Blood pressure increase preceded spontaneous and paracetamol-induced, early ductal closure in very preterm infants

To investigate the blood pressure (BP) and ductal calibre patterns associated with early ductal closure in very low gestational age (<32 weeks) infants.

Blood pressure was continuously measured intra-arterially among 43 infants participating in a randomised, double-blind trial of 4 days prophylactic intravenous paracetamol. Early closure of the ductus was verified by daily ultrasound examinations. The BP recordings, before and after the verified ductal closure, were examined and compared to control infants without ductal closure. In the 24-h preceding the ultrasound-verified ductal closure, periods of increased BP were searched and identified as suggestive ductal closure time points. In control infants without ductal closure, BP trends were examined during the corresponding age.

Mean arterial BP increased significantly before ductal closure (p < 0.001) and stayed higher than in the control group. Mean BP during the 8 h preceding closure significantly predicted the ductal closure [OR 2.094 (95% CI 1.209-3.630), p = 0.008], and multiple potential confounders failed to abolish this association. A linear decrease pattern in ductal calibre was significantly associated with the ductal closure.

Blood pressure increased and stabilised before the early ductal closure, offering potential implications on treatment strategies of very premature infants.