Effect of doxapram on cerebral blood flow velocity in preterm infants.

BACKGROUND: Doxapram is used to treat apnea of prematurity when there is an insufficient response to methylxanthine treatment. As an unwanted side effect, reduced cerebral perfusion has been seen in methylxanthine-treated infants while effects of doxapram on the cerebral perfusion have not been studied yet.

PATIENTS AND METHODS: Fifteen preterm infants treated with doxapram were included in the study. Birth weight ranged from 380 g to 1150 g (median 740 g), gestational age from 24 to 27 weeks (median 26 weeks). Infants received a doxapram loading dose (2.5 mg/kg) over a 30-minute period, followed by a continuous infusion of 0.5 mg/kg/h. Using Doppler sonography, blood flow velocities and the resistance index were measured in the anterior cerebral artery. Measurements were performed at baseline and 30 and 120 minutes after the start of doxapram.

RESULTS: Maximal systolic blood flow velocity (V(max)) decreased significantly after the infants had received the loading dose (V(max) baseline: 40.7 cm/s +/- 6.9 [mean +/- SD]; V(max) 30 min: 35 cm/s +/- 8.9; p = 0.0017) but returned to near baseline values at 120 min (38.5 +/- 9.0, p = 0.22). End-diastolic, time-averaged, and time-averaged maximal velocities did not change significantly at 30 or 120 min.

CONCLUSIONS: Doxapram induced a significant decrease in maximal cerebral blood flow velocity. Further studies are needed to assess whether this decrease may be critical to cerebral white matter perfusion in the vulnerable preterm infant.