Week 6 Flashcards
Airway resistance accounts for how much of the total resistance in the lungs?
~80%
Why is airway resistance so important to consider in the paediatric population?
children have smaller diameter airways and therefore the same amount of narrowing will cause much greater breathing difficulties in a child than an adult
What is tracheal tug?
an effect seen in children in respiratory distress
the tracheal does not have mature cartilage formation yet and the increased flow generated to overcome airway resistance will lead to tracheal wall compression
only seen from several months of age as the neck in neonates is hidden by the chin
What are some other signs of respiratory distress in children?
nasal flaring (an attempt to reduce airway resistance by increasing the diameter of the nasal airway)
stridor (which is much more serious in this population, physio treatment may aggravate stridor)
increased respiratory rate
recessions (mostly seen around the ribs and sternum as a sign of increase WOB)
When do collateral channels develop in children?
from 1 year
Pores of Kohn (after one year)
Canals of Lambert (from 5 years)
Channels of Martin (only in diseased lungs)
Are the effects of alveolar interdependence increased or decreased in the <12 month old?
decreased
due to the lack of collateral channels supporting aeration through each alveoli
What are some strategies to treat lobar collapse in an intubated child?
manual hyperinflations (without exceeding 10-20% of the peak inspiratory pressure)
end expiratory pressure (particularly useful when de-recruitment is in play)
What are some strategies to treat lobar collapse in a self ventilation child?
all aiming to get air behind the lungs:
postural drainage
thoracic stretch (particularly in side lying)
augmenting volume (i.e. demand ventilation via mobilisation or deep breathing)
sustained expiratory manoeuvres (‘squeezing’ one lung to force ventilation into the other lung)
peak expiratory pressure (PEP)
What is the difference in shape between an infants thorax and an adults?
adults have a ellipsoid shape and infants have a more rounded shape, with ribs sitting horizontal rather than downward
When does the childs thorax shape change?
when they achieve sitting (due to the abdominal muscular activity exerting a downward pull on the thoracic cage)
by 10 the rib angle is similar to an adults
When can a child affecting increase their tidal volume?
once they’re sitting up (~8-12 months), unable to before this due to the compliance of the chest wall
Why do we want to avoid taking a child to the end of expiration during treatment?
to avoid encroaching on their closing capacity
children will inspire prior to the full expiration to avoid this
What conditions/situations decrease FRC below closing capacity in children?
supine in infants
anaesthesia
pulmonary oedema
respiratory distress syndrome (RDS)
diffuse lung injury
tipped positioning
What conditions/situations increase closing capacity above FRC in children?
smoke inhalation
asthma
bronchopulmonary dysplasia (BPD)
bronchiolitis
age
mucus plugging
Contrast adult diaphragm muscle fibres to an infants.
adults diaphragm is made up of 55% slow twitch (type 1) fibres, whereas an infant is born at term with only 25% and even less if pre-term (10%)
this means the infants diaphragm muscle is going to fatigue much more quickly than an adults
