# Awake Intubation Techniques

## Indications for Awake Intubation

### Absolute Indications

Awake intubation is absolutely indicated for a known difficult airway with anticipated difficult mask ventilation and difficult intubation, a previous failed intubation documented in records, significant airway pathology (tumor, abscess, epiglottitis, Ludwig angina, expanding hematoma), severe cervical spine instability requiring neurologic assessment during intubation, and any anticipated "cannot intubate, cannot oxygenate" scenario.

### Strong Relative Indications

Strong relative indications include multiple predictors of difficult airway (limited mouth opening, reduced neck mobility, Mallampati IV, short TMD), unstable cervical spine, severe morbid obesity with OSA and a short thick neck, full stomach combined with an anticipated difficult airway (awake intubation preserves airway reflexes), and a history of difficult intubation requiring multiple attempts.

### Patient Selection Considerations

The patient must be cooperative and able to follow commands. Awake intubation is not feasible in patients with altered mental status, severe anxiety unresponsive to sedation, or in most pediatric patients. Relative contraindications include local anesthetic allergy and airway bleeding that would obscure the bronchoscopic view.

## Airway Topicalization

### Goals

The goals of topicalization are to abolish the gag reflex, suppress the cough reflex, and provide comfort during instrumentation by blocking sensory innervation of the oropharynx, hypopharynx, and larynx. This allows passage of a bronchoscope or laryngoscope while the patient is awake.

### Innervation of the Airway

The nasal cavity is innervated by the anterior ethmoidal nerve (V1) and sphenopalatine nerve (V2). The oropharynx and base of tongue are supplied by the glossopharyngeal nerve (CN IX). The supraglottic larynx from epiglottis to vocal cords receives sensation from the internal branch of the superior laryngeal nerve (SLN, a vagus branch). The subglottic larynx and trachea are innervated by the recurrent laryngeal nerve (vagus branch).

| Region | Nerve | Cranial Nerve Origin | Block Technique |
|---|---|---|---|
| Nasal cavity | Anterior ethmoidal (V1), Sphenopalatine (V2) | Trigeminal (V) | Pledgets with 4% lidocaine along nasal floor |
| Oropharynx / tongue base | Glossopharyngeal (CN IX) | CN IX | Topical spray/gargle; glossopharyngeal block (rarely needed) |
| Supraglottic larynx (epiglottis to cords) | Internal branch of SLN | Vagus (X) | Superior laryngeal nerve block at hyoid |
| Subglottic larynx / trachea | Recurrent laryngeal nerve | Vagus (X) | Transtracheal injection or spray-as-you-go |

### Topicalization Techniques

#### Nebulized Lidocaine

Nebulizing 4-6 mL of 4% lidocaine over 15-20 minutes provides broad topicalization of the entire upper airway. It is simple and non-invasive but has variable efficacy. A large amount of lidocaine is absorbed, so total dose must be monitored. It is often used in combination with other methods.

#### Lidocaine Gargle and Spray

Options include 4% lidocaine viscous gargle for oropharyngeal anesthesia, lidocaine spray (4% or 10%) to the posterior pharynx and tongue base, atomized lidocaine via a MADgic or DeVilbiss atomizer, and "spray as you go" technique through the bronchoscope working channel.

#### Vasoconstrictor for Nasal Route

Oxymetazoline 0.05% (Afrin) or phenylephrine 0.25-0.5% sprayed into both nares reduces nasal mucosal engorgement and bleeding risk. This should be applied before nasal airway insertion or nasal intubation.

#### Lidocaine-Soaked Cotton Pledgets

For nasal topicalization, cotton-tipped applicators soaked in 4% lidocaine are placed along the nasal floor, targeting the sphenopalatine ganglion posterior to the middle turbinate. They are left in place for 5-10 minutes.

### Nerve Blocks for Airway Anesthesia

#### Superior Laryngeal Nerve Block

This blocks the internal branch of the SLN, which provides sensation from the base of the tongue to the vocal cords. The technique involves palpating the greater cornu of the hyoid bone, walking the needle off inferiorly, penetrating the thyrohyoid membrane, and injecting 2-3 mL of 2% lidocaine bilaterally. Risks include hematoma (from proximity to the superior laryngeal artery) and inadvertent vascular injection. The block abolishes gag and cough reflexes at the supraglottic level.

