Pulmonary hypertension in newborn infants: pathophysiology, clinical assessment and management

Abstract Clinically significant pulmonary hypertension (PH) affects up to 1 in 2000 infants after birth and is a major contributor to morbidity and mortality globally in newborn populations. Pulmonary hypertension is a component of many different neonatal diseases and can present a significant treatment challenge in both acute and chronic stages. PH is most commonly due to elevated pulmonary vascular resistance (PVR). This may be caused by structural and functional changes in the pulmonary vasculature, which may be combined with left, right or bi-ventricular dysfunction. Elevated PVR is frequently present from birth due to failure of the normal transition from fetal to extra-uterine environments, giving rise to the classic presentation of persistent pulmonary hypertension of the newborn (PPHN). Regardless of aetiology, the hallmarks of clinically significant PH are hypoxaemic right-to-left shunting, and cardiac dysfunction resulting in systemic cyanosis, hypotension and acidosis. Assessment of these informs targeted treatment aimed at optimising PVR and a supporting cardiac function. In this review we aim to provide an overview of the underlying pathophysiological concepts in PH, and use this to guide practical clinical management in all infants with PH. Based on the latest available evidence we discuss assessment of the severity of PH, and a structured, targeted approach to clinical management, acknowledging areas of uncertainty and controversy.