so here we have the model of the
neonatal school we can see the prominent
fontanel in the front and in the back
but what we want to think about now is
the is the floor of the mouth and we can
see that the mandible the lower jaw is
not as proportionately large or rigid as
as it would be in the adult and
basically all of the cartilages in the
upper airway of an infant - softer and
more flexible than they are in order
children and adults and this lack of
rigidity means structures are not fully
maintained their own fully maintained an
anatomical architecture due to lack of
rigidity and this means there can easily
be distortions and the patency of your
per airway is more likely to be
distorted because of this lack of
rigidity and the cartilages so for
example the floor of the infant mouth is
less rigid than in the adult and as
we've seen the mandible is shorter and
not as well-formed and what this means
is the floor of the mouth is easily
compressible and this is why we must be
careful not to distort these tissues
when air may airway management is
required
you
well well you catch me with the trickier
in front of me hey in roughly the right
anatomical position so we have the
larynx and the thyroid gland in the
trachea and the right main bronchus and
the left main bronchus going down to the
the lower and segmental bronchi now as
we've already mentioned the cartilage
comprised in the upper airway in infants
is relatively soft and pliable and this
is also true of the rings of cartilage
supporting the patency of the trachea
and in infants the airway the trick here
is relatively short too narrow and this
is how wide it is it's four millimeters
it's the size of this straw in a neonate
and young child very narrow now the
internal diameter of the trier trachea
does increase throughout childhood is
about the same diameter in millimeters
as the child's age in years so this tube
is seven millimeter so that would be
roughly equivalent to a seven-year-old
Shakya and in adults the overall
diameter is only 12 millimeters so the
combination of narrow diameter and soft
cartilage explains why over extension of
the infant neck can cause the keel
stretching we don't want that and this
means that the infant airway can become
compromised with the head if the heads
in extension position and this is why
airway patency is optimized in infants
with the head in the the neutral
position so we don't want they had to be
extended and we don't want it to be
flexed we wanted to be in a neutral
position because we've only got this
this four millimeters to play with here
so here we see our neonatal skull again
and for the first few months of life the
nostrils are small meaning the
communication from the outside air into
the anterior nasal cavity is relatively
narrow so here we have the nasal
cavities all being an adult model and a
gets in through the nostrils or the
external nares into the nasal cavities
but despite the nos was being narrow
near Nate's and children up to three to
six months of age of long been thought
to be obligate nose breathers and this
means these young children will be
unable to effectively breathe through
their mouths
however babies will breathe through
their mouths when they're crying and in
addition recent recent studies have
shown that infants can breathe through
their mouths
both spontaneously and during a nays of
occlusion now if unable to breathe
through the nose the soft palate will uh
will lift creating a passage between the
tongue and the soft palate means the air
can get through the oral cavity so
normally in the trial the soft palate
will be relatively closed near the
tongue so that's the tongue and that's
the soft palate they will be closed but
if a baby can't breathe through the nose
then they they should lift their soft
palate and if the soft palate is no
longer the soft palate is no longer in
contact with the tongue if it's opened
that opens that in a way just there and
that will allow air to go through the
mouth and down into the trachea which of
course exactly what we need so what this
means that it's probably better to
describe children in the first six
months of life as preferential nose
breathers but nevertheless under normal
circumstances neonates and young
children do breathe predominantly
through the nose observation of nasal
patency is of course a very important
clinical observe
Oshin upper respiratory tract infections
are common in young children and this
will stimulate mucus production from the
nasal cavity and mucus may still block
the nostrils leading to airway
compromise the advantage of nasal
breathing of course is that young
children are able to suckle for long
periods so the suckling through their
mouth milks going in through their down
through the oropharynx into the
esophagus but at the same time they can
breathe through their nasal cavities so
nasal breathing allows children to
swallow without aspiration of milk into
the airways now let's think about the
