Persistent Pulmonary Hypertension of the Newborn ✅ Flashcards
Under normal circumstances, what happens to pulmonary vascular resistance after birth?
It falls rapidly
What happens if pulmonary vascular resistance does not fall rapidly after birth?
PPHN ensues
What effect does PPHN have on circulation?
It leads to a variable degree of right-to-left shunt of blood through the foramen ovale and ductus arteriosus.
There is also intrapulmonary shunting.
What does right-to-left shunting of blood through the foramen ovale and ductus arteriosus result in?
Severe hypoxaemia
What can produce a similar clinical picture to PPHN?
- Decreased systemic vascular resistance
- Any condition in which the PVR:SVR ratio is more than 1
When might PVR be ‘appropriately’ elevated?
As a result of an appropriate response to an underlying acute pathological state, e.g. pneumothorax or pneumonia
What are the categories of conditions that can cause increased pulmonary vascular resistance?
- Normal pulmonary vascular morphology
- Abnormal pulmonary vascular morphology
Give 4 causes of increased pulmonary vascular resistance with normal pulmonary vascular morphology?
- Asphyxia
- Meconium aspiration syndrome
- Parenchymal lung disease
- Sepsis/pneumonia
Give 4 causes of increased pulmonary vascular resistance with abnormal morphology of pulmonary vasculature
- Pulmonary hypoplasia
- Congenital diaphragmatic hernia
- Congenital pulmonary airway malformations
- Structurally abnormal heart disease
Give 2 examples of structural heart disease that can cause increased pulmonary vascular resistance?
- Left ventricular outflow tract obstruction
- Anomalous pulmonary venous drainage
What non-structural factors can impact pulmonary vascular reactivity and pressure?
- Hypoxia
- Hypercarbia
- Acidosis
How do hypoxia, hypercarbia, and acidosis affect pulmonary vascular reactivity and pressure?
They cause vasoconstriction and elevate pulmonary artery pressure
What effect might hypoxia, hypercarbia, and acidosis have on the circulation of a newborn?
Their presence may lead to failure of adaptation from fetal to neonatal (adult type) circulation
What are the differential diagnoses of persistent hyperaemia in the term/near term infant?
- Primary lung disease
- Cyanotic congenital heart disease
- PPHN, with or without lung disease
What is echocardiography useful for when evaluating persistent hyperaemia in a term/near-term infant?
- Confirming presence of PPHN
- Identifying congenital heart disease
