Persistent pulmonary hypertension in neonates with perinatal asphyxia and therapeutic hypothermia: a frequent and perilous combination.

(1) To investigate whether neonates with perinatal asphyxia and therapeutic hypothermia more often developed PPHN compared to a control group with perinatal asphyxia not treated with hypothermia; (2) To identify risk factors for severe PPHN during hypothermia and evaluate short-term outcome. This single-center retrospective cohort study included (near-)term neonates with perinatal asphyxia admitted between 2004 and 2016. Neonates with perinatal asphyxia and hypothermia were compared to a historical control group without hypothermia. Primary outcome was PPHN, defined as severe hypoxemia requiring mechanical ventilation and inhaled nitric oxide, confirmed by echocardiography. Short-term adverse outcome was defined as mortality within one month and/or severe brain injury on MRI. Incidence of PPHN was 23% (26/114) in the hypothermia group and 11% (8/70) in controls. In multivariate analysis, PPHN was 2.5 times more common among neonates with hypothermia. Neonates developing PPHN during hypothermia often had higher fraction of inspired oxygen at baseline. PPHN was not associated with a higher risk of severe brain injury. However, early mortality was higher and three infants died due to severe refractory PPHN during hypothermia. In this study PPHN occurred more often since the introduction of therapeutic hypothermia. This was usually reversible and did not lead to overall increased adverse outcome. However, in individual cases with PPHN deterioration occurred rapidly. In such cases the benefits of hypothermia should be weighed against the risk of a complicated, fatal course.