Effect of patency of the ductus arteriosus on blood pressure in very preterm infants.

Forty one preterm infants (birth weight < 1500 g) were studied by daily Doppler echocardiography for the first week of life to examine the effect of a haemodynamically significant ductus arteriosus (HSDA) on systemic blood pressure. Hourly records of blood pressure were averaged for each infant to produce a 24 hour mean value and the infants were then allocated to groups according to whether, by echocardiographic criteria, there was a HSDA on that day. In infants from 1000 to 1500 g the differences in all parameters of blood pressure between those with and without a HSDA were not significant. In infants < 1000 g the mean blood pressure was significantly less in the infants with a HSDA throughout the first week of life. Systolic blood pressure was reduced by as much as diastolic blood pressure and as a result the pulse pressure did not differ. Infants < 1000 g with a HSDA were given more plasma and a greater number received inotropic support. Gestational age, respiratory disease severity, and complication rates did not differ between those with and without a HSDA. The possibility of a clinically silent HSDA should be considered before large amounts of plasma volume expanders are given to treat hypotension in infants < 1000 g.