the tongue now here we have the tongue
in the mouth and the tongue grows less
than other parts of the body that
therefore it's relatively large in
younger children and if an adult the
child is unconscious the tongue may fall
back obstructing the airway leading to
blockage of the airway with consequent
asphyxiation and as the tongue is larger
in children in comparison to the
surrounding anatomical structures this
risk of airway obstruction is increased
in in younger children and this model
shows out here that the tongue can
obstruct the back of the airway that's
why we need to open the airway in older
children by extending the airway in
neonates and infants by maintaining a
neutral position as we elevate the earth
and evading the shoulders somewhat to
pull the head into a neutral position
now we've already seen the children have
a proportionately large head compared to
the rest of their body but they also
have a proportionately short neck and
combined with the large head this tends
to cause neck
action the head is moved forward and
this of course can make airway control
difficult to the level of consciousness
is reduced now of course infection of
the tonsils are common in children these
are the Palatine tonsils here and
further up we have the pharyngeal
tonsils here and when these pharyngeal
tonsils are inflamed and enlarged that
we for some reason they change their
name and we call them the adenoids so
these are the adenoids just here and the
adenoids and tonsils like all the
lymphoid tissue will enlarge when it's
infected now although lymphoid tissue
does act to fight infection sometimes
bacteria and viruses can lodge within
the lymphoid tissue itself and they can
actually multiply within the lymphoid
tissue causing infection and this can
lead to chronic infection and subsequent
swelling caused by hypertrophy as
there's an increase in the size of the
cells in the lymphoid tissue in
classically three to eight year olds are
prone to this chronic er a denote Amsale
hypertrophy and you can see that because
of the position of the adenoids here or
the adenoids when they're inflamed this
can inflame really quite significantly
and can significantly block off the
nasopharynx because this is the way that
the air is getting from the nose down
through to the lower parts of the Franks
and the airway so large adenoids can
largely or even some cases block off the
of the part of the airway through the
nose there at the level of the
nasopharynx and this is the most common
cause of obstructive sleep apnea before
puberty and if enlargements an ongoing
problem the adenoids and tonsils may
need to be surgically removed now moving
further down we now want to think about
the epiglottis this is the epiglottis
here and the epiglottis covers this area
here which is the top of the airway and
is called the glottis so the epiglottis
is covering the glottis and the size of
proportion of the epiglottis are
different in children in adults the
epiglottis is typically more broad and
rigid and in infants and young children
the epiglottis is relatively large long
and floppy and relatively narrow and
positionally it also projects
posteriorly over the glottis at an angle
of about 45 degrees so the epiglottis in
children it is more posterior projecting
Maule over the opening of the glottis
and the combination of a relatively
large epiglottis and the position just
above the opening of the airway means
that if it becomes inflamed the swollen
structure has the potential to occlude
the upper Airways leading to obstruction
so the epiglottis is relatively large in
children compared to the smaller
anatomical size of the anatomical
structures roundabout and remember in
the neonatal infant this straw is the
diameter of the trachea the Chukyo
diameter is four millimeters so there's
not a great deal of spare anatomical
space to maintain the patency of the
upper airway so bacterial infection of
the epiglottis in early life can
therefore lead to swelling and edema
which may potentially block off the
airway now epiglottitis is classically
associated with the Hamas influenza type
B but with the hip vaccination this
presentation is much less common so we
see far fewer children coming in with
epiglottitis now than we used to of
course there's other bacterial
infections can cause epiglottitis in
georgia but we are seeing much less
since the introduction of the other the
hip vaccine I actually worked on a local
intensive care unit before the hip
vaccine was brought in and it was quite
common the children with epiglottitis
will come in for
monitoring of their airway but
thankfully much less common presentation
now now the larynx is this cartilaginous
structure at the top of the airway this
is the hyoid bone this is the the large
front cartilages of the the larynx the
thyroid cartilage and if we open this up
we can see here we've got the the vocal
chords inside so these are the vocal
chords here and these are sometimes
called the fossa false vocal cords on
