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Severe PPHN in paediatric patients

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"persistent pulmonary hypertension of the newborn" AND treatment

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severe persistent pulmonary hypertension newborn management guidelines 2025

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persistent pulmonary hypertension of the newborn right-to-left shunt echocardiogram diagram

Severe Persistent Pulmonary Hypertension of the Newborn (PPHN)

What it is

PPHN is failure of the normal postnatal fall in pulmonary vascular resistance (PVR), so PVR stays at or returns to systemic/suprasystemic levels after birth. This keeps the ductus arteriosus and foramen ovale open, producing right-to-left shunting that bypasses the lungs - sometimes called "persistent fetal circulation" (Barash, Cullen, and Stoelting's Clinical Anesthesia, 9e, p. 3578).

Etiology and risk factors

Most commonly seen in term or post-term infants, those delivered by cesarean section, and neonates with fetal distress/low Apgar scores. Precipitating causes include:
  • Severe birth asphyxia, meconium aspiration syndrome, sepsis/pneumonia
  • Congenital diaphragmatic hernia (CDH) and other causes of pulmonary hypoplasia (renal agenesis)
  • Hyperviscosity syndrome (polycythemia)
  • In utero ductal constriction from maternal NSAID use
  • Maternal diabetes, maternal asthma
  • Often idiopathic
(The Harriet Lane Handbook, 23rd ed., p. 651; Barash, p. 3578)

Diagnostic features

PPHN typically presents within 12-24 hours of birth with:
  • Severe hypoxemia (PaO2 <35-45 mmHg in 100% O2) that is disproportionate to the degree of radiographic lung disease
  • A structurally normal heart with right-to-left shunting at the foramen ovale and/or ductus arteriosus
  • A significant pre-/postductal oxygen saturation gradient (≥7-15 mmHg)
  • It is critical to rule out cyanotic congenital heart disease: if oxygenation does not improve with supplemental O2, do a detailed cardiac exam, hyperoxia test, and echocardiogram
(Harriet Lane Handbook, p. 651-652)
Severity is graded using the Oxygenation Index (OI): OI = (Mean airway pressure × FiO2 × 100) / PaO2
An OI ≥15-25 signals significant disease requiring escalation of vasodilator therapy; severe PPHN is generally defined by OI >25-40 or refractory hypoxemia, and is the threshold used for ECMO consideration.

Management of severe PPHN

1. General supportive care
  • Correct predisposing/reversible factors: hypoglycemia, hypothermia, polycythemia, acidosis
  • Minimize handling/noxious stimuli; sedation (occasionally paralysis) in intubated infants
  • Maintain systemic blood pressure and perfusion with volume expansion and/or inotropes to reverse right-to-left shunting
  • Optimize oxygen-carrying capacity (transfusion as indicated)
  • Avoid severe hyperventilation/hypocarbia (PCO2 <30 mmHg) - risks myocardial ischemia, reduced cerebral blood flow, barotrauma, and chronic lung disease; gentle ventilation with adequate lung recruitment is preferred, with high-frequency ventilation and exogenous surfactant as adjuncts
  • Goal: PaO2 60-100 mmHg, normocapnia, preductal SpO2 typically 92-97% (some protocols target 93-98% in severe disease with acidosis/hypothermia)
2. Pulmonary vasodilator therapy
  • Inhaled nitric oxide (iNO) - the only FDA-approved agent for PPHN. Typical starting dose 20 ppm (lower, ~10 ppm, may suffice in preterm infants); little added benefit above 40 ppm. Watch for methemoglobinemia and NO2 toxicity. Response should be assessed within 30-60 minutes of initiation, and iNO should be started only with preserved LV systolic function - if severe LV dysfunction is found on echo after starting, iNO should be discontinued (per 2025 multidisciplinary consensus recommendations).
  • Sildenafil (PDE5 inhibitor) - increasing use, particularly where iNO is unavailable or as a weaning adjunct
  • Prostacyclin analogs (e.g., epoprostenol) - inhaled or IV
  • Bosentan (endothelin receptor antagonist) and milrinone - used as adjuvant therapy in refractory cases, though evidence is more limited
  • Point-of-care echocardiography is increasingly used to guide therapy and assess RV/LV function
3. Extracorporeal membrane oxygenation (ECMO) Reserved for severe cardiovascular instability or refractory hypoxemia:
  • OI >40 sustained for >3 hours, or
  • Alveolar-arterial O2 gradient ≥610 for 8 hours
  • Candidates typically need to be >2000 g and >34 weeks gestation
  • Obtain head ultrasound (± EEG) before cannulation to screen for intracranial hemorrhage
  • Meconium aspiration is the most common indication for neonatal ECMO and carries the highest survival among indications
(Harriet Lane Handbook, p. 652; Barash, p. 3578-3579; Sabiston Textbook of Surgery)

Prognosis

Survival correlates directly with successful correction of the underlying cause and the degree to which therapy lowers PVR. Ischemic encephalopathy and other hypoxic complications are major adverse prognostic factors. Maintaining right ventricular function is considered paramount to survival.

Recent evidence (worth flagging alongside textbook guidance)

A 2025 multidisciplinary consensus (CHOP) reinforces iNO at 20 ppm as first-line with the LV-function caveat above. A 2024 network meta-analysis comparing PPHN treatments and a 2024 systematic review of ECMO outcomes in PPHN are available for deeper reading if needed:
  • Fei Q et al. "Comparison of Different Treatments of PPHN: A Systematic Review and Network Meta-Analysis," Crit Care Med 2024 (PMID: 38363176)
  • Alhumaid S et al. "International treatment outcomes of neonates on ECMO with PPHN: a systematic review," J Cardiothorac Surg 2024 (PMID: 39182148)
  • Gao N et al. "Bosentan in the treatment of PPHN: a systematic review and meta-analysis," Cardiol Young 2024 (PMID: 38329072)
These don't contradict the textbook approach but add current comparative-effectiveness data on adjuvant vasodilators (sildenafil, bosentan, milrinone) beyond iNO monotherapy - useful if you're managing a case refractory to first-line iNO/ECMO criteria.
Let me know if you want me to go deeper into any specific piece - e.g., ECMO cannulation criteria and technique, the CDH-specific PPHN pathway, or a comparison of the vasodilator agents with dosing.
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