Developmental Aspects of Lung Disease Flashcards
What are the 5 stages in lung morphogenesis?
- embryonic
- pseudo-glandular
- canalicular
- saccular
- alveolar
When is extra-uterine life possible?
i.e. premature babies
at late canalicular/early saccular stage (22-24 weeks)
What happens in the embryonic stage of lung morphogenesis?
- The respiratory diverticulum buds off the duodenum structure.
- Cells of trachea are cuboidal.
- Appearance of lung buds, main pulmonary arteries, trachea and main bronchi.
What happens in the pseudoglandular stage of lung morphogenesis?
- all conducting airways and accompanying vessels form.
- wall structure and epithelial cells differentiate.
What is the canalicular stage of lung morphogenesis?
- Respiratory airways form.
- Blood-gas barrier thins
- surfactant appears
What is the saccular stage of lung development?
- saccules and then alveoli appear.
- air spaces expand
- surfactant detectable in amniotic fluid
What is the alveolar stage of lung morphogenesis?
- Secondary septation of alveoli which begins in utero, but continues after birth.
- alveoli multiply for 2-4 years.
What stages of morphogenesis are the conducting zones developed?
What are these?
embryonic and psuedoglandular
bronchi, bronchioles and terminal bronchioles
Outline four upper congenital respiratory abnormalities.
- tracheal agenesis
- tracheal stenosis
- tracheomalacia
- tracheo-oesophagul fistula
Outline four upper congenital respiratory abnormalities.
- Lung agenesis/ Pulmonary Hypoplasia - Bronchogenic cyst - CPAM - Congenital Diaphragmatic Hernia
What is tracheal stenosis?
When is it likely to develop?
- Complete tracheal cartilage rings, may be generalized or segmental, causes narrowing of trachea.
- the rings harden to early and cause blockages.
Originates in the earlier stages of lung morphogenesis
What is tracheomalacia and in what stage of lung development is it likely to originate from?
- trachea and bronchi are floppy due to softening
- originates in earlier stages of lung morphogenesis
What does tracheomalacia present with? (4)
- Barking cough
- Recurrent “croup” infection
- Breathless on exertion
- Stridor/wheeze – sucking in sound, whistling wheeze
How does tracheomalacia develop over time?
How is it treated?
What can worsen the situation?
Treated with physiotherapy and antibiotics.
Tracheal rings strengthen over time with growth.
Salbutamol
What is tracheo-oesphageal fistula?
Abnormal connection between trachea and oesphagus.
What does tracheo-oesphageal fistula present with?
How is it treated?
- Choking
- Colour change
- Cough with feeding
- Unable to pass NG
Surgery
What is CPAM?
Congenital Pulmonary Airway Malformation
- a rare congenital birth defect that includes a cystic mass of abnormal lung tissue.
What is pulmonary agenesis/hypoplasia and in what stage of lung development is it likely to originate from?
(2)
- Incomplete development of the lungs, resulting in an abnormally low number or size of bronchopulmonary segments or alveoli.
- originates in earlier stages of lung morphogenesis.
How does the diaphragm develop?
Membranes develop towards the centre of the embryo until the fuse in the centre.
What may happen if the diaphragm doesn’t develop correctly?
Congenital Diaphragmatic Hernia
What can a congenital diaphragmatic hernia result in?
2
- pulmonary hypertension
- pulmonary hypoplasia
What is transient tachypnoea of the newborn?
When might it occur?
- amnionic fluid remains in the lung after birth, resolves in 24-48hrs
- C-section: lungs not squeezed as they come out birth canal.
What is a surfactant deficiency called?
IFDS (Infant Respiratory Distress Syndrome)
What is the treatment for IRDS, both pre- and antenatal?
3
- Antenatal steroids (if going into early labor)
- Surfactant replacement
- Appropriate ventilation and nutrition
Chronic Lung Disease associated with _________ where ongoing _______ requirement at term.
Also called _________ __________.
prematurity
oxygen
bronchopulmonary dysplasia
What are the antenatal causes of adult lung disease (COPD)?
6
- Nicotine exposure
- Infection
- Maternal nutrition
- Maternal micronutrients/vitamins
- Low birth weight/prematurity
- Antenatal steroids - IRDS
What are the post-natal causes of adult lung disease?
6
- Barker hypothesis
- Recurrent infection
- Growth – underweight/overweight
- Tobacco exposure
- Environmental pollution
- Micronutrients/vitamins
What is remodelling?
What leads to remodelling? (3)
Alteration of airway structure following external influence.
- Environmental exposures
- Chronic diseases of childhood
- Infection
Name a childhood lung condition which may lead to remodelling?
bronchial asthma
What are causes of chronic neonatal lung disease?
3
- Chronic inflammation
- Interference inter-cellular signalling
- Treatment toxicity e.g. O2
