Developmental aspects of lung disease Flashcards
What is the groove that the lungs develop from?
Sulcus laryngeotrachealis or the laryngeotracheal groove
What buds from the laryngeotracheal groove?
Lung primordium
Which pharyngeal arch artery pair forms the pulmonary circulation?
6th pharyngeal arch aortic artery
What occurs in the canalicular stage that means the foetus is then able to live outside the uterus from around 24 weeks?
Differentiation of type II pneumocytes into flattened type I cells
Proliferation of capillaries into the mesenchyme
How can we measure clinically the maturity of an foetus’ lungs?
Lungs are now producing a large amount of the amniotic fluid (surfactant) - the ratio of lecithin to sphingomyelin in the amniotic fluid increases with foetal age
How long does alveolarisation continue after birth?
1 and half years after birth
How many alveoli are in new borns?
100-150 million
How many alveoli are there once you reach 3-8 years old?
200-600 million
Name some congenital lung diseases that result from embryonic stage defects
Tracheal or laryngeal stenosis
Pulmonary agenesis
Trachea-oesophageal fistula/atresia
Diaphragmatic abnormalities - hernia, eventration
When do the 4 components of the primitive diaphragm seal to form the mature diaphragm?
18 weeks
Name some congenital lung diseases associated tie pseudo glandular stage defects
Pulmonary sequestration (intralobular/extralobular)
Cystadenomatoid malformation
Cyst formation
What type of pulmonary sequestration is more common?
Intralobular, presents later on in childhood due to recurrent infections
How does extra lobular pulmonary sequestration usually present?
Less common, seen in neonates. Cyanosis and respiratory distress
Which side of the diaphragm is more likely to have a hernia?
Left - liver on right can act as a plug
What are the major complications associated with diaphragmatic abnormalities?
Pulmonary hypoplasia
Persistent pulmonary hypertension
What is the most common cause of respiratory distress in newborns?
Transient tachypnoea of the newborn
List some causes of respiratory distress in newborns
Transient tachypnoea of the newborn
Surfactant deficiency - HMD
Chronic neonatal lung disease
Describe transient tachypnoea of the newborn
Period of rapid breathing (>30-60/min) following birth, likely due to retained lung fluid which hasn’t been absorbed as fast by the pulmonary lymphatic system
Describe some signs and symptoms of transient tachypnoea
Rapid breathing (>30-60/min) Hyperinflated lungs (CXR) Prominent pulmonary vascular markings (CXR) Flattening of the diaphragm (CXR) Fluid in horizontal fissure (CXR)
How do you treat transient tachypnoea of the newborn?
Supplemental oxygen
Antibiotics
What can induce transient tachypnoea of the newborn?
Caesarean section
Pulmonary immaturity
Surfactant deficiency
What are the secretory organelles in type II pneumocytes which excrete surfactant?
Lamellar bodies
How do you treat neonates with surfactant deficiency?
Antenatal glucocorticoids Surfactant replacement therapy Oxygen CPAP Mechanical ventilation
Why are glucocorticoids used in babies with surfactant deficiency?
Stimulates surfactant production
How long does it take for glucocorticoids to take effect?
5 days
When a baby is to be delivered early (e.g. emergency, pre-eclampsia), how can we prevent respiratory distress of the baby?
Glucocorticoids 5 days prior
Describe chronic neonatal lung disease
Development of fibrous tissue due to chronic inflammation. Caused by genetics, infection etc.
What are the possible long term effects of chronic neonatal lung disease?
Increased severity bronchiolitis
Causes asthma
Could lead to development of COPD later on
What are some antenatal causes of adult long disease?
In utero nicotine exposure Nutrition Sex? Low birth weight/prematurity Micornutrients/vitamins
What are some postnatal causes of adult long disease?
Infection Growth Environmental tobacco smoke Environmental pollutants Micronutrients/vitamins
What is the 3rd leading cause of death in the world?
COPD
