Final answer:
For an infant with persistent pulmonary hypertension receiving mechanical ventilatory support, initiating inhaled nitric oxide is the recommended treatment to improve pulmonary blood flow and oxygenation, as preductal SPO2 levels are already sufficient (option c).
Step-by-step explanation:
An infant with persistent pulmonary hypertension (PPHN), already intubated and receiving mechanical ventilatory support, showing presaturation oxygen levels (preductal SPO2) ranging from 95% to 98%, indicates that oxygenation is currently sufficient. However, the primary concern in PPHN is to improve pulmonary blood flow and reduce pulmonary artery pressures, which would enhance oxygenation and gas exchange.
The recommended treatment would be initiating inhaled nitric oxide (iNO), which is a potent vasodilator specifically effective within the lungs. It helps to relax smooth muscle cells within the pulmonary vessels, reducing pulmonary vascular resistance and aiding in the treatment of PPHN. This selective pulmonary vasodilation can improve ventilation-perfusion (V/Q) mismatch and oxygenation without causing systemic hypotension.
Other treatments such as increasing FiO2 are only considered when preductal SPO2 levels are low, and surfactant administration is usually considered for RDS due to surfactant deficiency, while decreasing PEEP might be harmful if the alveolar recruitment is needed. Therefore, iNO would be the most appropriate intervention to consider for an infant with PPHN in this scenario.
Hence, the answer is option c.