5.7 Airway

Question 1

Indications for airway blocks:

Answer 1

Indications for airway blocks:

1.
for awake intubation in patients 
with airway compromise, 
trauma to the upper airway, 
or cervical instability

2.
to allow tolerance of 
nasal endotracheal tube, 
oral endotracheal tube
or tracheal tubes in 
critically ill patients 
in intensive care (sometimes

3.
transoesophageal echocardiography in an awake patient

Question 2

Airway block

Answer 2

This acts by
abolishing the gag reflex,
glottis closure reflex
and the cough reflex.

Stapedial reflex involves
the facial nerve
(not blocked in airway blocks).

Question 3

TABLE 5.31 Airway reflexes

Answer 3

TABLE 5.31 Airway reflexes

Reflex Afferent Efferent

Gag Glossopharyngeal Vagus

Glottis closure Superior laryngeal nerve Vagus

Cough Superior and recurrent laryngeal nerves Vagus

Question 4

Gag

Answer 4

Gag Glossopharyngeal Vagus

Question 5

Glottis

Answer 5

Glottis closure Superior laryngeal nerve Vagus

Question 6

Cough

Answer 6

Cough Superior and recurrent laryngeal nerves Vagus

Question 7

Innervation of the airway

Nasal cavity and nasopharynx

Answer 7

Innervation of the airway (three neural pathways)

Nasal cavity and nasopharynx

Maxillary branches of the trigeminal nerve (V1)

Question 8

Innervation of the airway

Oropharynx

Answer 8

Oropharynx

Glossopharyngeal nerve (CNIX)

Question 9

Innervation of the airway

Larynx and trachea

Answer 9

Larynx and trachea

Vagus nerve (CNX)

Question 10

Airway blocks

what doesnt need to blocked in face

Answer 10

The facial nerve does not
participate in airway reflexes and
need not be blocked.

The mandibular nerve supplies
sensation to anterior two thirds of the
tongue and need not be blocked.

Question 11

What supplies nasal cavity

Answer 11

The ophthalmic and maxillary divisions
of trigeminal nerves supply
the nasal cavity and have to be blocked.

Question 12

Can a single block catch airway

Answer 12

Since the airway is supplied by
three different cranial nerves, no single
block can be used to anaesthetise them.

Question 13

Can a single technique effective anaesthetise airway

Answer 13

However,
local anaesthetic nebulisation
(4% lignocaine for 10–15 minutes) usually anaesthetises the entire airway effectively.

Question 14

Anaesthesia of the nasal cavity nerves

Answer 14

Anterior ethmoidal nerves

Sphenopalatine ganglion:

Question 15

Anterior ethmoidal nerves

Nerve
Derived
from
Innervation Location of applicator

Answer 15

Anterior ethmoidal nerves

Ophthalmic division (V1)

Anterior part of nasal
septum and lateral wall

Along the superior turbinate,
resting against the cribriform

Question 16

Sphenopalatine ganglion:

Nerve
Derived
from
Innervation Location of applicator

Answer 16

Sphenopalatine ganglion:
nasopalatine, greater and
lesser palatine nerves

Maxillary
division
(V2)

Posterior and inferior
parts of nasal septum
and lateral wall

Along the middle turbinate
resting against the sphenoid
bone (most important

Question 17

Anaesthesia of the nasal cavity

drugs

Answer 17

Drugs used:
Anaesthetic:
4% lignocaine (maximum 500 mg)

Vasoconstrictor: cocaine is a 4% solution
(maximum 200 mg) or

epinephrine (1:200 000) or
0.05% phenylephrine.

Question 18

Anaesthesia of the nasal cavity

Answer 18

Technique:

the patient is most comfortable when the
head of the bed is
elevated approximately 30°.

Then 6–8-cm-long cotton-tipped
applicators or wide cotton pledgets
soaked in the drug solution
are inserted into both nares as follows:

Question 19

Anaesthesia of the nasal cavity

different locations

Answer 19

1.
first applicator along the
inferior turbinate to rest a
gainst theposterior nasopharyngeal wall

2.
second applicator is placed in a
cephalad angulation along the middle turbinate, against the sphenoid bone (most important, as it
anaesthetises branches of the sphenopalatine ganglia)

3.
third applicator may be placed 
along the superior turbinate, 
resting against the cribriform plate, 
anaesthetising the anterior ethmoid nerve.

Question 20

Anaesthesia of the nasal cavity

how long for step one

what next

Answer 20

The applicators/pledgets are left in place for 5 minutes.

Next, nasal cavity is dilated with

nasal airways bilaterally (in increasing sizes)

by lubricating with
2%–5% lignocaine jelly.

