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Persistent Pulmonary Hypertension (PPHN)

Persistent Pulmonary Hypertension (PPHN). F. Hazel R. Villa, MD PL1. Objectives. to review the fetal,transitional and postnatal circulation in relation to PPHN To understand the pathophysiology of PPHN as it applies to clinical manifestations and management. VASOCONSTRICTORS

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Persistent Pulmonary Hypertension (PPHN)

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  1. Persistent Pulmonary Hypertension (PPHN) F. Hazel R. Villa, MD PL1

  2. Objectives • to review the fetal,transitional and postnatal circulation in relation to PPHN • To understand the pathophysiology of PPHN as it applies to clinical manifestations and management

  3. VASOCONSTRICTORS (Maintain high fetal PVR) Norepinephrine A-adrenergic stimulation Hypoxia Endothelin Thromboxanes Leukotrienes Platelet activating factor PGF2a VASODILATORS (Decrease PVR during transition) PGI2, PGD2, PGE2 Nitric oxide Cyclic GMP Cyclic AMP Oxygen Adenosine Bradykinin Pulmonary vessels

  4. Fetal circulation

  5. Fetal circulation • pO2, PGI2, NO • ADMA -- competes with arginine inhibit NOS • Vasoconstriction

  6. Postnatal circulation

  7. Transitional circulation

  8. Transitional to postnatal • At birth • increase in NO, NOS- cGMP increase guanylate cyclase- cGMP increase in PGI2 (effect of estrogen) cAMP DDAH metabolizes ADMA • Vasodilatation

  9. Transitional to postnatal • At birth ventilation increase pulmonary blood flow Oxygenation

  10. Transitional to postnatal • Oxygen- stimulates NOS, COX1 • Pulmonary blood flow- release of NO, PGI2 • Evidence: NO-cGMP pathway is a more potent modulator of pulmonary vascular tone

  11. Increase in SVR • Removal of the placenta • Catecholamine associated with birth • Cold environment

  12. Postnatal decrease in PVR • Expansion of the lung • Adequate ventilation, oxygenation • Clearance of fetal lung fluid

  13. 3 types of abnormalities • Maladaptation • Maldevelopment • Underdevelopment

  14. Maladaptation • Prototype: Meconium aspiration pneumonia • Pneumonia, RDS • Obstruction of the airways • Chemical pneumonitis • Release of endothelin,thromboxane vasoconstrictors

  15. Maldevelopment • Prototype: Idiopathic PPHN • (“black lung” PPHN) • Vessel wall thickening • Smooth muscle hyperplasia • Cause – intrauterine exposure to NSAID • constriction of ductus arteriosus • genetic

  16. Maldevelopment • Disruption of NO-cGMP pathway • Disruption of PGI2-cAMP pathway • Guanylate cyclase is less active • Increased ROS (reactive oxygen species) vasoconstrictor • Increased thromboxane, endothelin

  17. Underdevelopment • Prototype: Congenital diaphragmatic hernia • Pulmonary hypoplasia • Decreased cross sectional area of pulmonary vasculature • Decreased pulmonary blood flow • Abnormal muscular hypertrophy of the pulm arterioles

  18. Clinical signs and symptoms • PE: • meconium staining • Prominent precordial impulse • Narrow split accentuated P2 • Systolic murmur LLSB

  19. Labs • CXR: CDH, decreased vascular markings, parenchymal disease • ECG: RV predominance, ST elevation • ABG: hyperoxic test (pO2 < 100 at 100% O2) • Pre and postductal ABG (R radial artery: umbilical artery/lower extremity) • 10-15% saturation and or 10-15mmHg pO2

  20. Labs • Echocardiography • Structural heart disease is determined • R-L shunting (Ductus or FO) • Pulmonary arterial pressure is measured

  21. Management • Oxygen 100% pO2 should be kept between 50-90mmHg (O2 saturation >90%) • Correct factors promoting vasoconstriction: hypoglycemia, hypocalcemia, anemia, hypovolemia • Optimize cardiac function (inotropic agents, volume expansion • Mechanical ventilation • Surfactant

  22. Management • Inhaled Nitric oxide- an ideal selective pulmonary vasodilator • OI of >25 • OI=(MAP x FiO2)/pO2 x 100 • Contraindications: CHD which are PDA dependent • (aortic stenosis, interrupted aortic arch, hypolastic heart syndrome) • May worsen pulmonary edema in obstructed TAPVR Used to transport patient for ECMO

  23. Management • ECMO • Goal of this treatment: • maintain adequate tissue oxygenation and • avoid irreversible lung injury, while PVR decreases and correcting pulm HTN • ECMO if OI is >40

  24. Other Pulmonary Vasodilators • Sildenafil- PDE5 inhibitor increased cGMP • Milrinone- PDE3 inhibitor increased cAMP • Inhaled PGI2 • Superoxide dismutase-superoxide scavenger • Dilates pulm vessels, and increase endogenous NO

  25. References • http://neoreviews.aappublications.org/cgi/content/full/8/1/e14 • http://www.utdol.com/utd/content/topic.do?topicKey=neonatol/1427&view=print • www.emedicine.com/ped/topic2530.htm • www.emedicine.com/PED/topic2530.htm • phassociation.org/medical/.../Summer_2006/persistent_ph_newborn.pdf

  26. Thank you!

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