared to standard techniques 1
• Direct or videolaryngoscopy during AEC-guided reintubation increases success and reduces complications 1

The Bailey Maneuver: LMA Exchange Under Anesthesia

If deep extubation is desired but reintubation would be difficult, consider the Bailey maneuver (LMA exchange technique) which provides a rescue airway during emergence, but this requires adequate anesthetic depth and is NOT performed blindly. 2

Critical Requirements for LMA Exchange:

• Ensure adequate anesthetic depth using volatile agent or TIVA to prevent laryngospasm, which is the primary complication 2
• The LMA must be inserted under adequate anesthesia with the patient still deeply anesthetized, not blindly inserted in an awake or lightly sedated patient 2
• Maintain continuous anesthetic supervision until the patient is awake and maintaining their own airway, as the period between extubation and full awakening is high-risk 2

Evidence on LMA Insertion with ETT In Situ:

• In elective settings with adequate anesthesia, LMA can be successfully positioned on first attempt in 95% of intubated patients, with successful placement in 100% with multiple attempts 3
• The most serious malposition (occurring in 5% of first attempts) is insufficient insertion depth, which could result in airway obstruction 3
• However, this technique requires proper training and is performed under controlled anesthetic conditions, not as a blind rescue maneuver 3

Why Blind LMA Insertion Is Not Recommended

Blind insertion of an LMA in awake or lightly sedated patients with an ETT in place carries significant risks:

• Inadequate anesthetic depth during LMA placement leads to laryngospasm, the primary complication of this approach 2
• In critically ill patients on controlled ventilation, LMA use resulted in 33% potentially catastrophic complications including loss of airway, inadequate ventilation leading to significant hypoxia, gastric distension and regurgitation 4
• The LMA does not provide a safe patent airway in critically sick populations on controlled ventilation and should not replace ETT for securing airways in high-risk situations 4

Common Pitfalls to Avoid

• Never attempt blind LMA insertion in awake or lightly sedated patients as a rescue technique—this is fundamentally different from the controlled Bailey maneuver performed under adequate anesthesia 2, 3
• Do not confuse the Bailey maneuver (controlled LMA exchange under deep anesthesia) with emergency blind LMA insertion—they are entirely different techniques with different risk profiles 2, 3
• Avoid oxygen insufflation through AEC except in extremis due to barotrauma risk; flows should not exceed 1-2 L/min and only when tip is confirmed above carina with route for exhaled gas 1
• Remember that AEC complications can be severe including tracheal perforation, interstitial pulmonary emphysema, and barotrauma from subcarinal jet ventilation 1

When to Postpone Extubation

Extubation is entirely elective—when the threat of airway compromise is severe, postpone extubation for hours or days to allow airway edema to resolve and match availability of skilled personnel. 1