5.7 Airway Flashcards
Indications for airway blocks:
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
Airway block
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).
TABLE 5.31 Airway reflexes
TABLE 5.31 Airway reflexes
Reflex Afferent Efferent
Gag Glossopharyngeal Vagus
Glottis closure Superior laryngeal nerve Vagus
Cough Superior and recurrent laryngeal nerves Vagus
Gag
Gag Glossopharyngeal Vagus
Glottis
Glottis closure Superior laryngeal nerve Vagus
Cough
Cough Superior and recurrent laryngeal nerves Vagus
Innervation of the airway
Nasal cavity and nasopharynx
Innervation of the airway (three neural pathways)
Nasal cavity and nasopharynx
Maxillary branches of the trigeminal nerve (V1)
Innervation of the airway
Oropharynx
Oropharynx
Glossopharyngeal nerve (CNIX)
Innervation of the airway
Larynx and trachea
Larynx and trachea
Vagus nerve (CNX)
Airway blocks
what doesnt need to blocked in face
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.
What supplies nasal cavity
The ophthalmic and maxillary divisions
of trigeminal nerves supply
the nasal cavity and have to be blocked.
Can a single block catch airway
Since the airway is supplied by
three different cranial nerves, no single
block can be used to anaesthetise them.
Can a single technique effective anaesthetise airway
However,
local anaesthetic nebulisation
(4% lignocaine for 10–15 minutes) usually anaesthetises the entire airway effectively.
Anaesthesia of the nasal cavity nerves
Anterior ethmoidal nerves
Sphenopalatine ganglion:
Anterior ethmoidal nerves
Nerve
Derived
from
Innervation Location of applicator
Anterior ethmoidal nerves
Ophthalmic division (V1)
Anterior part of nasal
septum and lateral wall
Along the superior turbinate,
resting against the cribriform
Sphenopalatine ganglion:
Nerve
Derived
from
Innervation Location of applicator
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
Anaesthesia of the nasal cavity
drugs
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.
Anaesthesia of the nasal cavity
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:
Anaesthesia of the nasal cavity
different locations
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.
Anaesthesia of the nasal cavity
how long for step one
what next
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.
Instillation technique
describe
issues
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.
Complications of nasal cavity topicalization
Complications are epistaxis, systemic toxicity and increased risk for
aspiration
Oropharyngeal anaesthesia
Oropharyngeal anaesthesia requires
blocking the
glossopharyngeal nerve.
This can be accomplished by
atomisation or CNIX block (bilateral).
Atomisation
Nerve block
Oropharyngeal anaesthesia
Atomisation
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.
Atomisation advantages
Advantages
re that it is
simple,
easy and
comfortable for patient,
with no special skill needed.
Atomisation Disadvantages
Disadvantages are
variable anaesthesia
and risk of neurological depression
in compromised patients.
Maximum safe plasma levels
of lignocaine are 5 mg/L.
Glossopharyngeal nerve block
intraoral approach.
dsecribe
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.
Superior laryngeal nerve (SLN) block
branch
the internal branch of the
superior laryngeal nerve originates
from the SLN lateral to the greater
cornu of the hyoid bone.
Superior laryngeal nerve (SLN) block path
It travels along inferior to the greater cornu,
then pierces the thyrohyoid membrane
and travels under the mucosa in the
pyriform recess
The internal branch of the SLN provides
The internal branch of the SLN
provides
sensory innervation
to the base of the tongue, superior epiglottis, aryepiglottic folds, arytenoids and laryngeal mucosa
The external
branch of the SLN supplies
The external branch of the SLN
supplies the motor innervation
to the cricothyroid muscle.
The SLN can be anaesthetised non-invasively
The SLN can be anaesthetised non-invasively
by keeping anaesthetic-soaked
gauze in the pyriform sinuses
bilaterally (using right-angle forceps).
SLN Block
where
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.
SLN Block
describe
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.
Recurrent laryngeal nerve (RLN) block
Recurrent laryngeal nerve (RLN) block
(transtracheal or translaryngeal
block):
the mucosa below the vocal cords
receives innervation from the RLN
Recurrent laryngeal nerve (RLN) block describe
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.
What happens when patient inspires during RLN block
This initiates a cough reflex and spreads the LA to both below and above the vocal cords (SLN and RLN territory)
