Developmental Aspects of Lung Disease Flashcards
What are the stages in lung morphogenesis?
Embryonic, Pseudoglandular, canalicular, saccular and alveolar
Explain the embryonic stage
3-18 weeks
Lung buds develop and divide to lobar buds which are derived from mesoderm
Mesoderm forms blood vessels
Explain the pseudoglandular stage?
5-17 weeks
Branching of airways and 16-25 primitive segmental bronchi formed
Develop cilia and mucous glands
Explain canalicular stage?
16-26 weeks
Lungs develop distal architecture. Terminal bronchioles, alveolar sacs and capillaries formed
Type 1 and 2 pneumocytes appear
What is the limit of viability?
24 weeks
Can be when the baby can be born premature and survive in intensive care
Explain the saccular stage
24-38 weeks
Alveolar sacs grow and become well formed
More surfactant produced
Bronchioles continue to elongate
Interstitial tissue becomes thinner
Explain the alveolar stage
36 weeks - term and beyond
Can breath independently
Cells are well differentiated and vascular more developed
How many alveolar sacs are there approx.?
Around 200-300 million at 3-8 years
How is congenital abnormalities diagnosed by antenatal screening?
Ultrasound and MRI
What are the signs of congenital abnormalities in newborns?
If they are tachypnoea, in respiratory distress or have feeding issues
What are the signs of congenital abnormalities in childhood?
Stridor/wheeze, recurrent pneumonia, cough and feeding issues
Explain laryngomalacia
There is floppiness of the airway and dynamic abnormal collapse of larynx or voice box
Commonly seen in infants
What are the symptoms of laryngomalacia?
Stridor, worse with feeding or when upset or excited
What is the management of laryngomalacia?
Will improve within the first year so usually no interference
Concern if affects feeding, growth or causes apnoea’s.
Exaplain tracheomalacia
Is floppiness of the trachea
Can be isolated in healthy infants and associated with genetic conditions.
May be caused by external compression (vessels, tumour)
What is the presentations of tracheomalacia?
Barking cough, recurrent croup, breathless on exertion and stridor/wheeze
What is the management for tracheomalacia?
No intervention usually required but can includes physio and antibiotics when unwell due to infection
Natural history resolution with time
Explain tracheooesophageal fistula?
Abnormal connection between trachea and oesophagus
Majority have associated oesophageal atresia and there is association with genetic condtitons