Pulmonary hypertension in extremely low birth weight infants: Characteristics and outcomes

Background: To determine the characteristics and outcomes of pulmonary arterial hypertension (PAH) in extremely low birth weight (ELBW) infants. Methods: A retrospective case-control study of all ELBW infants admitted to a level III neonatal intensive care unit (NICU) between January 1, 2003 and December 31, 2010. Results: During the study period, 450 ELBW infants were admitted. 6.4% (29/450) were diagnosed with PAH and were matched to 26 controls. The mean gestational age of infants with PAH and their controls were similar [24.5±1.3 vs. 24.9±1.8 weeks (P=0.26)]; however the cases were smaller at birth than were controls [640.7±119.5 vs. 727.0±184.5 g (P=0.04)]. The diagnosis of PAH was made at a mean postnatal age of 131.8±53.7 days. Infants with PAH had a higher rate of intrauterine exposure to illicit maternal drug use [12/29 (41%) vs. 1/25 (4%); P=0.001], a longer duration of initial mechanical ventilation [74.9±28.3 vs. 59.1±27.8 days; P=0.04)], a higher incidence of severe BPD [23/29 (79%) vs. 13/26 (50%); P=0.02], and a greater NICU mortality rate [12/29 (41%) vs. 4/26 (15%); P=0.04]. Conclusion: PAH in ELBW infants is associated with maternal illicit drug use in pregnancy, longer exposure to mechanical ventilation, severe bronchopulmonary dysplasia and a significant increase in early mortality.