Bronchopulmonary Dysplasia ✅ Flashcards
How is bronchopulmonary dysplasia defined clinically?
On the basis of clinic signs and dependence on ambient oxygen either at 28 days, or more usually at 36 weeks post menstrual age
What is the limitation of using oxygen requirement as a measure of severity of bronchopulmonary dysplasia?
It is a subjective measure and leads to marked variation in prevalence of BPD between units
What has been proposed as a result of difficulties arising from using oxygen requirement to measure severity of BPD?
A stricter physiologic definition
How is BPD identified using the stricter physiologic definition?
Undergo an oxygen challenge test
What happens in the oxygen challenge test?
Infants receiving less than 30% supplemental oxygen undergo a stepwise 2% reduction of supplemental oxygen until they are breathing room air
When are babies classified as having no BPD after the oxygen challenge test?
Oxygen saturation >90% for 60 minutes in room air
When are babies classified as having BPD after the oxygen challenge test?
If saturation <90% during the observation period
What are babies undergoing an oxygen challenge test monitored for?
- Apnoea
- Bradycardia
- Increased oxygen requirements
What happens if apnoea, bradycardia, or increased oxygen requirement occurs during the oxygen challenge test?
It is considered a test failure and categorised as BPD
What is the advantage of using the oxygen challenge test to identify BPD?
It provides an objective assessment of the presence and severity of underlying lung disease
How does the incidence of BPD in VLBW infants differ when using the oxygen challenge test compared to standard criteria?
10% compared to 25%
What does the pathogenesis of BPD involve?
- Underdeveloped lungs due to prematurity
- Initial injury to the lung due to primary disease process, e.g. RDS
- Ventilator-induced lung injury mediated through barotrauma (high pressure)
- Volutrauma
- Oxygen toxicity
- Inflammatory cascade
- Inadequate nutrition
What causes volutrauma?
Inappropriately high or low tidal delivery
What is the underlying problem with pulmonary mechanics in BPD?
- Reduction in lung compliance
- Increased airway resistance
What does a reduction in lung compliance and increased airway resistance lead to in BPD?
Increased work of breathing
What change in pulmonary mechanics may become more significant in later BPD?
Expiratory flow limitation
What happens to functional residual capacity in BPD?
May be reduced initially, but can increase in later stages
Why is functional residual capacity initially reduced in BPD?
Due to atelectasis
Why can functional residual capacity increase in later stages of BPD?
Due to air trapping and hyperinflation
What changes are found in the lungs of extremely premature infants?
- Alveolar simplification
- Reduction in overall surface area for gas exchange
- Failure of secondary alveolar crest to form normal alveoli (epithelial and endothelial cell growth abnormalities)
What is the treatment for BPD once it has developed?
Supportive
What is the prognosis for BPD?
Most infants ultimately achieve normal lung function
What does BPD increase the risk of?
- Death in the first year of life
- Reactive airway disease
- Viral infection
- Growth failure
- Neurodevelopmental abnormalities
Which viral infection are patients with BPD particularly susceptible to?
RSV
