Developmental aspects of lung disease Flashcards
Names of stages of lung morphogenesis
embryonic pseudo-glandular canalicular saccular alveolar
at which stage of life can you survive due to your lungs being sufficiently developed
24-26 weeks
this is within the canalicular stage
what happens in embryonic stage lung morphogenesis
tube forms from the top of the foetus to the bottom. This divides into right and left airways.
Primitive trachea and larynx formed
what happens during canalicular?
last generations of the lung periphery formed epithelial differentiation- cells flatten/become squamous, air-blood barrier formed to allow for gas exchange.
what happens in pseudo glandular stage
cartilage begins to form
major airways formed
lung lobes formed
no air sacs and no possibility of gas exchange yet though
alveolar stage
smaller and smaller alveoli, improving surface area allowing for more gas exchange
what happens in saccular stage
expansion of air spaces surfactant detectable in amniotic fluid
what happens with lung growth in postnatal
the alveolar septation (division) continues into late childhood/early adulthood
which stages does the umbrella term ‘organogenesis’ in lung development cover?
embryonic
pseudoglandular
which stages does the umbrella term ‘differentiation’ in lung development cover?
canalicular
saccular
alveolar
prediction of problems in lung development
you can predict problems/ type of problems depending on which stage it occurs at
what is pulmonary sequestration
rare malformation (present from birth) where non-functioning lung tissue is separated from the rest of the lung and supplied with blood from an unusual source, often an artery from systemic circulation
what problems can arise later on in lung development
bronchogenic cysts
solid tissues
sequestration
lobar emphysema- air can enter lung but can’t escape
when are abnormal features presented?
75% in fetal ultrasound
10% in newborn
15% in childhood
problems that present in a newborn
tachypnea - breathing fast
respiratory distress
problems that present in childhood
stridor- noisy breathing- turbulent air flow
recurrent pneumonia
incidental finding
when are the majority of lung problems picked up?
in foetal ultrasounds
NHS usually offers 2 scans during pregnancy
within 8-14 weeks and 18-21 weeks
What are 2 common congenital lung diseases?
tracheo-bronchomalacia
pulmonary adenomatoid malformation
symptoms of tracheo-bronchomalacia lung disease
barking/seal like cough
early onset/ recurrent croup
breathless on exertion
stridor/wheeze
management of tracheo-bronchomalacia lung disease
Airway clearance physiotherapy
Antibiotics
Avoid “asthma” treatment (especially bronchodilators)
symptoms of adenomatoid malformation describe + what is the management
may resolve in utero but possible risk of malignant change
if asymptomatic - leave the legions alone
development of the diaphragm
a variety of embryonic/primitive tissue contributes to the diaphragm- they join up and become a fibrous band
it is complete by 18 weeks
What is tracheal, laryngeal stenosis
narrowing of the airway
what is pulmonary agenesis?
complete absence of the lung parenchyma, bronchus and lung vasculature
what are diaphragmatic abnormalities?
Diaphragmatic hernia
Eventration
describe diaphragmatic hernia
usually occurs on the left lung
pulmonary hypoplasia (underformation)
cystic looking lesion
describe eventration
incomplete muscularisation of the diaphragm- area of floppiness, thin membrane
functional changes in lung at birth
at birth there is a change from fluid secretion to fluid absorption hence why first few breaths are the hardest. Newborns need to push fluid out of their lungs
what is ‘wet lung’
a name for tachypnea - fast breathing
a newborn might have a weak cry and fast, labored breathing. This is caused by extra amniotic fluid in the lungs (wasn’t able to push out as well as necessary)
is wet lung resolvable?
it usually resolves in 24-48 hours
normally associated with casesarean section delivery
what is surfactant
detergent like fluid that stabilises alveoli by reducing surface tension and preventing them from collapsing
it also promotes gas exchange
which types of pneuomcytes produce surfactant
type 2
what happens with surfactant production if you are born too early
you won’t have produced surfactant and so your alveoli are more likely to collapse
what’s the treatment for surfactant deficiency?
Antenatal glucocorticoids
Surfactant replacement
Mechanical ventilation- noninvasive is CPAP (mask)
why is it bad for a mother to smoke during pregnancy?
nicotine can cross the placenta barrier and will interfere with/ affect the development of prenatal airways
define remodelling
alteration of structure following an external influence ie smoking
pre-natal nicotine exposure can lead to what?
Lung hypoplasia (under development)
Reduced alveolarisation
Reduced lung function (small airways)
Increased incidence wheeze syndromes
Increased susceptibility to infection
Interference of inter-cellular signalling
What is meant by respiratory parenchyma?
Pulmonary parenchyma is a term for lung tissue, including bronchioles, interstitium and alveoli
