Pediatric Lung Diseases Flashcards
Respiratory Distress Syndrome aka?
Hyaline Membrane Disease
Most common cause of respiratory failure in preterm infant
RDS
- Lung disease in a preterm infant resulting from what?
- Major cause of morbidity and mortality in infants born prior to ___ wks gestation
- What has changed clinical course and decreased morbidity and mortality rates?
- insufficient surfactant
- 30
- Exogenous surfactant
Incidence and severity ↑’d in male infants. Why?
↑’d circulating androgens ↓ lung maturity and surfactant production by type II pneumocytes
Risk factors:
Increased Incidence
in the following?
6
- Low gestation
- Male sex
- White race
- Maternal diabetes
- C-section pre-onset of labor
- Perinatal asphyxia
- Maternal hypertension
Why is maternal diabetes a risk factor for RDS?
↑’d insulin ↓’s lung maturation and surfactant production
Risk factor: Decreased incidence for RDS?
4
- Prolonged rupture of membranes
- Chronic congenital infections
- Maternal substance abuse
- Antenatal corticosteroid exposure
2 Major Issues in PP of RDS?
Immature lungs
Lack of surfactant
Infants may be born in:
what of lung development? (two stages)
At these stages what developmental issues might be a problem? 2
- Canalicular stage
16-26 wks - Saccular stage
24-38 wks - May have primitive airspaces with undifferentiated pneumocytes
- No juxtaposition of airway epithelium and capillaries
What happens during the canalicular phase of development in the fetus for the lungs? 3
- Last generations of the lung periphery formed
- Epithelial differentiation
- Air-blood barrier formed
What happens during the saccular phase of development in the frtus for the lungs? 2
- Expantion of air spaces
2. Surfactant detectable in amniotic fluid
Surfactant:
- Appears in fetal lung at _____wks
- Made by what cells?
- Adequate amounts not produced until about ___ wks
- What are the functions of surfactant? 3
- 23-24
- type II pneumocyte
- 35
- Reduces surface tension in alveolar spaces
- Facilitates lung expansion
- Prevents alveolar collapse
Very premature infants frequently have:
2
These may further contribute to what?
- Excessively compliant chest walls
- Weakness of the respiratory muscles
Alveolar collapse
Pathophysiology of RDS?
7
- Alveolar collapse alters nl ventilation/perfusion relationship
- Produces pulmonary shunting → progressive arterial hypoxemia → metabolic acidosis
- Hypoxemia and acidosis → vasoconstriction → decreased pulmonary blood flow (pulmonary hypertension)
- May produce R→L shunting through PFO and PDA → worsening hypoxemia
- Pulmonary blood flow may subsequently increase
- –Decreased vascular resistance and persistence of PDA - ↑’d pulmonary blood flow leads to accumulation of fluid and protein in interstitial and alveolar spaces
- Protein in alveolar spaces deactivates surfactant
- Atelectasis and ↑’d dead space → ?
- Intrapulmonary and extrapulmonary shunting → ?
- Atelectasis, ↑PaCO2, hypoxemia →?
- ↑PaCO2 → ?
- Hypoxemia → ?
- ↑PaCO2
- hypoxemia
- tachypnea
- respiratory acidosis
- metabolic acidosis
Hyaline Membrane Disease aka?
RDS