Developmental Aspects of Lung Disease Flashcards
What are the stages of lung morphogenesis?
Embryonic, Pseudo-glandular, Canalicular, Saccular, Alveolar
When is extra-uterine life possible?
Later canalicular/early saccular stage (23-25 weeks)
What occurs during Embryonic stage?
From the primitive gut (oesophagus) grows the trachea and larynx. Trachea starts to bud into the left and right airways.
What happens during the pseudo-glandular stage?
Cartilage is beginning to form, major airways formed with the lobes. No air sacs at the end of the tubes so no gas exchange.
What happens during the Canalicular stage?
Tubes are branching more and epithelia start to flatten and become thinner. Air-blood barrier formed. Vessels and capillaries closely aligned.
What occurs during the Alveolar stage?
Septation (divide) occurring which improves the surface area to allow gas exchange to be sufficient.
What happens during postnatal lung growth?
Alveolar separation continues, increased alveolar dimensions, increase in number of alveoli
What happens during Saccular stage?
Expansion of airways, surfactant detectable in amnionic fluid.
What stages are part of Organogenesis?
Embryonic and pseudo-glandular.
When does surfactant production begin?
Surfactant production begins at 25 weeks
What conditions are connect with an early on deformity of the lung?
Airway stenosis - narrowing
Airway Malacia - softening of the cartilage
Pulmonary agenesis - lung isn’t developed
Pulmonary hypoplasia
What conditions occur as a result of mutation with a later onset?
Bronchogenic cyst
Congenital pulmonary abnormalities
Lobar emphysema - alveoli not well developed
cystadenomatoid malformation
Sequestration - look normal but not in traditional anatomy
When do the presenting features occur?
Fetal ultrasound (75%)
Newborn (10%)
Childhood (15%)
What conditions can be diagnosed in Newborn?
Tachypnea - fast breathing
Respiratory distress
What conditions can be diagnosed in childhood?
Stridor/wheeze Recurrent pneumonia (same region)
What does a malformation look like in an ultrasound?
Lungs mainly filled with fluid which should appear white - abnormalities usually bit darker
What do abnormalities look like in X-rays?
White patch filled with fluid.
Describe Tracheo-bronchmalacia (weak cartilage rings).
Barking/seal like cough, Early onset, breathlessness on exertion, stridor/wheeze. Rely on smooth muscle to maintain airway - don’t use Bronchodilator.
Describe Pulmonary Cystic Adenomatoid malformation.
May resolve spontaneously, Conservative management if asymptomatic, possible risk of malignant change.
How is the diaphragm developed?
Variety primitive tissues contribute to it.
Describe a diaphragm hernia.
Pulmonary hypolasion (underdeveloped), persistent pulmonary hypotension (high blood pressure)
What is a diaphragm eventration?
Diaphragm is sitting higher up or rather than looking dome shaped its edges are sharper.
What is an abnormality in the fluid capacity at birth?
Change from fluid secretion to fluid absorption. Normally the secreting organ becomes the absorbing one. In this case there is a slowing down of the functional change.
What is the functional change in surfactant system?
Surfactant stabilises alveoli and promotes gas exchanage
Describe Hyaline Membrane Disease (RDS)
Surfactant deficiency. Treated with surfactant replacement, Antenatal glucocorticoids.
When does endogenous production begin if suffering with RDS?
5 days
What are antenatal origins of adult lung disease?
In utero nicotine exposure, fetal infection, maternal nutrition, low birth weight, maternal micronutrients/vitamins
What are the Post-natal origins of Adult lung disease?
Infection, growth, ETS, environmental pollution, micronutrients/vitamins
what causes a rapid decline is FEV1 and at what age will they develop respiratory symptoms?
Smoking, symptoms at roughly 65-70 years.
What is the definition of remodelling?
Alteration of structure following an external influence
What does pre-natal nicotine exposure cause?
Lung hypoplasia, reduced alveolarisation, reduced lung function, increased wheeze, increased susceptibility to infection, interference of inter-cellular signalling
What remodelling occurs in asthma?
Chronic inflammation, increased bronchial responsiveness, increased mucus secretion, airway oedema, airway narrowing.
What remodelling occurs in chronic neonatal lung disease?
Chromic inflammation, interference of signalling, treatment toxicity. Mosaic appearance with different shades = collapsing alveoli
What is the 3rd leading cause of death
COPD
What causes the remodelling of airways?
Antenatal programming, environmental exposures and gene interactions
How can we track development of COPD?
Low lung function and CT scans
