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Surfactant Deficiency Syndrome

Surfactant Deficiency Syndrome. C. Antonio Jesurun, M.D. Professor Pediatrics. SURFACTANT. BEGINS TO ACCUMULATE AT 20-24 WEEKS GESTATION.

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Surfactant Deficiency Syndrome

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  1. Surfactant Deficiency Syndrome C. Antonio Jesurun, M.D. Professor Pediatrics

  2. SURFACTANT • BEGINS TO ACCUMULATE AT 20-24 WEEKS GESTATION

  3. PREMATURITYSurfactant Structurally Deficiency Atelactasis Immature Lung V/Q Mismatch Hypoventilation ACUTE CHRONIC Respiratory & High Fi0² & Baro Metabolic Acidosis or Volutrauma Pulmonary Vasoconstriction Inflammatory Antioxidant Cell Influx Reduction Impaired endothelial and Cytokine Free-radical Epithelial integrity Release reactions Proteinaceous exudate Lung Injury Hypoxemia & Hypercarbia Chronic Lung Disease / BPD SDS

  4. SurfactantStructurally DeficiencyAtelactasisImmature Lung V/Q Mismatch Hypoventilation ACUTE CHRONIC PREMATURITY Hypoxemia & Hypercarbia

  5. Hypoxemia & Hypercarbia ACUTE CHRONIC Respiratory & High Fi0² & Baro Metabolic Acidosis or Volutrauma Pulmonary Vasoconstriction Inflammatory Antioxidant Cell Influx Reduction Impaired endothelial and Cytokine Free-radical epithelial integrityReleasereactions Proteinaceous exudate Lung Injury SDS Chronic Lung Disease / BPD

  6. Functionsof Lung Surfactant • Increases alveolar stability • Improve alveolar inflation uniformity • Reduces driving force for pulmonary edema • Prevents collapse of alveoli during expiration • Lowers surface tension during expiration; increases it during inspiration • Decreases negative pressures needed to open airways and decreases work of breathing

  7. Hyaline Membrane Disease Increased Frequency with: • Prematurity • Multiple Pregnancy • Precipitous Delivery • Asphyxia • IDM • C/Section • Previous Sibling with SDS

  8. CARDIOPULMONARY PATHOPHYSIOLOGY • Decreased lung compliance • Increased pulmonary resistance

  9. Accelerated Maturation • Severe pregnancy-induced hypertension • Cardiovascular hypertension • Renal hypertension • Sickle Disease • Diabetes mellitus, Classes F & R (some Class D) • Placental infarction (placental insufficiency) • Prolonged rupture of membranes • Chronic retroplacental bleeding (“chronic abruptio placenta”) • Hyperthyroidism • Racial differences (e.g.,Afro-American)

  10. Delayed Maturation • Diabetes mellitus, Class A (some Classes B & C) • Hydrops fetalis • Smaller fraternal twin • Non-hypertensive, chronic glomerulonephritis

  11. Advantages of Surfactant • Increased Lung Compliance (V/P) • Decreased Work of Breathing • Alveolar Stability • Decreased Opening Pressure • Enchanced Alveolar Fluid Clearance • Decreased Precapillary Tone • Reversible Surface Tension • Protection of Epithelial Cell Surfaces

  12. Roles of Surfactant Apoproteins • Largely determines adsorption characteristics • SP-B and SP-C increase adsorption of DPPC and other phospholipids to air-water interface & facilitate re-spreading on successive cycles • SP-B is essential for normal surfactant function • SP-D has probable metabolic role

  13. SURFACTANT RE-UTILIZATION • 95 % lecithin • 80% phosphotidylglycerol • -newborn more efficient than adult

  14. Evolution of Exogenous Surfactant Replacement Therapy IRDS=RDS=HMD=SDS

  15. Evolution of Exogenous Surfactant Replacement Therapy • 1950’s • Surfactants demonstrated in mammalian lung; deficiency implicated in pathophysiology of respiratory distress syndrome (RDS) • 1960’s • Clinical studies of surfactant replacement unsuccessful due to misconception that dipalmitoylphosphatidylcholine (DPPC) equivalent to natural lung surfactant

  16. Evolution of Exogenous Surfactant Replacement Therapy (cont.) • 1970’s • Instillation of natural surfactant containing lipids and proteins prolonged animal survival. • 1980’s • Exogenous surfactants reduced severity of SDS in premature infants. • 1990’s • Exogenous surfactants credited for decline in infant mortality.

  17. SURFACTANTS AVAILABLE • Human • Synthetic • Animal lung extract • Combination of CLE and synthetic

  18. SURVANTA (Beractant) Studies • Definitions Prevention – Prophylactic administration within first 15 minutes of life to infants at risk Rescue – Administration within 8 hours of birth, after a definitive diagnosis of SDS

  19. SURVANTA (Beractant) StudiesClinical design: Multiple-Dose • First Dose – (Prevention) Within 15 minutes of birth (Rescue) Within 8 hours of birth: with SDS Repeat doses- (Prevention) If SDS has developed, intubated, and FiO2 > 30% (Rescue) If intubated, FiO2 > 30% (Prevention) Up to 4 doses in 48 hours (Rescue) Up to 4 doses in 48 hours

  20. SURVANTA (Beractant) Dosage • 100 mg phospholipids/kg birthweight (4ml/kg) • Up to 4 doses in first 48 hours of life • Doses 6 or more hours apart

  21. EFFECTS OF SURFACTANT • Rapid improvement of lung compliance • Rapid improvement of oxygenation • May have transient bradycardia

  22. SURFACTANT REPLACEMENT 19% DECLINE IN EXPECTED MORTALITY LOWER RATE OF PNEUMOTHORAX Also: Lower rate of PIE Lower rate of IVH

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