Persistent pulmonary hypertension (PPH) Flashcards
Define
Occurs when pulmonary vascular resistance remains abnormally elevated after birth, resulting in right-to-left shunting of blood through the foetal circulatory pathways
Aetiology
Life-threatening
Usually associated with:
* Birth asphyxia
* Meconium aspiration
* Septicaemia
* RDS
It can also occur as a primary disorder
Normally, there is a progressive fall in PVR with a rise in SVR after birth which results in the increase in pulmonary blood flow and oxygen uptake in the lung. PPHN occurs if factors interfere with this process.
Occurs in term or late preterm infants ≥ 34 weeks
THREE types of abnormalities of the pulmonary vasculature:
* Underdevelopment
* Maldevelopment
* Maladaptation
Presentation
IU or perinatal asphyxia- foetal bradycardia or tachycardia, meconium staining
Respiratory distress within first 24 hours of life- tachypnoea, retractions, grunting
May have difference in pre- and post-ductal saturations
Cyanosis occurs soon after birth
NOTE: heart murmurs and signs of heart failure are often ABSENT
Investigation
Examination
Basic observations- pulse oximetry: difference between pre- and post-ductal saturations (> 10%)
Blood gases
Apgar score- low
CXR- normal but there may be some pulmonary oligaemia
An urgent echocardiogram- DIAGNOSTIC(excludes congenital heart disease and identifies the signs of pulmonary hypertension e.g. raised pulmonary pressures and tricuspid regurgitation)
Management
Supportive cardiorespiratory care
* Supplemental oxygen
* Mechanical ventilation NOTE: high-frequency oscillatory ventilation may be useful
* Fluid therapy and inotropic agents for circulatory support
* Correction of acidosis
In severe cases or those to fail to respond to supportive measures:
* Vasodilatory agents: Inhaled nitric oxide (iNO)
* Extracorporeal membrane oxygen (ECMO) : This is where the infant is placed on heart and lung bypass for several days
If still do not respond despite iNO and ECMO:
Other vasodilators: Sildenafil (Viagra)
Complications
Complications
ECMO can cause increased risk of developmental delay, motor disability, hearing deficits, chronic health problems
Death
Prognosis
Depends on severity
