Developmental Aspects of Lung Disease Flashcards
How many stages are there in lung morphogenesis?
5
What is the first stage in lung morphogenesis and when does it take place?
Embryonic
3-8 weeks approx.
What is the second stage in lung morphogenesis and when does it take place?
Pseudoglandular
5-27 weeks approx.
What is the third stage in lung morphogenesis and when does it take place?
Canalicular
16-26 weeks approx.
What is the fourth stage in lung morphogenesis and when does it take place?
Saccular
24-38 weeks approx.
What is the fifth stage in lung morphogenesis and when does it take place?
Alveolar
36 weeks- 2/3 years approx.
What happens in the embryonic phase?
The lung bud (respiratory diverticulum) develops from the foetal foregut.
What should have happened by week 5 of the embryonic phase?
Two primary lung buds are visible.
What do the lung buds divide into?
Divide into lobar buds
How many lobar buds are on the right?
3
How many lobar buds on the left?
2
Where are the lung buds derived from?
Endoderm
Where are the blood vessels and connective tissues derived from?
Mesoderm
What happens in the Pseudoglandular stage?
Rapid branching of the airways.
Which types of specialised cell may appear in the airways during the pseudogladnular stage?
Cillia
Mucous glands
What happens in the canalicular phase?
Lungs develop their distal architecture- terminal bronchioles, alveolar sacs and capillary blood vessels
Which cells appears in the canalicular stage?
Type one and two pneumocytes
What do type 1 pneumocytes have?
Very thin membranes to allow gas exchange to take place
What do type 2 pneumocytes produce?
Surfacant
What is the limit of viability?
When it is possible for a foetus delivered prematurely to successfully survive with intensive care support.
What happens in the saccular phase?
Alveolar sacs grow in size and become well-formed.
The bronchioles continue to elongate, interstitial tissue between the sacs reduce and the alveolar walls be come thinner which will improve gas exchange.
What happens is the alveolar phase?
The lungs can independent sustain breathing without support.
What is meant by a congenital abnormality?
Airway abnormalities present a birth.
Is laryngomalacia an upper or lower resp. abnormality?
Upper
Is Congenital Diaphragmatic Hernia an upper or lower resp. abnormality?
Lower
Is CPAM (congenital pulmonary airway malformation) an upper or lower resp. abnormality?
Lower
Is tracheomalacia an upper or lower resp. abnormality?
Upper
Is Tracheo-oesphageal fistula an upper or lower resp. abnormality?
Upper
How can congenital abnormalities be discovered before birth?
Antenatal screening via MRI or ultrasound
List some of the presenting congenital abnormality symptoms in new-borns.
Tachypnoea
Respiratory distress
Feeding issues
List some of the presenting congenital abnormality symptoms in childhood.
Stridor/wheeze
Recurrent pneumonia
Cough
Feeding issues
What happens in Laryngomalacia?
Dynamic abnormal collapse of larynx or voice box
When is laryngomalacia commonly seen?
In infants about 6 weeks onwards
What will children with laryngomalacia usually present with?
Stridor which gets worse when feeding or the child is excited/upset
Discuss when it may be appropriate to give treatment to a child w laryngomalacia?
If it affects feeding, growth or causes pauses in breathing (apnoea’s)
What is tracheomalacia?
Dynamic abnormal collapse of tracheal walls
What is the clinical presentation for tracheomalacia?
Barking cough
Recurrent “croup”
Breathless on exertion
Stridor/wheeze
What may the management of tracheomalacia include?
Physiotherapy and antibiotics if the child is unwell.
What is a Tracheo-oesphageal fistula?
Abnormal connection between trachea and oesphagus
What is tracheooesophageal fistula usually associated with?
Genetics
What other association can those w tracheooesophageal fistula have?
Oesophageal atresia
What is the presentation for those w tracheooesophageal fistula?
Choking
Colour change
Cough with feeding
Unable to pass NG
What treatment is there for tracheooesophageal fistula?
Surgical repair
What are some possible complications of tracheooesophageal fistula?
Tracheomalacia, strictures, leak and reflux
What is Congenital Pulmonary Airway Malformation (CPAM)?
Abnormal non-functioning lung tissue
What is a Congenital Diaphragmatic Hernia?
Diaphragm develops from multiple tissues around 7 weeks and closes by 18 weeks
What side does Congenital Diaphragmatic Hernia usually affect?
Left
What is the management for Congenital Diaphragmatic Hernia?
Surgical repair
What changes happen after the first birth after birth?
Lungs inflate and fluid in lungs is absorbed
What is Transient Tachypnoea of Newborn?
Fluid in lungs does not move effectively.
What is Transient Tachypnoea of Newborn usually associated with?
Caesarean section
What is Respiratory Distress Syndrome (RDS) due to?
Surfactant deficiency
What is the treatment for RDS?
Antenatal steroids
Surfactant replacement
Appropriate ventilation and nutrition
How can chronic lung disease be related to birth?
Associated with prematurity where ongoing oxygen requirement at term
What is chronic lung disease associated with?
Increased childhood respiratory morbidity
List some of the individual factors which may influence lung function at the age of 15.
Age
Gender
Height
List some of the environmental/lifestyle factors which may influence lung function at the age of 15.
Air pollution
Smoking
Second hand smoking
BMI
Serum vitamin D conc.
List some of the allergic diseases which may influence lung function at the age of 15.
Asthma
Rhinitis
Aero/food allergen sensitization
List some of the earl life events which may influence lung function at the age of 15.
Parental atopy
Parental education
Maternal age at delivery
Maternal smoking during pregnancy
Second hand smoke
Season of birth
Weight at birth
Lung infections
Define remodelling.
Alteration of airway structure following external influence
Which external influences may cause remodelling?
Environmental exposures- smoking
Chronic diseases of childhood- chronic lung disease, asthma
Infection
Why does remodelling lead to abnormalities of the airway?
Due to interference of inter-cellular signalling
Describe some changes in the airway after remodelling.
Reduction of lumen with increased mucus plugging
Changes to cells, usually increasing mucus production
Increase in number of inflammatory cells
In which diseases might remodelling be seen?
Asthma
Chronic lung disease of prematurity
What things can the process of chronic inflammation lead to?
Increased bronchial responsiveness
Increase mucus secretion
Airway oedema
Airway narrowing
List some factors which increase a child’s risks of having normal lung function in later life.
Genetics
Preterm birth
Early life exposures
LRTI
Childhood persistent asthma
