Hypertensive peaks in the pathogenesis of intraventricular hemorrhage in the newborn. Abolition by phenobarbitone sedation.

Mean arterial blood pressure (MABP) was measured continuously for 3 to 5 days after birth in 27 premature infants with a birth weight under 1500 g, and who required umbilical artery catheterisation. All had respiratory distress syndrome (RDS). Intraventricular hemorrhage (IVH) occurred in 9 infants (33%), diagnosed by computered tomography (CT). IVH was more common in infants of lower gestational age, in infants delivered vaginally and in infants with perinatal asphyxia. Variable increases in MABP over the resting value occurred in all infants associated with increases in both active and passive motor activity. In 6 infant pairs matched for birth weight, gestational age, mode of delivery and severity of perinatal asphyxia, the infants who developed IVH had higher peak MABP valued compared to matched controls. Resting and minimum MABP values were not different in the two groups. We conclude that the large increases in arterial blood pressure which occur with both spontaneous motor activity and in association with nursing procedures, are an important cause of development of IVH in very low birth weight infants. An example is given to show that pressure peaks can be abolished by phenobarbitone sedation.