oxygen or ventilator pressures that can injure the lung. Hyperventilation can also have
adverse effects on cerebral perfusion and induces hearing loss (blood supply to cochlea
is part of cerebral circulation).
Initial treatment:
- Treat metabolic derangements: correct hypoglycemia, hypocalcemia, hypothermia and
metabolic acidosis as they can aggravate PPHN - Optimize lung recruitment: mechanical ventilation, use high frequency oscillator as
indicated, surfactant treatment for parenchymal lung disease. Optimize cardiac output
and left ventricular function: ensure optimal preload with volume expansion, use
inotropic agents, vasopressors
Pulmonary vasodilators: Inhaled nitric oxide (INO) is the primary agent used in PPHN.
INO causes selective pulmonary vasodilation when administered directly into the lungs.
INO has been shown to decrease the use of ECMO/mortality in RCT. INO can also be
safely given through CPAP or nasal cannula. INO is started at a dose of 20 parts per
million (PPM); higher doses don’t improve the response rate and increase the risk of
methemoglobin (MetHb) formation. 70% of hypoxic neonates with PPHN show a
positive response (increase in PaO2 by at least 20 torr). Once the baby is stable, wean
FiO2 and ventilator pressures. INO can be weaned every 6- 12 hours once ventilator
settings are at a reasonable level. The weaning algorithm is 20- 10 - 5 - 4 - 3 - 2 - 1 - 0.5PPM
and then off. MetHb level should be checked at 24 and 48 hours after starting INO and