Persistent fetal circulation/pulmonary hypertension can be triggered by which condition in the newborn?

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Persistent fetal circulation, now called persistent pulmonary hypertension of the newborn, happens when the normal drop in pulmonary vascular resistance after birth fails to occur. That keeps blood flowing through fetal pathways and causes severe hypoxemia because the lungs aren’t adequately perfused and oxygenated. Anything that increases pulmonary vasoconstriction or worsens oxygenation can trigger this condition. Acidosis promotes pulmonary vasoconstriction, and when hypothermia causes metabolic acidosis, it pushes the pulmonary vessels to stay constricted. That keeps the high resistance state and preserves the fetal circulation pattern. So acidosis from hypothermia directly contributes to triggering persistent pulmonary hypertension. In contrast, high oxygen tends to relieve the condition, while hypoglycemia or disturbances like hyperkalemia don’t directly provoke the pulmonary vasoconstriction central to this issue.