An infant receiving supplemental oxygen has SpO₂ 95% and PaO₂ 68 mm Hg but hemoglobin 7.2 g/dL, weak pulses, capillary refill of 5 seconds, and a rising lactate. Which physiologic problem is most consistent with these findings?

A 28-week infant has immediate respiratory distress and a low-volume granular radiograph. Which additional finding would most strongly increase concern for congenital pneumonia rather than uncomplicated RDS?

A term infant has a weak, hoarse cry and recurrent coughing with desaturation during feeds. Which disorder should be prioritized?

Which physiologic effect is the primary reason caffeine is used to treat apnea of prematurity?

Which outcome best demonstrates a therapeutic response to caffeine?

A 27-week infant with RDS is receiving conventional pressure-controlled ventilation. FiO₂ rises from 0.30 to 0.48. Breath sounds are symmetric, chest rise is modest, PaCO₂ remains within target, and the chest radiograph shows low lung volumes. Which adjustment most directly treats the oxygenation problem?

An infant with echocardiogram-confirmed PPHN has optimized lung volume, iNO, and physiology-directed hemodynamic support. Over 2 hours, OI rises from 24 to 34, lactate increases, and urine output falls. Which action is most appropriate?

A newborn with early, prolonged oligohydramnios has a small chest, persistent hypoxemia, pulmonary hypertension, and limited recruitment despite higher inflation pressures. Which diagnosis best explains this pattern?

A patient with Type A blood accidentally receives a transfusion of Type B erythrocytes. Why can this transfusion produce a dangerous reaction?

As the ventricles continue to relax, ventricular pressure eventually falls below atrial pressure. What happens next?