Evolving blood pressure dynamics for extremely preterm infants

OBJECTIVE: To examine changes in arterial blood pressure (ABP) after birth in extremely preterm infants. STUDY DESIGN: Prospective observational study of infants 23(0/7) – 26(6/7) weeks gestational age (GA). Antihypotensive therapy use and ABP measurements were recorded for the first 24 hours. RESULTS: A cohort of 367 infants had 18,709 ABP measurements recorded. ABP decreased for the first three hours, reached a nadir at 4 – 5 hours, then increased at an average rate of 0.2 mmHg / hour. The rise in ABP from hour 4 – 24 was similar for untreated infants (n=164) and infants given any antihypotensive therapy (n=203), a fluid bolus (n=135), or dopamine (n=92). GA specific trends were similar. ABP tended to be lower as GA decreased, but varied widely at each GA. CONCLUSION: Arterial blood pressure increased spontaneously over the first 24 postnatal hours for extremely preterm infants. The rate of rise in ABP did not change with antihypotensive therapy.