Developmental aspects of lung disease Flashcards
When does the embryonic phase take place ?
3-18 weeks
What happens during the embryonic phase ?
Lung buds start to develop as a respiratory diverticulum from the foetal foregut
2 lung buds-> lobar buds derived from endoderm
Tissues- mesoderm
When does the Pseudoglandular phase take place ?
5-17 weeks
What happens in the Pseudoglandular phase ?
Rapid branching of the airways
16-25 primitive segmental bronchi
Cilia and mucous glands start to appear
When does the canalicular phase take place ?
16-26 weeks
What happens during the canalicular phase ?
Distal architecture
Terminal bronchioles and alveoli form gas exchange units
Type I and type II pneumocytes appear
When does the saccular phase take place ?
24-38 weeks
What happens during the saccular phase ?
Alveolar sacs grow
More surfactant produces
Bronchioles elongate
When does the alveolar phase take place ?
36 weeks - 2/3 years
What happens during the alveolar phase ?
Lungs can independent sustain breathing
What happens during postnatal lung growth ?
Alveolar septation continue after birth
20-60 million at birth to 200-300 million at age 3-8
What is laryngomalacia ?
Commonly seen in infants
Present with stridor, worse with feeding or when upset/excited
Will improve within 1st year of life
Concern if affects feeding, growth or cause apnoea’s
What is tracheomalacia ?
Can be isolated in healthy infants
Associated with genetic conditions
May be caused by external compression
What is the presentation of tracheomalacia ?
Barking cough
Recurrent croup
Breathless on exertion
Stridor/wheeze
What is the management of tracheomalacia ?
Management includes physio and antibiotics when unwell
Natural history resolution with time
What is Tracheo-oesphageal fistula ?
Abnormal connection between trachea and oesphagus
Majority have associated oesphageal atresia
Association with genetic conditions
What is the presentation of Tracheo-oesphageal fistula ?
Choking
Colour change
Cough with feeding
Unable to pass NG
What is the treatment of Tracheo-oesphageal fistula ?
Surgical repair
What are the complications of Tracheo-oesphageal fistula ?
Tracheomalacia
Strictures
Leak and reflux
What is congenital pulmonary airway malformation ?
Abnormal non-functioning lung tissue 80% detected antenatally Occur spontaneously May resolve spontaneously in utero Conservative management if asymptomatic Surgical intervention may be required Possible risk of malignant chnage
What is congenital diaphragmatic hernia ?
Diaphragm develops from multiple tissues around 7 weeks and closes by 18 weeks
CDH affects 1 in 2500 births
Different types, most common Bochdalek (90%)
Usually left side > right side
Most diagnosed antenatally
Some cases diagnosis late
What is neonatal lung disease ?
Significant changes occur at birth after the 1st breath
Lungs inflate and fluid in lungs is absorbed
What is IRDS caused by ?
Surfactant deficiency
How can IRDS be treated ?
Antenatal steroids
Surfactant replacement
Appropriate ventilation and nutrition
What is chronic lung disease associated with ?
prematurity where ongoing oxygen requirement at term
What is remodelling ?
Alteration of airway structure following external influence:
- environmental exposures
- chronic diseases of childhood
- infection
Leads to abnormalities due to interference of inter- cellular signalling
