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
When can tracheo-oesophageal diagnosed?
Can be antenatally or postnatally (more common)
What are the presentations of tracheo-oesophageal?
Choking, colour change, cough when feeding and unable to pass NG (nasal gastric)
What is the treatment for tracheo-oesophageal?
Surgical repair
What are the complications of surgery to tracheo-oesophageal?
Tracheomalacia, strictures, leak and reflux
Explain congenital pulmonary airway malformation (CPAM)?
Abnormal non-functioning lung tissue
Most detected antenatally
Occurs sporadically so no association to underlying health condition
What is the management for CPAM?
May resolve spontaneously in utero but follow up
Conservative management if asymptomatic
Surgical intervention may be required if symptoms and unwell
What is the risk with CPAM?
Possible risk of malignant change?
Explain congenital diaphragmatic hernia?
An absent or partially formed diaphragm results in an abnormal opening (hernia) that allows the stomach and intestines to move into the chest cavity and crowd the heart and lungs
Usually left side
What is the most common type of congenital diaphragmatic hernia?
Bochdalek
What is the management of congenital diaphragmatic hernia?
Surgical repair
Prognosis then depends on degree of lung hypoplasia
What is neonatal lung disease?
Significant changes occur at birth after first breath
What is transient tachypnoea of newborn?
Fluid in lungs not moving
Due to lung inflation when child moves through birth canal and having vigorous breath
Usually Caesarean section
When does transient tachypnoea of newborns improve?
Within 1 -2 days
Explain Respiratory Distress Syndrome (RDS)
Due to surfactant deficiency and also called hyaline membrane disease
Occurs in preterm infants but some term infants
What is the treatment for RDS?
Antenatal steroids for lung development
Surfactant replacement - directly to lungs by tube
Appropriate ventilation and nutrition
Explain Bronchopulmonary dysplasia?
Chronic lung disease associated with prematurity where ongoing O2 requirement at term
Multifactorial causes
What does Bronchopulmonary dysplasia mean for the newborn?
Associated with increased childhood resp. morbidity
Leads to chronic obstructive picture - as smaller lungs and increased O2 requirement
What individual factors affects relationship between foetal/child and adult lung disease?
Sex, age and height
What early life events may affect relationship between foetal/child and adult lung disease?
Parental atopy, education, premature, maternal smoking, birth weight, breastfeeding, peak weight and lung functions
What allergic disease can affect the relationship between foetal/child and adult lung disease?
Asthma, Rhinitis, Aeor-/ food allergen and sensitisation
What are environmental lifestyle factors affect the relationship between foetal/child and adult lung disease?
Air pollution, second hand smoke exposure, smoking, serum vit D conc., and BMI
Explain remodelling
Alteration of airway structure following external influence
Leads to abnormalities due to interference of inter-cellular signalling
What are the external influences causing alteration of airway (remodelling)?
Environmental exposures
Chronic disease of childhood
Infection
What are the alterations of remodelling seen in airways?
Increased mucous production, inflammatory cells and vasodilation
Hypertrophy of smooth muscle, thickening, oedema
What resp. disease is remodelling seen in?
Asthma and Chronic lung disease of prematurity
What does chronic inflammation lead to?
Increased bronchial responsiveness
Increased mucous secretion
Airway oedema
Airway narrowing
What can lung function decline lead to in adults?
COPD
