Risk factors and prognosis of bronchopulmonary dysplasia associated pulmonary hypertension in preterm infants

Abstract

Objective: To analyze clinical features, prognosis and risk factors of bronchopulmonary dysplasia (BPD) associated pulmonary hypertension (PH). Methods: Clinical data of 338 infants with BPD were collected from the neonatal intensive care unit (NICU) in Shenzhen Maternity and Child Healthcare Hospital, Southern Medical University between January 2016 and December 2018. These infants were divided into PH group and non-PH group. The clinical features and prognosis were compared between these two groups by Chi-square test or nonparametric test. Risk factors for BPD-PH were analyzed with binary logistic regression model. Results: Among the 338 BPD infants, 314 had no PH (92.9%) and 24 had PH (7.1%), with an average gestational age of (27.1±1.8) weeks, and 206 were males and 132 females.PH infants had younger gestational age ((26.4±2.1) vs. (27.2±1.7) weeks, t=2.201, P=0.028) and lower birth weight ((798±255) vs. (1 003±240) g, t=4.030, P<0.01), compared to non-PH infants. Besides, duration of mechanical ventilation and non-invasive positive pressure ventilation were higher in PH group than that in non-PH group (14.3 (2.1, 43.7) vs. 0.5 (0, 4.7) d, Z=-4.553, P<0.01; 30.0 (22.5, 64.2) vs. 15.0 (7.0, 26.0) d, Z=-4.838, P<0.01). The proportions of maternal hypertension, small for gestational age (SGA), late onset sepsis, ventilator associated pneumonia, hemodynamically significant patent ductus arteriosus (hsPDA), patent ductus arteriosus (PDA) requiring ligation, severe BPD and severe extrauterine growth retardation (EUGR) were higher in PH group than those in non-PH group ((20.8% (5/24) vs. 6.4% (20/314), 33.3% (8/24) vs. 7.6% (24/314), 54.2% (13/24) vs. 7.3% (23/314), 25.0% (6/24) vs. 6.1% (19/314), 75.0% (18/24) vs. 39.2% (123/314), 45.8% (11/24) vs. 1.9% (6/314), 66.7% (16/24) vs. 7.3% (23/314), 75.0% (18/24) vs. 45.5% (143/314), all P<0.05). Multivariate logistic regression analysis showed that maternal hypertension (OR=12.950, 95%CI: 1.740-96.385), severe bronchopulmonary dysplasia (OR=10.160, 95%CI: 2.725-37.884), SGA (OR=4.992, 95%CI: 1.432-16.920), PDA requiring ligation (OR=19.802, 95%CI: 3.297-118.921), severe EUGR (OR=20.316, 95%CI: 2.221-185.853) were independent risk factors of BPD associated PH. In the 24 infants with PH, all 7 mild PH infants and 8 moderate PH infants survived, while 4 out of 9 severe PH infants died. Among the survivors, the longest duration of oxygen therapy was up to the corrected gestational age of 1 year and 2 months. Conclusions: PH is a severe complication of BPD, and associated with higher mortality and poor prognosis. Echocardiography screening and regular post-discharge follow up are recommended for BPD infants with risk factors of PH.