Awake Fibre-optic intubation

Question 1

List the nerves (and their origins) of the nose, pharynx and larynx

Answer 1

NOSE (TRIGEMINAL - CN V)

ANTERIOR ETHMOIDAL NERVE (Trigeminal - ophthalmic)
- The rest of the nose (not innervated by palatine nerves)

GREATER AND LESSER PALATINE NERVES (Trigeminal - maxillary)

• Anterior 2 thirds of the nasal septum
• Nasal turbinates

PHARYNX (GLOSSOPHARYNGEAL - CN IX)

• Posterior 1/3 tongue
• Vallecula
• Walls of the pharynx
• Anterior surface of epiglottis
• Tonsils

SUPERIOR LARYNGEAL NERVE (VAGUS)

• Posterior aspect epiglottis
• Aryepiglottal folds
• Arytenoids

RECURRENT LARYNGEAL NERVE (VAGUS)

• Vocal folds
• Trachea

Question 2

Which is the only local anaesthetic with vasoconstrictor properties and where is it useful

Answer 2

Cocaine - useful for local anaesthetic of the nose which is particularly vascular.

Question 3

What percentage preparations of cocaine are available and what is the maximum recommended dose and in which patient s should it be used with caution

Answer 3

5% and 10% - comes in paste form

Maximum recommended dose = 1.5 mg/kg

Caution in patients with:

1. Coronary artery disease
2. Hypertension
3. Pseudocholinesterase deficiency

Question 4

What is Moffett’s solution

Answer 4

Commonly used mixture used for rhinological procedures to provide local anaesthesia, vasoconstriction and decongestion:

1. Cocaine 2ml 10%
2. Adrenalin 1 ml 1:1000
3. NaHCO3 2 ml
4. NaCL 0.9% 5ml

Makes 10 ml Moffett’s solution

Question 5

What is Zahnne’s technique for awake fibre-optic intubation

Answer 5

Apply O2 early (High flow versus Non-rebreather.
Patient seated upright (Preox and applicaiton of local easier)

1. TCI - Minto - Remifentanyl - Cet1.5 - 3.0 ng/ml ± ketamine in 10mg increments.
2. Lidocaine Nebs: 4% lidocaine
3. Xylocaine (10%) to throat 10 - 15 sprays
4. Remicaine 2% jelly into nose
5. Transtracheal lignocaine 2%
6. Lignocaine 2% - Superior laryngeal nerve block
7. Preoxygenate
8. Bronchoscope
9. Small tube ± paeds bougie depending

ALSO

• Spray as you go technique via epidural catheter.
• Ribbon gauze soaked in local anaesthetic

Question 6

What are the different vasoconstrictor agents that can be used during topicalization to prevent bleeding from the nasal cavity.

Answer 6

1. Cocaine 5% or 10% paste
2. Co-phenylcaine: 125mg lidocaine + 12.5 mg phenyl
3. Oxymetazoline 0.05%

Question 7

What is the McKenzie technique for topical application of anaesthetics

Answer 7

If no spray or atomizer available:

20G cannula – 3 way tap – insulin syringe – O2 tubing with the 3rd port of 3 way connect to a 5ml syringe containing local anaesthetic/vasoconstrictor.

connect to O2 source at 2 - 4 l/minute and inject slowly.

Question 8

What is the maximum dose of topical local anaesthetic for topicalisation before awake flexible scope intubation?

Answer 8

9mg/kg

Question 9

What regional nerve block techniques can be used to anaesthetize the airway. What are the nerves that supply the nose and how are these blocked

Answer 9

1. Glossopharyngeal block
2. Superior laryngeal block
3. Translaryngeal block

Nose - Blocked using topicalisation
Greater and Lesser Palatine nerves
- Anterior 2/3rds nasal septa
- Turbinates

Anterior ethmoidal nerves
- everywhere else in the nose

Question 10

Why is the glossopharyngeal nerve block useful

Answer 10

Glossopharyngeal provides the sensory limb of the gag reflex –> therefore very useful during this procedure.

Question 11

Describe the landmark techniques used for glossopharyngeal nerve block

Answer 11

INTRAORAL

• Sufficient mouth opening required
• Identify posterior tonsillar pillar = palatopharyngeal arch (posterior to palatoglossal arch)
• Inject 2 - 5mls 2% lidocaine using 22 to 25 G needle submucosally after negative aspiration 0.5cm lateral to the lateral edge of the tongue where it joins the floor of the mouth –> USE TONGUE DEPRESSOR
• Point of injection: CAUDAL ASPECT POSTERIOR TONSILLAR PILLAR
• Repeat on the other side

PERISTYOLID APPROACH

• Needle perpindicular to styloid
• Go posteriorly until styloid lost
• Inject 5 - 7 ml lidocaine 2%

Question 12

Describe how to do a superior laryngeal nerve block using the landmark approach

Answer 12

EXTERNAL approach

1. Supine with slight extension of neck
2. Locate hyoid bone
3. Gently displace hyoid bone toward the side that the block is being performed
4. 25 G needle inserter laterally aiming toward the greater cornu of the hyoid.
5. Once contact with the hyoid bone is made, walk the needle off the bone inferiorly and inject 2 ml 2% lidocaine which will block both internal andexternal branches of superior laryngeal nerve.
6. If needle is advanced too far, it will pierce the thyrohyoid membrane and only block the internal branch –> if this happens inject a further 2mls whilst removing the needle to ensure the external branch is also blocked.

INTERNAL approach
1. Gauze soaked in lidocaine placed in the piriform fossae using Krause’s forceps for 5 - 10 minutes.

Question 13

Describe the landmark technique for doing a Recurrent laryngeal nerve block

Answer 13

TRANSLARYNGEAL BLOCK performed not direct recurrent laryngeal nerve block as the motor and sensory fibers run together. these nerves innervate all the muscles of the larynx except the cricothyroid muscle and block could lead to bilateral vocal cord paralysis and airway obstruction.

1. Supine
2. Inject 5 ml 4% lignocaine throught the cricothyroid membrane after aspirating bubbles –> rapid injection causes cough which will help disperse the local anaesthetic to block the nerves.

Question 14

What is NYSORA’s preferred technique

Answer 14

Sit patient as upright as tolerable.
Administer supplemental oxygen (via Hudson mask or nasal cannulae).
Attach full monitoring.
Start remifentanil (1–3 ng/mL) and propofol (0.5–1 μg/mL) TCI infusion. Do not give a bolus dose. Titrate the dose according to the patient’s level of sedation.
Start to topicalize the nasopharynx with Moffett’s solution sprayed via MAD.
Topicalize the oropharynx with 4% lidocaine using a MAD.
After topicalization, suction any secretions using a soft suction catheter; this also tests the effectiveness of the local anesthetic.
If patient does not tolerate the suction catheter, spray oropharynx with 2–4 sprays of 10% lidocaine.
Preload the fiberscope with a nasal endotracheal tube (ETT) (size 6/6.5 outer diameter [OD]).
Start fiberoscopy via the nasopharynx and visualize the vocal cords.
Pass the fiberscope into the trachea.
“Railroad” the lubricated ETT over the scope gently into the trachea, trying not to touch the carina with the fiberscope.
Confirm correct placement of the ETT by visualizing the carina and ETT.
Connect the ETT to the anesthetic circuit and capnography.
Gently inflate the cuff of the ETT.
Keep hold of the ETT until it has been safely secured.
Patient is now safe to anesthetize