#### Transtracheal Block (Recurrent Laryngeal Nerve)

This blocks sensory innervation below the vocal cords. The technique involves identifying the cricothyroid membrane, inserting a needle midline, aspirating air (confirming tracheal entry), and rapidly injecting 3-4 mL of 4% lidocaine at end of expiration. The patient will cough vigorously, dispersing lidocaine over the vocal cords and trachea. Risks include bleeding and subcutaneous emphysema. Some practitioners avoid this block because it eliminates the cough reflex and protective laryngeal reflexes, increasing aspiration risk — it is particularly avoided in full-stomach patients.

#### Glossopharyngeal Nerve Block

This blocks sensation to the posterior third of the tongue, vallecula, epiglottis, and pharynx. The technique involves injecting 2-3 mL of 2% lidocaine at the base of the palatoglossal arch bilaterally. It is rarely performed in modern practice because topicalization is usually sufficient.

### "Spray As You Go" (SAYGO) Technique

Lidocaine is injected through the working channel of the flexible bronchoscope as it advances. Aliquots of 1-2 mL of 2-4% lidocaine are sprayed sequentially onto the epiglottis, vocal cords, and trachea. A 30-60 second wait after each application allows the local anesthetic to take effect. This is the most commonly used technique for subglottic anesthesia, avoids the risks of transtracheal injection, and requires careful monitoring of total lidocaine dose.

### Maximum Lidocaine Dose

The topical dose limit is generally cited as 4-5 mg/kg, though some sources allow up to 9 mg/kg for topical airway application due to slower absorption. For a typical adult, 300-500 mg total across all routes is reasonable. Signs of toxicity include perioral numbness, tinnitus, dizziness, seizures, and cardiac arrhythmias. Absorption varies by site and technique, making exact plasma level prediction difficult.

## Sedation for Awake Intubation

### Goals

The ideal state is a calm, cooperative, spontaneously breathing patient with adequate anxiolysis for comfort while maintaining responsiveness to commands and avoiding respiratory depression or loss of airway reflexes.

### Dexmedetomidine

Many practitioners consider dexmedetomidine the first-line sedation agent. It provides anxiolysis, mild analgesia, and an antisialagogue effect with minimal respiratory depression while maintaining airway reflexes. A typical protocol is a loading dose of 0.5-1 mcg/kg over 10-20 minutes followed by an infusion of 0.3-0.7 mcg/kg/hr. The patient remains arousable and cooperative. Disadvantages include slow onset and the risk of bradycardia and hypotension.

### Remifentanil

This ultra-short-acting opioid provides analgesia and excellent cough suppression. TCI (where available) or manual infusion at 0.02-0.05 mcg/kg/min is used. The risk of respiratory depression, chest wall rigidity, and apnea requires careful titration. It is best used by experienced practitioners.

### Midazolam

Midazolam provides anxiolysis and amnesia. Small titrated doses of 0.5-2 mg IV are given. The risk of over-sedation, respiratory depression, and paradoxical agitation makes it less predictable. It is often combined with fentanyl (25-50 mcg).

### Combination Approaches

Common modern approaches include dexmedetomidine plus topicalization (most popular), midazolam plus fentanyl plus topicalization (classic approach), and remifentanil plus propofol TCI (advanced technique requiring experience). The key principle is that less is more — over-sedation should be avoided.

## Flexible Bronchoscopic Intubation (FBI)

### Equipment

Equipment includes a flexible bronchoscope (adult: 4-5 mm outer diameter), an appropriate-size ETT loaded on the bronchoscope (lubricated), anti-fog solution, a light source and display, suction, and a bite block or oral airway to prevent scope damage (for the oral route).

### Oral Approach

A bite block or Ovassapian airway (or Williams airway) is inserted to channel the scope. The bronchoscope is advanced in the midline toward the uvula, then curved posteriorly. The epiglottis, arytenoids, and vocal cords are identified. The bronchoscope is passed through the vocal cords into the trachea (visualizing tracheal rings and carina). The ETT is railroaded over the bronchoscope, rotating 90 degrees counterclockwise if it impinges on the arytenoid. Tube position is confirmed with the bronchoscope before withdrawal.

### Nasal Approach

The nasal approach is often preferred for awake intubation because it is better tolerated and provides a natural pathway to the glottis. Both nares are vasoconstricted and anesthetized. A lubricated ETT is inserted nasally to the posterior pharynx (warming the softened tube reduces trauma). The bronchoscope is advanced through the nasally placed ETT, navigated to the glottis, and passed through the cords. The ETT is railroaded over the bronchoscope into the trachea. Minimum ETT size is 6.0-6.5 mm nasal; larger tubes increase epistaxis risk.

