Persistent Pulmonary Hypertension of the Newborn: A Practical Review for UK Level 2 Local Neonatal Units.

In persistent pulmonary hypertension of the newborn (PPHN), pulmonary vascular resistance fails to fall after birth, resulting in right-to-left shunting and hypoxemia out of proportion to the underlying lung disease. Inhaled nitric oxide (iNO) is generally provided by tertiary neonatal intensive care units and neonatal transport teams, while extracorporeal membrane oxygenation (ECMO) is confined to a small number of designated centers. Most affected infants are therefore first recognized and stabilized in a level 2 local neonatal unit, which can provide intubation, ventilation, arterial access, and circulatory support but does not routinely provide iNO or ECMO. This narrative review provides a descriptive synthesis of current guidance rather than a systematic evidence synthesis. It focuses on what a level 2 team can do during the first one to two hours and while awaiting the transport team. It draws on four publicly available UK guidelines, produced by two regional neonatal networks, an NHS trust, and a neonatal transport service, alongside international guidance, neonatal transport literature, and underlying trial evidence. The four are appraised against the domains of the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument. None reports a search strategy, grades its recommendations, or declares a conflict of interest, so all four are treated here as consensus documents rather than evidence-based guidelines. The review addresses recognition and the pre- to post-ductal saturation gap, accurate calculation of the oxygenation index in both millimeters of mercury and kilopascals, ventilation and lung volume, oxygenation, carbon dioxide and pH, circulation and metabolic control, sedation, and escalation and transfer. Five escalation decisions are distinguished: contacting the neonatal transport service, discussing the infant with the ECMO center, determining the transfer destination, assessing ECMO eligibility, and initiating ECMO. The level 2 unit is responsible for recognition, stabilization, and contacting the transport service. The discussion with the ECMO center and the choice of destination are led by the transport service and the tertiary unit, and ECMO eligibility and initiation are decisions for the receiving ECMO center. The oxygenation index prompting contact with the ECMO center is therefore not an ECMO initiation criterion. The review also identifies that the numerical ECMO initiation threshold commonly attributed to the Extracorporeal Life Support Organization derives from a 2017 supplement rather than the current guideline, which states the criterion without a number. The four differ across six clinically relevant thresholds, while UK practice diverges from international recommendations most clearly over sildenafil. The review concludes with recommendations for locally agreed thresholds, reliable oxygenation-index calculation, training and imaging access, and shared audit and research. Effective early management depends on timely recognition, optimization of lung and systemic physiology, accurate severity assessment, and early communication with the transport and tertiary teams, all of which lie within the capability of a level 2 unit.