Persistent Pulmonary Hypertension in the Newborn

CAUSES

• persistent foetal circulation (PFC): failure of conversion, non-closure of ductus arteriosus or foramen ovale
• respiratory event + hypoxia: meconium aspiration, pneumonia, congenital lung hypoplasia, diaphragmatic hernia
• sepsis -> acidosis -> prevents closure of the ductus arteriosus: group B Strep, endotoxin
• haematological: hyperviscosity syndrome

DIAGNOSIS

• shock
• septic screen
• CXR: often normal
• ECHO: no LV or congenital lesion, RV or RA dilation, TR, shunt from PDA or PFO
• hyperoxia test: sampling of right radial artery and umbilical artery catheter in high O2 (cardiac lesion = no differential between samples, PPHN = > 20% difference in SaO2, right radial > UAC from right to left shunt)

MANAGEMENT

• transfer to PICU
• airway control – intubation is mandatory
• ventilation to normalise pCO2 and adequate oxygenation
• circulatory management: IVF boluses 10-20mL/kg up to 60mL/kg, achieve adequate cardiac filling volumes and pressure, prostaglandin infusion until echocardiographic evidence of a duct-independent lesion, dobutamine infusion for fluid-refractory shock
• normoglycaemia
• remove treat and control cause of sepsis: panculture, empiric antibiotic therapy (ampicillin/gentamicin/acyclovir)
• correct acidosis
• if evidence of fluid and vasopressor refractory shock with RV dysfunction and PPHN on echo with ScvO2 <70% commence salvage therapy

SALVAGE THERAPY

• pulmonary vasodilation: iNO, inhaled or infused prostaglandin
• ECMO: refractory PPHN to iNO

PROGNOSIS

• recovers over 3-5 days
• normal tone and musculature of pulmonary artery occurs
• good long term cardiovascular and survival if isolated

Further reading

• Wiesbauer F. Hypertension. Medmastery