1. Good Morning and Welcome Applicants!
January 27, 2011

2. Pulmonary HTN Pulmonary Artery Pressure =
L atrial pressure + (pulm flow x pulm vascular resis)
Any increase can lead to pulm HTN

3. Pulmonary HTN Progressive Pulmonary artery pressure Untreated
>25 mm Hg
Untreated
RV unable to support circulation
Prognosis determined by reversibility of underlying process

4. PPHN Most common cause of PHTN in the newborn
0.2% of newborns
Usually associated with respiratory conditions
Elevated pulm vasc resistance
Right to left shunting
Foramen ovale
Ductus arteriosis
Significant hypoxemia
Idiopathic

5. Highly vascular placenta serves as the organ for gas exchange and contributes to a lowered fetal systemic arterial pressure
Therefore, since the lungs are not needed for gas exchange, the pulmonary vessels are constricted, making pulmonary and systemic pressures nearly equal % of the cardiac output is going to bypass the lungs
At birth, the PAP decreases to 50% of systemic artery pressure and pulmonary blood flow increases almost tenfold. Changes in pressure are due to increased arterial pH, oxygen tension, the physical pulling open on capillaries accompanied by lung inflation, local endogenous vasoregulatory mediators including NO, and removal of the low-resistance placenta.
Should have the greatest decline over the first 24 hours and falls over first 2 postnatal weeks.

6. Many processes interrupt the normal transition and result in PPHN
Maladaption – normal pulmonary arterial number and muscularization but have a disruption in the decrease in the PVR normally seen
-perinatal asphyxia, sepsis, PNA, MAS, acidosis
- imbalance of local vasodilatory and vasoconstrictor metabolites
Other – chronic in utero hypoxia – increase and extension of medial muscle thickness,
obstruction accompanying polycythemia or TAPVR
decrease in the number of pulmonary arteries (pulmonary hypoplasia, CDH, oligohydramnios)

7. PPHN Presentation Profound and labile hypoxemia
Out of proportion to parenchymal disease
Birth or gradual changes
Cyanosis
Grunting
Flaring
Retractions
Tachypnea
Tachycardia
Shock

8. PPHN Wide variety of severity Hypoxemia and acidosis
Normal perfusion to shock
Hypoxemia and acidosis
Further constricts the pulmonary vessels increasing the PH and creating a cycle

9. PPHN Shunting PDA Pre and post ductal PaO2 gradient of >20 mmHg
O2 saturation gradient of >5%

10. PPHN X-rays Underlying illness Clear Diminished vascular markings
Slightly dilated heart
Idiopathic

11. PPHN Echo Must exclude cyanotic heart disease
R to L shunting across foramen ovale or ductus arteriosis
Deviation of the atrial septum
Ventricular septum
Right atrial enlargement
Tricuspid regurgitation

12. PPHN Treatment Underlying disturbances Minimal Stimulation
Hypoglycemia
Hypocalcemia
Polycythemia
Hypothermia
Minimal Stimulation
Calcium

13. PPHN Treatment Increase systemic resistance
Volume
Inotropic
Decrease R to L shunt
Decrease pulmonary vascular resistance
Oxygen
iNO
iNO is reduced by hemoglobin so there is almost no systemic vasodilatory effects

14. PPHN Treatment Mechanical ventilation High-frequency ventilation
Sedation
Surfactant
ECMO
Adequate oxygenation using the lowest possible mean airway pressures and PEEPs, 100% O2 with slow wean

15. PPHN Outcomes 95% Meconium aspiration
50% Congenital diaphragmatic hernia
Neurodevelopmental impairment
Neurosensory hearing loss
Behavioral problems
Respiratory difficulties
Most likely due to the underlying condition and severity
Parenchymal disease has the best prognosis, maldevelopment has the worst, overall 70-75%
80% of infants will be normal