Developmental aspects of Lung Disease Flashcards
what forms during the embryology of the respiratory tract
- The respiratory tract, diaphragm and lungs do form early in embryonic development.
describe the stages of embryonic development
- Embryonic 3-8 weeks
- Pseudo-glandular 5-17 weeks
- Canalicular 16-26 weeks
- Saccular 24-38 weeks
- Alveolar 36 weeks – 2/3 years
what happens during the embryonic stage?
- 3-8 weeks
- formation of trachea and main bronchi and lung buds.
what happens during the pseudo glandular stage?
- 5-17 weeks
- the spreading of the bronchi where all conducting airways form. The accompanying blood vessels also form, the wall structure and epithelial cells differentiate.
- Cilia develops at 13 weeks.
- Bronchi forms at around 8-13 weeks
- Bronchioli forms at 3-10 weeks
what happens during the canalicular stage?
- 16-26 weeks
- is where the early gas exchange structures form.
- The Lungs becomes extremely vascularised.
- Surfactant production appears. This is the age at which babies can be born.
what happens during the saccular stage?
- 24-38 weeks
- further evolution of gas exchange structures where saccules and then alveoli appear. Type 1 and Type 2 cells. Pre-cursors to alveoli.
what happens during the alveolar stage?
- 36 weeks- 2/3 years
- usually happens after the child is born and continues to grow over the next 3-12 years.
describe the development of the diaphragm
- which is essential for respiration
- develops from multiple tissues at around 7 weeks.
- Innervated by the phrenic nerve.
- Closure by around 18 weeks.
what are the common congenital anomalies affecting the respiratory tract?
Upper (Tracheo-Bronchial):
- Tracheal agenesis and stenosis
- Tracheomalacia
- Tracheo-oesophageal fistula
Lower (broncho-pulmonary):
- Lung agensis/pulmonary hypoplasia
- Bronchogenic cyst
- CPAM
- Congenital Diaphragmatic Hernia
tracheal Agenesis
- Presents at birth, the trachea is completely Absent
- acute respiratory distress and inability to intubate
tracheal stenosis
- presents at birth or within the first year
- tracheal cartilage rings are complete too early, and are fixed.
- NARROWING of the trachea
- may be generalised or segmental
Tracheomalacia
- “Softening”. Floppiness of the airways
- flaccidity of tracheal cartilage
- Dynamic abnormal collapse of tracheal walls.
- May be caused by external compression
what is the presentation and management of tracheomalcia?
Presentation:
- Barking cough
- Stridor/wheeze
Management:
- physio and antibiotics.
Tracheo-oesophageal fistula
- ABNORMAL connection between trachea and oesophagus
- Associated with genetic conditions
- Can be diagnosed antenatally or postnatally
presentation, treatment and complications of trachea-oesophageal fistula?
Presentation:
- Choking
- Colour change
- Cough with feeding
- Unable to pass a nasogastric tube
Treatment:
- Surgical repair
Complications:
- Prone to leaks around the site, reflux, tracheomalacia
LOWER (broncho pulmonary conditions)
Congenital pulmonary airway malformation (CPAM)
- Cystic mass of abnormal lung tissue.
- Abnormal non-functioning lung tissue
- 80% is detected antenatally
- Occurs sporadically
- May resolve spontaneously in utero
- Conservative management if asymptomatic
- Possible risk of malignant change
Congenital Diaphragmatic hernia
- A defect in the diaphragm.
- The diaphragm separates the organs in the abdomen from those in the chest
- There are different types, most common one is Bochdalek (90%)
- Usually the left side rather than the right side
- Most are diagnosed antenatall
management and prognosis of congenital diaphragmatic hernia
Management: surgical repair
Prognosis depends on the degree of lung hypoplasia
Presenting features of anomalies affecting the respiratory tract
- Antenatal screening (ultrasound)
- Feotal abnormality scan at around 20 weeks
- New born:
o Tachypnoea (suggest resp system is impaired)
o Respiratory distress
o Feeding issues
- Childhood: o Recurrent pneumonia (croup the infection of upper airways which suggests a structural abnormality) o Stridor (inspiratory sucking in sound) o Wheeze o Feeding issues
- Asymptomatic:
o Incidental finding
describe the changes in the lung after birth
- Significant changes occur at birth after the babies first breath
- The lungs inflate and fluid in the lungs is ABSORBED
- Transient tachyponoea of newborn:
o Associated with C SECTION
o but it Improves within 1-2 days
when does surfactant production begin?
- during the canicular stage (16-26)
- type 2 pneumocytes differentiate at 24 -34 weeks
(reminder than surface cells reduce surface tension, promoting gas exchange)
what can occur in preterm infants with surfactant deficiency (hyaline membrane disease)?
describe the treatment
- Respiratroy distress syndrome
- Antenatal steroids
- Surfactant replacement
- Appropriate ventilation and nutrition
Understand the relationship between respiratory illness in childhood
- Antenatal:
- Nicotine exposure from mother
- Mothers nutrition
- Mothers micronutrients/ vitamins
- Infection
- Low weight at birth/premature
- Antenatal steroids
Understand the relationship between respiratory illness in adulthood
- Post natal
- Early life events reduce normal growth and lung function
- Barker hypothesis
- Infection
- Growth
- Tobacco exposure
- Environmental pollution
- Micronutrients/vitamins
-May lead to the risk of future COPD
what is remodelling
- Aspects of the airways and lungs change because of external influences:
- Environmental exposure
- Early allergy and gene interactions
- Chronic diseases of childhood
- Infection
causes of remodelling
• Interference of inter-cellular signalling
where is remodelling seen?
-Asthma
- wider lumen, significant changes in surface and interstially
- Chronic inflammation
- Increased bronchial responsiveness
- Increase mucus secretion
- Airway oedema
- Airway narrowing
-Chronic lung disease:
- Chronic inflammation
- Interference inter-cellular signalling
- Treatment toxicity
U_n_d_e_r_s_t_a_n_d_ t_h_e “t_r_a_c_k_i_n_g” o_f p_u_l_m_o_n_a_r_y f_u_n_c_t_i_o_n f_r_o_m e_a_r_l_y l_i_f_e i_n_t_o a_d_u_l_t_h_o_o_d _and factors which influence tracking
- Early lung function tracks in adulthood
- Stopping smoking decreases pulmonary lung function
- Premature births peak to a lower baseline of FEV and fall earlier on