Question 21

Instillation technique

describe

issues

Answer 21

Instillation technique:

with the patient’s head low,
or with a pillow under the patient’s shoulder,
LA is instilled in the nasal cavity

(10 minutes for each side).

It can lead to total spinal anaesthesia,
as it involves injection into
the nasal cavity near the cribriform plate.

Question 22

Complications of nasal cavity topicalization

Answer 22

Complications are epistaxis, systemic toxicity and increased risk for
aspiration

Question 23

Oropharyngeal anaesthesia

Answer 23

Oropharyngeal anaesthesia requires
blocking the

glossopharyngeal nerve.

This can be accomplished by
atomisation or CNIX block (bilateral).

Atomisation
Nerve block

Question 24

Oropharyngeal anaesthesia

Atomisation

Answer 24

Atomisation:

10% lignocaine spray (each puff has 20 mg).

2% viscous lignocaine (10 mL) gargles for 10 minutes.

4% lignocaine (5–10 mL) with 1:200 000
epinephrine nebulisation for 15–20 minutes.

Cetacaine spray (mix of 14% benzocaine and 2% tetracaine): more toxicity.

Question 25

Atomisation advantages

Answer 25

Advantages

re that it is
simple,
easy and
comfortable for patient,

with no special skill needed.

Question 26

Atomisation Disadvantages

Answer 26

Disadvantages are
variable anaesthesia

and risk of neurological depression
in compromised patients.

Question 27

Maximum safe plasma levels

Answer 27

of lignocaine are 5 mg/L.

Question 28

Glossopharyngeal nerve block

intraoral approach.

dsecribe

Answer 28

Glossopharyngeal nerve (lingual branch):

blocked bilaterally
intraoral approach.

Initially, topical anaesthesia is
provided to oral cavity
by abovementioned methods.

Next the tongue is depressed 
(with a tongue depressor)
and a spinal needle (9–10 cm 25 G) 
is used to inject 0.5% lignocaine (2 mL)
0.5 cm below the mucosa of the base of anterior tonsillar pillar after aspiration. 

It is repeated on the other side.

Although it is more effective, it is
more discomforting than atomisation.

Question 29

Superior laryngeal nerve (SLN) block

branch

Answer 29

the internal branch of the
superior laryngeal nerve originates
from the SLN lateral to the greater
cornu of the hyoid bone.

Question 30

Superior laryngeal nerve (SLN) block path

Answer 30

It travels along inferior to the greater cornu,

then pierces the thyrohyoid membrane
and travels under the mucosa in the
pyriform recess

Question 31

The internal branch of the SLN provides

Answer 31

The internal branch of the SLN
provides

sensory innervation

to the base of the tongue, 
superior epiglottis, 
aryepiglottic folds,
arytenoids and 
laryngeal mucosa

Question 32

The external

branch of the SLN supplies

Answer 32

The external branch of the SLN
supplies the motor innervation
to the cricothyroid muscle.

Question 33

The SLN can be anaesthetised non-invasively

Answer 33

The SLN can be anaesthetised non-invasively
by keeping anaesthetic-soaked
gauze in the pyriform sinuses
bilaterally (using right-angle forceps).

Question 34

SLN Block

where

Answer 34

Alternatively,

it can be blocked invasively
at the greater cornu of the hyoid
bone bilaterally by walking the needle off it,
into the thyrohyoid membrane.

Question 35

SLN Block

describe

Answer 35

greater cornu of the hyoid
bone bilaterally by walking the needle off it,
into the thyrohyoid membrane.

At a depth of 1–2 cm,

2 mL of 2% lignocaine (with epinephrine) 
is injected (after negative aspiration) 

between the thyrohyoid membrane and pharyngeal
mucosa.

The block is repeated on the opposite side.

Question 36

Recurrent laryngeal nerve (RLN) block

Answer 36

Recurrent laryngeal nerve (RLN) block
(transtracheal or translaryngeal
block):

the mucosa below the vocal cords
receives innervation from the RLN

Question 37

Recurrent laryngeal nerve (RLN) block describe

Answer 37

With the patient supine and the
neck hyperextended,

a 20-G intravenous cannula
is inserted into the cricoid membrane.

After tracheal entry is
confirmed by air aspiration,
stellate is removed and 4 mL of 2% lignocaine
(with epinephrine) is injected as the patient inspires.

Question 38

What happens when patient inspires during RLN block

Answer 38

This initiates a cough
reflex and spreads the
 LA to both below and
 above the vocal cords (SLN and
RLN territory)