6. Historical Perspectives of BPD
• Non-existent disease until advent of mechanical
ventilation for ill newborns in the 60’s.
• First description by Northway in 1967.
• Initial report mostly in larger, more mature
premature newborns treated with mechanical
ventilation.
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7. Definition of BPD
• Bancalari defined BPD as need for ventilation,
oxygen requirement at 28 days and abnormal CXR.
• Shennan proposed need for supplemental oxygen at
36 weeks corrected gestational age.
• Walsh (et al.) developed physiologic definition:
35–37 weeks, treated with mechanical ventilation,
CPAP or supplemental oxygen needing 30% oxygen
to keep sats 90%–96%.
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8. Definition
• ATS proposed correct term is bronchopulmonary
dysplasia (BPD) so as to differentiate BPD from
other causes of chronic respiratory disorders in
infants.
• Chronic lung disease of prematurity is another term
commonly used.
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9. Epidemiology
• Less than 30 weeks gestation (usually 28 weeks or
less).
• Birth weight <1250 grams.
• Males > females.
• The lower the gestational age, the greater the risk.
• Due to increased survival in VLBW babies,
prevalence of BPD is increased.
• Severity of the new BPD is less than the old BPD.
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11. 5 Stages of Lung Development
http://www.cincinnatichildrens.org/research/div/pulmonary-biology/morphogenesis.htm.
Accessed on June 7, 2010.
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12. Pathophysiology
• Old BPD pre-surfactant era
• New BPD post-surfactant era
•Genetic predisposition (polygenic ?)
•Oxygen toxicity
•Pulmonary inflammation/chemical mediators
•Barotrauma vs volutrauma
•Infection/chorioamnionitis/preeclampsia
•Stage of lung growth
•Alveolar simplification
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17. Pattern of Alternating Atelectasis and
Overinflation Old BPD
T. Allen Merritt, MD., William H. Northway, Jr., MD., Bruce R. Boynton, MD. Contemporary Issues in Fetal and
Neonatal Medicine. 4 Bronchopulmonary Dysplasia. Boston: Blackwell Scientific Publications; 1988:165.
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18. Histopathology of “New” BPD
• Decreased, large and simplified alveoli (alveolar
hypoplasia, decreased acinar complexity)
• Decreased, dysmorphic capillaries
• Variable interstitial fibroproliferation
• Less severe arterial/arteriolar vascular lesions
• Negligible airway epithelial lesions
• Variable airway smooth muscle hyperplasia
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19. Comparison of Normal Lungs and New BPD
A. 5-month-old infant born at term. B. Infant who has BPD, born at
28 weeks’ gestation, lung
biopsy at 8 months.
Jobe, A. NeoReviews Vol.7 No.10 2006 e531 2006.
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20. Clinical
• Physical exam
• Tachypnea
• Tachycardia
• Increased work of breathing
• Retractions
• Nasal flaring
• Grunting
• Crackles
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21. Laboratory Findings in Infants with BPD
• ABG
• Chronic respiratory acidosis with compensatory
metabolic alkalosis, hypoxia
• CXR
• Normal-to-increased lung volumes
• Bilateral interstitial changes of a variable nature
• Pulmonary function
• Decreased lung/respiratory compliance
• Increased airway resistance/obstruction
• Airway hyper responsiveness/asthma
• Ventilation/perfusion abnormalities
• Cardiac
• Pulmonary hypertension
• Silent ASD
• Aorta-pulmonary collaterals
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25. Lung Repair and Remodeling
• Severe BPD may be associated with abnormal
vascular remodeling
• Decreased angiogenesis
• Vascular reactivity
• Narrowing of blood vessel diameter
• Pulmonary hypertension
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26. Biochemistry
• Alterations in growth factors predispose
developmental arrest of lung in the new BPD
•TGF-beta1 decreased
•VEGF decreased
•TGF-alpha decreased
•PDGF decreased
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27. Management
• Diet
•Increased energy requirements
•Vitamin A
•120 kcal/kg/day
•NG or GT supplementation
•Swallowing dysfunction (vocal cord paralysis
following PDA ligation)
• Immunizations
•RSV (synagis, H1N1, influenza)
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29. Respiratory Pump Function
• The ability of the pump to bring about normal gas
exchange is dependent on the balance between the
mechanical load placed on the pump and the
intrinsic function of the respiratory muscles.