### Tips for Success

Maintaining the bronchoscope in the midline and staying in the center of the lumen is essential. If the view is lost (white-out or red-out), the scope should be withdrawn slightly and reoriented. Secretions should be suctioned and lidocaine applied as needed. The scope should be kept straight, avoiding excessive flexion that reduces image quality. Anti-fog measures include warming the scope and applying anti-fog solution to the lens.

## Awake Video Laryngoscopy

### Technique

Awake video laryngoscopy is an alternative to flexible bronchoscopy. The patient is topicalized and sedated as for FBI, then a VL blade is inserted gently to obtain the glottic view. The ETT is passed under video guidance. It requires adequate mouth opening and patient cooperation, and it is less equipment-intensive than FBI. Growing evidence supports efficacy comparable to FBI in selected patients.

### Limitations

It requires adequate mouth opening (not feasible with severe trismus), is more stimulating than nasal FBI (gagging with blade insertion), is less useful for the nasal route, and can be compromised by blood and secretions obscuring the camera.

<image>An anatomical diagram of airway innervation showing the sensory nerve supply at each level: nasal cavity (anterior ethmoidal, sphenopalatine), oropharynx (glossopharyngeal CN IX), supraglottic larynx (internal branch of superior laryngeal nerve), and subglottic/tracheal (recurrent laryngeal nerve). Color-coded regions on a sagittal section of the upper airway correspond to each nerve territory. Needle placement sites for SLN block (at hyoid) and transtracheal block (at cricothyroid membrane) are marked with injection points.</image>

<image>A step-by-step procedural illustration of awake nasal flexible bronchoscopic intubation: (1) nasal vasoconstriction and topicalization, (2) nasal ETT placement to posterior pharynx, (3) bronchoscope advancement through ETT with view of epiglottis and vocal cords, (4) scope passage through glottis showing tracheal rings and carina, (5) ETT railroaded over scope into trachea, (6) bronchoscopic confirmation of ETT above carina. Patient shown awake, sedated with dexmedetomidine, with monitors attached.</image>

<image>A comparison panel of three sedation strategies for awake intubation: Column 1 - Dexmedetomidine (dosing, onset, advantages of cooperative sedation and antisialagogue effect, disadvantages of slow onset and bradycardia). Column 2 - Remifentanil (dosing, rapid onset, advantage of cough suppression, disadvantage of apnea risk). Column 3 - Midazolam + Fentanyl (dosing, classic approach, advantage of amnesia, disadvantage of respiratory depression). A spider chart compares each on dimensions of anxiolysis, respiratory preservation, cough suppression, hemodynamic stability, and ease of titration.</image>

## Clinical Pearls

The key to successful awake intubation is excellent topicalization — time spent on airway anesthesia pays dividends because a well-topicalized patient requires minimal sedation. "Spray as you go" through the bronchoscope working channel is the most practical method for progressive airway anesthesia and avoids the risks of nerve blocks. Dexmedetomidine has become the preferred sedation agent for awake intubation because it preserves spontaneous ventilation, reduces secretions, and maintains a cooperative patient. The nasal route is often better tolerated and provides a more natural pathway to the glottis — it should be considered the default for awake FBI unless contraindicated by coagulopathy, nasal pathology, or basilar skull fracture. A backup plan is always needed: if awake intubation fails, options include waking the patient, trying an alternative approach, or proceeding with careful induction with airway rescue equipment ready. Practicing awake intubation on elective patients with normal airways builds proficiency before encountering a true difficult airway emergency. Total lidocaine dose must be monitored meticulously because local anesthetic toxicity during airway topicalization is a real risk, especially with multiple application methods.

## References

- Ahmad I, et al. Difficult Airway Society guidelines for awake tracheal intubation in adults. *Anaesthesia*. 2020;75(4):509-528.
- Apfelbaum JL, et al. 2022 ASA practice guidelines for management of the difficult airway. *Anesthesiology*. 2022;136(1):31-81.
- Simmons ST, Schleich AR. Airway regional anesthesia for awake fiberoptic intubation. *Reg Anesth Pain Med*. 2002;27(2):180-192.
- Johnston KD, Rai MR. Conscious sedation for awake fibreoptic intubation: a review of the literature. *Can J Anaesth*. 2013;60(6):584-599.
- Kundra P, et al. Dexmedetomidine versus midazolam for awake nasotracheal fiberoptic intubation. *J Anaesthesiol Clin Pharmacol*. 2014;30(4):550-554.