Cerebral blood flow velocity changes after rapid administration of surfactant

A computer linked Doppler system was used to make continuous measurements of cerebral blood flow velocity (CBFV) from the middle cerebral artery, mean arterial blood pressure (MAP) from the umbilical artery, and heart rate before, during, and for 20 minutes after the endotracheal administration of 200 mg/kg of porcine surfactant in 10 preterm infants with respiratory distress syndrome. Within two minutes of surfactant administration, there was a median fall of 6 mm Hg (15%) fall in MAP and 36% in CBFV. There was a change in the Doppler spectra with almost complete loss of diastolic velocities. A rapid reduction in pulmonary vascular resistance with consequent left to right ductal shunting is one possible cause. These acute changes in MAP and CBFV after bolus surfactant administration may increase the risk of intraventricular haemorrhage.