• Respiratory muscle fatigue is a state that develops
when respiratory muscles are unable to maintain the
targeted force output on repeated contractions and
is reversible with rest.
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30. Optimum Medical Criteria for Home Management of Chronic
Respiratory Failure in Infants with Bronchopulmonary Dysplasia
• Clinical
•Positive trend on growth curve (weight)
•Stamina for periods of play
•Extended period of stability
• Physiologic
•30% or less oxygen
•pCO2 less than 50 torr
•IMV of 30 or less
•Stable airway, mature fistula
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31. Goals of Home Mechanical Ventilation
• Increase chest wall mobility and lung growth (wean steroids)
• Prevention of respiratory failure (neuromuscular disorders)
• Prevent atelectasis/prevent overinflation
• Provide respiratory muscle rest
• Minimize iatrogenic lung injury
• Prevent respiratory muscle atrophy
• Liberation from mechanical ventilation
• Safe environment
• Family bonding and nurturing
• Promote normal growth and development
• Reduce costs
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32. Physiologic Changes Promoting Liberation from
Mechanical Ventilation
• Change in muscle fiber cell type composition of the
diaphragm (type II cells to type I cells )
• Lung growth
• Increased compliance
• Decreased airway resistance
• Increased alveoli—increased surface area for
gas exchange; improve V/Q mismatch, decrease
oxygen needs and decrease pCO2
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33. Physiologic Changes Promoting Liberation from
Mechanical Ventilation
• Chest wall
• Increase ossification—more rigid, less
compliant, stabilize lung volumes
• Dynamic FRC—changes to static FRC
• Increased stability of small and large airways
• Increase respiratory muscle pump function
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34. Weaning
• No single ventilator mode or strategy has been
shown to be more effective than another in weaning
children from mechanical ventilation.
• The most common strategy used is called sprinting
or diaphragm training. The diaphragm is the most
important respiratory muscle.
• Dependent on underlying diagnosis.
• Complicating factors may stall weaning.
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35. Weaning
• SIMV and pressure support
•Wean down pressure support first 15-10-8
• SIMV
•Wean rate to background (20) then CPAP trials during
the day or periods of decreased IMV, allow muscles to
rest at night
• Nocturnal ventilation
•Increase nose filter trials or trach collar time during the
day with gradual reduction in nocturnal IMV to CPAP
• Trach collar and nose filter combination 24 hrs/day for 3
months, then airway evaluation by ENT for decannulation
• Oxygen requirement is not a limiting factor
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36. Monitoring During the Weaning Process
• Weight gain and feeding habits
• Stamina for play time
• Oxygen needs
• End-tidal CO2
• Developmental progress
• Work of breathing
• Pulmonary hypertension
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37. Positive Outcome for BPD
with Respiratory Failure
Trach Home
Increasing Acuity
• •
Off vent
•
•
4 8 12 16 20 24
Time (months) Decannulation
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58. Long-Term Outcome
• Severe BPD associated with poorer
neurodevelopmental outcome--males worse than
females
• Increased risk for abnormal PFT but many not
symptomatic (obstructive lung disease)
• Increased risk for asthma
• Increased incidence of abnormal chest CT
abnormalities
• Increased risk for COPD as adults?
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61. 22 ½ Week Female- S/P Trach, Vent- Age 7
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62. Conclusions
• The “new” BPD represents an arrest in lung development.
• Long-term pulmonary function is generally low-normal or mildly
abnormal for majority of the “new BPD.”
• Post chronic respiratory failure patients are more likely to have
obstructive pulmonary disease.
• At risk for long-term respiratory morbidity, hospitalization, asthma
and COPD; recent study suggests 2.4-fold increase risk for asthma.
• Neurodevelopmental outcome correlates with severity of lung
disease, clearly an increase in ADHD (increase 60%) and autism.
• Uncommon disease among infants with birth weights >1500 grams.
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