What is the rate of tongue obstructing the airway during anesthesia?

Rate of Tongue Obstruction During Anesthesia

Upper airway obstruction due to the tongue is a common occurrence during anesthesia, with evidence showing it primarily occurs at the level of the soft palate rather than the tongue itself, contrary to traditional belief. 1

Mechanism of Tongue-Related Airway Obstruction

Airway obstruction during anesthesia occurs primarily due to:

• Loss of muscle tone that is normally present in the awake state 2
• Anesthetic agents inhibiting respiratory activity of upper airway muscles more than the diaphragm 1
• The velopharynx (soft palate area) being particularly narrow and predisposed to obstruction 2

Magnetic resonance imaging studies have demonstrated that during propofol anesthesia:

• The minimum anteroposterior diameter of the pharynx at the level of the soft palate decreases from 6.6 ± 2.2 mm (awake) to 2.7 ± 1.5 mm (anesthetized) 1
• The pharyngeal volume significantly decreases during anesthesia 1

Risk Factors for Airway Obstruction

Patients with the following characteristics are at higher risk:

• History of obstructive sleep apnea or snoring 2
• Obesity 2
• Maxillary hypoplasia 2
• Mandibular retrusion 2
• Bulbar muscle weakness 2
• Specific obstructive lesions (nasal obstruction, adenotonsillar hypertrophy) 2

Management of Airway Obstruction

The French guidelines for airway management recommend the following approach for managing airway obstruction during anesthesia 3:

1. First step: Optimize head position

   • Ensure proper flexion of neck and extension of head
   • Apply jaw thrust or chin lift techniques 4
   • Consider inserting an oral or nasopharyngeal airway
   • Apply CPAP if needed (increases anteroposterior diameter at soft palate level from 2.7 mm to 8.43 mm) 1

2. If obstruction persists:

   • Insert a supraglottic airway device (maximum 3 attempts) 3
   • Consider using a supraglottic airway rather than tracheal intubation for short-lasting elective superficial surgery 3

3. If ventilation remains inadequate:

   • Return to mask ventilation
   • Consider waking the patient
   • If oxygenation cannot be maintained, proceed to emergency front-of-neck access 3

Prevention of Airway Obstruction

To prevent tongue-related airway obstruction:

• Perform thorough preoperative airway assessment to identify at-risk patients 2
• Consider awake tracheal intubation for patients with anticipated difficult airways 5
• Maintain spontaneous breathing until intubation when airway difficulties are anticipated 2
• Consider using a laryngeal mask airway (LMA) in appropriate cases 2
• Apply nasal CPAP as a pneumatic splint when needed 1

Extubation Considerations

The Difficult Airway Society guidelines recommend special precautions during extubation:

• Plan and prepare for potential re-intubation 3
• Ensure immediate availability of appropriate staff, equipment, and drugs 3
• Extubate when the patient is awake, responsive to commands, maintaining oxygen saturation, and generating satisfactory tidal volume 3
• Consider head-up position for extubation, especially in obese patients 3
• Maintain high vigilance for upper airway obstruction during emergence 3

Important Caveats

• Contrary to traditional belief, ultrasound assessment shows that tongue movement during anesthesia induction is inconsistent in direction and minimal (not more than 8 mm in anterior tongue and 6 mm in posterior tongue) 6
• Persistent laryngoscopy attempts should be avoided as they increase the risk of patient injury 5
• Rare cases of massive tongue swelling causing airway obstruction post-extubation have been reported and require immediate reintubation 7