A term newborn (38 weeks, male) delivered vaginally after meconium-stained amniotic fluid is noted to have tachypnea (RR 68/min), grunting, and intercostal retractions within 2 hours of birth. Oxygen saturation is 88% on room air. Chest X-ray shows patchy infiltrates with hyperinflation and a barrel-shaped chest. The infant is alert and feeding attempts are normal. What is the most appropriate immediate next step in management?