top better to call them the vestibular
folds there they are protecting the the
upper airway and this is the epiglottis
that would fold down over the glottis
during swallowing and what we see here
this is the cricoid cartilage that's the
front of the cricoid cartilage and
that's the back of the cricoid cartilage
much wider at the back as we probably
see on on this section that's the that's
the cricoid cartilage just there the
first full ring of cartilage much wider
at the back and part of the reason the
neck is shorter in children is that the
larynx is shorter and the laryngeal
structures are more overlapping so this
is the adult one and we can see there's
a nice gap between the hyoid bone and
the thyroid cartilage in a nice gap
between the thyroid cartilage and the
cricoid cartilage that's the
cricothyroid ligament there if you ever
need to do an emergency cricothyrotomy
so in the other we have this space here
and we have this space here but with
children they're more compressed in
these structures will overlap in the
neonate so in the adult the whole larynx
is longer in the child the whole larynx
is shorter
part of the reason that the neck is
shorter in in neonates and infants and
this model allows us to equate the
position of the anatomical structures
with the with the vertebrae
so this is the part of section of c1
we'd see here first cervical vertebrae
that's so c2 there three four five six
seven so that would make that the very
start of which vertebrae would that be
what if that's c7 that's going to be t1
thoracic vertebrae one at that level
there and in adults we can see that the
larynx is level with c5 and c6 so at the
c5 c6 level in adults but because in
children the neck is much shorter in
children the larynx is more at the level
of c2 and c3 making the neck and very
much shorter in children and as we've
stressed before all cartilaginous
portions of the airway are softer in
children and more compliant in infants
especially for the first year of life
and this increases the flexibility of
anatomical structure such as the
epiglottis the larynx the rings of
cartilage and support the patency of the
bronchial tree and stiffening of
cartilage progresses throughout
childhood into the teenage years it's an
ongoing process now here we have the as
we've said the cricoid cartilages there
that's the front and that's the back of
the cricoid cartilage and again as
infants have a short neck the cricoid
ring is located approximately at the
level of c4 in children c4 vertebrae c4
c4 so that's 2 3 4 so the cricoid ring
in a child is right up at about that
level there compared to being down here
in the adult so birth this tripod ring
is it about c4 three four is at that
level there but at age six the cricoid
ring has moved down to the level of c5
so that's 2 3 4 5 so it's moved down to
there by
time the child is is six years old and
as we've seen in the adult as is
illustrated in this model around about
the level of a level of c6 now in
children under the age of ten the area
inside this cricoid ring here this area
here inside the cricoid ring in children
younger than ten this this area inside
the cricoid ring has been considered to
be the narrowest portion of the upper
airway within the cricoid ring and of
course the cricoid ring is a complete
ring as we've seen a complete complete
ring of cartilage and that's in contrast
to the rings in the cartilage in the
trachea which are incomplete to allow
the movement of a food bolus down the
esophagus
so this cricoid ring is a complete ring
of cartilage now having said that in
children under the age of ten this area
is the narrowest portion of the upper
airway some invivo in life studies have
found that the the glottic opening is
smaller at some time sometimes so that
would be the glottic opening there as
opposed to the gap between the cricoid
ring there but despite this the distend
ability of the glottic tissues and the
rigid nature of the cricoid cartilage
there still leads to the effect of this
area of the cricoid ring being
functionally the narrowest part of the
airway and the airway within the cricoid
ring this area here the airway inside is
lined by ciliated pseudostratified
epithelium
but it's loosely bound to connective
tissue called areolar tissue and this
loose arrangement means the cricoid area
which is already narrow is prone to a
demitasse swelling and edema may be
caused by any form of information such
as burns or hot gases allergic or
inflammatory reactions and indeed
medical interventions so inflammation
they can cause to narrowing
of this already narrow part of the
child's airway now this is an important
consideration whenever we're thinking
about children's airway because
resistance to flow in the airway is
governed by Pru cells law and what this
means is if the radius of an airway is
halved the resistance to flow will
increase by a factor of 16 so any
narrowing of any part of the airway is
significant in children